.NET Remoting Priyanka Bharatula

Introduction .NET Remoting allows an application to make an object available across remoting boundaries, which includes different appdomains, processes or even different computers connected by a network. The framework provides a number of services, including object activation and object lifetime support, as well as communication channels which are responsible for transporting messages to and from remote applications.

.NET Remoting Components A remotable object: Which is an object that contain some properties and methods located in one application domain and you need to call its methods or properties from another application domain or process. A host application: This is the host of the remotable object also called as the server application. The main task of this host is to listen to requests for the hosted remotable object. A client application: This is the application which makes requests for the remotable object.

Types of Remotable Objects There are 3 types of remotable objects that you can configure and choose from depending on the requirements of your application. Single Call: Service one and only one request coming in Singleton Call: Service multiple clients and is useful when data needs to be shared explicilty between several clients. Client Activation: Richer than singleton in many aspects as they can store the state information between method calls for its specific client.

.Net Remoting Basics Different Ways of defining interfaces: Shared Assembly Shared Interface or Base Objects Generated Metadata Assembly (SoapSuds) Serialization of Data: Encoding/Decoding of Objects natively supported Just need to mark such objects with [Serializable] attribute or implement the interface ISerializable Lifetime Management: Open network connection between client-server Combined reference counting and pinging mechanisms Objects get lifetime when created (reset: time-to-live) Sponsor registered with a server-side object Multiserver/Multiclient: .Net automatically keeps track of remote object’s origin

Remotable Types Marshal-by-value: - all serializable types. - can be used as parameters of remote calls where copy of the object is passed to the remote application. Marshal-by-object: - Types derived from System.MarshalByRefObject - A proxy is passed to the remote application where methods are executed remotely

Managing Life Time of an Object Lease-based object lifetime Each server-object associated with a lease on creation Lease has time-to-live counter, decremented in certain intervals In addition, a defined amount of time is added on every method call a client places on remote object Upon reaching zero time, framework looks for a sponsor registered with the lease.

Managing Life Time of an Object ... sponsor is an object running on sever itself, client or any machine reachable via a network An object subject to garbage collection if A sponsor decides lease will not be renewed Framework unable to contact any registered sponsors If a client references time out object, an exception is thrown System.Runtime.Remoting.Lifetime class

Channels Channels are responsible for passing messages across remoting boundaries. Channels must be registered before objects are created as per application domain. Two pre-defined .NET Remoting channels existing are the TcpChannel and the HttpChannel.

Remoting Architecture

Activation Server activated objects(SAO) : - constructed implicitly by the server when a method is invoked for the first time - can be either singleton/single call Client activated objects(CAO) : - constructed explicitly by the client using new or Activator.CreateInstance with an arbitrary constructor. - stateful objects

Types of Invocation Synchronous Calls Client waits until server finishes processing the request Asynchronous Calls Delegates at work One-Way Calls Framework does not guarantee their execution Method cannot have return values or out parameters No exception thrown even if server is down or the method call is malformed Used in uncritical logging or tracing facilities

.Net Remoting Vs Web Services XML Web Services simple, loosely coupled programming model. can be accessed only over HTTP and work in a stateless environment. services hosted in IIS. .Net Remoting Tightly coupled and more complex programming model. can be accessed over any protocol and support both stateful and stateless environments. services hosted in any AppDomain.

References Advanced .Net Remoting – Ingo Rammer & Mario http://www.thinktecture.com/ .Net Remoting Technical Overview http://msdn.microsoft.com/en-us/library/kwdt6w2k(VS.71).aspx .NET Remoting Versus Web Services http://www.developer.com/net/net/article.php/11087_2201701_1

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