WebSocket sample

Code Sample
06/21/2023

Shows how to send and receive data using the WebSocket classes in the Windows.Networking.Sockets namespace.

The sample demonstrates the following:

Making a WebSocket connection, sending and receiving data, and closing the connection.
Handling both trusted (hard coded) URI inputs and unvalidated (user-entered) URI inputs.
Accessing the server certificate information and perform custom validation (if needed) when using a secure Websocket (wss://) endpoint.
Providing a custom client certificate to use when establishing a secure Websocket connection.

Note: This sample is part of a large collection of UWP feature samples. You can download this sample as a standalone ZIP file from docs.microsoft.com, or you can download the entire collection as a single ZIP file, but be sure to unzip everything to access shared dependencies. For more info on working with the ZIP file, the samples collection, and GitHub, see Get the UWP samples from GitHub. For more samples, see the Samples portal on the Windows Dev Center.

Windows 10 provides support for the client use of WebSockets in a Universal Windows Platform (UWP) app. The Windows.Networking.Sockets namespace defines two types of WebSocket objects for use by clients:

MessageWebSocket is suitable for typical scenarios where messages are not extremely large. Both UTF-8 and binary messages are supported.
StreamWebSocket is more suitable for scenarios in which large files (such as photos or movies) are being transferred, allowing sections of a message to be read with each read operation rather than reading the entire message at once. Only binary messages are supported.

Both MessageWebSocket and StreamWebSocket connections are demonstrated in this sample. This sample shows how to use the following features:

Use a MessageWebSocket to send UTF-8 text messages. The server will echo the messages back.
Use a StreamWebSocket to send binary data. The server will echo the binary data back.
Use the ClientCertificate property of StreamWebSocketControl to provide client authentication information when connecting to a secure server.

Note This sample by default requires network access using the loopback interface.

Network capabilities

This sample requires that network capabilities be set in the Package.appxmanifest file to allow the app to access the network at runtime. These capabilities can be set in the app manifest using Microsoft Visual Studio.

Private Networks (Client & Server): The sample has inbound and outbound network access on a home or work network (a local intranet). Even though this sample by default runs on loopback, it needs either the Private Networks (Client & Server) or Internet (Client) capability in order to access the network and send and receive data. The Private Networks (Client & Server) capability is represented by the Capability name = "privateNetworkClientServer" tag in the app manifest.
If the sample is modified to connect to the server component running on a different device on the Internet (a more typical app), the Internet (Client) capability must be set for the client component. This is represented by the Capability name = "internetClient".

Other resources

Adding support for networking
Connecting with WebSockets
How to configure network capabilities
How to connect with a MessageWebSocket
How to connect with a StreamWebSocket

Reference

MessageWebSocket StreamWebSocket Windows.Networking.Sockets

Windows.Networking.Sockets

WebSocket sample for JavaScript (archived)

System requirements

Windows 10

Build the sample

If you download the samples ZIP, be sure to unzip the entire archive, not just the folder with the sample you want to build.
Start Microsoft Visual Studio and select File > Open > Project/Solution.
Starting in the folder where you unzipped the samples, go to the Samples subfolder, then the subfolder for this specific sample, then the subfolder for your preferred language (C++, C#, or JavaScript). Double-click the Visual Studio Solution (.sln) file.
Press Ctrl+Shift+B, or select Build > Build Solution.

Run the sample

The next steps depend on whether you just want to deploy the sample or you want to both deploy and run it.

Deploying the sample

Select Build > Deploy Solution.

Deploying and running the Windows version of the sample

To debug the sample and then run it, press F5 or use Debug > Start Debugging. To run the sample without debugging, press Ctrl+F5 or use Debug > Start Without Debugging.

For the app to attempt a WebSocket connection, this sample requires that a web server is available that supports WebSockets. The web server must also have a WebSocketSample path available to access. The web server must be started before the app is run. The sample includes a PowerShell script that will install and enable IIS on a local computer and enable WebSocket connections. The easiest way to run the sample is to use the provided web server scripts. The PowerShell script that will install IIS on the local computer, create the WebSocketSample folder on the server, copy files to this folder, and enable IIS.

Browse to the Server folder in your sample folder to setup and start the web server. There are two options possible.

Start PowerShell elevated (Run as administrator) and run the following command:

.\SetupServer.ps1

Note that you may also need to change script execution policy.
Start an elevated Command Prompt (Run as administrator) and run following command:

PowerShell.exe -ExecutionPolicy Unrestricted -File SetupServer.ps1

When the web server is not needed anymore, please browse to the Server folder in you sample folder and run one of the following:

Start PowerShell elevated (Run as administrator) and run the following command:

.\RemoveServer.ps1

Note that you may also need to change script execution policy.
Start an elevated Command Prompt (Run as administrator) and run following command:

PowerShell.exe -ExecutionPolicy Unrestricted -File RemoveServer.ps1

The sample can run using any web server, not only the one provided with the sample. If IIS is used on a different computer, then the previous scripts can be used with minor changes.

Copy the Server folder to the device where IIS will be run.
Run the above scripts to install and enable IIS and enable WebSocket connections.

The sample must also be updated when run against a non-localhost web server. To configure the sample for use with IIS on a different device:

Additional capabilities may need to be added to the app manifest for the sample. For example, Internet (Client & Server) if the web server is located on the Internet not on a local intranet.
The hostname of the server to connect to also needs to be updated. This can be handled in two ways. The ServerAddressField element in the HTML or XAML files can be edited so that "localhost" is replaced by the hostname or IP address of the web server. Alternately when the app is run, enter the hostname or IP address of the web server instead of the default "localhost" value in the Server Address field.

Note IIS is not available on ARM builds nor on Windows Phone. Instead, set up the web server on a separate 64-bit or 32-bit computer and follow the steps for using the sample against non-localhost web server.

However if a server different than IIS is used, then this requires some special configuration of the server.

Copy file Server\webSite\EchoWebSocket.ashx to the WebSocketSample folder on the web server.
Copy file Server\webSite\EchoWebSocket.ashx again to the same folder on the web server, but rename to EchoWebSocketWithClientAuthentication.ashx.
Configure the web server to accept WebSocket connections, and configure the web server to require SSL connection and client certificate on the EchoWebSocketWithClientAuthentication.ashx page.

To configure the sample for use with a web server different than IIS not using localhost:

Additional capabilities may need to be added to the app manifest for the sample. For example, Internet (Client & Server) if the web server is located on the Internet not on a local intranet.
The URI of the server to connect to also needs to be updated. This can be handled in two ways. The ServerAddressField element in the HTML or XAML files can be edited so that "localhost" is replaced by the hostname or IP address of the web server. Alternately when the app is run, enter the hostname or IP address of the web server instead of the default "localhost" value in the Server Address field.

Deploying and running the Windows Phone version of the sample

IIS is not available on Windows Phone. For the app to attempt a WebSocket connection to a server that supports WebSockets, there are two options:

The easiest way to run the sample is to use the provided web server scripts on a separate 64-bit or 32-bit device that can run IIS. Follow the instructions for deploying and running the Windows version of the sample using IIS on a different device.
Use a web server different than IIS on a separate device. Follow the instructions for deploying and running the Windows version of the sample using a non-IIS web server.

Known issues

The client certificate API demonstrated in scenario 3 does not currently work on XBOX.