10-04-2017, 07:58 PM
This article is presented by:
Deepti Singhvi
Nitesh Agrawal
Department of Information Technology
Shrinathji Institute of Technology & Engineering
Nathdwara ( Rajsamand )
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Abstract
RMI applications often comprise two separate programs, a server and a client. A typical server program creates some remote objects, makes references to these objects accessible, and waits for clients to invoke methods on these objects. A typical client program obtains a remote reference to one or more remote objects on a server and then invokes methods on them. RMI provides the mechanism by which the server and the client communicate and pass information back and forth. Such an application is sometimes referred to as a distributed object application.
Why Use RMI?
The term n-tier architecture has become more common. To the left is an example of a 3-tier architecture. At tier 1 is the database which could be any database that you have connectivity to. Tier 2 contains an application which has access to the database. The tier 2 application understands the business logic of needed to comuicate with the tier 1 database. The tier 2 server application acts as a go between for the clients to speak with the database. The tier 2 server application may contain security contraints for differnt types of clients and may also insure that the proper data is entered into the tier 1 database. Clients are on tier 3. The platforms supported depend on the tier 2 applciation. RMI is very useful for communication between tier 3 clients and tier 2 server applications.
The server must first bind its name to the registry
The client lookup the server name in the registry to establish remote references.
The Stub serializing the parameters to skeleton, the skeleton invoking the remote method and serializing the result back to the stub.
Introduction:-
The first layer is the Stub/Skeleton Layer. This layer is responsible for managing the remote object interface between the client and server.
The second layer is the Remote Reference Layer (RRL). This layer is responsible for managing the "liveliness" of the remote objects. It also manages the communication between the client/server and virtual machine s, (e.g., threading, garbage collection, etc.) for remote objects.
The third layer is the transport layer. This is the actual network/communication layer that is used to send the information between the client and server over the wire. It is currently TCP/IP based. If you are familiar with RPC, it is a UDP-based protocol which is fast but is stateless and can lose packets. TCP is a higher-level protocol that manages state and error correction automatically, but it is correspondingly slower than UDP.