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Ejemplo de comunicación remota: publicación dinámica

  • Artículo

Este tema es específico de una tecnología heredada que se mantiene para la compatibilidad con versiones anteriores con aplicaciones existentes y no se recomienda para nuevo desarrollo. Las aplicaciones distribuidas se deberían desarrollar utilizando  Windows Communication Foundation (WCF).

.NET Remoting solo admite constructores predeterminados con tipos utilizables de forma remota activados en el servidor. Para publicar un objeto después de haberlo creado con un constructor concreto y tener el control completo sobre la publicación de esa instancia específica, puede publicar su instancia mediante programación.

1t63e8ff.Caution(es-es,VS.100).gifPrecaución:
.NET Remoting no lleva a cabo la autenticación o el cifrado de forma predeterminada. Por consiguiente, se recomienda que dé todos los pasos necesarios para comprobar la identidad de los clientes o de los servidores antes de interactuar de forma remota con ellos. Dado que las aplicaciones de .NET Remoting exigen permisos FullTrust para ejecutarse, si a un cliente no autorizado se le permitiera el acceso a su servidor, el cliente podría ejecutar el código como si fuese un cliente de plena confianza. Autentique siempre los extremos y cifre las secuencias de comunicación. Para obtener más información, vea Seguridad en comunicación remota.

Para compilar y ejecutar este ejemplo

  1. Escriba los siguientes comandos en el símbolo del sistema:

    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

  2. Abra dos símbolos del sistema que señalen al mismo directorio. En uno, escriba servidor. En el otro, escriba cliente.

  3. Para dejar de publicar el objeto remoto en copias intermedias, presione Entrar en el símbolo del sistema del servidor y vuelva a ejecutar el cliente para observar las excepciones diferentes producidas para las copias intermedias diferentes. Esta aplicación se ejecuta en un solo equipo o a través de una red. Si desea ejecutar esta aplicación a través de una red, debe reemplazar "localhost" en la configuración del cliente por el nombre del equipo remoto.

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);
            }
        }
    }
}

Vea también

Referencia

RemotingServices.Marshal Method
RemotingServices.Disconnect Method
ChannelServices.UnregisterChannel Method

Otros recursos

Ejemplos de comunicación remota