Represents the properties and methods of a default HTTP handler.
Assembly: System.Web (in System.Web.dll)
Thetype exposes the following members.
|BeginProcessRequest||Initiates an asynchronous call to the HTTP handler.|
|EndProcessRequest||Provides an end method for an asynchronous process.|
|Equals(Object)||Determines whether the specified object is equal to the current object. (Inherited from Object.)|
|Finalize||Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)|
|GetHashCode||Serves as the default hash function. (Inherited from Object.)|
|GetType||Gets the Type of the current instance. (Inherited from Object.)|
|MemberwiseClone||Creates a shallow copy of the current Object. (Inherited from Object.)|
|OnExecuteUrlPreconditionFailure||Called when preconditions prevent the object from processing a request.|
|OverrideExecuteUrlPath||Overrides the target URL for the current request.|
|ProcessRequest||Enables a object to process of HTTP Web requests.|
|ToString||Returns a string that represents the current object. (Inherited from Object.)|
A object intercepts incoming requests in the HTTP pipeline when both request interception has been configured through Internet Information Services (IIS) 6.0 and no explicit httpHandlers bindings apply to the requested extension.
Request interception can be set up through the wildcard application mapping feature introduced in IIS 6.0. For more information, search the MSDN Library for information about using wildcard application maps to remap a URL.
The class implements the IHttpAsyncHandler interface to provide asynchronous request processing. For general information about HTTP handlers, see HTTP Handlers and HTTP Modules Overview. Additionally, for more information see the following:
About creating asynchronous HTTP handlers, see Walkthrough: Creating an Asynchronous HTTP Handler.
About registering HTTP handlers, see How to: Register HTTP Handlers.
Classes can derive from the class to provide customized handling of requests. An asynchronous HTTP handler that is derived from the could override the BeginProcessRequest method to change how requests are processed.
A does not use ASP.NET errors. Existing content that uses IIS errors or a propriety ISAPI custom error mechanism would work unchanged.
The following code example demonstrates how to implement a customized HTTP handler by deriving from the class.
Public Class defaulthttpexampleVB Inherits DefaultHttpHandler Private _context As HttpContext Public Overrides Function BeginProcessRequest _ (ByVal context As HttpContext, _ ByVal callback As AsyncCallback, _ ByVal state As Object) As IAsyncResult Dim ar As New AsyncResultSample(callback, state) _context = context Return (ar) End Function Public Overrides Sub EndProcessRequest(ByVal result As IAsyncResult) _context.Response.Write("EndProcessRequest called.") End Sub ' This method should not be called asynchronously. Public Overrides Sub ProcessRequest(ByVal context As HttpContext) Throw New InvalidOperationException _ ("Asynchronous processing failed.") End Sub ' Enables pooling when set to true Public Overrides ReadOnly Property IsReusable() As Boolean Get Return True End Get End Property End Class ' Tracks state between the begin and end calls. Class AsyncResultSample Implements IAsyncResult Private callback As AsyncCallback = Nothing Private _asyncState As Object Private _isCompleted As Boolean Friend Sub New(ByVal cb As AsyncCallback, ByVal state As Object) Me.callback = cb _asyncState = state _isCompleted = False End Sub Public ReadOnly Property AsyncState() As Object _ Implements IAsyncResult.AsyncState Get Return _asyncState End Get End Property Public ReadOnly Property CompletedSynchronously() _ As Boolean Implements IAsyncResult.CompletedSynchronously Get Return False End Get End Property Public ReadOnly Property AsyncWaitHandle() _ As WaitHandle Implements IAsyncResult.AsyncWaitHandle Get Throw New InvalidOperationException _ ("ASP.NET should not use this property .") End Get End Property Public ReadOnly Property IsCompleted() _ As Boolean Implements IAsyncResult.IsCompleted Get Return IsCompleted End Get End Property Friend Sub SetCompleted() _isCompleted = True If (callback <> Nothing) Then callback(Me) End If End Sub End Class