遠端處理範例：存留期
下列程式碼範例示範數個存留使用期案例。CAOClient.exe 會註冊發起者，而在初始使用期後，這個發起者會在與遠端型別中所指定之時間的不同時間更新使用期。請注意，MyClientSponsor 會擴充 MarshalByRefObject 以傳址方式傳遞給遠端使用期管理員；如果沒有擴充，但卻使用 SerializableAttribute 屬性，則會以傳值方式傳遞發起者，並以一般方式執行該發起者，但卻是在伺服器應用程式定義域內執行。
這個應用程式可在單一電腦上或跨網路執行。如果想要透過網路執行這個應用程式，則必須將用戶端組態中的 "localhost" 取代為遠端電腦的名稱。
這個範例使用以 Visual Basic 和 C# 撰寫的程式碼。其中會提供 RemoteType.cs 和 CAOClient.cs，但指定的命令列不會編譯它。
警告
.NET 遠端處理預設不會執行驗證或加密。因此，建議在與用戶端或伺服器進行遠端互動之前，先採取所有必要步驟以驗證這些用戶端或伺服器的識別。因為 .NET 遠端處理應用程式需要 FullTrust 權限才能執行，所以如果將伺服器的存取權授與未授權用戶端，則該用戶端可如受到完全信任般地執行程式碼。請一律驗證您的端點並加密通訊資料流，方法是在網際網路資訊服務 (IIS) 中裝載遠端處理的型別，或建置自訂通道接收組，以完成這項作業。
編譯這個範例
在命令提示字元中輸入下列命令：
vbc /t:library RemoteType.vb
csc /r:RemoteType.dll server.cs
vbc /r:RemoteType.dll CAOClientVB.vb
CAOClient 檔案
//CAOClient.cs
using System;
using System.Runtime.Remoting;
using System.Runtime.Remoting.Lifetime;
public class Client{
public static void Main(string[] Args){
// Loads the configuration file.
RemotingConfiguration.Configure("CAOclient.exe.config");
ClientActivatedType CAObject = new ClientActivatedType();
ILease serverLease = (ILease)RemotingServices.GetLifetimeService(CAObject);
MyClientSponsor sponsor = new MyClientSponsor();
// Note: If you do not pass an initial time, the first request will
// be taken from the LeaseTime settings specified in the
// server.exe.config file.
serverLease.Register(sponsor);
// Calls same method on each object.
Console.WriteLine("Client-activated object: " + CAObject.RemoteMethod());
Console.WriteLine("Press Enter to end the client application domain.");
Console.ReadLine();
}
}
public class MyClientSponsor : MarshalByRefObject, ISponsor{
private DateTime lastRenewal;
public MyClientSponsor(){
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);
}
}
' CAOClientVB.vb
Imports System
Imports System.Runtime.Remoting
Imports System.Runtime.Remoting.Lifetime
Public Class Client
<MTAThread()> _
Public Shared Sub Main()
' Loads the configuration file.
RemotingConfiguration.Configure("CAOclient.exe.config")
Dim CAObject As ClientActivatedType = New ClientActivatedType()
Dim ServerLease As ILease = CType(RemotingServices.GetLifetimeService(CAObject), ILease)
Dim sponsor As MyClientSponsor = New MyClientSponsor()
' Note: If you do not pass an initial time, the first request will be taken from
' the LeaseTime settings specified in the server.exe.config file.
ServerLease.Register(sponsor)
' Calls same method on each object.
Console.WriteLine("Client-activated object: " & CAObject.RemoteMethod())
Console.WriteLine("Press Enter to end the client application domain.")
Console.ReadLine()
End Sub 'Main
End Class 'Client
Public Class MyClientSponsor
Inherits MarshalByRefObject
Implements ISponsor
Private LastRenewal As DateTime
Public Sub New()
LastRenewal = DateTime.Now
End Sub ' MyClientSponsor
Public Function Renewal(ByVal lease As ILease) As TimeSpan Implements ISponsor.Renewal
Console.WriteLine("I've been asked to renew the lease.")
Dim Latest As DateTime = DateTime.Now
Console.WriteLine("Time since last renewal: " & (Latest.Subtract(LastRenewal)).ToString())
LastRenewal = Latest
Return TimeSpan.FromSeconds(20)
End Function 'Renewal
End Class 'MyClientSponsor
RemoteType 檔案
'RemoteType.vb
Imports System
Imports System.Runtime.Remoting.Lifetime
Imports System.Security.Principal
Public class ClientActivatedType
Inherits MarshalByRefObject
Public Function RemoteMethod() As String
' 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
End Function 'RemoteMethod
' Overrides the lease settings for this object.
Public Overrides Function InitializeLifetimeService() As Object
Dim lease As ILease = CType(MyBase.InitializeLifetimeService(), ILease)
If lease.CurrentState = LeaseState.Initial Then
' Normally, the initial lease time would be much longer.
' It is shortened here for demonstration purposes.
lease.InitialLeaseTime = TimeSpan.FromSeconds(3)
lease.SponsorshipTimeout = TimeSpan.FromSeconds(10)
lease.RenewOnCallTime = TimeSpan.FromSeconds(2)
End If
Return lease
End Function 'InitializeLifetimeService
End Class 'ClientActivatedType
// RemoteType.cs
using System;
using System.Runtime.Remoting.Lifetime;
using System.Security.Principal;
public class ClientActivatedType : MarshalByRefObject{
// Overrides the lease settings for this object.
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;
}
}
Server.cs
using System;
using System.Runtime.Remoting;
public class Server{
public static void Main(string[] Args){
// Loads the configuration file.
RemotingConfiguration.Configure("server.exe.config");
Console.WriteLine("The server is listening. Press Enter to exit....");
Console.ReadLine();
Console.WriteLine("Recycling memory...");
GC.Collect();
GC.WaitForPendingFinalizers();
}
}
Server.exe.config
<configuration>
<system.runtime.remoting>
<application>
<service>
<activated type="ClientActivatedType, RemoteType"/>
</service>
<channels>
<channel port="8080" ref="http"/>
</channels>
</application>
</system.runtime.remoting>
</configuration>
CAOclient.exe.config
<configuration>
<system.runtime.remoting>
<application>
<client url="http://localhost:8080">
<activated type="ClientActivatedType, RemoteType"/>
</client>
<channels>
<channel ref="http" port="0">
<serverProviders>
<formatter ref="soap" typeFilterLevel="Full"/>
<formatter ref="binary" typeFilterLevel="Full"/>
</serverProviders>
</channel>
</channels> </application>
</system.runtime.remoting>
</configuration>