Using IHttpAsyncHandler and XMLHttpRequest to “push” messages to the client

Boek, Karel

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30 Sep 2009CPL4 min read

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How you can let a web browser be a "listener" for chat messages pushed from a web server.

<?xml version="1.0"?>
<configuration>
	<configSections>
		<sectionGroup name="system.web.extensions" type="System.Web.Configuration.SystemWebExtensionsSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
			<sectionGroup name="scripting" type="System.Web.Configuration.ScriptingSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
				<section name="scriptResourceHandler" type="System.Web.Configuration.ScriptingScriptResourceHandlerSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/>
				<sectionGroup name="webServices" type="System.Web.Configuration.ScriptingWebServicesSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
					<section name="jsonSerialization" type="System.Web.Configuration.ScriptingJsonSerializationSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="Everywhere"/>
					<section name="profileService" type="System.Web.Configuration.ScriptingProfileServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/>
					<section name="authenticationService" type="System.Web.Configuration.ScriptingAuthenticationServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/>
					<section name="roleService" type="System.Web.Configuration.ScriptingRoleServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/>
				</sectionGroup>
			</sectionGroup>
		</sectionGroup>
	</configSections>
	<appSettings/>
	<connectionStrings/>
	<system.web>
		<!-- 
            Set compilation debug="true" to insert debugging 
            symbols into the compiled page. Because this 
            affects performance, set this value to true only 
            during development.
        -->
		<compilation debug="true">
			<assemblies>
				<add assembly="System.Core, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
				<add assembly="System.Data.DataSetExtensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
				<add assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
				<add assembly="System.Xml.Linq, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/></assemblies>
		</compilation>
		<authentication mode="Windows"/>
		<customErrors mode="Off"/>
		<pages>
			<controls>
				<add tagPrefix="asp" namespace="System.Web.UI" assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
				<add tagPrefix="asp" namespace="System.Web.UI.WebControls" assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
			</controls>
		</pages>
		<httpHandlers>
			<remove verb="*" path="*.asmx"/>
			<add verb="*" path="*.asmx" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
			<add verb="*" path="*_AppService.axd" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
			<add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" validate="false"/>
			<add verb="GET,POST" path="MyAsyncHandler.ashx" type="SandBox.CometSample.MyAsyncHandler, SandBox.CometSample" validate="false"/>
			<add verb="GET,POST" path="MyMessageHandler.ashx" type="SandBox.CometSample.MyMessageHandler, SandBox.CometSample" validate="false"/>
		</httpHandlers>
		<httpModules>
			<add name="ScriptModule" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
		</httpModules>
	</system.web>
	<system.codedom>
		<compilers>
			<compiler language="c#;cs;csharp" extension=".cs" warningLevel="4" type="Microsoft.CSharp.CSharpCodeProvider, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
				<providerOption name="CompilerVersion" value="v3.5"/>
				<providerOption name="WarnAsError" value="false"/>
			</compiler>
		</compilers>
	</system.codedom>
	<!-- 
        The system.webServer section is required for running ASP.NET AJAX under Internet
        Information Services 7.0.  It is not necessary for previous version of IIS.
    -->
	<system.webServer>
		<validation validateIntegratedModeConfiguration="false"/>
		<modules>
			<remove name="ScriptModule"/>
			<add name="ScriptModule" preCondition="managedHandler" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
		</modules>
		<handlers>
			<remove name="WebServiceHandlerFactory-Integrated"/>
			<remove name="ScriptHandlerFactory"/>
			<remove name="ScriptHandlerFactoryAppServices"/>
			<remove name="ScriptResource"/>
			<add name="ScriptHandlerFactory" verb="*" path="*.asmx" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
			<add name="ScriptHandlerFactoryAppServices" verb="*" path="*_AppService.axd" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
			<add name="ScriptResource" preCondition="integratedMode" verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
			<add name="MyAsyncHandler" verb="GET,POST" path="MyAsyncHandler.ashx" type="SandBox.CometSample.MyAsyncHandler, SandBox.CometSample"/>
			<add name="MyMessageHandler" verb="GET,POST" path="MyMessageHandler.ashx" type="SandBox.CometSample.MyMessageHandler, SandBox.CometSample"/>
		</handlers>
		<urlCompression doStaticCompression="true" doDynamicCompression="false"/>
		<defaultDocument>
			<files>
				<add value="Default.aspx"/>
			</files>
		</defaultDocument>
	</system.webServer>
	<runtime>
		<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
			<dependentAssembly>
				<assemblyIdentity name="System.Web.Extensions" publicKeyToken="31bf3856ad364e35"/>
				<bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="3.5.0.0"/></dependentAssembly>
			<dependentAssembly>
				<assemblyIdentity name="System.Web.Extensions.Design" publicKeyToken="31bf3856ad364e35"/>
				<bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="3.5.0.0"/></dependentAssembly></assemblyBinding></runtime></configuration>

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License

This article, along with any associated source code and files, is licensed under The Common Public License Version 1.0 (CPL)

Written By

Boek, Karel

Software Developer Raskenlund

Norway

Professional System Architect and Developer

Using IHttpAsyncHandler and XMLHttpRequest to “push” messages to the client

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