Type: System.Runtime.Remoting.Messaging.AsyncResult

System.Runtime.Remoting.Messaging.AsyncResult Class

Assembly: Mscorlib.dll
Namespace: System.Runtime.Remoting.Messaging

Summary: Encapsulates the results of an asynchronous operation on an asynchronous delegate.

C# Syntax:


        public class AsyncResult : IAsyncResult, IMessageSink

Remarks

The AsyncResult class is used in conjunction with asynchronous delegates. The IAsyncResult returned from the delegate's BeginInvoke method can be cast to an AsyncResult. The AsyncResult has the AsyncResult.AsyncDelegate property that holds the delegate object on which the async call was invoked.

For more information about BeginInvoke and asynchronous delegates, see .

Example

The following code example demonstrates the use of the AsyncResult class to retrieve the results of an asynchronous operation on an asynchronous delegate.

using System;
using System.Threading;
using System.Runtime.Remoting;
using System.Runtime.Remoting.Contexts;
using System.Runtime.Remoting.Messaging;

// Context-bound type with the Synchronization context attribute.
[Synchronization()]
public class SampleSyncronized : ContextBoundObject {

    // A method that does some work, and returns the square of the given number.
    public int Square(int i)  {

        Console.Write("The hash of the thread executing ");
        Console.WriteLine("SampleSyncronized.Square is: {0}", 
                             Thread.CurrentThread.GetHashCode());
        return i*i;
    }
}

// The async delegate used to call a method with this signature asynchronously.
public delegate int SampSyncSqrDelegate(int i);

public class AsyncResultSample {

    // Asynchronous Callback method.
    public static void MyCallback(IAsyncResult ar) {

        // Obtains the last parameter of the delegate call.
        int value = Convert.ToInt32(ar.AsyncState);

        // Obtains return value from the delegate call using EndInvoke.
        AsyncResult aResult = (AsyncResult)ar;
        SampSyncSqrDelegate temp = (SampSyncSqrDelegate)aResult.AsyncDelegate;
        int result = temp.EndInvoke(ar);

        Console.Write("Simple.SomeMethod (AsyncCallback): Result of ");
        Console.WriteLine("{0} in SampleSynchronized.Square is {1} ", value, result);
    }

    public static void Main() {

        int result;
        int param;

        // Creates an instance of a context-bound type SampleSynchronized.
        SampleSyncronized sampSyncObj = new SampleSyncronized();

        // Checks whether the object is a proxy, since it is context-bound.
        if (RemotingServices.IsTransparentProxy(sampSyncObj))
            Console.WriteLine("sampSyncObj is a proxy.");
        else
            Console.WriteLine("sampSyncObj is NOT a proxy.");

        param = 10;

        Console.WriteLine("");
        Console.WriteLine("Making a synchronous call on the context-bound object:");

        result = sampSyncObj.Square(param);
        Console.Write("The result of calling sampSyncObj.Square with ");
        Console.WriteLine("{0} is {1}.", param, result);
        Console.WriteLine("");

        SampSyncSqrDelegate sampleDelegate = new SampSyncSqrDelegate(sampSyncObj.Square);
        param = 8;

        Console.WriteLine("Making a single asynchronous call on the context-bound object:");

        IAsyncResult ar1 = sampleDelegate.BeginInvoke( param, 
                              new AsyncCallback(AsyncResultSample.MyCallback), 
                              param);

        Console.WriteLine("Waiting for the asynchronous call to complete...");
        WaitHandle wh = ar1.AsyncWaitHandle;
        wh.WaitOne();

        Console.WriteLine("");
        Console.WriteLine("Waiting for the AsyncCallback to complete...");
        Thread.Sleep(1000);
    }
}

System.Runtime.Remoting.Messaging.AsyncResult Member List:

Public Properties

AsyncDelegate	Read-only Gets the delegate object on which the asynchronous call was invoked.
AsyncState	Read-only Gets the object provided as the last parameter of a BeginInvoke method call.
AsyncWaitHandle	Read-only Gets a WaitHandle that encapsulates Win32 synchronization handles, and allows the implementation of various synchronization schemes.
CompletedSynchronously	Read-only Gets a value indicating whether the BeginInvoke call completed synchronously.
EndInvokeCalled	Read-write Gets or sets a value indicating whether EndInvoke has been called on the current AsyncResult.
IsCompleted	Read-only Gets a value indicating whether the server has completed the call.
NextSink	Read-only Public reserved. Gets the next message sink in the sink chain.

Public Methods

AsyncProcessMessage	Public reserved.
Equals (inherited from System.Object)	See base class member description: System.Object.Equals Derived from System.Object, the primary base class for all objects.
GetHashCode (inherited from System.Object)	See base class member description: System.Object.GetHashCode Derived from System.Object, the primary base class for all objects.
GetReplyMessage	Public reserved. Returns the reply message returned from a method call.
GetType (inherited from System.Object)	See base class member description: System.Object.GetType Derived from System.Object, the primary base class for all objects.
SetMessageCtrl	Public reserved. Sets the IMessageCtrl object for the current method call which provides a way to control asynchronous messages once they have dispatched.
SyncProcessMessage	Public reserved.
ToString (inherited from System.Object)	See base class member description: System.Object.ToString Derived from System.Object, the primary base class for all objects.

Protected Methods

Finalize (inherited from System.Object)	See base class member description: System.Object.Finalize Derived from System.Object, the primary base class for all objects.
MemberwiseClone (inherited from System.Object)	See base class member description: System.Object.MemberwiseClone Derived from System.Object, the primary base class for all objects.

Hierarchy:

System.Object

System.Runtime.Remoting.Messaging.AsyncResult

System.Runtime.Remoting.Messaging.AsyncResult Member Details

Property: AsyncDelegate (read-only)

Summary: Gets the delegate object on which the asynchronous call was invoked.

C# Syntax:


            public virtual object AsyncDelegate {get;}

Remarks

The AsyncResult.AsyncDelegate property can be cast to the actual class of the user-defined delegate.

For example, if the user-defined delegate is of type MyDelegate, in order to access MyDelegate.EndInvoke, the asynchronous delegate must be cast to MyDelegate. The MyDelegate.EndInvoke can be called in the async callback function (of type AsyncCallback) to obtain the results of the originally submitted MyDelegate.BeginInvoke.

Example

The following code example demonstrates how to get the delegate object on which the asynchronous call was invoked from the AsyncResult. For the complete example code, see the example for the AsyncResult class.

    // Asynchronous Callback method.
    public static void MyCallback(IAsyncResult ar) {

        // Obtains the last parameter of the delegate call.
        int value = Convert.ToInt32(ar.AsyncState);

        // Obtains return value from the delegate call using EndInvoke.
        AsyncResult aResult = (AsyncResult)ar;
        SampSyncSqrDelegate temp = (SampSyncSqrDelegate)aResult.AsyncDelegate;
        int result = temp.EndInvoke(ar);

        Console.Write("Simple.SomeMethod (AsyncCallback): Result of ");
        Console.WriteLine("{0} in SampleSynchronized.Square is {1} ", value, result);
    }