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This article is about the sample analysis of Marshal, Disconnect and lifecycle and tracking services in Microsoft .net Remoting. The editor thinks it is very practical, so share it with you as a reference and follow the editor to have a look.

I. Activation of remote objects

There are three activation methods in Remoting, and the general implementation is done through the static methods of the RemotingServices class. The work process is actually to register the remote object with the channel. Because Remoting does not provide a corresponding Unregister method to unregister remote objects, Microsoft recommends pairing Marshal with Disconnect if you need to register / unregister specified objects. I have already mentioned in "Net Remoting Basics" that the Marshal () method converts a MarshalByRefObject class object into an ObjRef class object, which stores all the relevant information needed to generate a proxy to communicate with the remote object. This allows the instance to be serialized for transmission between application domains and over the network, and can be called by the client. The Disconnect () method disconnects the concrete instance object from the channel.

According to the above instructions, the Marshal () method Marshal-by-Reference,MBR the remote object by reference and puts the object's proxy information into the channel. The client can get it through Activator.GetObject (). If the user wants to log out of the object, call the Disconnect () method. So is there lifecycle management for marshalled remote objects in this way? This is the problem to be described in this article.

II. Life cycle

In CLR, the framework provides a GC (garbage collector) to manage the life cycle of objects in memory. Similarly,. Net Remoting uses a distributed garbage collection that manages the life cycle of remote objects based on lease.

Early DCOM's management of the object life cycle was to use ping and reference counting to determine when the object should be garbage collected. However, the network traffic caused by ping is a painful burden on the performance of distributed applications, which greatly affects the overall performance of distributed processing. .net Remoting introduces a lease manager in each application domain, keeping a reference to the lease object for each server-side SingleTon, or for each client-activated remote object. (note: for server-side activated SingleCall mode, because it is stateless, for each activated remote object, the GC of CLR automatically reclaims, so for remote objects activated in SingleCall mode, there is no lifecycle management. )

1. Lease

A lease is an object that encapsulates the timespan value and is used to manage the lifetime of remote objects. The ILease interface that defines the lease function is provided in .net Remoting. When Remoting activates a remote object through SingleTon mode or client activation mode, the leased object calls the InitializeLifetimeService method inherited from System.MarshalByRefObject and requests the lease from the object.

The ILease interface defines properties about the life cycle, all of which are timespan values. As follows:

InitialLeaseTime: initialization validity time. Default is 300s. If 0, it never expires.

RenewOnCallTime: the lease update time when a method of the remote object is called. The default is 120 seconds.

SponsorshipTimeout: timeout value, the time Remoting will wait after notifying Sponsor (initiator) that the lease expires. The default is 120 seconds.

CurrentLeaseTime: the current lease time, the value of InitializeLeaseTime when the lease is obtained for the first time.

Because the remote object of Remoting inherits MarshalByRefObject, it inherits the InitializeLifetimeService method by default, so the relevant properties of the lease are the default values. If you want to change these settings, you can override the method in the remote object. For example:

Public override object InitializeLifetimeService () {ILease lease = (ILease) base.InitializeLifetimeService (); if (lease.CurrentState = = LeaseState.Initial) {lease.InitialLeaseTime = TimeSpan.FromMinutes (1); lease.RenewOnCallTime = TimeSpan.FromSeconds (20);} return lease;}

You can also ignore this method and change the lease cycle of the object to infinite:

Public override object InitializeLifetimeService () {return null;}

2. Lease Manager

If the lease mentioned earlier is mainly applied to each specific remote object, then the lease manager is a manager dedicated to managing the life cycle of the remote object on the server side, which maintains a System.Hashtable member and maps the lease to an System.DateTime instance to indicate when each lease should expire. Remoting uses polling to wake up the lease manager for a certain amount of time to check whether each lease expires. The default is to wake up every 10 seconds. The polling interval can be configured, such as setting the polling interval to 5 minutes:

LifetimeService.LeaseManagerPollTime = System.TimeSpan.FromMinutes (5)

We can also set the properties of the remote object lease in the lease manager, such as changing the initial valid time of the remote object to permanent:

LifetimeServices.LeaseTime = TimeSpan.Zero

We can also set the life cycle through configuration files, such as:

Note: the pollTime in the configuration file is the polling interval LeaseManagerPollTime of the lease manager mentioned above.

The lease manager's lifecycle settings are for all remote objects on the server. When we set the properties of the lease through the configuration file or the lease manager, the life cycle of all remote objects follows this setting, unless we change the configuration by overriding the InitializeLifetimeService method on the specified remote object. That is, the lease configuration of the remote object takes precedence over the server-side configuration.

3. Sponsor (Sponsor)

The initiator is for the client. The remote object is the object that the initiator wants to lease, and the initiator can sign a lease with the server to agree on the lease time. Once it expires, the sponsor can renew the lease, just like the lease of the tenant in real life and the relationship between the landlord and the tenant.

The ClientSponsor class is defined in the System.Runtime.Remoting.Lifetime namespace in .net Framework, which inherits System.MarshalByRefObject and implements the ISponsor interface. For the properties and methods of the ClientSponsor class, refer to MSDN.

For the client to use the initiator mechanism, an instance of the ClientSponsor class must be created. Then call the relevant methods such as the Register () or Renewal () methods to register the remote object or extend the life cycle. Such as:

RemotingObject obj = new RemotingObject (); ClientSponsor sponsor = new ClientSponsor (); sponsor.RenewalTime = TimeSpan.FromMinutes (2); sponsor.Register (obj)

The renewal time can also be set directly in the constructor of ClientSponsor, such as:

ClientSponsor sponsor = new ClientSponsor (TimeSpan.FromMinutes (2)); sponsor.Register (obj)

We can also write our own Sponsor to manage the initiator mechanism, which must inherit from ClientSponsor and implement the ISponsor interface.

III. Tracking service

As mentioned earlier, we want to determine whether there is lifecycle management for marshalling remote objects through Marshal. In Remoting, you can monitor the marshalling process of MBR objects by tracking service programs.

We can create a simple trace handler that implements the interface ITrackingHandler. The interface ITrackingHandler defines three methods, MarshalObject, UnmarshalObject, and DisconnectedObject. When a remote object is marshalled, ungrouped, and disconnected, the corresponding method is called. Here is the code for the trace processing class:

Public class MyTracking:ITrackingHandler {public MyTracking () {/ TODO: add constructor logic / /} public void MarshaledObject (object obj,ObjRef or) {Console.WriteLine () here; Console.WriteLine ("object" + obj.Tostring () + "is marshaled at" + DateTime.Now.ToShortTimeString ());} public void UnmarshaledObject (object obj,ObjRef or) {Console.WriteLine () Console.WriteLine (object + obj.Tostring () + is unmarshaled at + DateTime.Now.ToShortTimeString ());} public void DisconnectedObject (object obj) {Console.WriteLine (obj.ToString () + "is disconnected at" + DateTime.Now.ToShortTimeString ());}}

Then create an instance of the trace processing class on the server side and register the trace service:

TrackingServices.RegisterTrackingHandler (new MyTracking ())

IV. Testing

1. Create two remote objects and override the InitializeLifetimeService method:

Object 1: AppService1

Initial life cycle: 1 minute

Public class AppService1:MarshalByRefObject {public void PrintString (string contents) {Console.WriteLine (contents);} public override object InitializeLifetimeService () {ILease lease = (ILease) base.InitializeLifetimeService (); if (lease.CurrentState = = LeaseState.Initial) {lease.InitialLeaseTime = TimeSpan.FromMinutes (1); lease.RenewOnCallTime = TimeSpan.FromSeconds (20);} return lease;}}

Object 2: AppService2

Initial life cycle: 3 minutes

Public class AppService2:MarshalByRefObject {public void PrintString (string contents) {Console.WriteLine (contents);} public override object InitializeLifetimeService () {ILease lease = (ILease) base.InitializeLifetimeService (); if (lease.CurrentState = = LeaseState.Initial) {lease.InitialLeaseTime = TimeSpan.FromMinutes (3); lease.RenewOnCallTime = TimeSpan.FromSeconds (40);} return lease;}}

For simplicity, both objects have the same method.

2. Server side

(1) first establish the monitoring and processing class as above

(2) Registration channel:

TcpChannel channel = new TcpChannel (8080); ChannelServices.RegisterChannel (channel)

(3) set the initial lease time of the lease manager to unlimited:

LifetimeServices.LeaseTime = TimeSpan.Zero

(4) create an instance of the tracking processing class and register the tracking service:

TrackingServices.RegisterTrackingHandler (new MyTracking ())

(5) marshalling two remote objects:

ServerAS.AppService1 service1 = new ServerAS1.AppService1 (); ObjRef objRef1 = RemotingServices.Marshal ((MarshalByRefObject) service1, "AppService1"); ServerAS.AppService2 service2 = new ServerAS1.AppService2 (); ObjRef objRef2 = RemotingServices.Marshal ((MarshalByRefObject) service2, "AppService2")

(6) keep the server running:

Console.WriteLine ("Remoting service starts, press exit..."); Console.ReadLine ()

3. Client

Get two remote objects through Activator.GetObject () and call their method PrintString. The code is abbreviated.

4. Run the test:

Running the server and client, because the monitor will monitor the marshalling process of the remote object, at the beginning of the run, it will show that the remote object has been Marshal:

Then the client invokes the PrintString method of the two remote objects, and the server accepts the string:

A minute later, the remote object is automatically Disconnect:

At this point, if the client wants to call remote object 1, it will throw a RemotingException exception

Another minute later, remote object 2 was Disconnect:

Users can also use this code to test whether the time of the RenewOnCallTime is correct. That is to say, when the object is not Disconnect, the life cycle of the calling object is no longer the original valid time value (InitialLeaseTime), but the lease update time value (RenewOnCallTime) from the moment the object is called. In addition, if the two remote objects do not override the InitializeLifetimeService method, the life cycle should be the value set by the lease manager, which is permanently valid (set to 0). Then these two objects will not be automatically Disconnect unless we explicitly specify that their connection be closed. Of course, if we explicitly close the connection, the tracker will still monitor it for changes and then display it.

Thank you for reading! This is the end of this article on "sample analysis of Marshal, Disconnect and life cycle and tracking services in Microsoft .net Remoting". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, you can share it for more people to see!

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