Comment : implémenter une opération de service asynchrone

Article
02/27/2011

Dans les applications Windows Communication Foundation (WCF), une opération de service peut être implémentée de façon asynchrone ou synchrone sans dicter au client comment l'appeler. Par exemple, les opérations de service asynchrones peuvent être appelées de façon synchrone, et inversement. Pour obtenir un exemple qui indique comment appeler une opération de façon asynchrone dans une application cliente, consultez Comment : appeler des opérations de service WCF de façon asynchrone. Pour plus d'informations sur le sujet suivant les operation synchrones et asynchrones, consultez Conception de contrats de service et Opérations synchrones et asynchrones. Cette rubrique décrit la structure de base d'une opération de service asynchrone, le code n'est pas complet. Pour obtenir un exemple complet côté service et côté client, consultez Asynchronous.

Implémenter une opération de service de façon asynchrone

Dans votre contrat de service, déclarez une paire de méthodes asynchrones conformément aux règles de design asynchrone .NET. La méthode Begin prend un paramètre, un objet de rappel et un objet d'état, puis retourne System.IAsyncResult et une méthode End correspondante qui prend System.IAsyncResult et retourne la valeur de retour. Pour plus d'informations sur les appels asynchrones, consultez Asynchronous Programming Design Patterns.

Marquez la méthode Begin de la paire de méthodes asynchrones avec l'attribut System.ServiceModel.OperationContractAttribute et affectez true à la propriété System.ServiceModel.OperationContractAttribute.AsyncPattern. Par exemple, le code suivant exécute les étapes 1 et 2.

  <OperationContractAttribute(AsyncPattern:=True)> _
  Function BeginServiceAsyncMethod(ByVal msg As String, ByVal callback As AsyncCallback, ByVal asyncState As Object) As IAsyncResult

  ' Note: There is no OperationContractAttribute for the end method.
  Function EndServiceAsyncMethod(ByVal result As IAsyncResult) As String
End Interface

  [OperationContractAttribute(AsyncPattern=true)]
  IAsyncResult BeginServiceAsyncMethod(string msg, AsyncCallback callback, object asyncState);

  // Note: There is no OperationContractAttribute for the end method.
  string EndServiceAsyncMethod(IAsyncResult result);
}

Implémentez la paire de méthodes Begin/End dans votre classe de service conformément aux règles de design asynchrone. Par exemple, l'exemple de code suivant présente une implémentation dans laquelle une chaîne est écrite dans la console, à la fois dans les parties Begin et End de l'opération de service asynchrone, et la valeur de retour de l'opération End est retournée au client. Pour obtenir un exemple de code complet, consultez la section Exemple.

Exemple

Les exemples de code suivants présentent :

Une interface de contrat de service avec :
1. Une opération SampleMethod synchrone.
2. Une opération BeginSampleMethod asynchrone.
3. Une paire d'opérations BeginServiceAsyncMethod/EndServiceAsyncMethod asynchrones.
Une implémentation de service utilisant un objet System.IAsyncResult.

Imports System
Imports System.Collections.Generic
Imports System.ServiceModel
Imports System.Text
Imports System.Threading

Namespace Microsoft.WCF.Documentation
  <ServiceContractAttribute(Namespace:="http://microsoft.wcf.documentation")> _
  Public Interface ISampleService

    <OperationContractAttribute> _
    Function SampleMethod(ByVal msg As String) As String

    <OperationContractAttribute(AsyncPattern := True)> _
    Function BeginSampleMethod(ByVal msg As String, ByVal callback As AsyncCallback, ByVal asyncState As Object) As IAsyncResult

    'Note: There is no OperationContractAttribute for the end method.
    Function EndSampleMethod(ByVal result As IAsyncResult) As String

    <OperationContractAttribute(AsyncPattern:=True)> _
    Function BeginServiceAsyncMethod(ByVal msg As String, ByVal callback As AsyncCallback, ByVal asyncState As Object) As IAsyncResult

    ' Note: There is no OperationContractAttribute for the end method.
    Function EndServiceAsyncMethod(ByVal result As IAsyncResult) As String
  End Interface

  Public Class SampleService
      Implements ISampleService
    #Region "ISampleService Members"

    Public Function SampleMethod(ByVal msg As String) As String Implements ISampleService.SampleMethod
      Console.WriteLine("Called synchronous sample method with ""{0}""", msg)
         Return "The sychronous service greets you: " & msg
    End Function

    ' This asynchronously implemented operation is never called because 
    ' there is a synchronous version of the same method.
    Public Function BeginSampleMethod(ByVal msg As String, ByVal callback As AsyncCallback, ByVal asyncState As Object) As IAsyncResult Implements ISampleService.BeginSampleMethod
      Console.WriteLine("BeginSampleMethod called with: " & msg)
      Return New CompletedAsyncResult(Of String)(msg)
    End Function

    Public Function EndSampleMethod(ByVal r As IAsyncResult) As String Implements ISampleService.EndSampleMethod
      Dim result As CompletedAsyncResult(Of String) = TryCast(r, CompletedAsyncResult(Of String))
      Console.WriteLine("EndSampleMethod called with: " & result.Data)
      Return result.Data
    End Function

    Public Function BeginServiceAsyncMethod(ByVal msg As String, ByVal callback As AsyncCallback, ByVal asyncState As Object) As IAsyncResult Implements ISampleService.BeginServiceAsyncMethod
      Console.WriteLine("BeginServiceAsyncMethod called with: ""{0}""", msg)
      Return New CompletedAsyncResult(Of String)(msg)
    End Function

    Public Function EndServiceAsyncMethod(ByVal r As IAsyncResult) As String Implements ISampleService.EndServiceAsyncMethod
      Dim result As CompletedAsyncResult(Of String) = TryCast(r, CompletedAsyncResult(Of String))
      Console.WriteLine("EndServiceAsyncMethod called with: ""{0}""", result.Data)
      Return result.Data
    End Function
    #End Region
  End Class

  ' Simple async result implementation.
  Friend Class CompletedAsyncResult(Of T)
      Implements IAsyncResult
    Private data_Renamed As T

    Public Sub New(ByVal data As T)
        Me.data_Renamed = data
    End Sub

    Public ReadOnly Property Data() As T
        Get
            Return data_Renamed
        End Get
    End Property

    #Region "IAsyncResult Members"
    Public ReadOnly Property AsyncState() As Object Implements IAsyncResult.AsyncState
        Get
            Return CObj(data_Renamed)
        End Get
    End Property

    Public ReadOnly Property AsyncWaitHandle() As WaitHandle Implements IAsyncResult.AsyncWaitHandle
        Get
            Throw New Exception("The method or operation is not implemented.")
        End Get
    End Property

    Public ReadOnly Property CompletedSynchronously() As Boolean Implements IAsyncResult.CompletedSynchronously
        Get
            Return True
        End Get
    End Property

    Public ReadOnly Property IsCompleted() As Boolean Implements IAsyncResult.IsCompleted
        Get
            Return True
        End Get
    End Property
    #End Region
  End Class
End Namespace

using System;
using System.Collections.Generic;
using System.ServiceModel;
using System.Text;
using System.Threading;

namespace Microsoft.WCF.Documentation
{
  [ServiceContractAttribute(Namespace="http://microsoft.wcf.documentation")]
  public interface ISampleService{

    [OperationContractAttribute]
    string SampleMethod(string msg);

    [OperationContractAttribute(AsyncPattern = true)]
    IAsyncResult BeginSampleMethod(string msg, AsyncCallback callback, object asyncState);

    //Note: There is no OperationContractAttribute for the end method.
    string EndSampleMethod(IAsyncResult result);

    [OperationContractAttribute(AsyncPattern=true)]
    IAsyncResult BeginServiceAsyncMethod(string msg, AsyncCallback callback, object asyncState);

    // Note: There is no OperationContractAttribute for the end method.
    string EndServiceAsyncMethod(IAsyncResult result);
  }

  public class SampleService : ISampleService
  {
    #region ISampleService Members

    public string  SampleMethod(string msg)
    {
      Console.WriteLine("Called synchronous sample method with \"{0}\"", msg);
        return "The sychronous service greets you: " + msg;
    }

    // This asynchronously implemented operation is never called because 
    // there is a synchronous version of the same method.
    public IAsyncResult BeginSampleMethod(string msg, AsyncCallback callback, object asyncState)
    {
      Console.WriteLine("BeginSampleMethod called with: " + msg);
      return new CompletedAsyncResult<string>(msg);
    }

    public string EndSampleMethod(IAsyncResult r)
    {
      CompletedAsyncResult<string> result = r as CompletedAsyncResult<string>;
      Console.WriteLine("EndSampleMethod called with: " + result.Data);
      return result.Data;
    }

    public IAsyncResult BeginServiceAsyncMethod(string msg, AsyncCallback callback, object asyncState) 
    {
      Console.WriteLine("BeginServiceAsyncMethod called with: \"{0}\"", msg);
      return new CompletedAsyncResult<string>(msg);
    }

    public string EndServiceAsyncMethod(IAsyncResult r)
    {
      CompletedAsyncResult<string> result = r as CompletedAsyncResult<string>;
      Console.WriteLine("EndServiceAsyncMethod called with: \"{0}\"", result.Data);
      return result.Data;
    }
    #endregion
  }

  // Simple async result implementation.
  class CompletedAsyncResult<T> : IAsyncResult
  {
    T data;

    public CompletedAsyncResult(T data)
    { this.data = data; }

    public T Data
    { get { return data; } }

    #region IAsyncResult Members
    public object AsyncState
    { get { return (object)data; } }

    public WaitHandle AsyncWaitHandle
    { get { throw new Exception("The method or operation is not implemented."); } }

    public bool CompletedSynchronously
    { get { return true; } }

    public bool IsCompleted
    { get { return true; } }
    #endregion
  }
}

Voir aussi

Concepts

Conception de contrats de service
Opérations synchrones et asynchrones

Partager via

Comment : implémenter une opération de service asynchrone

Implémenter une opération de service de façon asynchrone

Exemple

Voir aussi

Concepts

Ressources supplémentaires