Accessing EJB components from a Remote Client

Question

Hi,
When an web component (Servlet/JSP/Java appl.) need to invoke an business method from an EJB, it first lookup for the registered name from the Application server and obtain the remote reference i.e. the EJB Remote interface. To do this, the client must have got the client-jar file containing the stub. Now, if in a distributed environment, my client is in a different machine and need to access the J2EE server across network, what would be the scenereo.
Is it so, for every EJB the client need to call, it must have got the client-jar file in it's local classpath ? this seems to be not at all feasible.
Is it so, the client loads the Stub acroos the network while obtaining the remote reference ?
Please inform me, what actually happens when a client invokes a EJB call deployed in any application server, across the network !!!
Regards,
Kaustuv Bhattacharya

Answer 1

Greetings,
Hi,
When an web component (Servlet/JSP/Java appl.) need to
invoke an business method from an EJB, it first lookup
for the registered name from the Application server
and obtain the remote reference i.e. the EJB Remote
interface. To do this, the client must have got the
client-jar file containing the stub. Now, if in aFor web components running in the same application context, the client-jar is not required - the server-jar also contains the necessary stubs. However, for application clients, the client-jar is required...
distributed environment, my client is in a different
machine and need to access the J2EE server across
network, what would be the scenereo.The client-jar must be distributed with your application, or accessible from a shared network resource, either way...
Is it so, for every EJB the client need to call, it
must have got the client-jar file in it's local
classpath? this seems to be not at all feasible.Yes, the client-jar must be included in the client's classpath... Why isn't it feasible? The client-jar(s) can easily be distributed with your application. The necessity to include them in the application's CLASSPATH does not necessitate their inclusion into the client-machine's CLASSPATH. Simply include the jar(s) as part of the JVM's -cp option.
Is it so, the client loads the Stub acroos the network
while obtaining the remote reference?A copy of the remote interface's stub file is included for casting purposes. However, a copy of the stub containing the correct communication parameters (such as TCP/IP port number, reference ID, etc. per vendor implementation...), for the remote reference does get downloaded.
Please inform me, what actually happens when a client
invokes a EJB call deployed in any application server,
across the network !!!The exact details are vendor specific and depends on the actual protocol in use by the stub-layer. However, the general behaviour is in-line with RMI(-IIOP) communication.
Regards,
Kaustuv BhattacharyaRegards,
Tony "Vee Schade" Cook