How to share objects across ears ?

Question

We need to define a set of classes and/or jar's that will be used across various
.ear file deployments. We can make these classes visible by putting them in BEA's
classpath, but that would mean restarting the server everytime there are changes
to such global classes:
1. What is the correct way to do this ? Can classes be redefined in (i.e. defined
in individual) various ear files ?
2. We have value classes that are passed between various session beans that reside
in DIFFERENT ear files (i.e. they are part of separate enterprise apps). How does
one define and reference such value classes ?
Thanks for your help in advance!

Answer 1

DP wrote:
Rob:
Thanks for your response(s). This actually leads to other related questions. What
is the recommendation for deployment in the following scenario: We have a requirement
of being able to hot deploy objects frequently in production. I understand that
the best way to accomplish this is to do an "exploded ear deployment".
(a) How can we deploy one or more ejbs in an exploded ear ? Can the EJBs be either
a set of .class files or a set of .jar files? In this context, what exactly is
the definition of an exploded ear ? Does it mean that all objects are packaged
only as .class files (i.e. no jar, wars whatsoever in the ear, correct ?) within
the directory ?You can either deploy the sub-components (eg EJBs, webapps etc)
archived, exploded or a mix.
Personally I prefer to just explode everything like this:
ear/META-INF/application.xml
ear/ejb/META-INF/ejb-jar.xml
ear/ejb/com/foo/MyEJB.class
>
(b) How can we deploy java objects ? Say we need to update a value class or a
non-J2EE class on the server. If we have an exploded ear, do we simply overwrite
the existing class file ? Will WL8.1 automatically read this newer class ? Similarly,
if we need to add a non-j2ee .class file, can it be just dropped into the exploded
ear directory without a server restart ?You should never need to restart the server to make an application change.
If you want to change an arbitrary class file in the app, then you can
just change the .class file and then use wldeploy or weblogic.Deployer
to redeploy the application.
You can do better if you know the class is only used in a particular web
application. In that case, you could redeploy just a particular webapp
without bouncing the rest of the app.
-- Rob
>
Thanks, again, for helping.
Rob Woollen <[email protected]> wrote:
Do you have any singletons? If so, then your best bet is to have the
classes in the CLASSPATH (at least the singletons).
If not, then you can have a separate copy of the classes in each EAR.
You'll need to ensure the classes that are passed between the EARs are
exactly the same in both EARS (same serial version uid.) WLS uses
serialization between applications, so the class will be serialized in
app-1's classloader and deserialized in app-2's classloader.
FWIW, we're well aware of this problem and are looking at building
better support for this into the next major version of WLS.
-- Rob
DP wrote:
We need to define a set of classes and/or jar's that will be used acrossvarious
ear file deployments. We can make these classes visible by puttingthem in BEA's
classpath, but that would mean restarting the server everytime thereare changes
to such global classes:
1. What is the correct way to do this ? Can classes be redefined in(i.e. defined
in individual) various ear files ?
2. We have value classes that are passed between various session beansthat reside
in DIFFERENT ear files (i.e. they are part of separate enterprise apps).How does
one define and reference such value classes ?
Thanks for your help in advance!