We have our EJBS deployed on oc4j  Server.Now we want
to migrate  from oc4j to weblogic.
Does any one know the state  forward wey to migrate
from oc4j to weblogic  platform

Could you please explain what is oc4j? As I know we
have application servers as WebSphere, WerbLogic,
jBoss(?) and some others. WebSphere, and Weblogic is
the must used in the market, but occ4j?

it is a j2ee server  from Oracle, it is actually an
improved version of Orion Application Server which is
entirely written in Java.
some people belive it has very suporior performance
and scalibility because of pure implementation in
java.

OC4J is Oracle's new J2ee container.
According to the benchmarks released by oracle and very according
to BEA's response to those (you need to read them to find out what
I'm talking about) oc4j  - which is based on Evermind's Orion - is
the fastest application server  currently available.
Please do not confuse oc4j with the previous versions of oracle's
application server.
If you are interested for more official documents and more specification
about this very interesting application server, I can send them to the
list.

Actually This is Our Client's requirement .They
realized that Weblogic is far better than oc4j.

Do you have any ide abt it ?

It's always the client who pays money, so states the final
decision, but are you his consultant? If so have you
make his aware of how much money he'll save/loose and
when deciding about his app. server?
I admit there are many reasons that may encourage
using BEA's Weblogic, but take care if this is really
the correct solusion ;)
BTW, about migration  from oc4j  to Weblogic, if you're
using versions of weblogic  prior to 6 you're in a
bad trouble. Since Weblogic 5.xx doesn't accept .ear
files.
I recommend 6.1+ , if you're having .ear files you need
only a bit changes in your application.xml and i think
web.xml (i'm not sure of the latter).
Also you need to replace oc4j's specific deployment
descriptors with weblogic's which needs studying its
DDT. But if you're building from scratch, you can use
weblogic's console to deploy EJBs, Web apps (war files),
and even j2ee applications.

Do you think that performance is everything? or even do you think that deployment from an .ear file is very important? I don't think so.

Have you ever had a complete cluster of at least 20 servers? In that case Weblogic is one the best and I think for serious clients who are concerned abt more than 100,000 users, robustness is everything !

For more information you may check this link:
www.javaworld.com/.../jw-0223-extremescale.html

What abt robustness of Orion or OC4j?

there exists reasons and needs for which
weblogic could be prefered to orion, which clustering many app. servers
(which is very rare but sometimes very important and reqired) is one of
those reasons.
I accept (as far as i know) that weblogic  is of the best (if not the best)
in clustering ....
But are you going to forget performace!!
It's not wise to confuse different capabilities of different app. servers.
I mean we need to consider our needs and constraints. Do we really need to
use clustering capabilities of weblogic and pay 10,000$ for each processor
in addition to 35,000$ which we pay for the app. server.
BTW, orion lacks clustering on ejbs  but oracle has enriched oc4j  with
such capabilities. Oracle is a big company and i hope they do a nice job,
but i've never read any article or spec. about oc4j's new clustering
features.

Everybody knows the Oracle. But most of people know only Oracle Application server  9i now days. My question is how much difference is there between OAS9i and OC4j?

Please don't think that I am trying to break anything but my effort is more on showing to people (who are usaually in development time not production) that development is not everything. Unfortunately, in Iran we are always developing for perhaps pilot projects and we don't host them. After that they will call a deployer and administrator and do rest of the things.

Please consider that if we want to use only a server for handling the users, we will not need (and we are not supposed) to use Enterprise Frameworks. In this case, the best solution probably is a Model 2 or MVC on JSP/Servlet/Java Beans technology. Because in this architecture, we don't have overhead of remove invocations.

Orion or may be OC4j are the best for development, I agree with you. But they are not good for production time. They are not robust. They do not have lots of capabilities of a serious application server. So, they become fast and high performance. But if a banking system wants to have a J2EE application, do you think that they will use an Orion for handling transactions?

I hope I have answered your question.

If you want to study more on things to consider when building a large business system, you can download new "EJB Mastering EJB 2.0" pdf file and check page#38.

Oracle 9iAS includes Oracle Report Server, Forms Server, Oracle Portal, Oracle Wireless (previously named Portal to Go) and other services, including in latest versions OC4J, the J2EE container licensed by Oracle from Orion. Until version 1.0.2.2.1 OC4J was an independent component of iAS, but in latest versions is included into Oracle9iAS. But, al least, is one more component included in all services iAS provides.
At first version, Oracle used Database as Java container, by providing a Oracle 8i (8.1.7) database with a embebed JVM (called Aurora). But the results were not succesful, and Oracle licensed Orion J2EE container.