Building Distributed Applications Efficiently Using .Net RemotingEver since the internet revolution started, it has become indispensable for the enterprise applications to communicate across the network to get information and service from different sources. Today, this communication is leveraged in many of the enterprise applications ranging from business to business (B2B) and Business to Consumer (B2C) categories. Further, it has become a key driver for building efficient distributed applications across platforms addressing complex business needs without rebuilding all of the components.
Building distributed applications efficiently implies the fact that their design will take care of the factors like performance, robustness, flexibility, maintainability, re-usability and scalability of components. .Net remoting provides a good architectural framework to develop distributed application taking into consideration of these factors. .Net remoting is based on the principles of SOA (Service Oriented Architecture) where it is not necessary for a client application to know about the implementation details of the service in the server, thus achieving a transparent way of inter-process communication. Also, any change in the server does not necessitate a corresponding change to the client. .Net Remoting was provided by Microsoft Corporation as a replacement for DCOM (Distributed Component Object Model) since DCOM was not able to support internet solutions. The .Net framework provides an option to customize different stages of communication between the client and the remote object in the server to suit to different remoting scenarios. For example, a channel used for communication between the client and server is pluggable and replaceable with either TCP or HTTP or any custom channel based on the requirement. Also, the rich class library provided by the framework helps to quickly create and use a remote object and the required web service. All the configurations for the communication with the remote object are based on XML files, instead of the registry-based settings in DCOM. Typically, in a web service, the object state on the server is not maintained since the transport protocol is based on HTTP. However, .Net Remoting provides the developer an option to maintain state or not by choosing the required activation model for the remote object such as Client activated or Server activated model. This is due to the fact that every remote object has a distributed identity, with the state being either Singleton or SingleCall type. If a remote object is created in Singleton mode, there will be one instance of the object servicing all the clients that access it and that object maintains its state by itself. In case of SingleCall type, there will be a new instance of object created for every call from the client and no state maintained anywhere. Remoting also provides a facility to allow the remote object on server to call the asynchronous methods on the client, performing callbacks using the 'delegate' and 'event' keyword and hence achieves two-way communication. Concept of .Net Remoting .Net remoting uses the concept of Application Domain - a boundary within which multiple applications run in the same process without affecting each other. Error thrown in one application domain will not affect the other application domain in the same process. The client in one Application Domain uses a proxy to call the remote object in the server in another Application Domain of another process. Messages from one client are serialized using a formatter and sent to the client channel. The server channel on the server deserializes the message using its formatter and calls the remote object to service the client.
Typically, remoting expects both the client and the server environment to run Common Language Runtime (CLR) and hence does not support heterogeneous environment directly. To use it in a heterogeneous environment, it provides another alternative option of using Web Services through HTTP. This causes a slight overhead in development time and transaction speed. Also, there is no in-built security mechanism within the remoting framework and hence care needs to be taken while developing secured applications. However, the above limitation out-weighs the benefits derived from the .Net Remoting framework. A right use of .Net Remoting features can provide maximum benefit to enterprise applications addressing today’s business needs.
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