UIAgentAsyncBeginRequest.cs source code in C# .NET

                        Code:
                         / WCF / WCF / 3.5.30729.1 / untmp / Orcas / SP / ndp / cdf / src / WCF / infocard / Service / managed / Microsoft / InfoCards / UIAgentAsyncBeginRequest.cs / 1 / UIAgentAsyncBeginRequest.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------------------------
//
// Presharp uses the c# pragma mechanism to supress its warnings. 
// These are not recognised by the base compiler so we need to explictly
// disable the following warnings. See http://winweb/cse/Tools/PREsharp/userguide/default.asp 
// for details. 
//
#pragma warning disable 1634, 1691      // unknown message, unknown pragma 



namespace Microsoft.InfoCards 
{
    using Microsoft.Win32.SafeHandles; 
    using System; 
    using System.Collections;
    using System.ComponentModel; 
    using System.Diagnostics;
    using System.Runtime.InteropServices;
    using System.Text;
    using System.Threading; 
    using System.IO;
 
    using Microsoft.InfoCards.Diagnostics; 
    using IDT = Microsoft.InfoCards.Diagnostics.InfoCardTrace;
 
    //
    // Summary:
    //  Base class for begining any async operations from the UI Agent.
    // 
    internal abstract class UIAgentAsyncBeginRequest : UIAgentRequest
    { 
        SafeWaitHandle m_agentEventHandle; 
        int m_asyncHandle;
 
        //
        // Summary:
        //  Creates an new UIAgentAsyncBeginRequest
        // 
        // Arguments:
        //  rpcHandle:  The RPC Context handle. 
        //  inArgs:     The stream to hold the input arguments 
        //  outArgs:    The stream to hold the output arguments
        //  parent:     the parent UI Request 
        //
        public UIAgentAsyncBeginRequest(
                            IntPtr rpcHandle,
                            Stream inArgs, 
                            Stream outArgs,
                            ClientUIRequest parent ) 
            : base( rpcHandle, inArgs, outArgs, parent ) 
        {
        } 

        //
        // Summary:
        //  Reads incoming params. 
        //
        // Remarks: 
        //  Reads the wait handle, and clones it for this process. 
        //
        protected sealed override void OnMarshalInArgs() 
        {
            IntPtr nativeEvent = IntPtr.Zero;

            BinaryReader breader = new InfoCardBinaryReader( InArgs, Encoding.Unicode ); 

            nativeEvent = Utility.ReadHandle( breader ); 
 
            //
            // Then translate the remote event handle into a locally valid handle. 
            //
            using( SafeWaitHandle waitHandle = new SafeWaitHandle( nativeEvent, false ) )
            {
                m_agentEventHandle = Utility.GetLocalHandleFromRemoteHandle( 
                                                                waitHandle,
                                                                (int) ParentRequest.UIAgentPid ); 
            } 

            OnMarshalAsyncInArgs( breader ); 
        }

        //
        // Summary: 
        // Called after the standard async args are already marsheled to allow derived classes to marshal op
        // specific arguments. 
        // 
        protected virtual void OnMarshalAsyncInArgs( BinaryReader reader )
        { 
            //
            // Default is to do nothing.
            //
        } 

        // 
        // Summary: 
        //  Process the Begin operateration.
        // 
        protected override void OnProcess()
        {

            AsyncParams param = CreateAsyncParams(); 
            param.AsyncResult.CancelCallback = new RpcAsyncResult.AsyncCancelCallback( AsyncCancel );
            IDT.Assert( null != param, "Null AsyncParams"  ); 
            try 
            {
                // 
                // Capture the async context handle.
                //
                m_asyncHandle = param.AsyncResult.Handle;
 

                IDT.Assert( 0 != m_asyncHandle, "null async context handle" ); 
 
                //
                // Start the operation. 
                //
                if (!ThreadPool.QueueUserWorkItem(IDT.ThunkCallback(new WaitCallback(AsyncEntry)), param))
                {
                    throw IDT.ThrowHelperError( new CommunicationException( SR.GetString( SR.UnableToQueueThreadpool ) ) ); 
                }
            } 
            catch 
            {
                // 
                // An error occured, be sure to dispose the async context.
                //      Should AsyncParams support dispose?
                //
                param.AsyncResult.Dispose(); 
                throw;
            } 
        } 

        // 
        // Summary:
        //  marshal the base async info out.
        //
        protected override void OnMarshalOutArgs() 
        {
            BinaryWriter bwriter = new BinaryWriter( OutArgs, Encoding.Unicode ); 
            IDT.Assert( 0 != m_asyncHandle, "null async handle" ); 
            bwriter.Write( m_asyncHandle );
        } 

        protected override void OnDisposeAsUser()
        {
            if( null != m_agentEventHandle ) 
            {
                m_agentEventHandle.Dispose(); 
                m_agentEventHandle = null; 
            }
        } 

        //
        // Summary:
        //  Creates the AsyncParams for the async operation. 
        //
        // Remarks: 
        //  By default, a UIAgentAsyncParams object is created, but derived classes 
        //  can change this by returning any AsyncParams derived class.
        // 
        protected virtual AsyncParams CreateAsyncParams( )
        {
            //
            // Get the name of this request type.  We put this in the asyncParams to make debugging easier. 
            //
            Type thisType = GetType(); 
 
            AsyncParams retParams = new UIAgentAsyncParams( thisType.Name,
                                                        ParentRequest, 
                                                        m_agentEventHandle,
                                                        this );

            // 
            // The asyncParams takes ownership of the handle.
            // 
            m_agentEventHandle = null; 

            return retParams; 
        }


        // 
        // Summary:
        //  Abstract entry point for the execution of the async operation. 
        // 
        protected abstract object AsyncExecute( AsyncParams asyncParam );
 
        //
        // Summary:
        //  Abstract entry point for the cancelation of the async operation.
        // 
        protected abstract void AsyncCancel( );
 
        // 
        // Summary:
        // This is a WaitCallback conformant wrapper for Async Requests 
        //
        // Parameters:
        // state        - An instance of a a AsyncParams class..
        // 
        // Remarks:
        // Running on threadpool thread. 
        // 
        private void AsyncEntry( object state )
        { 
            //
            // Consider for future -- see bug 38733 -- Clear out thread context here (in a finally block)
            //
 
            AsyncParams param = (AsyncParams)state;
            try 
            { 
                if( param.AsyncResult.IsCanceled )
                { 
                    param.AsyncResult.Exception = new Win32Exception( NativeMethods.ERROR_CANCELLED );
                }
                else
                { 
                    param.AsyncResult.Result = AsyncExecute( param );
                } 
            } 
#pragma warning disable 56500       // do not catch non-recoverable exceptions
 
            catch( Exception e )
            {
                if( IDT.IsFatal( e ) )
                { 
                    InfoCardService.Crash( e );
                } 
                // 
                // Ensure that the result is completed.
                // 

                //
                // Even if it is InfoCardBaseException, we're simply transferring it.
                // 
                param.AsyncResult.Exception = e;
            } 
#pragma warning restore 56500 

            // 
            // The complete method should not throw any exceptions.
            //
            param.AsyncResult.Complete();
 
            //
            // Consider for future -- see bug 38733 -- Clear out thread context here (in a finally block) 
            // 
        }
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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UIAgentAsyncBeginRequest.cs source code in C# .NET

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