Distributed Systems - Essay Example

It comprises of a stub and skeleton each at the client and server side respectively, wherein the stub is an object implementing the same interface as that of the remote object. The stub implementation is not the real one, which means it acts as a proxy. In fact, a Stub is a client side object but maintains a reference to the actual server side object. The reference maintained by the stub is the virtual reference which is through network connections for which the relevant resources are provided by the RMI runtime environment which is responsible for establishing socket connections with the other end.

The request of the client sent through the network connections, are received by the server side Skeleton, which performs the opposite operation as done by the Stub (unmarshalling) and services the request which again is de-serialized by the stub. 6) The relevant data required to perform the method invocation will also be sent along the request in a network representable format. The transportable format is known as marshaling. RMI implements marshaling through serialization feature of the java language.

Both the ends are in java Serialization. 1) The major drawback it holds is that, RMI only works where both server and client side programs are implemented in the same language that is JAVA. It wont support the implementation in any other language. CORBA is an abbreviation. RMI implements marshaling through serialization feature of the java language. Both the ends are in java Serialization.7) It mainly supports object-by-value.8) It relies on naming service for the distribution of stubs over the network which is analogous to the telephone directory, where it associates a unique name to the object, given by us.

Disadvantages1) The major drawback it holds is that, RMI only works where both server and client side programs are implemented in the same language that is JAVA. It wont support the implementation in any other language.2) Since it implements RPC style, the client is blocked till the procedure returns. This style of communication is synchronous by nature.3) Java call semantics are changed so that thread identity is not maintained. 4) An high end application can become slow if the implementation involves RMI.5) There are limited development tools. 6) Clients need access to the latest stubs as more and more functionalities are incorporated.

CORBA CORBA is an abbreviation for Common Object Request Architecture. It is a specification for developing distributed application which is object oriented and language independent. CORBA provides interoperability between various platforms. Since the choice of a Operation System is not going to make any difference. The heart of CORBA application is a piece of software infrastructure ORB (Object Request Broker). ORB provides a communication bus for applications to interact with each other. It's a piece of software infrastructure given by vendors where from jdk1.

2 onwards the java API for CORBA is known as JavaIDL. CORBA allows us to invoke remote operations as if they are local methods. This is possible due to the existence of a proxy which we call as stub in the CORBA