ASP.NET Core SignalR configuration
JSON/MessagePack serialization options
ASP.NET Core SignalR supports two protocols for encoding messages: JSON and MessagePack. Each protocol has serialization configuration options.
JSON serialization can be configured on the server using the AddJsonProtocol extension method. AddJsonProtocol
can be added after AddSignalR in Startup.ConfigureServices
. The AddJsonProtocol
method takes a delegate that receives an options
object. The PayloadSerializerOptions property on that object is a System.Text.Json
JsonSerializerOptions object that can be used to configure serialization of arguments and return values. For more information, see the System.Text.Json documentation.
For example, to configure the serializer to not change the casing of property names, rather than the default camel case names, use the following code in Program.cs
:
builder.Services.AddSignalR()
.AddJsonProtocol(options => {
options.PayloadSerializerOptions.PropertyNamingPolicy = null;
});
In the .NET client, the same AddJsonProtocol
extension method exists on HubConnectionBuilder. The Microsoft.Extensions.DependencyInjection
namespace must be imported to resolve the extension method:
// At the top of the file:
using Microsoft.Extensions.DependencyInjection;
// When constructing your connection:
var connection = new HubConnectionBuilder()
.AddJsonProtocol(options => {
options.PayloadSerializerOptions.PropertyNamingPolicy = null;
})
.Build();
Note
It's not possible to configure JSON serialization in the JavaScript client at this time.
Switch to Newtonsoft.Json
If you need features of Newtonsoft.Json
that aren't supported in System.Text.Json
, see Switch to Newtonsoft.Json
.
MessagePack serialization options
MessagePack serialization can be configured by providing a delegate to the AddMessagePackProtocol call. See MessagePack in SignalR for more details.
Note
It's not possible to configure MessagePack serialization in the JavaScript client at this time.
Configure server options
The following table describes options for configuring SignalR hubs:
Option | Default Value | Description |
---|---|---|
ClientTimeoutInterval |
30 seconds | The server considers the client disconnected if it hasn't received a message (including keep-alive) in this interval. It could take longer than this timeout interval for the client to be marked disconnected due to how this is implemented. The recommended value is double the KeepAliveInterval value. |
HandshakeTimeout |
15 seconds | If the client doesn't send an initial handshake message within this time interval, the connection is closed. This is an advanced setting that should only be modified if handshake timeout errors are occurring due to severe network latency. For more detail on the handshake process, see the SignalR Hub Protocol Specification. |
KeepAliveInterval |
15 seconds | If the server hasn't sent a message within this interval, a ping message is sent automatically to keep the connection open. When changing KeepAliveInterval , change the ServerTimeout or serverTimeoutInMilliseconds setting on the client. The recommended ServerTimeout or serverTimeoutInMilliseconds value is double the KeepAliveInterval value. |
SupportedProtocols |
All installed protocols | Protocols supported by this hub. By default, all protocols registered on the server are allowed. Protocols can be removed from this list to disable specific protocols for individual hubs. |
EnableDetailedErrors |
false |
If true , detailed exception messages are returned to clients when an exception is thrown in a Hub method. The default is false because these exception messages can contain sensitive information. |
StreamBufferCapacity |
10 |
The maximum number of items that can be buffered for client upload streams. If this limit is reached, the processing of invocations is blocked until the server processes stream items. |
MaximumReceiveMessageSize |
32 KB | Maximum size of a single incoming hub message. Increasing the value might increase the risk of Denial of service (DoS) attacks. |
MaximumParallelInvocationsPerClient |
1 | The maximum number of hub methods that each client can call in parallel before queueing. |
DisableImplicitFromServicesParameters |
false |
Hub method arguments are resolved from DI if possible. |
Options can be configured for all hubs by providing an options delegate to the AddSignalR
call in Program.cs
.
builder.Services.AddSignalR(hubOptions =>
{
hubOptions.EnableDetailedErrors = true;
hubOptions.KeepAliveInterval = TimeSpan.FromMinutes(1);
});
Options for a single hub override the global options provided in AddSignalR
and can be configured using AddHubOptions:
builder.Services.AddSignalR().AddHubOptions<ChatHub>(options =>
{
options.EnableDetailedErrors = true;
});
Advanced HTTP configuration options
Use HttpConnectionDispatcherOptions
to configure advanced settings related to transports and memory buffer management. These options are configured by passing a delegate to MapHub in Program.cs
.
using Microsoft.AspNetCore.Http.Connections;
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddRazorPages();
builder.Services.AddSignalR();
var app = builder.Build();
if (!app.Environment.IsDevelopment())
{
app.UseExceptionHandler("/Error");
app.UseHsts();
}
app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();
app.UseAuthorization();
app.MapRazorPages();
app.MapHub<ChatHub>("/chathub", options =>
{
options.Transports =
HttpTransportType.WebSockets |
HttpTransportType.LongPolling;
}
);
app.Run();
The following table describes options for configuring ASP.NET Core SignalR's advanced HTTP options:
Option | Default Value | Description |
---|---|---|
ApplicationMaxBufferSize |
64 KB | The maximum number of bytes received from the client that the server buffers before applying backpressure. Increasing this value allows the server to receive larger messages faster without applying backpressure, but can increase memory consumption. |
TransportMaxBufferSize |
64 KB | The maximum number of bytes sent by the app that the server buffers before observing backpressure. Increasing this value allows the server to buffer larger messages faster without awaiting backpressure, but can increase memory consumption. |
AuthorizationData |
Data automatically gathered from the Authorize attributes applied to the Hub class. |
A list of IAuthorizeData objects used to determine if a client is authorized to connect to the hub. |
Transports |
All Transports are enabled. | A bit flags enum of HttpTransportType values that can restrict the transports a client can use to connect. |
LongPolling |
See below. | Additional options specific to the Long Polling transport. |
WebSockets |
See below. | Additional options specific to the WebSockets transport. |
MinimumProtocolVersion |
0 | Specify the minimum version of the negotiate protocol. This is used to limit clients to newer versions. |
CloseOnAuthenticationExpiration |
false | Set this option to enable authentication expiration tracking, which will close connections when a token expires. |
The Long Polling transport has additional options that can be configured using the LongPolling
property:
Option | Default Value | Description |
---|---|---|
PollTimeout |
90 seconds | The maximum amount of time the server waits for a message to send to the client before terminating a single poll request. Decreasing this value causes the client to issue new poll requests more frequently. |
The WebSocket transport has additional options that can be configured using the WebSockets
property:
Option | Default Value | Description |
---|---|---|
CloseTimeout |
5 seconds | After the server closes, if the client fails to close within this time interval, the connection is terminated. |
SubProtocolSelector |
null |
A delegate that can be used to set the Sec-WebSocket-Protocol header to a custom value. The delegate receives the values requested by the client as input and is expected to return the desired value. |
Configure client options
Client options can be configured on the HubConnectionBuilder
type (available in the .NET and JavaScript clients). It's also available in the Java client, but the HttpHubConnectionBuilder
subclass is what contains the builder configuration options, as well as on the HubConnection
itself.
Configure logging
Logging is configured in the .NET Client using the ConfigureLogging
method. Logging providers and filters can be registered in the same way as they are on the server. See the Logging in ASP.NET Core documentation for more information.
Note
In order to register Logging providers, you must install the necessary packages. See the Built-in logging providers section of the docs for a full list.
For example, to enable Console logging, install the Microsoft.Extensions.Logging.Console
NuGet package. Call the AddConsole
extension method:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub")
.ConfigureLogging(logging => {
logging.SetMinimumLevel(LogLevel.Information);
logging.AddConsole();
})
.Build();
In the JavaScript client, a similar configureLogging
method exists. Provide a LogLevel
value indicating the minimum level of log messages to produce. Logs are written to the browser console window.
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub")
.configureLogging(signalR.LogLevel.Information)
.build();
Instead of a LogLevel
value, you can also provide a string
value representing a log level name. This is useful when configuring SignalR logging in environments where you don't have access to the LogLevel
constants.
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub")
.configureLogging("warn")
.build();
The following table lists the available log levels. The value you provide to configureLogging
sets the minimum log level that will be logged. Messages logged at this level, or the levels listed after it in the table, will be logged.
String | LogLevel |
---|---|
trace |
LogLevel.Trace |
debug |
LogLevel.Debug |
info or information |
LogLevel.Information |
warn or warning |
LogLevel.Warning |
error |
LogLevel.Error |
critical |
LogLevel.Critical |
none |
LogLevel.None |
Note
To disable logging entirely, specify signalR.LogLevel.None
in the configureLogging
method.
For more information on logging, see the SignalR Diagnostics documentation.
The SignalR Java client uses the SLF4J library for logging. It's a high-level logging API that allows users of the library to choose their own specific logging implementation by bringing in a specific logging dependency. The following code snippet shows how to use java.util.logging
with the SignalR Java client.
implementation 'org.slf4j:slf4j-jdk14:1.7.25'
If you don't configure logging in your dependencies, SLF4J loads a default no-operation logger with the following warning message:
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
This can safely be ignored.
Configure allowed transports
The transports used by SignalR can be configured in the WithUrl
call (withUrl
in JavaScript). A bitwise-OR of the values of HttpTransportType
can be used to restrict the client to only use the specified transports. All transports are enabled by default.
For example, to disable the Server-Sent Events transport, but allow WebSockets and Long Polling connections:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", HttpTransportType.WebSockets | HttpTransportType.LongPolling)
.Build();
In the JavaScript client, transports are configured by setting the transport
field on the options object provided to withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", { transport: signalR.HttpTransportType.WebSockets | signalR.HttpTransportType.LongPolling })
.build();
In this version of the Java client websockets is the only available transport.
In the Java client, the transport is selected with the withTransport
method on the HttpHubConnectionBuilder
. The Java client defaults to using the WebSockets transport.
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withTransport(TransportEnum.WEBSOCKETS)
.build();
Note
The SignalR Java client doesn't support transport fallback yet.
Configure bearer authentication
To provide authentication data along with SignalR requests, use the AccessTokenProvider
option (accessTokenFactory
in JavaScript) to specify a function that returns the desired access token. In the .NET Client, this access token is passed in as an HTTP "Bearer Authentication" token (Using the Authorization
header with a type of Bearer
). In the JavaScript client, the access token is used as a Bearer token, except in a few cases where browser APIs restrict the ability to apply headers (specifically, in Server-Sent Events and WebSockets requests). In these cases, the access token is provided as a query string value access_token
.
In the .NET client, the AccessTokenProvider
option can be specified using the options delegate in WithUrl
:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", options => {
options.AccessTokenProvider = async () => {
// Get and return the access token.
};
})
.Build();
In the JavaScript client, the access token is configured by setting the accessTokenFactory
field on the options object in withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", {
accessTokenFactory: () => {
// Get and return the access token.
// This function can return a JavaScript Promise if asynchronous
// logic is required to retrieve the access token.
}
})
.build();
In the SignalR Java client, you can configure a bearer token to use for authentication by providing an access token factory to the HttpHubConnectionBuilder. Use withAccessTokenFactory to provide an RxJava Single<String>. With a call to Single.defer, you can write logic to produce access tokens for your client.
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withAccessTokenProvider(Single.defer(() -> {
// Your logic here.
return Single.just("An Access Token");
})).build();
Configure timeout and keep-alive options
Additional options for configuring timeout and keep-alive behavior:
Option | Default value | Description |
---|---|---|
WithServerTimeout |
30 seconds (30,000 milliseconds) | Timeout for server activity and is set directly on HubConnectionBuilder. If the server hasn't sent a message in this interval, the client considers the server disconnected and triggers the Closed event (onclose in JavaScript). This value must be large enough for a ping message to be sent from the server and received by the client within the timeout interval. The recommended value is a number at least double the server's keep-alive interval (WithKeepAliveInterval ) value to allow time for pings to arrive. |
HandshakeTimeout |
15 seconds | Timeout for initial server handshake and is available on the HubConnection object itself. If the server doesn't send a handshake response in this interval, the client cancels the handshake and triggers the Closed event (onclose in JavaScript). This is an advanced setting that should only be modified if handshake timeout errors are occurring due to severe network latency. For more detail on the handshake process, see the SignalR Hub Protocol Specification. |
WithKeepAliveInterval |
15 seconds | Determines the interval at which the client sends ping messages and is set directly on HubConnectionBuilder. This setting allows the server to detect hard disconnects, such as when a client unplugs their computer from the network. Sending any message from the client resets the timer to the start of the interval. If the client hasn't sent a message in the ClientTimeoutInterval set on the server, the server considers the client disconnected. |
In the .NET Client, timeout values are specified as TimeSpan
values.
The following example shows values that are double the default values:
var builder = new HubConnectionBuilder()
.WithUrl(Navigation.ToAbsoluteUri("/chathub"))
.WithServerTimeout(TimeSpan.FromSeconds(60))
.WithKeepAliveInterval(TimeSpan.FromSeconds(30))
.Build();
builder.On<string, string>("ReceiveMessage", (user, message) => ...
await builder.StartAsync();
Configure stateful reconnect
SignalR stateful reconnect reduces the perceived downtime of clients that have a temporary disconnect in their network connection, such as when switching network connections or a short temporary loss in access.
Stateful reconnect achieves this by:
- Temporarily buffering data on the server and client.
- Acknowledging messages received (ACK-ing) by both the server and client.
- Recognizing when a connection is up and replaying messages that might have been sent while the connection was down.
Stateful reconnect is available in ASP.NET Core 8.0 and later.
Opt in to stateful reconnect at both the server hub endpoint and the client:
Update the server hub endpoint configuration to enable the
AllowStatefulReconnects
option:app.MapHub<MyHub>("/hubName", options => { options.AllowStatefulReconnects = true; });
Optionally, the maximum buffer size in bytes allowed by the server can be set globally or for a specific hub with the
StatefulReconnectBufferSize
option:The
StatefulReconnectBufferSize
option set globally:builder.AddSignalR(o => o.StatefulReconnectBufferSize = 1000);
The
StatefulReconnectBufferSize
option set for a specific hub:builder.AddSignalR().AddHubOptions<MyHub>(o => o.StatefulReconnectBufferSize = 1000);
The
StatefulReconnectBufferSize
option is optional with a default of 100,000 bytes.Update JavaScript or TypeScript client code to enable the
withStatefulReconnect
option:const builder = new signalR.HubConnectionBuilder() .withUrl("/hubname") .withStatefulReconnect({ bufferSize: 1000 }); // Optional, defaults to 100,000 const connection = builder.build();
The
bufferSize
option is optional with a default of 100,000 bytes.Update .NET client code to enable the
WithStatefulReconnect
option:var builder = new HubConnectionBuilder() .WithUrl("<hub url>") .WithStatefulReconnect(); builder.Services.Configure<HubConnectionOptions>(o => o.StatefulReconnectBufferSize = 1000); var hubConnection = builder.Build();
The
StatefulReconnectBufferSize
option is optional with a default of 100,000 bytes.
Configure additional options
Additional options can be configured in the WithUrl
(withUrl
in JavaScript) method on HubConnectionBuilder
or on the various configuration APIs on the HttpHubConnectionBuilder
in the Java client:
.NET Option | Default value | Description |
---|---|---|
AccessTokenProvider |
null |
A function returning a string that is provided as a Bearer authentication token in HTTP requests. |
SkipNegotiation |
false |
Set this to true to skip the negotiation step. Only supported when the WebSockets transport is the only enabled transport. This setting can't be enabled when using the Azure SignalR Service. |
ClientCertificates |
Empty | A collection of TLS certificates to send to authenticate requests. |
Cookies |
Empty | A collection of HTTP cookies to send with every HTTP request. |
Credentials |
Empty | Credentials to send with every HTTP request. |
CloseTimeout |
5 seconds | WebSockets only. The maximum amount of time the client waits after closing for the server to acknowledge the close request. If the server doesn't acknowledge the close within this time, the client disconnects. |
Headers |
Empty | A Map of additional HTTP headers to send with every HTTP request. |
HttpMessageHandlerFactory |
null |
A delegate that can be used to configure or replace the HttpMessageHandler used to send HTTP requests. Not used for WebSocket connections. This delegate must return a non-null value, and it receives the default value as a parameter. Either modify settings on that default value and return it, or return a new HttpMessageHandler instance. When replacing the handler make sure to copy the settings you want to keep from the provided handler, otherwise, the configured options (such as Cookies and Headers) won't apply to the new handler. |
Proxy |
null |
An HTTP proxy to use when sending HTTP requests. |
UseDefaultCredentials |
false |
Set this boolean to send the default credentials for HTTP and WebSockets requests. This enables the use of Windows authentication. |
WebSocketConfiguration |
null |
A delegate that can be used to configure additional WebSocket options. Receives an instance of ClientWebSocketOptions that can be used to configure the options. |
ApplicationMaxBufferSize |
1 MB | The maximum number of bytes received from the server that the client buffers before applying backpressure. Increasing this value allows the client to receive larger messages faster without applying backpressure, but can increase memory consumption. |
TransportMaxBufferSize |
1 MB | The maximum number of bytes sent by the user application that the client buffers before observing backpressure. Increasing this value allows the client to buffer larger messages faster without awaiting backpressure, but can increase memory consumption. |
In the .NET Client, these options can be modified by the options delegate provided to WithUrl
:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", options => {
options.Headers["Foo"] = "Bar";
options.SkipNegotiation = true;
options.Transports = HttpTransportType.WebSockets;
options.Cookies.Add(new Cookie(/* ... */);
options.ClientCertificates.Add(/* ... */);
})
.Build();
In the JavaScript Client, these options can be provided in a JavaScript object provided to withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", {
// "Foo: Bar" will not be sent with WebSockets or Server-Sent Events requests
headers: { "Foo": "Bar" },
transport: signalR.HttpTransportType.LongPolling
})
.build();
In the Java client, these options can be configured with the methods on the HttpHubConnectionBuilder
returned from the HubConnectionBuilder.create("HUB URL")
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withHeader("Foo", "Bar")
.shouldSkipNegotiate(true)
.withHandshakeResponseTimeout(30*1000)
.build();
Additional resources
JSON/MessagePack serialization options
ASP.NET Core SignalR supports two protocols for encoding messages: JSON and MessagePack. Each protocol has serialization configuration options.
JSON serialization can be configured on the server using the AddJsonProtocol extension method, which can be added after AddSignalR in your Startup.ConfigureServices
method. The AddJsonProtocol
method takes a delegate that receives an options
object. The PayloadSerializerSettings property on that object is a Json.NET JsonSerializerSettings
object that can be used to configure serialization of arguments and return values. For more information, see the Json.NET documentation.
For example, to configure the serializer to use "PascalCase" property names, rather than the default camel case names, use the following code in Startup.ConfigureServices
:
services.AddSignalR()
.AddJsonProtocol(options => {
options.PayloadSerializerSettings.ContractResolver =
new DefaultContractResolver();
});
In the .NET client, the same AddJsonProtocol
extension method exists on HubConnectionBuilder. The Microsoft.Extensions.DependencyInjection
namespace must be imported to resolve the extension method:
// At the top of the file:
using Microsoft.Extensions.DependencyInjection;
// When constructing your connection:
var connection = new HubConnectionBuilder()
.AddJsonProtocol(options => {
options.PayloadSerializerSettings.ContractResolver =
new DefaultContractResolver();
})
.Build();
Note
It's not possible to configure JSON serialization in the JavaScript client at this time.
MessagePack serialization options
MessagePack serialization can be configured by providing a delegate to the AddMessagePackProtocol call. See MessagePack in SignalR for more details.
Note
It's not possible to configure MessagePack serialization in the JavaScript client at this time.
Configure server options
The following table describes options for configuring SignalR hubs:
Option | Default Value | Description |
---|---|---|
HandshakeTimeout |
15 seconds | If the client doesn't send an initial handshake message within this time interval, the connection is closed. This is an advanced setting that should only be modified if handshake timeout errors are occurring due to severe network latency. For more detail on the handshake process, see the SignalR Hub Protocol Specification. |
KeepAliveInterval |
15 seconds | If the server hasn't sent a message within this interval, a ping message is sent automatically to keep the connection open. When changing KeepAliveInterval , change the ServerTimeout or serverTimeoutInMilliseconds setting on the client. The recommended ServerTimeout or serverTimeoutInMilliseconds value is double the KeepAliveInterval value. |
SupportedProtocols |
All installed protocols | Protocols supported by this hub. By default, all protocols registered on the server are allowed. Protocols can be removed from this list to disable specific protocols for individual hubs. |
EnableDetailedErrors |
false |
If true , detailed exception messages are returned to clients when an exception is thrown in a Hub method. The default is false because these exception messages can contain sensitive information. |
Options can be configured for all hubs by providing an options delegate to the AddSignalR
call in Startup.ConfigureServices
.
public void ConfigureServices(IServiceCollection services)
{
services.AddSignalR(hubOptions =>
{
hubOptions.EnableDetailedErrors = true;
hubOptions.KeepAliveInterval = TimeSpan.FromMinutes(1);
});
}
Options for a single hub override the global options provided in AddSignalR
and can be configured using AddHubOptions:
services.AddSignalR().AddHubOptions<ChatHub>(options =>
{
options.EnableDetailedErrors = true;
});
Advanced HTTP configuration options
Use HttpConnectionDispatcherOptions
to configure advanced settings related to transports and memory buffer management. These options are configured by passing a delegate to MapHub in Startup.Configure
.
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
app.UseSignalR((configure) =>
{
var desiredTransports =
HttpTransportType.WebSockets |
HttpTransportType.LongPolling;
configure.MapHub<ChatHub>("/chathub", (options) =>
{
options.Transports = desiredTransports;
});
});
}
The following table describes options for configuring ASP.NET Core SignalR's advanced HTTP options:
Option | Default Value | Description |
---|---|---|
ApplicationMaxBufferSize |
32 KB | The maximum number of bytes received from the client that the server buffers. Increasing this value allows the server to receive larger messages, but can negatively impact memory consumption. |
AuthorizationData |
Data automatically gathered from the Authorize attributes applied to the Hub class. |
A list of IAuthorizeData objects used to determine if a client is authorized to connect to the hub. |
TransportMaxBufferSize |
32 KB | The maximum number of bytes sent by the app that the server buffers. Increasing this value allows the server to send larger messages, but can negatively impact memory consumption. |
Transports |
All Transports are enabled. | A bit flags enum of HttpTransportType values that can restrict the transports a client can use to connect. |
LongPolling |
See below. | Additional options specific to the Long Polling transport. |
WebSockets |
See below. | Additional options specific to the WebSockets transport. |
The Long Polling transport has additional options that can be configured using the LongPolling
property:
Option | Default Value | Description |
---|---|---|
PollTimeout |
90 seconds | The maximum amount of time the server waits for a message to send to the client before terminating a single poll request. Decreasing this value causes the client to issue new poll requests more frequently. |
The WebSocket transport has additional options that can be configured using the WebSockets
property:
Option | Default Value | Description |
---|---|---|
CloseTimeout |
5 seconds | After the server closes, if the client fails to close within this time interval, the connection is terminated. |
SubProtocolSelector |
null |
A delegate that can be used to set the Sec-WebSocket-Protocol header to a custom value. The delegate receives the values requested by the client as input and is expected to return the desired value. |
Configure client options
Client options can be configured on the HubConnectionBuilder
type (available in the .NET and JavaScript clients). It's also available in the Java client, but the HttpHubConnectionBuilder
subclass is what contains the builder configuration options, as well as on the HubConnection
itself.
Configure logging
Logging is configured in the .NET Client using the ConfigureLogging
method. Logging providers and filters can be registered in the same way as they are on the server. See the Logging in ASP.NET Core documentation for more information.
Note
In order to register Logging providers, you must install the necessary packages. See the Built-in logging providers section of the docs for a full list.
For example, to enable Console logging, install the Microsoft.Extensions.Logging.Console
NuGet package. Call the AddConsole
extension method:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub")
.ConfigureLogging(logging => {
logging.SetMinimumLevel(LogLevel.Information);
logging.AddConsole();
})
.Build();
In the JavaScript client, a similar configureLogging
method exists. Provide a LogLevel
value indicating the minimum level of log messages to produce. Logs are written to the browser console window.
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub")
.configureLogging(signalR.LogLevel.Information)
.build();
Note
To disable logging entirely, specify signalR.LogLevel.None
in the configureLogging
method.
For more information on logging, see the SignalR Diagnostics documentation.
The SignalR Java client uses the SLF4J library for logging. It's a high-level logging API that allows users of the library to choose their own specific logging implementation by bringing in a specific logging dependency. The following code snippet shows how to use java.util.logging
with the SignalR Java client.
implementation 'org.slf4j:slf4j-jdk14:1.7.25'
If you don't configure logging in your dependencies, SLF4J loads a default no-operation logger with the following warning message:
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
This can safely be ignored.
Configure allowed transports
The transports used by SignalR can be configured in the WithUrl
call (withUrl
in JavaScript). A bitwise-OR of the values of HttpTransportType
can be used to restrict the client to only use the specified transports. All transports are enabled by default.
For example, to disable the Server-Sent Events transport, but allow WebSockets and Long Polling connections:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", HttpTransportType.WebSockets | HttpTransportType.LongPolling)
.Build();
In the JavaScript client, transports are configured by setting the transport
field on the options object provided to withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", { transport: signalR.HttpTransportType.WebSockets | signalR.HttpTransportType.LongPolling })
.build();
Configure bearer authentication
To provide authentication data along with SignalR requests, use the AccessTokenProvider
option (accessTokenFactory
in JavaScript) to specify a function that returns the desired access token. In the .NET Client, this access token is passed in as an HTTP "Bearer Authentication" token (Using the Authorization
header with a type of Bearer
). In the JavaScript client, the access token is used as a Bearer token, except in a few cases where browser APIs restrict the ability to apply headers (specifically, in Server-Sent Events and WebSockets requests). In these cases, the access token is provided as a query string value access_token
.
In the .NET client, the AccessTokenProvider
option can be specified using the options delegate in WithUrl
:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", options => {
options.AccessTokenProvider = async () => {
// Get and return the access token.
};
})
.Build();
In the JavaScript client, the access token is configured by setting the accessTokenFactory
field on the options object in withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", {
accessTokenFactory: () => {
// Get and return the access token.
// This function can return a JavaScript Promise if asynchronous
// logic is required to retrieve the access token.
}
})
.build();
In the SignalR Java client, you can configure a bearer token to use for authentication by providing an access token factory to the HttpHubConnectionBuilder. Use withAccessTokenFactory to provide an RxJava Single<String>. With a call to Single.defer, you can write logic to produce access tokens for your client.
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withAccessTokenProvider(Single.defer(() -> {
// Your logic here.
return Single.just("An Access Token");
})).build();
Configure timeout and keep-alive options
Additional options for configuring timeout and keep-alive behavior are available on the HubConnection
object itself:
Option | Default value | Description |
---|---|---|
ServerTimeout |
30 seconds (30,000 milliseconds) | Timeout for server activity. If the server hasn't sent a message in this interval, the client considers the server disconnected and triggers the Closed event (onclose in JavaScript). This value must be large enough for a ping message to be sent from the server and received by the client within the timeout interval. The recommended value is a number at least double the server's KeepAliveInterval value to allow time for pings to arrive. |
HandshakeTimeout |
15 seconds | Timeout for initial server handshake. If the server doesn't send a handshake response in this interval, the client cancels the handshake and triggers the Closed event (onclose in JavaScript). This is an advanced setting that should only be modified if handshake timeout errors are occurring due to severe network latency. For more detail on the handshake process, see the SignalR Hub Protocol Specification. |
In the .NET Client, timeout values are specified as TimeSpan
values.
Configure additional options
Additional options can be configured in the WithUrl
(withUrl
in JavaScript) method on HubConnectionBuilder
or on the various configuration APIs on the HttpHubConnectionBuilder
in the Java client:
.NET Option | Default value | Description |
---|---|---|
AccessTokenProvider |
null |
A function returning a string that is provided as a Bearer authentication token in HTTP requests. |
SkipNegotiation |
false |
Set this to true to skip the negotiation step. Only supported when the WebSockets transport is the only enabled transport. This setting can't be enabled when using the Azure SignalR Service. |
ClientCertificates |
Empty | A collection of TLS certificates to send to authenticate requests. |
Cookies |
Empty | A collection of HTTP cookies to send with every HTTP request. |
Credentials |
Empty | Credentials to send with every HTTP request. |
CloseTimeout |
5 seconds | WebSockets only. The maximum amount of time the client waits after closing for the server to acknowledge the close request. If the server doesn't acknowledge the close within this time, the client disconnects. |
Headers |
Empty | A Map of additional HTTP headers to send with every HTTP request. |
HttpMessageHandlerFactory |
null |
A delegate that can be used to configure or replace the HttpMessageHandler used to send HTTP requests. Not used for WebSocket connections. This delegate must return a non-null value, and it receives the default value as a parameter. Either modify settings on that default value and return it, or return a new HttpMessageHandler instance. When replacing the handler make sure to copy the settings you want to keep from the provided handler, otherwise, the configured options (such as Cookies and Headers) won't apply to the new handler. |
Proxy |
null |
An HTTP proxy to use when sending HTTP requests. |
UseDefaultCredentials |
false |
Set this boolean to send the default credentials for HTTP and WebSockets requests. This enables the use of Windows authentication. |
WebSocketConfiguration |
null |
A delegate that can be used to configure additional WebSocket options. Receives an instance of ClientWebSocketOptions that can be used to configure the options. |
In the .NET Client, these options can be modified by the options delegate provided to WithUrl
:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", options => {
options.Headers["Foo"] = "Bar";
options.Cookies.Add(new Cookie(/* ... */);
options.ClientCertificates.Add(/* ... */);
})
.Build();
In the JavaScript Client, these options can be provided in a JavaScript object provided to withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", {
skipNegotiation: true,
transport: signalR.HttpTransportType.WebSockets
})
.build();
In the Java client, these options can be configured with the methods on the HttpHubConnectionBuilder
returned from the HubConnectionBuilder.create("HUB URL")
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withHeader("Foo", "Bar")
.shouldSkipNegotiate(true)
.withHandshakeResponseTimeout(30*1000)
.build();
Additional resources
JSON/MessagePack serialization options
ASP.NET Core SignalR supports two protocols for encoding messages: JSON and MessagePack. Each protocol has serialization configuration options.
JSON serialization can be configured on the server using the AddJsonProtocol extension method, which can be added after AddSignalR in your Startup.ConfigureServices
method. The AddJsonProtocol
method takes a delegate that receives an options
object. The PayloadSerializerSettings property on that object is a Json.NET JsonSerializerSettings
object that can be used to configure serialization of arguments and return values. For more information, see the Json.NET documentation.
For example, to configure the serializer to use "PascalCase" property names, rather than the default camel case names, use the following code in Startup.ConfigureServices
:
services.AddSignalR()
.AddJsonProtocol(options => {
options.PayloadSerializerSettings.ContractResolver =
new DefaultContractResolver();
});
In the .NET client, the same AddJsonProtocol
extension method exists on HubConnectionBuilder. The Microsoft.Extensions.DependencyInjection
namespace must be imported to resolve the extension method:
// At the top of the file:
using Microsoft.Extensions.DependencyInjection;
// When constructing your connection:
var connection = new HubConnectionBuilder()
.AddJsonProtocol(options => {
options.PayloadSerializerSettings.ContractResolver =
new DefaultContractResolver();
})
.Build();
Note
It's not possible to configure JSON serialization in the JavaScript client at this time.
MessagePack serialization options
MessagePack serialization can be configured by providing a delegate to the AddMessagePackProtocol call. See MessagePack in SignalR for more details.
Note
It's not possible to configure MessagePack serialization in the JavaScript client at this time.
Configure server options
The following table describes options for configuring SignalR hubs:
Option | Default Value | Description |
---|---|---|
ClientTimeoutInterval |
30 seconds | The server considers the client disconnected if it hasn't received a message (including keep-alive) in this interval. It could take longer than this timeout interval for the client to be marked disconnected due to how this is implemented. The recommended value is double the KeepAliveInterval value. |
HandshakeTimeout |
15 seconds | If the client doesn't send an initial handshake message within this time interval, the connection is closed. This is an advanced setting that should only be modified if handshake timeout errors are occurring due to severe network latency. For more detail on the handshake process, see the SignalR Hub Protocol Specification. |
KeepAliveInterval |
15 seconds | If the server hasn't sent a message within this interval, a ping message is sent automatically to keep the connection open. When changing KeepAliveInterval , change the ServerTimeout or serverTimeoutInMilliseconds setting on the client. The recommended ServerTimeout or serverTimeoutInMilliseconds value is double the KeepAliveInterval value. |
SupportedProtocols |
All installed protocols | Protocols supported by this hub. By default, all protocols registered on the server are allowed. Protocols can be removed from this list to disable specific protocols for individual hubs. |
EnableDetailedErrors |
false |
If true , detailed exception messages are returned to clients when an exception is thrown in a Hub method. The default is false because these exception messages can contain sensitive information. |
Options can be configured for all hubs by providing an options delegate to the AddSignalR
call in Startup.ConfigureServices
.
public void ConfigureServices(IServiceCollection services)
{
services.AddSignalR(hubOptions =>
{
hubOptions.EnableDetailedErrors = true;
hubOptions.KeepAliveInterval = TimeSpan.FromMinutes(1);
});
}
Options for a single hub override the global options provided in AddSignalR
and can be configured using AddHubOptions:
services.AddSignalR().AddHubOptions<ChatHub>(options =>
{
options.EnableDetailedErrors = true;
});
Advanced HTTP configuration options
Use HttpConnectionDispatcherOptions
to configure advanced settings related to transports and memory buffer management. These options are configured by passing a delegate to MapHub in Startup.Configure
.
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
app.UseSignalR((configure) =>
{
var desiredTransports =
HttpTransportType.WebSockets |
HttpTransportType.LongPolling;
configure.MapHub<ChatHub>("/chathub", (options) =>
{
options.Transports = desiredTransports;
});
});
}
The following table describes options for configuring ASP.NET Core SignalR's advanced HTTP options:
Option | Default Value | Description |
---|---|---|
ApplicationMaxBufferSize |
32 KB | The maximum number of bytes received from the client that the server buffers. Increasing this value allows the server to receive larger messages, but can negatively impact memory consumption. |
AuthorizationData |
Data automatically gathered from the Authorize attributes applied to the Hub class. |
A list of IAuthorizeData objects used to determine if a client is authorized to connect to the hub. |
TransportMaxBufferSize |
32 KB | The maximum number of bytes sent by the app that the server buffers. Increasing this value allows the server to send larger messages, but can negatively impact memory consumption. |
Transports |
All Transports are enabled. | A bit flags enum of HttpTransportType values that can restrict the transports a client can use to connect. |
LongPolling |
See below. | Additional options specific to the Long Polling transport. |
WebSockets |
See below. | Additional options specific to the WebSockets transport. |
The Long Polling transport has additional options that can be configured using the LongPolling
property:
Option | Default Value | Description |
---|---|---|
PollTimeout |
90 seconds | The maximum amount of time the server waits for a message to send to the client before terminating a single poll request. Decreasing this value causes the client to issue new poll requests more frequently. |
The WebSocket transport has additional options that can be configured using the WebSockets
property:
Option | Default Value | Description |
---|---|---|
CloseTimeout |
5 seconds | After the server closes, if the client fails to close within this time interval, the connection is terminated. |
SubProtocolSelector |
null |
A delegate that can be used to set the Sec-WebSocket-Protocol header to a custom value. The delegate receives the values requested by the client as input and is expected to return the desired value. |
Configure client options
Client options can be configured on the HubConnectionBuilder
type (available in the .NET and JavaScript clients). It's also available in the Java client, but the HttpHubConnectionBuilder
subclass is what contains the builder configuration options, as well as on the HubConnection
itself.
Configure logging
Logging is configured in the .NET Client using the ConfigureLogging
method. Logging providers and filters can be registered in the same way as they are on the server. See the Logging in ASP.NET Core documentation for more information.
Note
In order to register Logging providers, you must install the necessary packages. See the Built-in logging providers section of the docs for a full list.
For example, to enable Console logging, install the Microsoft.Extensions.Logging.Console
NuGet package. Call the AddConsole
extension method:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub")
.ConfigureLogging(logging => {
logging.SetMinimumLevel(LogLevel.Information);
logging.AddConsole();
})
.Build();
In the JavaScript client, a similar configureLogging
method exists. Provide a LogLevel
value indicating the minimum level of log messages to produce. Logs are written to the browser console window.
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub")
.configureLogging(signalR.LogLevel.Information)
.build();
Note
To disable logging entirely, specify signalR.LogLevel.None
in the configureLogging
method.
For more information on logging, see the SignalR Diagnostics documentation.
The SignalR Java client uses the SLF4J library for logging. It's a high-level logging API that allows users of the library to choose their own specific logging implementation by bringing in a specific logging dependency. The following code snippet shows how to use java.util.logging
with the SignalR Java client.
implementation 'org.slf4j:slf4j-jdk14:1.7.25'
If you don't configure logging in your dependencies, SLF4J loads a default no-operation logger with the following warning message:
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
This can safely be ignored.
Configure allowed transports
The transports used by SignalR can be configured in the WithUrl
call (withUrl
in JavaScript). A bitwise-OR of the values of HttpTransportType
can be used to restrict the client to only use the specified transports. All transports are enabled by default.
For example, to disable the Server-Sent Events transport, but allow WebSockets and Long Polling connections:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", HttpTransportType.WebSockets | HttpTransportType.LongPolling)
.Build();
In the JavaScript client, transports are configured by setting the transport
field on the options object provided to withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", { transport: signalR.HttpTransportType.WebSockets | signalR.HttpTransportType.LongPolling })
.build();
In this version of the Java client websockets is the only available transport.
Configure bearer authentication
To provide authentication data along with SignalR requests, use the AccessTokenProvider
option (accessTokenFactory
in JavaScript) to specify a function that returns the desired access token. In the .NET Client, this access token is passed in as an HTTP "Bearer Authentication" token (Using the Authorization
header with a type of Bearer
). In the JavaScript client, the access token is used as a Bearer token, except in a few cases where browser APIs restrict the ability to apply headers (specifically, in Server-Sent Events and WebSockets requests). In these cases, the access token is provided as a query string value access_token
.
In the .NET client, the AccessTokenProvider
option can be specified using the options delegate in WithUrl
:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", options => {
options.AccessTokenProvider = async () => {
// Get and return the access token.
};
})
.Build();
In the JavaScript client, the access token is configured by setting the accessTokenFactory
field on the options object in withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", {
accessTokenFactory: () => {
// Get and return the access token.
// This function can return a JavaScript Promise if asynchronous
// logic is required to retrieve the access token.
}
})
.build();
In the SignalR Java client, you can configure a bearer token to use for authentication by providing an access token factory to the HttpHubConnectionBuilder. Use withAccessTokenFactory to provide an RxJava Single<String>. With a call to Single.defer, you can write logic to produce access tokens for your client.
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withAccessTokenProvider(Single.defer(() -> {
// Your logic here.
return Single.just("An Access Token");
})).build();
Configure timeout and keep-alive options
Additional options for configuring timeout and keep-alive behavior are available on the HubConnection
object itself:
Option | Default value | Description |
---|---|---|
ServerTimeout |
30 seconds (30,000 milliseconds) | Timeout for server activity. If the server hasn't sent a message in this interval, the client considers the server disconnected and triggers the Closed event (onclose in JavaScript). This value must be large enough for a ping message to be sent from the server and received by the client within the timeout interval. The recommended value is a number at least double the server's KeepAliveInterval value to allow time for pings to arrive. |
HandshakeTimeout |
15 seconds | Timeout for initial server handshake. If the server doesn't send a handshake response in this interval, the client cancels the handshake and triggers the Closed event (onclose in JavaScript). This is an advanced setting that should only be modified if handshake timeout errors are occurring due to severe network latency. For more detail on the handshake process, see the SignalR Hub Protocol Specification. |
KeepAliveInterval |
15 seconds | Determines the interval at which the client sends ping messages. Sending any message from the client resets the timer to the start of the interval. If the client hasn't sent a message in the ClientTimeoutInterval set on the server, the server considers the client disconnected. |
In the .NET Client, timeout values are specified as TimeSpan
values.
Configure additional options
Additional options can be configured in the WithUrl
(withUrl
in JavaScript) method on HubConnectionBuilder
or on the various configuration APIs on the HttpHubConnectionBuilder
in the Java client:
.NET Option | Default value | Description |
---|---|---|
AccessTokenProvider |
null |
A function returning a string that is provided as a Bearer authentication token in HTTP requests. |
SkipNegotiation |
false |
Set this to true to skip the negotiation step. Only supported when the WebSockets transport is the only enabled transport. This setting can't be enabled when using the Azure SignalR Service. |
ClientCertificates |
Empty | A collection of TLS certificates to send to authenticate requests. |
Cookies |
Empty | A collection of HTTP cookies to send with every HTTP request. |
Credentials |
Empty | Credentials to send with every HTTP request. |
CloseTimeout |
5 seconds | WebSockets only. The maximum amount of time the client waits after closing for the server to acknowledge the close request. If the server doesn't acknowledge the close within this time, the client disconnects. |
Headers |
Empty | A Map of additional HTTP headers to send with every HTTP request. |
HttpMessageHandlerFactory |
null |
A delegate that can be used to configure or replace the HttpMessageHandler used to send HTTP requests. Not used for WebSocket connections. This delegate must return a non-null value, and it receives the default value as a parameter. Either modify settings on that default value and return it, or return a new HttpMessageHandler instance. When replacing the handler make sure to copy the settings you want to keep from the provided handler, otherwise, the configured options (such as Cookies and Headers) won't apply to the new handler. |
Proxy |
null |
An HTTP proxy to use when sending HTTP requests. |
UseDefaultCredentials |
false |
Set this boolean to send the default credentials for HTTP and WebSockets requests. This enables the use of Windows authentication. |
WebSocketConfiguration |
null |
A delegate that can be used to configure additional WebSocket options. Receives an instance of ClientWebSocketOptions that can be used to configure the options. |
In the .NET Client, these options can be modified by the options delegate provided to WithUrl
:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", options => {
options.Headers["Foo"] = "Bar";
options.Cookies.Add(new Cookie(/* ... */);
options.ClientCertificates.Add(/* ... */);
})
.Build();
In the JavaScript Client, these options can be provided in a JavaScript object provided to withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", {
skipNegotiation: true,
transport: signalR.HttpTransportType.WebSockets
})
.build();
In the Java client, these options can be configured with the methods on the HttpHubConnectionBuilder
returned from the HubConnectionBuilder.create("HUB URL")
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withHeader("Foo", "Bar")
.shouldSkipNegotiate(true)
.withHandshakeResponseTimeout(30*1000)
.build();
Additional resources
JSON/MessagePack serialization options
ASP.NET Core SignalR supports two protocols for encoding messages: JSON and MessagePack. Each protocol has serialization configuration options.
JSON serialization can be configured on the server using the AddJsonProtocol extension method. AddJsonProtocol
can be added after AddSignalR in Startup.ConfigureServices
. The AddJsonProtocol
method takes a delegate that receives an options
object. The PayloadSerializerOptions property on that object is a System.Text.Json
JsonSerializerOptions object that can be used to configure serialization of arguments and return values. For more information, see the System.Text.Json documentation.
For example, to configure the serializer to not change the casing of property names, rather than the default camel case names, use the following code in Startup.ConfigureServices
:
services.AddSignalR()
.AddJsonProtocol(options => {
options.PayloadSerializerOptions.PropertyNamingPolicy = null;
});
In the .NET client, the same AddJsonProtocol
extension method exists on HubConnectionBuilder. The Microsoft.Extensions.DependencyInjection
namespace must be imported to resolve the extension method:
// At the top of the file:
using Microsoft.Extensions.DependencyInjection;
// When constructing your connection:
var connection = new HubConnectionBuilder()
.AddJsonProtocol(options => {
options.PayloadSerializerOptions.PropertyNamingPolicy = null;
})
.Build();
Note
It's not possible to configure JSON serialization in the JavaScript client at this time.
Switch to Newtonsoft.Json
If you need features of Newtonsoft.Json
that aren't supported in System.Text.Json
, see Switch to Newtonsoft.Json
.
MessagePack serialization options
MessagePack serialization can be configured by providing a delegate to the AddMessagePackProtocol call. See MessagePack in SignalR for more details.
Note
It's not possible to configure MessagePack serialization in the JavaScript client at this time.
Configure server options
The following table describes options for configuring SignalR hubs:
Option | Default Value | Description |
---|---|---|
ClientTimeoutInterval |
30 seconds | The server considers the client disconnected if it hasn't received a message (including keep-alive) in this interval. It could take longer than this timeout interval for the client to be marked disconnected due to how this is implemented. The recommended value is double the KeepAliveInterval value. |
HandshakeTimeout |
15 seconds | If the client doesn't send an initial handshake message within this time interval, the connection is closed. This is an advanced setting that should only be modified if handshake timeout errors are occurring due to severe network latency. For more detail on the handshake process, see the SignalR Hub Protocol Specification. |
KeepAliveInterval |
15 seconds | If the server hasn't sent a message within this interval, a ping message is sent automatically to keep the connection open. When changing KeepAliveInterval , change the ServerTimeout or serverTimeoutInMilliseconds setting on the client. The recommended ServerTimeout or serverTimeoutInMilliseconds value is double the KeepAliveInterval value. |
SupportedProtocols |
All installed protocols | Protocols supported by this hub. By default, all protocols registered on the server are allowed. Protocols can be removed from this list to disable specific protocols for individual hubs. |
EnableDetailedErrors |
false |
If true , detailed exception messages are returned to clients when an exception is thrown in a Hub method. The default is false because these exception messages can contain sensitive information. |
StreamBufferCapacity |
10 |
The maximum number of items that can be buffered for client upload streams. If this limit is reached, the processing of invocations is blocked until the server processes stream items. |
MaximumReceiveMessageSize |
32 KB | Maximum size of a single incoming hub message. Increasing the value may increase the risk of Denial of service (DoS) attacks. |
Options can be configured for all hubs by providing an options delegate to the AddSignalR
call in Startup.ConfigureServices
.
public void ConfigureServices(IServiceCollection services)
{
services.AddSignalR(hubOptions =>
{
hubOptions.EnableDetailedErrors = true;
hubOptions.KeepAliveInterval = TimeSpan.FromMinutes(1);
});
}
Options for a single hub override the global options provided in AddSignalR
and can be configured using AddHubOptions:
services.AddSignalR().AddHubOptions<ChatHub>(options =>
{
options.EnableDetailedErrors = true;
});
Advanced HTTP configuration options
Use HttpConnectionDispatcherOptions
to configure advanced settings related to transports and memory buffer management. These options are configured by passing a delegate to MapHub in Startup.Configure
.
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
app.UseRouting();
app.UseEndpoints(endpoints =>
{
endpoints.MapHub<ChatHub>("/chathub", options =>
{
options.Transports =
HttpTransportType.WebSockets |
HttpTransportType.LongPolling;
});
});
}
The following table describes options for configuring ASP.NET Core SignalR's advanced HTTP options:
Option | Default Value | Description |
---|---|---|
ApplicationMaxBufferSize |
32 KB | The maximum number of bytes received from the client that the server buffers before applying backpressure. Increasing this value allows the server to receive larger messages more quickly without applying backpressure, but can increase memory consumption. |
AuthorizationData |
Data automatically gathered from the Authorize attributes applied to the Hub class. |
A list of IAuthorizeData objects used to determine if a client is authorized to connect to the hub. |
TransportMaxBufferSize |
32 KB | The maximum number of bytes sent by the app that the server buffers before observing backpressure. Increasing this value allows the server to buffer larger messages more quickly without awaiting backpressure, but can increase memory consumption. |
Transports |
All Transports are enabled. | A bit flags enum of HttpTransportType values that can restrict the transports a client can use to connect. |
LongPolling |
See below. | Additional options specific to the Long Polling transport. |
WebSockets |
See below. | Additional options specific to the WebSockets transport. |
The Long Polling transport has additional options that can be configured using the LongPolling
property:
Option | Default Value | Description |
---|---|---|
PollTimeout |
90 seconds | The maximum amount of time the server waits for a message to send to the client before terminating a single poll request. Decreasing this value causes the client to issue new poll requests more frequently. |
The WebSocket transport has additional options that can be configured using the WebSockets
property:
Option | Default Value | Description |
---|---|---|
CloseTimeout |
5 seconds | After the server closes, if the client fails to close within this time interval, the connection is terminated. |
SubProtocolSelector |
null |
A delegate that can be used to set the Sec-WebSocket-Protocol header to a custom value. The delegate receives the values requested by the client as input and is expected to return the desired value. |
Configure client options
Client options can be configured on the HubConnectionBuilder
type (available in the .NET and JavaScript clients). It's also available in the Java client, but the HttpHubConnectionBuilder
subclass is what contains the builder configuration options, as well as on the HubConnection
itself.
Configure logging
Logging is configured in the .NET Client using the ConfigureLogging
method. Logging providers and filters can be registered in the same way as they are on the server. See the Logging in ASP.NET Core documentation for more information.
Note
In order to register Logging providers, you must install the necessary packages. See the Built-in logging providers section of the docs for a full list.
For example, to enable Console logging, install the Microsoft.Extensions.Logging.Console
NuGet package. Call the AddConsole
extension method:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub")
.ConfigureLogging(logging => {
logging.SetMinimumLevel(LogLevel.Information);
logging.AddConsole();
})
.Build();
In the JavaScript client, a similar configureLogging
method exists. Provide a LogLevel
value indicating the minimum level of log messages to produce. Logs are written to the browser console window.
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub")
.configureLogging(signalR.LogLevel.Information)
.build();
Instead of a LogLevel
value, you can also provide a string
value representing a log level name. This is useful when configuring SignalR logging in environments where you don't have access to the LogLevel
constants.
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub")
.configureLogging("warn")
.build();
The following table lists the available log levels. The value you provide to configureLogging
sets the minimum log level that will be logged. Messages logged at this level, or the levels listed after it in the table, will be logged.
String | LogLevel |
---|---|
trace |
LogLevel.Trace |
debug |
LogLevel.Debug |
info or information |
LogLevel.Information |
warn or warning |
LogLevel.Warning |
error |
LogLevel.Error |
critical |
LogLevel.Critical |
none |
LogLevel.None |
Note
To disable logging entirely, specify signalR.LogLevel.None
in the configureLogging
method.
For more information on logging, see the SignalR Diagnostics documentation.
The SignalR Java client uses the SLF4J library for logging. It's a high-level logging API that allows users of the library to choose their own specific logging implementation by bringing in a specific logging dependency. The following code snippet shows how to use java.util.logging
with the SignalR Java client.
implementation 'org.slf4j:slf4j-jdk14:1.7.25'
If you don't configure logging in your dependencies, SLF4J loads a default no-operation logger with the following warning message:
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
This can safely be ignored.
Configure allowed transports
The transports used by SignalR can be configured in the WithUrl
call (withUrl
in JavaScript). A bitwise-OR of the values of HttpTransportType
can be used to restrict the client to only use the specified transports. All transports are enabled by default.
For example, to disable the Server-Sent Events transport, but allow WebSockets and Long Polling connections:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", HttpTransportType.WebSockets | HttpTransportType.LongPolling)
.Build();
In the JavaScript client, transports are configured by setting the transport
field on the options object provided to withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", { transport: signalR.HttpTransportType.WebSockets | signalR.HttpTransportType.LongPolling })
.build();
In this version of the Java client websockets is the only available transport.
In the Java client, the transport is selected with the withTransport
method on the HttpHubConnectionBuilder
. The Java client defaults to using the WebSockets transport.
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withTransport(TransportEnum.WEBSOCKETS)
.build();
Note
The SignalR Java client doesn't support transport fallback yet.
Configure bearer authentication
To provide authentication data along with SignalR requests, use the AccessTokenProvider
option (accessTokenFactory
in JavaScript) to specify a function that returns the desired access token. In the .NET Client, this access token is passed in as an HTTP "Bearer Authentication" token (Using the Authorization
header with a type of Bearer
). In the JavaScript client, the access token is used as a Bearer token, except in a few cases where browser APIs restrict the ability to apply headers (specifically, in Server-Sent Events and WebSockets requests). In these cases, the access token is provided as a query string value access_token
.
In the .NET client, the AccessTokenProvider
option can be specified using the options delegate in WithUrl
:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", options => {
options.AccessTokenProvider = async () => {
// Get and return the access token.
};
})
.Build();
In the JavaScript client, the access token is configured by setting the accessTokenFactory
field on the options object in withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", {
accessTokenFactory: () => {
// Get and return the access token.
// This function can return a JavaScript Promise if asynchronous
// logic is required to retrieve the access token.
}
})
.build();
In the SignalR Java client, you can configure a bearer token to use for authentication by providing an access token factory to the HttpHubConnectionBuilder. Use withAccessTokenFactory to provide an RxJava Single<String>. With a call to Single.defer, you can write logic to produce access tokens for your client.
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withAccessTokenProvider(Single.defer(() -> {
// Your logic here.
return Single.just("An Access Token");
})).build();
Configure timeout and keep-alive options
Additional options for configuring timeout and keep-alive behavior are available on the HubConnection
object itself:
Option | Default value | Description |
---|---|---|
ServerTimeout |
30 seconds (30,000 milliseconds) | Timeout for server activity. If the server hasn't sent a message in this interval, the client considers the server disconnected and triggers the Closed event (onclose in JavaScript). This value must be large enough for a ping message to be sent from the server and received by the client within the timeout interval. The recommended value is a number at least double the server's KeepAliveInterval value to allow time for pings to arrive. |
HandshakeTimeout |
15 seconds | Timeout for initial server handshake. If the server doesn't send a handshake response in this interval, the client cancels the handshake and triggers the Closed event (onclose in JavaScript). This is an advanced setting that should only be modified if handshake timeout errors are occurring due to severe network latency. For more detail on the handshake process, see the SignalR Hub Protocol Specification. |
KeepAliveInterval |
15 seconds | Determines the interval at which the client sends ping messages. Sending any message from the client resets the timer to the start of the interval. If the client hasn't sent a message in the ClientTimeoutInterval set on the server, the server considers the client disconnected. |
In the .NET Client, timeout values are specified as TimeSpan
values.
Configure additional options
Additional options can be configured in the WithUrl
(withUrl
in JavaScript) method on HubConnectionBuilder
or on the various configuration APIs on the HttpHubConnectionBuilder
in the Java client:
.NET Option | Default value | Description |
---|---|---|
AccessTokenProvider |
null |
A function returning a string that is provided as a Bearer authentication token in HTTP requests. |
SkipNegotiation |
false |
Set this to true to skip the negotiation step. Only supported when the WebSockets transport is the only enabled transport. This setting can't be enabled when using the Azure SignalR Service. |
ClientCertificates |
Empty | A collection of TLS certificates to send to authenticate requests. |
Cookies |
Empty | A collection of HTTP cookies to send with every HTTP request. |
Credentials |
Empty | Credentials to send with every HTTP request. |
CloseTimeout |
5 seconds | WebSockets only. The maximum amount of time the client waits after closing for the server to acknowledge the close request. If the server doesn't acknowledge the close within this time, the client disconnects. |
Headers |
Empty | A Map of additional HTTP headers to send with every HTTP request. |
HttpMessageHandlerFactory |
null |
A delegate that can be used to configure or replace the HttpMessageHandler used to send HTTP requests. Not used for WebSocket connections. This delegate must return a non-null value, and it receives the default value as a parameter. Either modify settings on that default value and return it, or return a new HttpMessageHandler instance. When replacing the handler make sure to copy the settings you want to keep from the provided handler, otherwise, the configured options (such as Cookies and Headers) won't apply to the new handler. |
Proxy |
null |
An HTTP proxy to use when sending HTTP requests. |
UseDefaultCredentials |
false |
Set this boolean to send the default credentials for HTTP and WebSockets requests. This enables the use of Windows authentication. |
WebSocketConfiguration |
null |
A delegate that can be used to configure additional WebSocket options. Receives an instance of ClientWebSocketOptions that can be used to configure the options. |
In the .NET Client, these options can be modified by the options delegate provided to WithUrl
:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", options => {
options.Headers["Foo"] = "Bar";
options.Cookies.Add(new Cookie(/* ... */);
options.ClientCertificates.Add(/* ... */);
})
.Build();
In the JavaScript Client, these options can be provided in a JavaScript object provided to withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", {
skipNegotiation: true,
transport: signalR.HttpTransportType.WebSockets
})
.build();
In the Java client, these options can be configured with the methods on the HttpHubConnectionBuilder
returned from the HubConnectionBuilder.create("HUB URL")
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withHeader("Foo", "Bar")
.shouldSkipNegotiate(true)
.withHandshakeResponseTimeout(30*1000)
.build();
Additional resources
JSON/MessagePack serialization options
ASP.NET Core SignalR supports two protocols for encoding messages: JSON and MessagePack. Each protocol has serialization configuration options.
JSON serialization can be configured on the server using the AddJsonProtocol extension method. AddJsonProtocol
can be added after AddSignalR in Startup.ConfigureServices
. The AddJsonProtocol
method takes a delegate that receives an options
object. The PayloadSerializerOptions property on that object is a System.Text.Json
JsonSerializerOptions object that can be used to configure serialization of arguments and return values. For more information, see the System.Text.Json documentation.
For example, to configure the serializer to not change the casing of property names, rather than the default camel case names, use the following code in Startup.ConfigureServices
:
services.AddSignalR()
.AddJsonProtocol(options => {
options.PayloadSerializerOptions.PropertyNamingPolicy = null
});
In the .NET client, the same AddJsonProtocol
extension method exists on HubConnectionBuilder. The Microsoft.Extensions.DependencyInjection
namespace must be imported to resolve the extension method:
// At the top of the file:
using Microsoft.Extensions.DependencyInjection;
// When constructing your connection:
var connection = new HubConnectionBuilder()
.AddJsonProtocol(options => {
options.PayloadSerializerOptions.PropertyNamingPolicy = null;
})
.Build();
Note
It's not possible to configure JSON serialization in the JavaScript client at this time.
Switch to Newtonsoft.Json
If you need features of Newtonsoft.Json
that aren't supported in System.Text.Json
, see Switch to Newtonsoft.Json
.
MessagePack serialization options
MessagePack serialization can be configured by providing a delegate to the AddMessagePackProtocol call. See MessagePack in SignalR for more details.
Note
It's not possible to configure MessagePack serialization in the JavaScript client at this time.
Configure server options
The following table describes options for configuring SignalR hubs:
Option | Default Value | Description |
---|---|---|
ClientTimeoutInterval |
30 seconds | The server considers the client disconnected if it hasn't received a message (including keep-alive) in this interval. It could take longer than this timeout interval for the client to be marked disconnected due to how this is implemented. The recommended value is double the KeepAliveInterval value. |
HandshakeTimeout |
15 seconds | If the client doesn't send an initial handshake message within this time interval, the connection is closed. This is an advanced setting that should only be modified if handshake timeout errors are occurring due to severe network latency. For more detail on the handshake process, see the SignalR Hub Protocol Specification. |
KeepAliveInterval |
15 seconds | If the server hasn't sent a message within this interval, a ping message is sent automatically to keep the connection open. When changing KeepAliveInterval , change the ServerTimeout or serverTimeoutInMilliseconds setting on the client. The recommended ServerTimeout or serverTimeoutInMilliseconds value is double the KeepAliveInterval value. |
SupportedProtocols |
All installed protocols | Protocols supported by this hub. By default, all protocols registered on the server are allowed. Protocols can be removed from this list to disable specific protocols for individual hubs. |
EnableDetailedErrors |
false |
If true , detailed exception messages are returned to clients when an exception is thrown in a Hub method. The default is false because these exception messages can contain sensitive information. |
StreamBufferCapacity |
10 |
The maximum number of items that can be buffered for client upload streams. If this limit is reached, the processing of invocations is blocked until the server processes stream items. |
MaximumReceiveMessageSize |
32 KB | Maximum size of a single incoming hub message. Increasing the value may increase the risk of Denial of service (DoS) attacks. |
Options can be configured for all hubs by providing an options delegate to the AddSignalR
call in Startup.ConfigureServices
.
public void ConfigureServices(IServiceCollection services)
{
services.AddSignalR(hubOptions =>
{
hubOptions.EnableDetailedErrors = true;
hubOptions.KeepAliveInterval = TimeSpan.FromMinutes(1);
});
}
Options for a single hub override the global options provided in AddSignalR
and can be configured using AddHubOptions:
services.AddSignalR().AddHubOptions<ChatHub>(options =>
{
options.EnableDetailedErrors = true;
});
Advanced HTTP configuration options
Use HttpConnectionDispatcherOptions
to configure advanced settings related to transports and memory buffer management. These options are configured by passing a delegate to MapHub in Startup.Configure
.
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
app.UseRouting();
app.UseEndpoints(endpoints =>
{
endpoints.MapHub<ChatHub>("/chathub", options =>
{
options.Transports =
HttpTransportType.WebSockets |
HttpTransportType.LongPolling;
});
});
}
The following table describes options for configuring ASP.NET Core SignalR's advanced HTTP options:
Option | Default Value | Description |
---|---|---|
ApplicationMaxBufferSize |
32 KB | The maximum number of bytes received from the client that the server buffers before applying backpressure. Increasing this value allows the server to receive larger messages more quickly without applying backpressure, but can increase memory consumption. |
AuthorizationData |
Data automatically gathered from the Authorize attributes applied to the Hub class. |
A list of IAuthorizeData objects used to determine if a client is authorized to connect to the hub. |
TransportMaxBufferSize |
32 KB | The maximum number of bytes sent by the app that the server buffers before observing backpressure. Increasing this value allows the server to buffer larger messages more quickly without awaiting backpressure, but can increase memory consumption. |
Transports |
All Transports are enabled. | A bit flags enum of HttpTransportType values that can restrict the transports a client can use to connect. |
LongPolling |
See below. | Additional options specific to the Long Polling transport. |
WebSockets |
See below. | Additional options specific to the WebSockets transport. |
MinimumProtocolVersion |
0 | Specify the minimum version of the negotiate protocol. This is used to limit clients to newer versions. |
The Long Polling transport has additional options that can be configured using the LongPolling
property:
Option | Default Value | Description |
---|---|---|
PollTimeout |
90 seconds | The maximum amount of time the server waits for a message to send to the client before terminating a single poll request. Decreasing this value causes the client to issue new poll requests more frequently. |
The WebSocket transport has additional options that can be configured using the WebSockets
property:
Option | Default Value | Description |
---|---|---|
CloseTimeout |
5 seconds | After the server closes, if the client fails to close within this time interval, the connection is terminated. |
SubProtocolSelector |
null |
A delegate that can be used to set the Sec-WebSocket-Protocol header to a custom value. The delegate receives the values requested by the client as input and is expected to return the desired value. |
Configure client options
Client options can be configured on the HubConnectionBuilder
type (available in the .NET and JavaScript clients). It's also available in the Java client, but the HttpHubConnectionBuilder
subclass is what contains the builder configuration options, as well as on the HubConnection
itself.
Configure logging
Logging is configured in the .NET Client using the ConfigureLogging
method. Logging providers and filters can be registered in the same way as they are on the server. See the Logging in ASP.NET Core documentation for more information.
Note
In order to register Logging providers, you must install the necessary packages. See the Built-in logging providers section of the docs for a full list.
For example, to enable Console logging, install the Microsoft.Extensions.Logging.Console
NuGet package. Call the AddConsole
extension method:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub")
.ConfigureLogging(logging => {
logging.SetMinimumLevel(LogLevel.Information);
logging.AddConsole();
})
.Build();
In the JavaScript client, a similar configureLogging
method exists. Provide a LogLevel
value indicating the minimum level of log messages to produce. Logs are written to the browser console window.
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub")
.configureLogging(signalR.LogLevel.Information)
.build();
Instead of a LogLevel
value, you can also provide a string
value representing a log level name. This is useful when configuring SignalR logging in environments where you don't have access to the LogLevel
constants.
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub")
.configureLogging("warn")
.build();
The following table lists the available log levels. The value you provide to configureLogging
sets the minimum log level that will be logged. Messages logged at this level, or the levels listed after it in the table, will be logged.
String | LogLevel |
---|---|
trace |
LogLevel.Trace |
debug |
LogLevel.Debug |
info or information |
LogLevel.Information |
warn or warning |
LogLevel.Warning |
error |
LogLevel.Error |
critical |
LogLevel.Critical |
none |
LogLevel.None |
Note
To disable logging entirely, specify signalR.LogLevel.None
in the configureLogging
method.
For more information on logging, see the SignalR Diagnostics documentation.
The SignalR Java client uses the SLF4J library for logging. It's a high-level logging API that allows users of the library to choose their own specific logging implementation by bringing in a specific logging dependency. The following code snippet shows how to use java.util.logging
with the SignalR Java client.
implementation 'org.slf4j:slf4j-jdk14:1.7.25'
If you don't configure logging in your dependencies, SLF4J loads a default no-operation logger with the following warning message:
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
This can safely be ignored.
Configure allowed transports
The transports used by SignalR can be configured in the WithUrl
call (withUrl
in JavaScript). A bitwise-OR of the values of HttpTransportType
can be used to restrict the client to only use the specified transports. All transports are enabled by default.
For example, to disable the Server-Sent Events transport, but allow WebSockets and Long Polling connections:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", HttpTransportType.WebSockets | HttpTransportType.LongPolling)
.Build();
In the JavaScript client, transports are configured by setting the transport
field on the options object provided to withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", { transport: signalR.HttpTransportType.WebSockets | signalR.HttpTransportType.LongPolling })
.build();
In this version of the Java client websockets is the only available transport.
In the Java client, the transport is selected with the withTransport
method on the HttpHubConnectionBuilder
. The Java client defaults to using the WebSockets transport.
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withTransport(TransportEnum.WEBSOCKETS)
.build();
Note
The SignalR Java client doesn't support transport fallback yet.
Configure bearer authentication
To provide authentication data along with SignalR requests, use the AccessTokenProvider
option (accessTokenFactory
in JavaScript) to specify a function that returns the desired access token. In the .NET Client, this access token is passed in as an HTTP "Bearer Authentication" token (Using the Authorization
header with a type of Bearer
). In the JavaScript client, the access token is used as a Bearer token, except in a few cases where browser APIs restrict the ability to apply headers (specifically, in Server-Sent Events and WebSockets requests). In these cases, the access token is provided as a query string value access_token
.
In the .NET client, the AccessTokenProvider
option can be specified using the options delegate in WithUrl
:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", options => {
options.AccessTokenProvider = async () => {
// Get and return the access token.
};
})
.Build();
In the JavaScript client, the access token is configured by setting the accessTokenFactory
field on the options object in withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", {
accessTokenFactory: () => {
// Get and return the access token.
// This function can return a JavaScript Promise if asynchronous
// logic is required to retrieve the access token.
}
})
.build();
In the SignalR Java client, you can configure a bearer token to use for authentication by providing an access token factory to the HttpHubConnectionBuilder. Use withAccessTokenFactory to provide an RxJava Single<String>. With a call to Single.defer, you can write logic to produce access tokens for your client.
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withAccessTokenProvider(Single.defer(() -> {
// Your logic here.
return Single.just("An Access Token");
})).build();
Configure timeout and keep-alive options
Additional options for configuring timeout and keep-alive behavior are available on the HubConnection
object itself:
Option | Default value | Description |
---|---|---|
ServerTimeout |
30 seconds (30,000 milliseconds) | Timeout for server activity. If the server hasn't sent a message in this interval, the client considers the server disconnected and triggers the Closed event (onclose in JavaScript). This value must be large enough for a ping message to be sent from the server and received by the client within the timeout interval. The recommended value is a number at least double the server's KeepAliveInterval value to allow time for pings to arrive. |
HandshakeTimeout |
15 seconds | Timeout for initial server handshake. If the server doesn't send a handshake response in this interval, the client cancels the handshake and triggers the Closed event (onclose in JavaScript). This is an advanced setting that should only be modified if handshake timeout errors are occurring due to severe network latency. For more detail on the handshake process, see the SignalR Hub Protocol Specification. |
KeepAliveInterval |
15 seconds | Determines the interval at which the client sends ping messages. Sending any message from the client resets the timer to the start of the interval. If the client hasn't sent a message in the ClientTimeoutInterval set on the server, the server considers the client disconnected. |
In the .NET Client, timeout values are specified as TimeSpan
values.
Configure additional options
Additional options can be configured in the WithUrl
(withUrl
in JavaScript) method on HubConnectionBuilder
or on the various configuration APIs on the HttpHubConnectionBuilder
in the Java client:
.NET Option | Default value | Description |
---|---|---|
AccessTokenProvider |
null |
A function returning a string that is provided as a Bearer authentication token in HTTP requests. |
SkipNegotiation |
false |
Set this to true to skip the negotiation step. Only supported when the WebSockets transport is the only enabled transport. This setting can't be enabled when using the Azure SignalR Service. |
ClientCertificates |
Empty | A collection of TLS certificates to send to authenticate requests. |
Cookies |
Empty | A collection of HTTP cookies to send with every HTTP request. |
Credentials |
Empty | Credentials to send with every HTTP request. |
CloseTimeout |
5 seconds | WebSockets only. The maximum amount of time the client waits after closing for the server to acknowledge the close request. If the server doesn't acknowledge the close within this time, the client disconnects. |
Headers |
Empty | A Map of additional HTTP headers to send with every HTTP request. |
HttpMessageHandlerFactory |
null |
A delegate that can be used to configure or replace the HttpMessageHandler used to send HTTP requests. Not used for WebSocket connections. This delegate must return a non-null value, and it receives the default value as a parameter. Either modify settings on that default value and return it, or return a new HttpMessageHandler instance. When replacing the handler make sure to copy the settings you want to keep from the provided handler, otherwise, the configured options (such as Cookies and Headers) won't apply to the new handler. |
Proxy |
null |
An HTTP proxy to use when sending HTTP requests. |
UseDefaultCredentials |
false |
Set this boolean to send the default credentials for HTTP and WebSockets requests. This enables the use of Windows authentication. |
WebSocketConfiguration |
null |
A delegate that can be used to configure additional WebSocket options. Receives an instance of ClientWebSocketOptions that can be used to configure the options. |
In the .NET Client, these options can be modified by the options delegate provided to WithUrl
:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", options => {
options.Headers["Foo"] = "Bar";
options.Cookies.Add(new Cookie(/* ... */);
options.ClientCertificates.Add(/* ... */);
})
.Build();
In the JavaScript Client, these options can be provided in a JavaScript object provided to withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", {
skipNegotiation: true,
transport: signalR.HttpTransportType.WebSockets
})
.build();
In the Java client, these options can be configured with the methods on the HttpHubConnectionBuilder
returned from the HubConnectionBuilder.create("HUB URL")
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withHeader("Foo", "Bar")
.shouldSkipNegotiate(true)
.withHandshakeResponseTimeout(30*1000)
.build();
Additional resources
JSON/MessagePack serialization options
ASP.NET Core SignalR supports two protocols for encoding messages: JSON and MessagePack. Each protocol has serialization configuration options.
JSON serialization can be configured on the server using the AddJsonProtocol extension method. AddJsonProtocol
can be added after AddSignalR in Startup.ConfigureServices
. The AddJsonProtocol
method takes a delegate that receives an options
object. The PayloadSerializerOptions property on that object is a System.Text.Json
JsonSerializerOptions object that can be used to configure serialization of arguments and return values. For more information, see the System.Text.Json documentation.
For example, to configure the serializer to not change the casing of property names, rather than the default camel case names, use the following code in Startup.ConfigureServices
:
services.AddSignalR()
.AddJsonProtocol(options => {
options.PayloadSerializerOptions.PropertyNamingPolicy = null;
});
In the .NET client, the same AddJsonProtocol
extension method exists on HubConnectionBuilder. The Microsoft.Extensions.DependencyInjection
namespace must be imported to resolve the extension method:
// At the top of the file:
using Microsoft.Extensions.DependencyInjection;
// When constructing your connection:
var connection = new HubConnectionBuilder()
.AddJsonProtocol(options => {
options.PayloadSerializerOptions.PropertyNamingPolicy = null;
})
.Build();
Note
It's not possible to configure JSON serialization in the JavaScript client at this time.
Switch to Newtonsoft.Json
If you need features of Newtonsoft.Json
that aren't supported in System.Text.Json
, see Switch to Newtonsoft.Json
.
MessagePack serialization options
MessagePack serialization can be configured by providing a delegate to the AddMessagePackProtocol call. See MessagePack in SignalR for more details.
Note
It's not possible to configure MessagePack serialization in the JavaScript client at this time.
Configure server options
The following table describes options for configuring SignalR hubs:
Option | Default Value | Description |
---|---|---|
ClientTimeoutInterval |
30 seconds | The server considers the client disconnected if it hasn't received a message (including keep-alive) in this interval. It could take longer than this timeout interval for the client to be marked disconnected due to how this is implemented. The recommended value is double the KeepAliveInterval value. |
HandshakeTimeout |
15 seconds | If the client doesn't send an initial handshake message within this time interval, the connection is closed. This is an advanced setting that should only be modified if handshake timeout errors are occurring due to severe network latency. For more detail on the handshake process, see the SignalR Hub Protocol Specification. |
KeepAliveInterval |
15 seconds | If the server hasn't sent a message within this interval, a ping message is sent automatically to keep the connection open. When changing KeepAliveInterval , change the ServerTimeout or serverTimeoutInMilliseconds setting on the client. The recommended ServerTimeout or serverTimeoutInMilliseconds value is double the KeepAliveInterval value. |
SupportedProtocols |
All installed protocols | Protocols supported by this hub. By default, all protocols registered on the server are allowed. Protocols can be removed from this list to disable specific protocols for individual hubs. |
EnableDetailedErrors |
false |
If true , detailed exception messages are returned to clients when an exception is thrown in a Hub method. The default is false because these exception messages can contain sensitive information. |
StreamBufferCapacity |
10 |
The maximum number of items that can be buffered for client upload streams. If this limit is reached, the processing of invocations is blocked until the server processes stream items. |
MaximumReceiveMessageSize |
32 KB | Maximum size of a single incoming hub message. Increasing the value may increase the risk of Denial of service (DoS) attacks. |
MaximumParallelInvocationsPerClient |
1 | The maximum number of hub methods that each client can call in parallel before queueing. |
Options can be configured for all hubs by providing an options delegate to the AddSignalR
call in Startup.ConfigureServices
.
public void ConfigureServices(IServiceCollection services)
{
services.AddSignalR(hubOptions =>
{
hubOptions.EnableDetailedErrors = true;
hubOptions.KeepAliveInterval = TimeSpan.FromMinutes(1);
});
}
Options for a single hub override the global options provided in AddSignalR
and can be configured using AddHubOptions:
services.AddSignalR().AddHubOptions<ChatHub>(options =>
{
options.EnableDetailedErrors = true;
});
Advanced HTTP configuration options
Use HttpConnectionDispatcherOptions
to configure advanced settings related to transports and memory buffer management. These options are configured by passing a delegate to MapHub in Startup.Configure
.
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
app.UseRouting();
app.UseEndpoints(endpoints =>
{
endpoints.MapHub<ChatHub>("/chathub", options =>
{
options.Transports =
HttpTransportType.WebSockets |
HttpTransportType.LongPolling;
});
});
}
The following table describes options for configuring ASP.NET Core SignalR's advanced HTTP options:
Option | Default Value | Description |
---|---|---|
ApplicationMaxBufferSize |
32 KB | The maximum number of bytes received from the client that the server buffers before applying backpressure. Increasing this value allows the server to receive larger messages more quickly without applying backpressure, but can increase memory consumption. |
AuthorizationData |
Data automatically gathered from the Authorize attributes applied to the Hub class. |
A list of IAuthorizeData objects used to determine if a client is authorized to connect to the hub. |
TransportMaxBufferSize |
32 KB | The maximum number of bytes sent by the app that the server buffers before observing backpressure. Increasing this value allows the server to buffer larger messages more quickly without awaiting backpressure, but can increase memory consumption. |
Transports |
All Transports are enabled. | A bit flags enum of HttpTransportType values that can restrict the transports a client can use to connect. |
LongPolling |
See below. | Additional options specific to the Long Polling transport. |
WebSockets |
See below. | Additional options specific to the WebSockets transport. |
MinimumProtocolVersion |
0 | Specify the minimum version of the negotiate protocol. This is used to limit clients to newer versions. |
The Long Polling transport has additional options that can be configured using the LongPolling
property:
Option | Default Value | Description |
---|---|---|
PollTimeout |
90 seconds | The maximum amount of time the server waits for a message to send to the client before terminating a single poll request. Decreasing this value causes the client to issue new poll requests more frequently. |
The WebSocket transport has additional options that can be configured using the WebSockets
property:
Option | Default Value | Description |
---|---|---|
CloseTimeout |
5 seconds | After the server closes, if the client fails to close within this time interval, the connection is terminated. |
SubProtocolSelector |
null |
A delegate that can be used to set the Sec-WebSocket-Protocol header to a custom value. The delegate receives the values requested by the client as input and is expected to return the desired value. |
Configure client options
Client options can be configured on the HubConnectionBuilder
type (available in the .NET and JavaScript clients). It's also available in the Java client, but the HttpHubConnectionBuilder
subclass is what contains the builder configuration options, as well as on the HubConnection
itself.
Configure logging
Logging is configured in the .NET Client using the ConfigureLogging
method. Logging providers and filters can be registered in the same way as they are on the server. See the Logging in ASP.NET Core documentation for more information.
Note
In order to register Logging providers, you must install the necessary packages. See the Built-in logging providers section of the docs for a full list.
For example, to enable Console logging, install the Microsoft.Extensions.Logging.Console
NuGet package. Call the AddConsole
extension method:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub")
.ConfigureLogging(logging => {
logging.SetMinimumLevel(LogLevel.Information);
logging.AddConsole();
})
.Build();
In the JavaScript client, a similar configureLogging
method exists. Provide a LogLevel
value indicating the minimum level of log messages to produce. Logs are written to the browser console window.
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub")
.configureLogging(signalR.LogLevel.Information)
.build();
Instead of a LogLevel
value, you can also provide a string
value representing a log level name. This is useful when configuring SignalR logging in environments where you don't have access to the LogLevel
constants.
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub")
.configureLogging("warn")
.build();
The following table lists the available log levels. The value you provide to configureLogging
sets the minimum log level that will be logged. Messages logged at this level, or the levels listed after it in the table, will be logged.
String | LogLevel |
---|---|
trace |
LogLevel.Trace |
debug |
LogLevel.Debug |
info or information |
LogLevel.Information |
warn or warning |
LogLevel.Warning |
error |
LogLevel.Error |
critical |
LogLevel.Critical |
none |
LogLevel.None |
Note
To disable logging entirely, specify signalR.LogLevel.None
in the configureLogging
method.
For more information on logging, see the SignalR Diagnostics documentation.
The SignalR Java client uses the SLF4J library for logging. It's a high-level logging API that allows users of the library to choose their own specific logging implementation by bringing in a specific logging dependency. The following code snippet shows how to use java.util.logging
with the SignalR Java client.
implementation 'org.slf4j:slf4j-jdk14:1.7.25'
If you don't configure logging in your dependencies, SLF4J loads a default no-operation logger with the following warning message:
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
This can safely be ignored.
Configure allowed transports
The transports used by SignalR can be configured in the WithUrl
call (withUrl
in JavaScript). A bitwise-OR of the values of HttpTransportType
can be used to restrict the client to only use the specified transports. All transports are enabled by default.
For example, to disable the Server-Sent Events transport, but allow WebSockets and Long Polling connections:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", HttpTransportType.WebSockets | HttpTransportType.LongPolling)
.Build();
In the JavaScript client, transports are configured by setting the transport
field on the options object provided to withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", { transport: signalR.HttpTransportType.WebSockets | signalR.HttpTransportType.LongPolling })
.build();
In this version of the Java client websockets is the only available transport.
In the Java client, the transport is selected with the withTransport
method on the HttpHubConnectionBuilder
. The Java client defaults to using the WebSockets transport.
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withTransport(TransportEnum.WEBSOCKETS)
.build();
Note
The SignalR Java client doesn't support transport fallback yet.
Configure bearer authentication
To provide authentication data along with SignalR requests, use the AccessTokenProvider
option (accessTokenFactory
in JavaScript) to specify a function that returns the desired access token. In the .NET Client, this access token is passed in as an HTTP "Bearer Authentication" token (Using the Authorization
header with a type of Bearer
). In the JavaScript client, the access token is used as a Bearer token, except in a few cases where browser APIs restrict the ability to apply headers (specifically, in Server-Sent Events and WebSockets requests). In these cases, the access token is provided as a query string value access_token
.
In the .NET client, the AccessTokenProvider
option can be specified using the options delegate in WithUrl
:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", options => {
options.AccessTokenProvider = async () => {
// Get and return the access token.
};
})
.Build();
In the JavaScript client, the access token is configured by setting the accessTokenFactory
field on the options object in withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", {
accessTokenFactory: () => {
// Get and return the access token.
// This function can return a JavaScript Promise if asynchronous
// logic is required to retrieve the access token.
}
})
.build();
In the SignalR Java client, you can configure a bearer token to use for authentication by providing an access token factory to the HttpHubConnectionBuilder. Use withAccessTokenFactory to provide an RxJava Single<String>. With a call to Single.defer, you can write logic to produce access tokens for your client.
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withAccessTokenProvider(Single.defer(() -> {
// Your logic here.
return Single.just("An Access Token");
})).build();
Configure timeout and keep-alive options
Additional options for configuring timeout and keep-alive behavior are available on the HubConnection
object itself:
Option | Default value | Description |
---|---|---|
ServerTimeout |
30 seconds (30,000 milliseconds) | Timeout for server activity. If the server hasn't sent a message in this interval, the client considers the server disconnected and triggers the Closed event (onclose in JavaScript). This value must be large enough for a ping message to be sent from the server and received by the client within the timeout interval. The recommended value is a number at least double the server's KeepAliveInterval value to allow time for pings to arrive. |
HandshakeTimeout |
15 seconds | Timeout for initial server handshake. If the server doesn't send a handshake response in this interval, the client cancels the handshake and triggers the Closed event (onclose in JavaScript). This is an advanced setting that should only be modified if handshake timeout errors are occurring due to severe network latency. For more detail on the handshake process, see the SignalR Hub Protocol Specification. |
KeepAliveInterval |
15 seconds | Determines the interval at which the client sends ping messages. Sending any message from the client resets the timer to the start of the interval. If the client hasn't sent a message in the ClientTimeoutInterval set on the server, the server considers the client disconnected. |
In the .NET Client, timeout values are specified as TimeSpan
values.
Configure additional options
Additional options can be configured in the WithUrl
(withUrl
in JavaScript) method on HubConnectionBuilder
or on the various configuration APIs on the HttpHubConnectionBuilder
in the Java client:
.NET Option | Default value | Description |
---|---|---|
AccessTokenProvider |
null |
A function returning a string that is provided as a Bearer authentication token in HTTP requests. |
SkipNegotiation |
false |
Set this to true to skip the negotiation step. Only supported when the WebSockets transport is the only enabled transport. This setting can't be enabled when using the Azure SignalR Service. |
ClientCertificates |
Empty | A collection of TLS certificates to send to authenticate requests. |
Cookies |
Empty | A collection of HTTP cookies to send with every HTTP request. |
Credentials |
Empty | Credentials to send with every HTTP request. |
CloseTimeout |
5 seconds | WebSockets only. The maximum amount of time the client waits after closing for the server to acknowledge the close request. If the server doesn't acknowledge the close within this time, the client disconnects. |
Headers |
Empty | A Map of additional HTTP headers to send with every HTTP request. |
HttpMessageHandlerFactory |
null |
A delegate that can be used to configure or replace the HttpMessageHandler used to send HTTP requests. Not used for WebSocket connections. This delegate must return a non-null value, and it receives the default value as a parameter. Either modify settings on that default value and return it, or return a new HttpMessageHandler instance. When replacing the handler make sure to copy the settings you want to keep from the provided handler, otherwise, the configured options (such as Cookies and Headers) won't apply to the new handler. |
Proxy |
null |
An HTTP proxy to use when sending HTTP requests. |
UseDefaultCredentials |
false |
Set this boolean to send the default credentials for HTTP and WebSockets requests. This enables the use of Windows authentication. |
WebSocketConfiguration |
null |
A delegate that can be used to configure additional WebSocket options. Receives an instance of ClientWebSocketOptions that can be used to configure the options. |
In the .NET Client, these options can be modified by the options delegate provided to WithUrl
:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", options => {
options.Headers["Foo"] = "Bar";
options.SkipNegotiation = true;
options.Transports = HttpTransportType.WebSockets;
options.Cookies.Add(new Cookie(/* ... */);
options.ClientCertificates.Add(/* ... */);
})
.Build();
In the JavaScript Client, these options can be provided in a JavaScript object provided to withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", {
// "Foo: Bar" will not be sent with WebSockets or Server-Sent Events requests
headers: { "Foo": "Bar" },
transport: signalR.HttpTransportType.LongPolling
})
.build();
In the Java client, these options can be configured with the methods on the HttpHubConnectionBuilder
returned from the HubConnectionBuilder.create("HUB URL")
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withHeader("Foo", "Bar")
.shouldSkipNegotiate(true)
.withHandshakeResponseTimeout(30*1000)
.build();
Additional resources
JSON/MessagePack serialization options
ASP.NET Core SignalR supports two protocols for encoding messages: JSON and MessagePack. Each protocol has serialization configuration options.
JSON serialization can be configured on the server using the AddJsonProtocol extension method. AddJsonProtocol
can be added after AddSignalR in Program.cs
. The AddJsonProtocol
method takes a delegate that receives an options
object. The PayloadSerializerOptions property on that object is a System.Text.Json
JsonSerializerOptions object that can be used to configure serialization of arguments and return values. For more information, see the System.Text.Json documentation.
For example, to configure the serializer to not change the casing of property names, rather than the default camel case names, use the following code in Program.cs
:
builder.Services.AddSignalR()
.AddJsonProtocol(options => {
options.PayloadSerializerOptions.PropertyNamingPolicy = null;
});
In the .NET client, the same AddJsonProtocol
extension method exists on HubConnectionBuilder. The Microsoft.Extensions.DependencyInjection
namespace must be imported to resolve the extension method:
// At the top of the file:
using Microsoft.Extensions.DependencyInjection;
// When constructing your connection:
var connection = new HubConnectionBuilder()
.AddJsonProtocol(options => {
options.PayloadSerializerOptions.PropertyNamingPolicy = null;
})
.Build();
Note
It's not possible to configure JSON serialization in the JavaScript client at this time.
Switch to Newtonsoft.Json
If you need features of Newtonsoft.Json
that aren't supported in System.Text.Json
, see Switch to Newtonsoft.Json
.
MessagePack serialization options
MessagePack serialization can be configured by providing a delegate to the AddMessagePackProtocol call. See MessagePack in SignalR for more details.
Note
It's not possible to configure MessagePack serialization in the JavaScript client at this time.
Configure server options
The following table describes options for configuring SignalR hubs:
Option | Default Value | Description |
---|---|---|
ClientTimeoutInterval |
30 seconds | The server considers the client disconnected if it hasn't received a message (including keep-alive) in this interval. It could take longer than this timeout interval for the client to be marked disconnected due to how this is implemented. The recommended value is double the KeepAliveInterval value. |
HandshakeTimeout |
15 seconds | If the client doesn't send an initial handshake message within this time interval, the connection is closed. This is an advanced setting that should only be modified if handshake timeout errors are occurring due to severe network latency. For more detail on the handshake process, see the SignalR Hub Protocol Specification. |
KeepAliveInterval |
15 seconds | If the server hasn't sent a message within this interval, a ping message is sent automatically to keep the connection open. When changing KeepAliveInterval , change the ServerTimeout or serverTimeoutInMilliseconds setting on the client. The recommended ServerTimeout or serverTimeoutInMilliseconds value is double the KeepAliveInterval value. |
SupportedProtocols |
All installed protocols | Protocols supported by this hub. By default, all protocols registered on the server are allowed. Protocols can be removed from this list to disable specific protocols for individual hubs. |
EnableDetailedErrors |
false |
If true , detailed exception messages are returned to clients when an exception is thrown in a Hub method. The default is false because these exception messages can contain sensitive information. |
StreamBufferCapacity |
10 |
The maximum number of items that can be buffered for client upload streams. If this limit is reached, the processing of invocations is blocked until the server processes stream items. |
MaximumReceiveMessageSize |
32 KB | Maximum size of a single incoming hub message. Increasing the value may increase the risk of Denial of service (DoS) attacks. |
MaximumParallelInvocationsPerClient |
1 | The maximum number of hub methods that each client can call in parallel before queueing. |
Options can be configured for all hubs by providing an options delegate to the AddSignalR
call in Program.cs
.
builder.Services.AddSignalR(hubOptions =>
{
hubOptions.EnableDetailedErrors = true;
hubOptions.KeepAliveInterval = TimeSpan.FromMinutes(1);
});
Options for a single hub override the global options provided in AddSignalR
and can be configured using AddHubOptions:
builder.Services.AddSignalR().AddHubOptions<ChatHub>(options =>
{
options.EnableDetailedErrors = true;
});
Advanced HTTP configuration options
Use HttpConnectionDispatcherOptions
to configure advanced settings related to transports and memory buffer management. These options are configured by passing a delegate to MapHub in Program.cs
.
using Microsoft.AspNetCore.Http.Connections;
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddRazorPages();
builder.Services.AddSignalR();
var app = builder.Build();
if (!app.Environment.IsDevelopment())
{
app.UseExceptionHandler("/Error");
app.UseHsts();
}
app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();
app.UseAuthorization();
app.MapRazorPages();
app.MapHub<ChatHub>("/chathub", options =>
{
options.Transports =
HttpTransportType.WebSockets |
HttpTransportType.LongPolling;
}
);
app.Run();
The following table describes options for configuring ASP.NET Core SignalR's advanced HTTP options:
Option | Default Value | Description |
---|---|---|
ApplicationMaxBufferSize |
64 KB | The maximum number of bytes received from the client that the server buffers before applying backpressure. Increasing this value allows the server to receive larger messages faster without applying backpressure, but can increase memory consumption. |
TransportMaxBufferSize |
64 KB | The maximum number of bytes sent by the app that the server buffers before observing backpressure. Increasing this value allows the server to buffer larger messages faster without awaiting backpressure, but can increase memory consumption. |
AuthorizationData |
Data automatically gathered from the Authorize attributes applied to the Hub class. |
A list of IAuthorizeData objects used to determine if a client is authorized to connect to the hub. |
Transports |
All Transports are enabled. | A bit flags enum of HttpTransportType values that can restrict the transports a client can use to connect. |
LongPolling |
See below. | Additional options specific to the Long Polling transport. |
WebSockets |
See below. | Additional options specific to the WebSockets transport. |
MinimumProtocolVersion |
0 | Specify the minimum version of the negotiate protocol. This is used to limit clients to newer versions. |
CloseOnAuthenticationExpiration |
false | Set this option to enable authentication expiration tracking which will close connections when a token expires. |
The Long Polling transport has additional options that can be configured using the LongPolling
property:
Option | Default Value | Description |
---|---|---|
PollTimeout |
90 seconds | The maximum amount of time the server waits for a message to send to the client before terminating a single poll request. Decreasing this value causes the client to issue new poll requests more frequently. |
The WebSocket transport has additional options that can be configured using the WebSockets
property:
Option | Default Value | Description |
---|---|---|
CloseTimeout |
5 seconds | After the server closes, if the client fails to close within this time interval, the connection is terminated. |
SubProtocolSelector |
null |
A delegate that can be used to set the Sec-WebSocket-Protocol header to a custom value. The delegate receives the values requested by the client as input and is expected to return the desired value. |
Configure client options
Client options can be configured on the HubConnectionBuilder
type (available in the .NET and JavaScript clients). It's also available in the Java client, but the HttpHubConnectionBuilder
subclass is what contains the builder configuration options, as well as on the HubConnection
itself.
Configure logging
Logging is configured in the .NET Client using the ConfigureLogging
method. Logging providers and filters can be registered in the same way as they are on the server. See the Logging in ASP.NET Core documentation for more information.
Note
In order to register Logging providers, you must install the necessary packages. See the Built-in logging providers section of the docs for a full list.
For example, to enable Console logging, install the Microsoft.Extensions.Logging.Console
NuGet package. Call the AddConsole
extension method:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub")
.ConfigureLogging(logging => {
logging.SetMinimumLevel(LogLevel.Information);
logging.AddConsole();
})
.Build();
In the JavaScript client, a similar configureLogging
method exists. Provide a LogLevel
value indicating the minimum level of log messages to produce. Logs are written to the browser console window.
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub")
.configureLogging(signalR.LogLevel.Information)
.build();
Instead of a LogLevel
value, you can also provide a string
value representing a log level name. This is useful when configuring SignalR logging in environments where you don't have access to the LogLevel
constants.
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub")
.configureLogging("warn")
.build();
The following table lists the available log levels. The value you provide to configureLogging
sets the minimum log level that will be logged. Messages logged at this level, or the levels listed after it in the table, will be logged.
String | LogLevel |
---|---|
trace |
LogLevel.Trace |
debug |
LogLevel.Debug |
info or information |
LogLevel.Information |
warn or warning |
LogLevel.Warning |
error |
LogLevel.Error |
critical |
LogLevel.Critical |
none |
LogLevel.None |
Note
To disable logging entirely, specify signalR.LogLevel.None
in the configureLogging
method.
For more information on logging, see the SignalR Diagnostics documentation.
The SignalR Java client uses the SLF4J library for logging. It's a high-level logging API that allows users of the library to choose their own specific logging implementation by bringing in a specific logging dependency. The following code snippet shows how to use java.util.logging
with the SignalR Java client.
implementation 'org.slf4j:slf4j-jdk14:1.7.25'
If you don't configure logging in your dependencies, SLF4J loads a default no-operation logger with the following warning message:
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
This can safely be ignored.
Configure allowed transports
The transports used by SignalR can be configured in the WithUrl
call (withUrl
in JavaScript). A bitwise-OR of the values of HttpTransportType
can be used to restrict the client to only use the specified transports. All transports are enabled by default.
For example, to disable the Server-Sent Events transport, but allow WebSockets and Long Polling connections:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", HttpTransportType.WebSockets | HttpTransportType.LongPolling)
.Build();
In the JavaScript client, transports are configured by setting the transport
field on the options object provided to withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", { transport: signalR.HttpTransportType.WebSockets | signalR.HttpTransportType.LongPolling })
.build();
In this version of the Java client websockets is the only available transport.
In the Java client, the transport is selected with the withTransport
method on the HttpHubConnectionBuilder
. The Java client defaults to using the WebSockets transport.
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withTransport(TransportEnum.WEBSOCKETS)
.build();
Note
The SignalR Java client doesn't support transport fallback yet.
Configure bearer authentication
To provide authentication data along with SignalR requests, use the AccessTokenProvider
option (accessTokenFactory
in JavaScript) to specify a function that returns the desired access token. In the .NET Client, this access token is passed in as an HTTP "Bearer Authentication" token (Using the Authorization
header with a type of Bearer
). In the JavaScript client, the access token is used as a Bearer token, except in a few cases where browser APIs restrict the ability to apply headers (specifically, in Server-Sent Events and WebSockets requests). In these cases, the access token is provided as a query string value access_token
.
In the .NET client, the AccessTokenProvider
option can be specified using the options delegate in WithUrl
:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", options => {
options.AccessTokenProvider = async () => {
// Get and return the access token.
};
})
.Build();
In the JavaScript client, the access token is configured by setting the accessTokenFactory
field on the options object in withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", {
accessTokenFactory: () => {
// Get and return the access token.
// This function can return a JavaScript Promise if asynchronous
// logic is required to retrieve the access token.
}
})
.build();
In the SignalR Java client, you can configure a bearer token to use for authentication by providing an access token factory to the HttpHubConnectionBuilder. Use withAccessTokenFactory to provide an RxJava Single<String>. With a call to Single.defer, you can write logic to produce access tokens for your client.
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withAccessTokenProvider(Single.defer(() -> {
// Your logic here.
return Single.just("An Access Token");
})).build();
Configure timeout and keep-alive options
Additional options for configuring timeout and keep-alive behavior are available on the HubConnection
object itself:
Option | Default value | Description |
---|---|---|
ServerTimeout |
30 seconds (30,000 milliseconds) | Timeout for server activity. If the server hasn't sent a message in this interval, the client considers the server disconnected and triggers the Closed event (onclose in JavaScript). This value must be large enough for a ping message to be sent from the server and received by the client within the timeout interval. The recommended value is a number at least double the server's KeepAliveInterval value to allow time for pings to arrive. |
HandshakeTimeout |
15 seconds | Timeout for initial server handshake. If the server doesn't send a handshake response in this interval, the client cancels the handshake and triggers the Closed event (onclose in JavaScript). This is an advanced setting that should only be modified if handshake timeout errors are occurring due to severe network latency. For more detail on the handshake process, see the SignalR Hub Protocol Specification. |
KeepAliveInterval |
15 seconds | Determines the interval at which the client sends ping messages. Sending any message from the client resets the timer to the start of the interval. If the client hasn't sent a message in the ClientTimeoutInterval set on the server, the server considers the client disconnected. |
In the .NET Client, timeout values are specified as TimeSpan
values.
Configure additional options
Additional options can be configured in the WithUrl
(withUrl
in JavaScript) method on HubConnectionBuilder
or on the various configuration APIs on the HttpHubConnectionBuilder
in the Java client:
.NET Option | Default value | Description |
---|---|---|
AccessTokenProvider |
null |
A function returning a string that is provided as a Bearer authentication token in HTTP requests. |
SkipNegotiation |
false |
Set this to true to skip the negotiation step. Only supported when the WebSockets transport is the only enabled transport. This setting can't be enabled when using the Azure SignalR Service. |
ClientCertificates |
Empty | A collection of TLS certificates to send to authenticate requests. |
Cookies |
Empty | A collection of HTTP cookies to send with every HTTP request. |
Credentials |
Empty | Credentials to send with every HTTP request. |
CloseTimeout |
5 seconds | WebSockets only. The maximum amount of time the client waits after closing for the server to acknowledge the close request. If the server doesn't acknowledge the close within this time, the client disconnects. |
Headers |
Empty | A Map of additional HTTP headers to send with every HTTP request. |
HttpMessageHandlerFactory |
null |
A delegate that can be used to configure or replace the HttpMessageHandler used to send HTTP requests. Not used for WebSocket connections. This delegate must return a non-null value, and it receives the default value as a parameter. Either modify settings on that default value and return it, or return a new HttpMessageHandler instance. When replacing the handler make sure to copy the settings you want to keep from the provided handler, otherwise, the configured options (such as Cookies and Headers) won't apply to the new handler. |
Proxy |
null |
An HTTP proxy to use when sending HTTP requests. |
UseDefaultCredentials |
false |
Set this boolean to send the default credentials for HTTP and WebSockets requests. This enables the use of Windows authentication. |
WebSocketConfiguration |
null |
A delegate that can be used to configure additional WebSocket options. Receives an instance of ClientWebSocketOptions that can be used to configure the options. |
ApplicationMaxBufferSize |
1 MB | The maximum number of bytes received from the server that the client buffers before applying backpressure. Increasing this value allows the client to receive larger messages faster without applying backpressure, but can increase memory consumption. |
TransportMaxBufferSize |
1 MB | The maximum number of bytes sent by the user application that the client buffers before observing backpressure. Increasing this value allows the client to buffer larger messages faster without awaiting backpressure, but can increase memory consumption. |
In the .NET Client, these options can be modified by the options delegate provided to WithUrl
:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", options => {
options.Headers["Foo"] = "Bar";
options.SkipNegotiation = true;
options.Transports = HttpTransportType.WebSockets;
options.Cookies.Add(new Cookie(/* ... */);
options.ClientCertificates.Add(/* ... */);
})
.Build();
In the JavaScript Client, these options can be provided in a JavaScript object provided to withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", {
// "Foo: Bar" will not be sent with WebSockets or Server-Sent Events requests
headers: { "Foo": "Bar" },
transport: signalR.HttpTransportType.LongPolling
})
.build();
In the Java client, these options can be configured with the methods on the HttpHubConnectionBuilder
returned from the HubConnectionBuilder.create("HUB URL")
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withHeader("Foo", "Bar")
.shouldSkipNegotiate(true)
.withHandshakeResponseTimeout(30*1000)
.build();
Additional resources
JSON/MessagePack serialization options
ASP.NET Core SignalR supports two protocols for encoding messages: JSON and MessagePack. Each protocol has serialization configuration options.
JSON serialization can be configured on the server using the AddJsonProtocol extension method. AddJsonProtocol
can be added after AddSignalR in Startup.ConfigureServices
. The AddJsonProtocol
method takes a delegate that receives an options
object. The PayloadSerializerOptions property on that object is a System.Text.Json
JsonSerializerOptions object that can be used to configure serialization of arguments and return values. For more information, see the System.Text.Json documentation.
For example, to configure the serializer to not change the casing of property names, rather than the default camel case names, use the following code in Program.cs
:
builder.Services.AddSignalR()
.AddJsonProtocol(options => {
options.PayloadSerializerOptions.PropertyNamingPolicy = null;
});
In the .NET client, the same AddJsonProtocol
extension method exists on HubConnectionBuilder. The Microsoft.Extensions.DependencyInjection
namespace must be imported to resolve the extension method:
// At the top of the file:
using Microsoft.Extensions.DependencyInjection;
// When constructing your connection:
var connection = new HubConnectionBuilder()
.AddJsonProtocol(options => {
options.PayloadSerializerOptions.PropertyNamingPolicy = null;
})
.Build();
Note
It's not possible to configure JSON serialization in the JavaScript client at this time.
Switch to Newtonsoft.Json
If you need features of Newtonsoft.Json
that aren't supported in System.Text.Json
, see Switch to Newtonsoft.Json
.
MessagePack serialization options
MessagePack serialization can be configured by providing a delegate to the AddMessagePackProtocol call. See MessagePack in SignalR for more details.
Note
It's not possible to configure MessagePack serialization in the JavaScript client at this time.
Configure server options
The following table describes options for configuring SignalR hubs:
Option | Default Value | Description |
---|---|---|
ClientTimeoutInterval |
30 seconds | The server considers the client disconnected if it hasn't received a message (including keep-alive) in this interval. It could take longer than this timeout interval for the client to be marked disconnected due to how this is implemented. The recommended value is double the KeepAliveInterval value. |
HandshakeTimeout |
15 seconds | If the client doesn't send an initial handshake message within this time interval, the connection is closed. This is an advanced setting that should only be modified if handshake timeout errors are occurring due to severe network latency. For more detail on the handshake process, see the SignalR Hub Protocol Specification. |
KeepAliveInterval |
15 seconds | If the server hasn't sent a message within this interval, a ping message is sent automatically to keep the connection open. When changing KeepAliveInterval , change the ServerTimeout or serverTimeoutInMilliseconds setting on the client. The recommended ServerTimeout or serverTimeoutInMilliseconds value is double the KeepAliveInterval value. |
SupportedProtocols |
All installed protocols | Protocols supported by this hub. By default, all protocols registered on the server are allowed. Protocols can be removed from this list to disable specific protocols for individual hubs. |
EnableDetailedErrors |
false |
If true , detailed exception messages are returned to clients when an exception is thrown in a Hub method. The default is false because these exception messages can contain sensitive information. |
StreamBufferCapacity |
10 |
The maximum number of items that can be buffered for client upload streams. If this limit is reached, the processing of invocations is blocked until the server processes stream items. |
MaximumReceiveMessageSize |
32 KB | Maximum size of a single incoming hub message. Increasing the value may increase the risk of Denial of service (DoS) attacks. |
MaximumParallelInvocationsPerClient |
1 | The maximum number of hub methods that each client can call in parallel before queueing. |
DisableImplicitFromServicesParameters |
false |
Hub method arguments will be resolved from DI if possible. |
Options can be configured for all hubs by providing an options delegate to the AddSignalR
call in Program.cs
.
builder.Services.AddSignalR(hubOptions =>
{
hubOptions.EnableDetailedErrors = true;
hubOptions.KeepAliveInterval = TimeSpan.FromMinutes(1);
});
Options for a single hub override the global options provided in AddSignalR
and can be configured using AddHubOptions:
builder.Services.AddSignalR().AddHubOptions<ChatHub>(options =>
{
options.EnableDetailedErrors = true;
});
Advanced HTTP configuration options
Use HttpConnectionDispatcherOptions
to configure advanced settings related to transports and memory buffer management. These options are configured by passing a delegate to MapHub in Program.cs
.
using Microsoft.AspNetCore.Http.Connections;
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddRazorPages();
builder.Services.AddSignalR();
var app = builder.Build();
if (!app.Environment.IsDevelopment())
{
app.UseExceptionHandler("/Error");
app.UseHsts();
}
app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();
app.UseAuthorization();
app.MapRazorPages();
app.MapHub<ChatHub>("/chathub", options =>
{
options.Transports =
HttpTransportType.WebSockets |
HttpTransportType.LongPolling;
}
);
app.Run();
The following table describes options for configuring ASP.NET Core SignalR's advanced HTTP options:
Option | Default Value | Description |
---|---|---|
ApplicationMaxBufferSize |
64 KB | The maximum number of bytes received from the client that the server buffers before applying backpressure. Increasing this value allows the server to receive larger messages faster without applying backpressure, but can increase memory consumption. |
TransportMaxBufferSize |
64 KB | The maximum number of bytes sent by the app that the server buffers before observing backpressure. Increasing this value allows the server to buffer larger messages faster without awaiting backpressure, but can increase memory consumption. |
AuthorizationData |
Data automatically gathered from the Authorize attributes applied to the Hub class. |
A list of IAuthorizeData objects used to determine if a client is authorized to connect to the hub. |
Transports |
All Transports are enabled. | A bit flags enum of HttpTransportType values that can restrict the transports a client can use to connect. |
LongPolling |
See below. | Additional options specific to the Long Polling transport. |
WebSockets |
See below. | Additional options specific to the WebSockets transport. |
MinimumProtocolVersion |
0 | Specify the minimum version of the negotiate protocol. This is used to limit clients to newer versions. |
CloseOnAuthenticationExpiration |
false | Set this option to enable authentication expiration tracking which will close connections when a token expires. |
The Long Polling transport has additional options that can be configured using the LongPolling
property:
Option | Default Value | Description |
---|---|---|
PollTimeout |
90 seconds | The maximum amount of time the server waits for a message to send to the client before terminating a single poll request. Decreasing this value causes the client to issue new poll requests more frequently. |
The WebSocket transport has additional options that can be configured using the WebSockets
property:
Option | Default Value | Description |
---|---|---|
CloseTimeout |
5 seconds | After the server closes, if the client fails to close within this time interval, the connection is terminated. |
SubProtocolSelector |
null |
A delegate that can be used to set the Sec-WebSocket-Protocol header to a custom value. The delegate receives the values requested by the client as input and is expected to return the desired value. |
Configure client options
Client options can be configured on the HubConnectionBuilder
type (available in the .NET and JavaScript clients). It's also available in the Java client, but the HttpHubConnectionBuilder
subclass is what contains the builder configuration options, as well as on the HubConnection
itself.
Configure logging
Logging is configured in the .NET Client using the ConfigureLogging
method. Logging providers and filters can be registered in the same way as they are on the server. See the Logging in ASP.NET Core documentation for more information.
Note
In order to register Logging providers, you must install the necessary packages. See the Built-in logging providers section of the docs for a full list.
For example, to enable Console logging, install the Microsoft.Extensions.Logging.Console
NuGet package. Call the AddConsole
extension method:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub")
.ConfigureLogging(logging => {
logging.SetMinimumLevel(LogLevel.Information);
logging.AddConsole();
})
.Build();
In the JavaScript client, a similar configureLogging
method exists. Provide a LogLevel
value indicating the minimum level of log messages to produce. Logs are written to the browser console window.
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub")
.configureLogging(signalR.LogLevel.Information)
.build();
Instead of a LogLevel
value, you can also provide a string
value representing a log level name. This is useful when configuring SignalR logging in environments where you don't have access to the LogLevel
constants.
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub")
.configureLogging("warn")
.build();
The following table lists the available log levels. The value you provide to configureLogging
sets the minimum log level that will be logged. Messages logged at this level, or the levels listed after it in the table, will be logged.
String | LogLevel |
---|---|
trace |
LogLevel.Trace |
debug |
LogLevel.Debug |
info or information |
LogLevel.Information |
warn or warning |
LogLevel.Warning |
error |
LogLevel.Error |
critical |
LogLevel.Critical |
none |
LogLevel.None |
Note
To disable logging entirely, specify signalR.LogLevel.None
in the configureLogging
method.
For more information on logging, see the SignalR Diagnostics documentation.
The SignalR Java client uses the SLF4J library for logging. It's a high-level logging API that allows users of the library to choose their own specific logging implementation by bringing in a specific logging dependency. The following code snippet shows how to use java.util.logging
with the SignalR Java client.
implementation 'org.slf4j:slf4j-jdk14:1.7.25'
If you don't configure logging in your dependencies, SLF4J loads a default no-operation logger with the following warning message:
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
This can safely be ignored.
Configure allowed transports
The transports used by SignalR can be configured in the WithUrl
call (withUrl
in JavaScript). A bitwise-OR of the values of HttpTransportType
can be used to restrict the client to only use the specified transports. All transports are enabled by default.
For example, to disable the Server-Sent Events transport, but allow WebSockets and Long Polling connections:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", HttpTransportType.WebSockets | HttpTransportType.LongPolling)
.Build();
In the JavaScript client, transports are configured by setting the transport
field on the options object provided to withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", { transport: signalR.HttpTransportType.WebSockets | signalR.HttpTransportType.LongPolling })
.build();
In this version of the Java client websockets is the only available transport.
In the Java client, the transport is selected with the withTransport
method on the HttpHubConnectionBuilder
. The Java client defaults to using the WebSockets transport.
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withTransport(TransportEnum.WEBSOCKETS)
.build();
Note
The SignalR Java client doesn't support transport fallback yet.
Configure bearer authentication
To provide authentication data along with SignalR requests, use the AccessTokenProvider
option (accessTokenFactory
in JavaScript) to specify a function that returns the desired access token. In the .NET Client, this access token is passed in as an HTTP "Bearer Authentication" token (Using the Authorization
header with a type of Bearer
). In the JavaScript client, the access token is used as a Bearer token, except in a few cases where browser APIs restrict the ability to apply headers (specifically, in Server-Sent Events and WebSockets requests). In these cases, the access token is provided as a query string value access_token
.
In the .NET client, the AccessTokenProvider
option can be specified using the options delegate in WithUrl
:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", options => {
options.AccessTokenProvider = async () => {
// Get and return the access token.
};
})
.Build();
In the JavaScript client, the access token is configured by setting the accessTokenFactory
field on the options object in withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", {
accessTokenFactory: () => {
// Get and return the access token.
// This function can return a JavaScript Promise if asynchronous
// logic is required to retrieve the access token.
}
})
.build();
In the SignalR Java client, you can configure a bearer token to use for authentication by providing an access token factory to the HttpHubConnectionBuilder. Use withAccessTokenFactory to provide an RxJava Single<String>. With a call to Single.defer, you can write logic to produce access tokens for your client.
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withAccessTokenProvider(Single.defer(() -> {
// Your logic here.
return Single.just("An Access Token");
})).build();
Configure timeout and keep-alive options
Additional options for configuring timeout and keep-alive behavior are available on the HubConnection
object itself:
Option | Default value | Description |
---|---|---|
ServerTimeout |
30 seconds (30,000 milliseconds) | Timeout for server activity. If the server hasn't sent a message in this interval, the client considers the server disconnected and triggers the Closed event (onclose in JavaScript). This value must be large enough for a ping message to be sent from the server and received by the client within the timeout interval. The recommended value is a number at least double the server's KeepAliveInterval value to allow time for pings to arrive. |
HandshakeTimeout |
15 seconds | Timeout for initial server handshake. If the server doesn't send a handshake response in this interval, the client cancels the handshake and triggers the Closed event (onclose in JavaScript). This is an advanced setting that should only be modified if handshake timeout errors are occurring due to severe network latency. For more detail on the handshake process, see the SignalR Hub Protocol Specification. |
KeepAliveInterval |
15 seconds | Determines the interval at which the client sends ping messages. Sending any message from the client resets the timer to the start of the interval. If the client hasn't sent a message in the ClientTimeoutInterval set on the server, the server considers the client disconnected. |
In the .NET Client, timeout values are specified as TimeSpan
values.
Configure additional options
Additional options can be configured in the WithUrl
(withUrl
in JavaScript) method on HubConnectionBuilder
or on the various configuration APIs on the HttpHubConnectionBuilder
in the Java client:
.NET Option | Default value | Description |
---|---|---|
AccessTokenProvider |
null |
A function returning a string that is provided as a Bearer authentication token in HTTP requests. |
SkipNegotiation |
false |
Set this to true to skip the negotiation step. Only supported when the WebSockets transport is the only enabled transport. This setting can't be enabled when using the Azure SignalR Service. |
ClientCertificates |
Empty | A collection of TLS certificates to send to authenticate requests. |
Cookies |
Empty | A collection of HTTP cookies to send with every HTTP request. |
Credentials |
Empty | Credentials to send with every HTTP request. |
CloseTimeout |
5 seconds | WebSockets only. The maximum amount of time the client waits after closing for the server to acknowledge the close request. If the server doesn't acknowledge the close within this time, the client disconnects. |
Headers |
Empty | A Map of additional HTTP headers to send with every HTTP request. |
HttpMessageHandlerFactory |
null |
A delegate that can be used to configure or replace the HttpMessageHandler used to send HTTP requests. Not used for WebSocket connections. This delegate must return a non-null value, and it receives the default value as a parameter. Either modify settings on that default value and return it, or return a new HttpMessageHandler instance. When replacing the handler make sure to copy the settings you want to keep from the provided handler, otherwise, the configured options (such as Cookies and Headers) won't apply to the new handler. |
Proxy |
null |
An HTTP proxy to use when sending HTTP requests. |
UseDefaultCredentials |
false |
Set this boolean to send the default credentials for HTTP and WebSockets requests. This enables the use of Windows authentication. |
WebSocketConfiguration |
null |
A delegate that can be used to configure additional WebSocket options. Receives an instance of ClientWebSocketOptions that can be used to configure the options. |
ApplicationMaxBufferSize |
1 MB | The maximum number of bytes received from the server that the client buffers before applying backpressure. Increasing this value allows the client to receive larger messages faster without applying backpressure, but can increase memory consumption. |
TransportMaxBufferSize |
1 MB | The maximum number of bytes sent by the user application that the client buffers before observing backpressure. Increasing this value allows the client to buffer larger messages faster without awaiting backpressure, but can increase memory consumption. |
In the .NET Client, these options can be modified by the options delegate provided to WithUrl
:
var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/chathub", options => {
options.Headers["Foo"] = "Bar";
options.SkipNegotiation = true;
options.Transports = HttpTransportType.WebSockets;
options.Cookies.Add(new Cookie(/* ... */);
options.ClientCertificates.Add(/* ... */);
})
.Build();
In the JavaScript Client, these options can be provided in a JavaScript object provided to withUrl
:
let connection = new signalR.HubConnectionBuilder()
.withUrl("/chathub", {
// "Foo: Bar" will not be sent with WebSockets or Server-Sent Events requests
headers: { "Foo": "Bar" },
transport: signalR.HttpTransportType.LongPolling
})
.build();
In the Java client, these options can be configured with the methods on the HttpHubConnectionBuilder
returned from the HubConnectionBuilder.create("HUB URL")
HubConnection hubConnection = HubConnectionBuilder.create("https://example.com/chathub")
.withHeader("Foo", "Bar")
.shouldSkipNegotiate(true)
.withHandshakeResponseTimeout(30*1000)
.build();
Additional resources
ASP.NET Core