Esempio di .NET Remoting: durate
Questo argomento è specifico di una tecnologia legacy mantenuta per una questione di compatibilità con le applicazioni esistenti di versioni precedenti e non è consigliato per il nuovo sviluppo. Le applicazioni distribuite devono ora essere sviluppate utilizzando Windows Communication Foundation (WCF).
Nell'esempio di codice seguente vengono illustrati diversi scenari di lease di durata. Client.exe registra uno sponsor che (dopo la durata del lease iniziale) rinnova il lease per un TimeSpan diverso da quello specificato in ClientActivatedType.InitializeLifetimeService(). Tenere presente che MyClientSponsor estende MarshalByRefObject per renserlo passabile per riferimento al gestore di lease (nel dominio dell'applicazione Server.exe). Questa applicazione è in esecuzione su un solo computer o attraverso una rete. Se si desidera eseguire questa applicazione su una rete, sarà necessario sostituire "localhost" nella configurazione client con il nome del computer remoto.
.gif "6tkeax11.Caution(it-it,VS.100).gif") Attenzione: |
|---|
| In .NET Remoting l'autenticazione o la crittografia non viene eseguita per impostazione predefinita. È pertanto consigliato che vengano effettuati tutti i passaggi necessari per verificare l'identità di client o server prima di interagirvi in modalità remota. Poiché le applicazioni di .NET Remoting richiedono autorizzazioni di tipo FullTrust per essere eseguite, se si concede l'accesso al proprio server a un client non autorizzato, questi potrebbe eseguire codice come se fosse completamente attendibile. Autenticare sempre gli endpoint e crittografare i flussi di comunicazione eseguendo l'hosting dei tipi remoti in Internet Information Services (IIS) o compilando una coppia di sink di canale personalizzata per eseguire questo lavoro. |
Eseguire Server.exe e quindi Client.exe. L'output dovrebbe essere simile al seguente:
Server.exe:
C:\projects\Lifetime\Server\bin>server
The server is listening. Press Enter to exit....
ClientActivatedType.RemoteMethod called.
Client.exe:
C:\projects\Lifetime\Client\bin>client
Client-activated object: RemoteMethod called. MyDomain\SomeUser
Press Enter to end the client application domain.
I've been asked to renew the lease.
Time since last renewal:00:00:09.9432506
I've been asked to renew the lease.
Time since last renewal:00:00:29.9237760
Per compilare questo esempio
Digitare i comandi seguenti al prompt dei comandi:
csc /t:library RemoteType.cs csc /r:System.Runtime.Remoting.dll /r:RemoteType.dll server.cs csc /r:System.Runtime.Remoting.dll /r:RemoteType.dll client.csvbc /t:library RemoteType.vb vbc /r:System.Runtime.Remoting.dll /r:RemoteType.dll server.vb vbc /r:System.Runtime.Remoting.dll /r:RemoteType.dll client.vb
RemoteType
using System;
using System.Runtime.Remoting.Lifetime;
using System.Security.Principal;
namespace RemoteType
{
public class ClientActivatedType : MarshalByRefObject
{
public override Object InitializeLifetimeService()
{
ILease lease = (ILease)base.InitializeLifetimeService();
// Normally, the initial lease time would be much longer.
// It is shortened here for demonstration purposes.
if (lease.CurrentState == LeaseState.Initial)
{
lease.InitialLeaseTime = TimeSpan.FromSeconds(3);
lease.SponsorshipTimeout = TimeSpan.FromSeconds(10);
lease.RenewOnCallTime = TimeSpan.FromSeconds(2);
}
return lease;
}
public string RemoteMethod()
{
// Announces to the server that the method has been called.
Console.WriteLine("ClientActivatedType.RemoteMethod called.");
// Reports the client identity name.
return "RemoteMethod called. " + WindowsIdentity.GetCurrent().Name;
}
}
}
Imports System
Imports System.Runtime.Remoting.Lifetime
Imports System.Security.Principal
Namespace RemoteType
Public Class ClientActivatedType
Inherits MarshalByRefObject
Public Overrides Function InitializeLifetimeService() As Object
Dim lease As ILease = MyBase.InitializeLifetimeService()
' Normally, the initial lease time would be much longer.
' It is shortened here for demonstration purposes.
If (lease.CurrentState = LeaseState.Initial) Then
lease.InitialLeaseTime = TimeSpan.FromSeconds(3)
lease.SponsorshipTimeout = TimeSpan.FromSeconds(10)
lease.RenewOnCallTime = TimeSpan.FromSeconds(2)
End If
Return lease
End Function
Public Function RemoteMethod() As String
Console.WriteLine("ClientActivatedType.RemoteMethod called.")
' Reports the client identity name.
Return "RemoteMethod called. " & WindowsIdentity.GetCurrent().Name
End Function
End Class
End Namespace
Server
using System;
using System.Runtime.Remoting;
namespace Server
{
class Program
{
static void Main(string[] args)
{
RemotingConfiguration.Configure("Server.exe.config", false);
Console.WriteLine("The server is listening. Press Enter to exit....");
Console.ReadLine();
}
}
}
Imports System
Imports System.Runtime.Remoting
Class Program
Shared Sub Main()
RemotingConfiguration.Configure("Server.exe.config", False)
Console.WriteLine("The server is listening. Press Enter to exit....")
Console.ReadLine()
End Sub
End Class
Server.exe.config
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<system.runtime.remoting>
<application>
<channels>
<channel ref="tcp" port="1234">
<serverProviders>
<formatter ref="binary" typeFilterLevel="Full"/>
</serverProviders>
<clientProviders>
<formatter ref="binary"/>
</clientProviders>
</channel>
</channels>
<service>
<activated type="RemoteType.ClientActivatedType, RemoteType" />
</service>
</application>
</system.runtime.remoting>
</configuration>
Client
using System;
using System.Runtime.Remoting;
using System.Runtime.Remoting.Lifetime;
using RemoteType;
class Client
{
static void Main(string[] args)
{
RemotingConfiguration.Configure("Client.exe.config",false);
ClientActivatedType obj = new ClientActivatedType();
ILease lease = (ILease)obj.GetLifetimeService();
MyClientSponsor sponsor = new MyClientSponsor();
lease.Register(sponsor);
Console.WriteLine("Client-activated object: " + obj.RemoteMethod());
Console.WriteLine("Press Enter to end the client application domain.");
Console.ReadLine();
}
}
public class MyClientSponsor : MarshalByRefObject, ISponsor
{
private DateTime lastRenewal;
public MyClientSponsor()
{
Console.WriteLine("MyClientSponsor.ctor called");
lastRenewal = DateTime.Now;
}
public TimeSpan Renewal(ILease lease)
{
Console.WriteLine("I've been asked to renew the lease.");
Console.WriteLine("Time since last renewal:" + (DateTime.Now - lastRenewal).ToString());
lastRenewal = DateTime.Now;
return TimeSpan.FromSeconds(20);
}
}
Imports System
Imports System.Runtime.Remoting
Imports System.Runtime.Remoting.Lifetime
Imports RemoteType
Class Client
Shared Sub Main()
RemotingConfiguration.Configure("Client.exe.config", False)
Dim obj As ClientActivatedType = New ClientActivatedType()
Dim lease As ILease = CType(obj.GetLifetimeService(), ILease)
Dim sponsor As MyClientSponsor = New MyClientSponsor()
lease.Register(sponsor)
Console.WriteLine("Client-activated object: " + obj.RemoteMethod())
Console.WriteLine("Press Enter to end the client application domain.")
Console.ReadLine()
End Sub
End Class
Public Class MyClientSponsor
Inherits MarshalByRefObject
Implements ISponsor
Dim lastRenewal As DateTime
Public Sub New()
lastRenewal = DateTime.Now
End Sub
Public Function Renewal(ByVal lease As System.Runtime.Remoting.Lifetime.ILease) As System.TimeSpan Implements System.Runtime.Remoting.Lifetime.ISponsor.Renewal
Console.WriteLine("I've been asked to renew the lease.")
Console.WriteLine("Time since last renewal:" + (DateTime.Now - lastRenewal).ToString())
lastRenewal = DateTime.Now
Return TimeSpan.FromSeconds(20)
End Function
End Class
Client.exe.config
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<system.runtime.remoting>
<application>
<channels>
<channel ref="tcp" port="0">
<clientProviders>
<formatter ref="binary"/>
</clientProviders>
<serverProviders>
<formatter ref="binary" typeFilterLevel="Full"/>
</serverProviders>
</channel>
</channels>
<client url="tcp://localhost:1234">
<activated type="RemoteType.ClientActivatedType, RemoteType" />
</client>
</application>
</system.runtime.remoting>
</configuration>