Exemple d'accès distant : publication dynamique

Article
04/22/2008

.NET Remoting prend en charge uniquement les constructeurs par défaut avec des types accessibles à distance et activés par le serveur. Pour publier un objet après l'avoir créé avec un constructeur spécifique et disposer d'un contrôle complet sur la publication de cette instance spécifique, vous pouvez publier votre instance par programme.

Attention :
.Par défaut, l'accès distant .NET ne procède ni à l'authentification ni au chiffrement. Par conséquent, il est recommandé que vous preniez toutes les mesures nécessaires à l'identification des clients et des serveurs avant d'interagir à distance avec eux. Comme les applications d'accès distant .NET requièrent des autorisations FullTrust pour s'exécuter, un client non autorisé pourrait exécuter du code comme s'il était d'un niveau de confiance suffisant s'il se voyait accorder l'accès à votre serveur. Veillez à toujours authentifier vos points de terminaison et à chiffrer les flux de données de communication. Pour plus d'informations consultez Sécurité dans l'accès distant.

.Par défaut, l'accès distant .NET ne procède ni à l'authentification ni au chiffrement. Par conséquent, il est recommandé que vous preniez toutes les mesures nécessaires à l'identification des clients et des serveurs avant d'interagir à distance avec eux. Comme les applications d'accès distant .NET requièrent des autorisations FullTrust pour s'exécuter, un client non autorisé pourrait exécuter du code comme s'il était d'un niveau de confiance suffisant s'il se voyait accorder l'accès à votre serveur. Veillez à toujours authentifier vos points de terminaison et à chiffrer les flux de données de communication. Pour plus d'informations consultez Sécurité dans l'accès distant.

Pour compiler et exécuter cet exemple

À l'invite de commandes, tapez la commande suivante :

vbc -t:library remote.vb
vbc -r:System.Runtime.Remoting.dll -r:remote.dll server.vb
vbc -r:System.Runtime.Remoting.dll -r:remote.dll client.vb

csc -t:library remote.cs
csc -r:System.Runtime.Remoting.dll -r:remote.dll server.cs
csc -r:System.Runtime.Remoting.dll -r:remote.dll client.cs

Remote

Imports System

Public Class ServiceClass
   Inherits MarshalByRefObject
   Private m_startTime As DateTime

   Public Sub New()
      Console.WriteLine("ServiceClass created without constructor. Instance hash is " & Me.GetHashCode().ToString())
      m_startTime = DateTime.Now
   End Sub   

   Overrides Protected Sub Finalize()
      Console.WriteLine("I'm being collected after " & (New TimeSpan(DateTime.Now.Ticks - m_startTime.Ticks)).ToString() & " seconds.")
      MyBase.Finalize()
   End Sub    

   Public Function GetServerTime() As DateTime
      Console.WriteLine("Time requested by a client.")
      Return DateTime.Now
   End Function   

   Public ReadOnly Property InstanceHash() As Integer
      Get
         Return Me.GetHashCode()
      End Get
   End Property 
End Class

using System;
using System.Collections.Generic;
using System.Text;

namespace Remote
{
    public class ServiceClass : MarshalByRefObject
    {
        private DateTime m_startTime;

        public ServiceClass()
        {
            Console.WriteLine("ServiceClass created without constructor. Instance hash is " + GetHashCode().ToString());
            m_startTime = DateTime.Now;
        }

        ~ServiceClass()
        {
            Console.WriteLine("I'm being collected after " + (new TimeSpan(DateTime.Now.Ticks - m_startTime.Ticks)).ToString() + " seconds.");
        }

        public DateTime GetServerTime()
        {
            Console.WriteLine("Time requested by a client.");
            return DateTime.Now;
        }

        public int InstanceHash
        {
            get { return GetHashCode(); }
        }
    }
}

Server

Imports System
Imports System.Runtime.Remoting
Imports System.Runtime.Remoting.Channels
Imports System.Runtime.Remoting.Channels.Http

Module Module1

  Sub Main()
    Dim channel As New HttpChannel(8080)
    ChannelServices.RegisterChannel(channel, False)

    Dim object1 As New ServiceClass()

    ' Creates the single instance of ServiceClass. All clients
    ' will use this instance.
    Dim ref1 As ObjRef = RemotingServices.Marshal(object1, "object1uri")
    Console.WriteLine("ObjRef.URI: " & ref1.URI)

    Console.WriteLine("Running. Press Enter to end publication.")
    Console.ReadLine()

    ' This unregisters the object from publication, but leaves
    ' the channel listening.
    RemotingServices.Disconnect(object1)
    Console.WriteLine()
    Console.WriteLine("Disconnected the object. Client now receives a RemotingException.")
    Console.WriteLine("Press Enter to unregister the channel.")
    Console.ReadLine()
    ' At this point, the ServerClass object still exists. The server
    ' could republish it.

    ' This unregisters the channel, but leaves the application 
    ' domain running.
    ChannelServices.UnregisterChannel(channel)
    Console.WriteLine("Unregistered the channel. Client now receives a WebException.")
    ' The ServerClass object still exists. The server could
    ' reregister the channel and republish the object.
    Console.WriteLine("The host application domain is still running. Press Enter to stop the process.")
    Console.ReadLine()

    ' The ServiceClass object's Finalize method writes a message to
    ' the console. A single object will almost always succeed in 
    ' running its Finalize method before the Console is finalized;
    ' in a larger application, you could ensure that all objects 
    ' finalize before the application ends by calling the garbage 
    ' collector and waiting.
    GC.Collect()
    GC.WaitForPendingFinalizers()
  End Sub
End Module

using System;
using System.Runtime.Remoting;
using System.Runtime.Remoting.Channels;
using System.Runtime.Remoting.Channels.Http;
using Remote;

namespace Server
{
    class Server
    {
        static void Main(string[] args)
        {
            HttpChannel channel = new HttpChannel(8080);
            ChannelServices.RegisterChannel(channel, false);

            ServiceClass object1 = new ServiceClass();

            // Creates the single instance of ServiceClass. All clients
            // will use this instance.

            ObjRef ref1 = RemotingServices.Marshal(object1, "object1uri");
            Console.WriteLine("ObjRef.URI: " + ref1.URI);

            Console.WriteLine("Running. Press Enter to end publication.");
            Console.ReadLine();

            // This unregisters the object from publication, but leaves
            // the channel listening.
            RemotingServices.Disconnect(object1);
            Console.WriteLine();
            Console.WriteLine("Disconnected the object. Client now receives a RemotingException.");
            Console.WriteLine("Press Enter to unregister the channel.");
            Console.ReadLine();

            // At this point, the ServerClass object still exists. The server
            // could republish it.

            // This unregisters the channel, but leaves the application 
            // domain running.
            ChannelServices.UnregisterChannel(channel);
            Console.WriteLine("Unregistered the channel. Client now receives a WebException.");

            // The ServerClass object still exists. The server could
            // reregister the channel and republish the object.
            Console.WriteLine("The host application domain is still running. Press Enter to stop the process.");
            Console.ReadLine();

            // The ServiceClass object's Finalize method writes a message to
            // the console. A single object will almost always succeed in 
            // running its Finalize method before the Console is finalized;
            // in a larger application, you could ensure that all objects 
            // finalize before the application ends by calling the garbage 
            // collector and waiting.
            GC.Collect();
            GC.WaitForPendingFinalizers();
        }
    }
}

Client

Imports System 
Imports System.Runtime.Remoting
Imports System.Runtime.Remoting.Channels
Imports System.Runtime.Remoting.Channels.Tcp
Imports System.Runtime.Remoting.Channels.Http

Public Class ClientProcess
   <MTAThread()> _
   Public Shared Sub Main()
      
      Dim channel As New HttpChannel(0)
      ChannelServices.RegisterChannel(channel, False)

      ' Registers the remote class. (This could be done with a
      ' configuration file instead of a direct call.)
      RemotingConfiguration.RegisterWellKnownClientType(Type.GetType("ServiceClass, remote"), "https://localhost:8080/object1uri")

      ' Instead of creating a new object, this obtains a reference
      ' to the server's single instance of the ServiceClass object.
      Dim object1 As ServiceClass = New ServiceClass()

      Try
         Console.WriteLine("ServerTime: " & object1.GetServerTime())
      Catch ex As Exception
         Console.WriteLine("Exception of type: " & ex.GetType.ToString & " occurred.")
         Console.WriteLine("Details: " & ex.Message)
      End Try

   End Sub     
End Class

using System;
using System.Runtime.Remoting;
using System.Runtime.Remoting.Channels;
using System.Runtime.Remoting.Channels.Tcp;
using System.Runtime.Remoting.Channels.Http;
using Remote;

namespace Client
{
    public class ClientProcess
    {
  [MTAThread]
        public static void Main(string[] args)
        {
            HttpChannel channel = new HttpChannel();
            ChannelServices.RegisterChannel(channel, false);

            // Registers the remote class. (This could be done with a
            // configuration file instead of a direct call.)
            RemotingConfiguration.RegisterWellKnownClientType(
                Type.GetType("Remote.ServiceClass, remote"),
                "https://localhost:8080/object1uri");

            // Instead of creating a new object, this obtains a reference
            // to the server's single instance of the ServiceClass object.
            ServiceClass object1 = new ServiceClass();

            try
            {
                Console.WriteLine("ServerTime: " + object1.GetServerTime());
            }
            catch (Exception ex)
            {
                Console.WriteLine("Exception of type: " + ex.ToString() + " occurred.");
                Console.WriteLine("Details: " + ex.Message);
            }
        }
    }
}