WebSocket <webSocket>


The <webSocket> element specifies the use of the WebSocketModule module with ASP.NET 4.5 to support writing server applications that communicate over the WebSocket Protocol. WebSocket enables you to provide full-duplex communications over a single TCP connection by using a stream of messages rather than a stream of bytes. This makes it easier to connect to data sources asynchronously in cloud deployments.


Version Notes
IIS 10.0 The <webSocket> element was not modified in IIS 10.0.
IIS 8.5 The <webSocket> element was not modified in IIS 8.5.
IIS 8.0 The <webSocket> element was introduced in IIS 8.0.
IIS 7.5 N/A
IIS 7.0 N/A
IIS 6.0 N/A


Windows Server 2012 or Windows Server 2012 R2

  1. On the taskbar, click Server Manager.
  2. In Server Manager, click the Manage menu, and then click Add Roles and Features.
  3. In the Add Roles and Features wizard, click Next. Select the installation type and click Next. Select the destination server and click Next.
  4. On the Server Roles page, expand Web Server (IIS), expand Web Server, expand Application Development, and then select WebSocket Protocol. Click Next.
    Screenshot of the Application Development list showing WebSocket Protocol selected. .
  5. On the Select Features page, click Next.
  6. On the Confirm installation selections page, click Install.
  7. On the Results page, click Close.

Windows 8 or Windows 8.1

  1. On the Start screen, move the pointer all the way to the lower left corner, right-click the Start button, and then click Control Panel. - In Control Panel, click Programs and Features, and then click Turn Windows features on or off.
  2. Expand Internet Information Services, expand World Wide Web Services, expand Application Development Features, and then select WebSocket Protocol.
    Screenshot showing the Application Development Features list with multiple selections and WebSocket Protocol highlighted.
  3. Click OK.
  4. Click Close.

How To

How to Use the IWebSocketContext API

Developers can use the IWebSocketContext API to create applications that implement bidirectional and fully duplex communications between client and server, sending streams of messages instead of bytes. The IWebSocketContext API exposes the necessary API's to read/write WebSocket data.

If an incoming request is to be accepted as a WebSocket request and subsequently upgraded, the handler must set the response status as 101. It should initiate an IHttpResponse->Flush, which will trigger the IIS WebSocket module to do the necessary work to send out the 101 response to the client.

Once the response is sent, the handler can get a pointer to the IWebSocketContext through the IHttpContext3's GetNamedContext API.

For more information, see IWebSocketContext interface.

How to configure webSocket

  1. Open Internet Information Services (IIS) Manager:

    • If you are using Windows Server 2012 or later:

      • On the taskbar, click Server Manager, click Tools, and then click Internet Information Services (IIS) Manager.
    • If you are using Windows 8 or later:

      • Hold down the Windows key, press the letter X, and then click Control Panel.
      • Click Administrative Tools, and then double-click Internet Information Services (IIS) Manager.
  2. In the Connections pane, select the server name to configure WebSocket for the server, or expand Sites and then select a site to configure WebSocket for the site, or expand a site and then select an application to configure WebSocket for the application.

  3. In the Home pane, double-click the Configuration Editor feature.

  4. For either a site or an application, select either web.config or applicationHost.config in the From text box.

  5. Select system.webServer/webSocket in the Section text box.

  6. Set enabled to True to enable webSocket or False to disable webSocket. Set pingInterval and receiveBufferLimit to the desired values.

    Screenshot of a portion of the Configuration Editor screen with enabled highlighted.

  7. Click Apply in the Actions pane.


The <webSocket> element is configured at the server, site, or application level.


Attribute Description
enabled Optional Boolean attribute.

Enables server applications to communicate over the WebSocket protocol.

The default value is true.
pingInterval Optional timeSpan attribute.

The interval at which a ping is sent over a WebSocket connection.

The default value is 00:00:00.
receiveBufferLimit Optional uint attribute.

The maximum size of the receive buffer for a WebSocket connection.

The default value is 4194304.

Child Elements


Configuration Sample

The following sample displays a <webSocket> element.


Sample Code

The following sample code configures <webSocket> for a site.


appcmd.exe set config "Default Web Site" -section:system.webServer/webSocket /enabled:"True" /receiveBufferLimit:"4194304" /pingInterval:"00:00:10"  /commit:apphost


You must be sure to set the commit parameter to apphost when using AppCmd.exe to configure these settings. This commits the configuration settings to the appropriate location section in the ApplicationHost.config file.


using System;
using System.Text;
using Microsoft.Web.Administration;

internal static class Sample {

    private static void Main() {
        using(ServerManager serverManager = new ServerManager()) { 
            Configuration config = serverManager.GetApplicationHostConfiguration();
            ConfigurationSection webSocketSection = config.GetSection("system.webServer/webSocket", "Default Web Site");
            webSocketSection["enabled"] = true;
            webSocketSection["receiveBufferLimit"] = 4194304;
            webSocketSection["pingInterval"] = TimeSpan.Parse("00:00:10");


Imports System
Imports System.Text
Imports Microsoft.Web.Administration
Module Sample

   Sub Main()
      Dim serverManager As ServerManager = New ServerManager
      Dim config As Configuration = serverManager.GetApplicationHostConfiguration
      Dim webSocketSection As ConfigurationSection = config.GetSection("system.webServer/webSocket", "Default Web Site")
      webSocketSection("enabled") = true
      webSocketSection("receiveBufferLimit") = 4194304
      webSocketSection("pingInterval") = TimeSpan.Parse("00:00:10")
   End Sub
End Module


var adminManager = new ActiveXObject('Microsoft.ApplicationHost.WritableAdminManager');
adminManager.CommitPath = "MACHINE/WEBROOT/APPHOST";

var webSocketSection = adminManager.GetAdminSection("system.webServer/webSocket", "MACHINE/WEBROOT/APPHOST/Default Web Site");
webSocketSection.Properties.Item("enabled").Value = true;
webSocketSection.Properties.Item("receiveBufferLimit").Value = 4194304;
webSocketSection.Properties.Item("pingInterval").Value = "00:00:10";



Set adminManager = CreateObject("Microsoft.ApplicationHost.WritableAdminManager")
adminManager.CommitPath = "MACHINE/WEBROOT/APPHOST"

Set webSocketSection = adminManager.GetAdminSection("system.webServer/webSocket", "MACHINE/WEBROOT/APPHOST/Default Web Site")
webSocketSection.Properties.Item("enabled").Value = true
webSocketSection.Properties.Item("receiveBufferLimit").Value = 4194303
webSocketSection.Properties.Item("pingInterval").Value = "00:00:20"



Set-WebConfigurationProperty -pspath 'MACHINE/WEBROOT/APPHOST' -location 'Default Web Site' -filter "system.webServer/webSocket" -name "enabled" -value "True"
Set-WebConfigurationProperty -pspath 'MACHINE/WEBROOT/APPHOST' -location 'Default Web Site' -filter "system.webServer/webSocket" -name "receiveBufferLimit" -value 4194303
Set-WebConfigurationProperty -pspath 'MACHINE/WEBROOT/APPHOST' -location 'Default Web Site' -filter "system.webServer/webSocket" -name "pingInterval" -value "00:00:20"