A port is of two types which will send or receive the
network calls inside the server.For example the mail
server's smtp will respond on port 25

RMI is remote method invocation.
When ever i am making a call to the remote bean,then the
representation of the bean as a stub is stored inside the
client side as a stub,which is local to the client,and which
minimizes the hectic network calls.And on the server side it
will be a skeleton which works like the same way

 The Java Remote Method Invocation (RMI) system 
allows an object running in one Java virtual machine
 to invoke methods on an object running 
in another Java virtual machine.
 RMI provides for remote communication between programs 
written in the Java programming language. 

Session beans are non-persistent enterprise beans. They can 
be stateful or stateless. A stateful session bean acts on 
behalf of a single client and maintains client-specific 
session information (called conversational state) across 
multiple method calls and transactions. It exists for the 
duration of a single client/server session. A stateless 
session bean, by comparison, does not maintain any 
conversational state. Stateless session beans are pooled by 
their container to handle multiple requests from multiple 
clients.

A bean is stateful or stateless can be inferred from its
deployment descriptor. 
i.e 
ejb-jar.xml
<session-type>Stateless</session-type>

In java interfaces are used instead of multiple inheritance
to overcome the problem of ambiguity. Ambiguity dont arise
due to interfaces because interfaces contain only abstract
methods that is juat declarations.

since java doesn,t support multiple inheritance,
to overcome the disadvntage of multiple inheritance
interfaces are came.

multiple inheritance means,many sub classes can share 
the properties of base class

interfaces are also providing the same feature
but,the class which is implemented the interface
that should give the definition for all the methods present
in the interface.
so,one interface can be implemented by no of classes
by this,the ambiguities are rectified in interfaces

sorry Padmaja,

Multiple inheritance is way of accessing one sub(child) class from multiple base(parent) classes.

in java is  possible through interfaces but not through classes.

session beans are function beans.two types of session beans 
are stateless & stateful.It is not persitent on three cases
 1. server crash
 2. server shutdown
 3. time out

where as entity beans are value beans. it contains only 
setter and getter methods.it is persistent bean.it 
maintains database, for storing objects. two types of 
entity bean are 
bean managed persistance & container managed persistance

Yes, Sure..............

yes container can manage the transaction,security and
persistence

yes