Пример удаленного взаимодействия. Асинхронное удаленное взаимодействие

Этот раздел относится к технологии прежних версий, которая сохраняется для обеспечения обратной совместимости с существующими приложениями и не рекомендуется для разработки новых приложений. Сейчас распределенные приложения следует создавать с помощью  Windows Communication Foundation (WCF).

В следующем примере приложения показано асинхронное программирование в сценарии удаленного взаимодействия. В этом примере сначала создается и вызывается асинхронный делегат удаленного объекта, чтобы показать, что поток ожидает возврата. Затем с помощью асинхронных делегатов и объекта ManualResetEvent вызывается метод удаленного объекта и ожидается ответ.

Это приложение выполняется на одном компьютере или в сети. Если требуется запускать это приложение в сети, необходимо в конфигурации клиента заменить "localhost" на имя удаленного компьютера.

0sa925ka.Caution(ru-ru,VS.100).gifВнимание!
По умолчанию при удаленном взаимодействии .NET Framework проверка подлинности и шифрование не выполняются. Поэтому рекомендуется принять все необходимые меры для проверки удостоверений клиентов и серверов до удаленного взаимодействия с ними. Поскольку для запуска приложений, использующих удаленное взаимодействие .NET Framework, требуются разрешения FullTrust, если неавторизованный клиент получит доступ к серверу, клиент сможет запускать код так, как если бы он был полностью доверенным. Всегда выполняйте проверку подлинности конечных точек и шифрование потоков взаимодействия, либо разместив типы, поддерживающие удаленное взаимодействие, в службах IIS, либо создав пользовательскую пару приемников каналов для выполнения этих задач.

Компиляция этого образца

  1. В командной строке введите следующие команды:

    vbc /t:library ServiceClass.vb
    vbc /r:ServiceClass.dll Server.vb
    vbc /r:ServiceClass.dll Client.vb
    
    csc /t:library ServiceClass.cs
    csc /r:ServiceClass.dll Server.cs
    csc /r:ServiceClass.dll Client.cs
    
  2. Откройте два окна командной строки, и перейдите в них в один каталог. В первом окне введите server. Во втором окне введите client.

ServiceClass

Imports System
Imports System.Runtime.Remoting

Public Class ServiceClass
    Inherits MarshalByRefObject

    Public Sub New()
        Console.WriteLine("ServiceClass created.")
    End Sub

    Public Function VoidCall() As String
        Console.WriteLine("VoidCall called.")
        Return "You are calling the void call on the ServiceClass."
    End Function

    Public Function GetServiceCode() As Integer
        Return Me.GetHashCode()
    End Function

    Public Function TimeConsumingRemoteCall() As String
        Console.WriteLine("TimeConsumingRemoteCall called.")

        For i As Integer = 0 To 20000
            Console.Write("Counting: " & i.ToString() & vbCr)
        Next
        Return "This is a time-consuming call."
    End Function
End Class
using System;
using System.Runtime.Remoting;
public class ServiceClass : MarshalByRefObject
{
    public ServiceClass()
    {
        Console.WriteLine("ServiceClass created.");
    }

    public string VoidCall()
    {
        Console.WriteLine("VoidCall called.");
        return "You are calling the void call on the ServiceClass.";
    }

    public int GetServiceCode()
    {
        return this.GetHashCode();
    }

    public string TimeConsumingRemoteCall()
    {
        Console.WriteLine("TimeConsumingRemoteCall called.");

        for (int i = 0; i < 20000; i++)
        {
            Console.Write("Counting: " + i.ToString());
            Console.Write("\r");
        }
        return "This is a time-consuming call.";
    }
}

Сервер

Imports System
Imports System.Runtime.Remoting

Public Class Server

    Public Shared Sub Main()
        RemotingConfiguration.Configure("server.exe.config", False)
        Console.WriteLine("Waiting...")
        Console.ReadLine()
    End Sub

End Class
using System;
using System.Runtime.Remoting;

public class Server
{
    public static void Main(string[] args)
    {
        RemotingConfiguration.Configure("server.exe.config", false);
        Console.WriteLine("Waiting...");
        Console.ReadLine();
    }
}

Server.exe.config

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <system.runtime.remoting>
    <application>
      <service>
        <wellknown 
           type="ServiceClass, ServiceClass"
           mode="Singleton"
           objectUri="ServiceClass.rem"
            />
      </service>
      <channels>
        <channel ref="http" 
                 port="8080" />
      </channels>
    </application>
  </system.runtime.remoting>
</configuration>

Клиент

Imports System
Imports System.Runtime.Remoting
Imports System.Runtime.Remoting.Messaging
Imports System.Threading

Public Class Client
    Inherits MarshalByRefObject
    Public Shared e As ManualResetEvent

    ' Declares two delegates, each of which represents 
    ' a function that returns a string. The names are strictly 
    ' for clarity in the code – there is no difference between
    ' the two delegates. (In fact, the same delegate type 
    ' could be used for both synchronous and asynchronous 
    ' calls.)

    Public Delegate Function RemoteSyncDelegate() As String
    Public Delegate Function RemoteAsyncDelegate() As String


    ' This is the call that the AsyncCallback delegate references
    <OneWay()> _
    Public Sub OurRemoteAsyncCallback(ByVal ar As IAsyncResult)
        Dim del As RemoteAsyncDelegate = CType(ar, AsyncResult).AsyncDelegate
        Console.WriteLine(vbLf & "**SUCCESS**: Result of the remote AsyncCallBack: " + del.EndInvoke(ar))

        ' Signal the thread.
        e.Set()
        Return
    End Sub

    Public Shared Sub Main()
        'IMPORTANT: .NET Framework remoting does not remote
        'static members. This class must be an instance before
        'the callback from the asynchronous invocation can reach this client.
        Dim clientApp As Client = New Client()
        clientApp.Run()
    End Sub

    Public Sub Run()
        'Enable this and the e.WaitOne call at the bottom if you 
        'are going to make more than one asynchronous call.

        e = New ManualResetEvent(False)

        Console.WriteLine("Remote synchronous and asynchronous delegates.")
        Console.WriteLine(New String("_", 80))
        Console.WriteLine()

        ' This is the only thing you must do in a remoting scenario
        ' for either synchronous or asynchronous programming 
        ' configuration.
        RemotingConfiguration.Configure("Client.exe.config", False)


        ' The remaining steps are identical to single-
        ' AppDomain programming.
        Dim obj As ServiceClass = New ServiceClass()

        ' This delegate is a remote synchronous delegate.
        Dim Remotesyncdel As RemoteSyncDelegate = New RemoteSyncDelegate(AddressOf obj.VoidCall)

        ' When invoked, program execution waits until the method returns.
        ' This delegate can be passed to another application domain
        ' to be used as a callback to the obj.VoidCall method.
        Console.WriteLine(Remotesyncdel())

        ' This delegate is an asynchronous delegate. Two delegates must 
        ' be created. The first is the system-defined AsyncCallback 
        ' delegate, which references the method that the remote type calls 
        ' back when the remote method is done.
        Dim RemoteCallback As AsyncCallback = New AsyncCallback(AddressOf OurRemoteAsyncCallback)

        ' Create the delegate to the remote method you want to use 
        ' asynchronously.
        Dim RemoteDel As RemoteAsyncDelegate = New RemoteAsyncDelegate(AddressOf obj.TimeConsumingRemoteCall)

        ' Start the method call. Note that execution on this 
        ' thread continues immediately without waiting for the return of 
        ' the method call. 
        Dim RemAr As IAsyncResult = RemoteDel.BeginInvoke(RemoteCallback, Nothing)

        ' If you want to stop execution on this thread to 
        ' wait for the return from this specific call, retrieve the 
        '  IAsyncResult returned from the BeginIvoke call, obtain its 
        ' WaitHandle, and pause the thread, such as the next line:
        ' RemAr.AsyncWaitHandle.WaitOne();

        ' To wait in general, if, for example, many asynchronous calls 
        ' have been made and you want notification of any of them, or, 
        ' like this example, because the application domain can be 
        ' recycled before the callback can print the result to the 
        ' console.
        ' e.WaitOne();

        ' This simulates some other work going on in this thread while the 
        ' async call has not returned. 
        Dim count As Integer = 0
        While Not RemAr.IsCompleted
            Console.Write("Not completed: " & count & vbCr)
            count = count + 1
            ' Make sure the callback thread can invoke callback.
            Thread.Sleep(1)
        End While

    End Sub
 
End Class
using System;
using System.Runtime.Remoting;
using System.Runtime.Remoting.Messaging;
using System.Threading;
using Shared;

public class Client : MarshalByRefObject
{
    public static ManualResetEvent e;

    // Declares two delegates, each of which represents 
    // a function that returns a string. The names are strictly 
    // for clarity in the code – there is no difference between
    // the two delegates. (In fact, the same delegate type could
    // be used for both synchronous and asynchronous calls.

    public delegate string RemoteSyncDelegate();
    public delegate string RemoteAsyncDelegate();

    // This is the call that the AsyncCallBack delegate references.
    [OneWayAttribute]
    public void OurRemoteAsyncCallBack(IAsyncResult ar)
    {
        RemoteAsyncDelegate del = (RemoteAsyncDelegate)((AsyncResult)ar).AsyncDelegate;
        Console.WriteLine("\r\n**SUCCESS**: Result of the remote AsyncCallBack: " + del.EndInvoke(ar));

        // Signal the thread.
        e.Set();
        return;
    }

    public static void Main(string[] Args)
    {
        // IMPORTANT: .NET Framework remoting does not remote
        // static members. This class must be an instance before
        // the callback from the asynchronous invocation can reach this client.
        Client clientApp = new Client();
        clientApp.Run();
    }

    public void Run()
    {
        // Enable this and the e.WaitOne call at the bottom if you 
        // are going to make more than one asynchronous call.
        e = new ManualResetEvent(false);
        Console.WriteLine("Remote synchronous and asynchronous delegates.");
        Console.WriteLine(new String('-', 80));
        Console.WriteLine();

        // This is the only thing you must do in a remoting scenario
        // for either synchronous or asynchronous programming 
        // configuration.
        RemotingConfiguration.Configure("Client.exe.config", false);

        // The remaining steps are identical to single-
        // AppDomain programming.
        ServiceClass obj = new ServiceClass();

        // This delegate is a remote synchronous delegate.
       RemoteSyncDelegate Remotesyncdel = new RemoteSyncDelegate(obj.VoidCall);

        // When invoked, program execution waits until the method returns.
        // This delegate can be passed to another application domain
        // to be used as a callback to the obj.VoidCall method.
        Console.WriteLine(Remotesyncdel());

        // This delegate is an asynchronous delegate. Two delegates must 
        // be created. The first is the system-defined AsyncCallback 
        // delegate, which references the method that the remote type calls 
        // back when the remote method is done.

        AsyncCallback RemoteCallback = new AsyncCallback(this.OurRemoteAsyncCallBack);

        // Create the delegate to the remote method you want to use 
        // asynchronously.
        RemoteAsyncDelegate RemoteDel = new RemoteAsyncDelegate(obj.TimeConsumingRemoteCall);

       // Start the method call. Note that execution on this 
       // thread continues immediately without waiting for the return of 
       // the method call. 
       IAsyncResult RemAr = RemoteDel.BeginInvoke(RemoteCallback, null);

       // If you want to stop execution on this thread to 
       // wait for the return from this specific call, retrieve the 
       // IAsyncResult returned from the BeginIvoke call, obtain its 
       // WaitHandle, and pause the thread, such as the next line:
       // RemAr.AsyncWaitHandle.WaitOne();

       // To wait in general, if, for example, many asynchronous calls 
       // have been made and you want notification of any of them, or, 
       // like this example, because the application domain can be 
       // recycled before the callback can print the result to the 
       // console.
       //e.WaitOne();

       // This simulates some other work going on in this thread while the 
       // async call has not returned. 
       int count = 0;
       while (!RemAr.IsCompleted)
       {
            Console.Write("\rNot completed: " + (++count).ToString());
            // Make sure the callback thread can invoke callback.
            Thread.Sleep(1);
        }
    }
}

Client.exe.config

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <system.runtime.remoting>
    <application>
      <client>
        <wellknown 
           type="ServiceClass, ServiceClass"
           url="http://localhost:8080/ServiceClass.rem"
            />
      </client>
      <channels>
        <channel 
           ref="http" 
           port="0"
            />
      </channels>
    </application>
  </system.runtime.remoting>
</configuration>

См. также

Основные понятия

Асинхронное удаленное взаимодействие

Другие ресурсы

Примеры удаленного взаимодействия