Remote Method Invocation in Object Oriented (Java):
RMI
is a technique, using Java language and development environment can write
Object Oriented Programming in which objects on different computers can
interact with each other over a network. RMI allows any Java object type
to be used - even if the client or server has never encountered it before. RMI
allows both client and server to dynamically load new object types as required.
The
RMI provides remote communication between the applications using two objects stub and skeleton
as shown in figure.
 |
| Remote Method Invocation in Java |
Implementation
· A stub program
in the client side
of the client-server relationship (this type relationship is mostly used in computing environments using different Operating Systems),
and a corresponding skeleton at the server end. The stub appears to the calling
program to be the program being called for a service. (Sun uses the term
proxy as a synonym for stub.)
· A Remote Reference Layer that can
behave differently depending on the parameters passed by the calling program.
For example, this layer can determine whether the request is to call a single
remote service or multiple remote programs as in a multicast.
· A Transport Connection Layer, which
sets up and manages the request.
Stub Mechanism
·
It initiates a connection with
remote Virtual Machine (JVM),
·
It writes and transmits (marshals)
the parameters to the remote Virtual Machine (JVM),
·
It waits for the result
·
It reads (unmarshals) the return
value or exception
·
It finally, returns the value to
the caller.
Skeleton Mechanism
·
It reads the parameter for the
remote method
·
It invokes the method on the actual
remote object, and
·
It writes and transmits (marshals)
the result to the caller.
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