How to exchange data between two web application (servlet)

Hello, all,
I have two servlets: SerlvetA and ServletB, they are deployed as web appA and appB in the same web container(tomcat)
How ServletA exchange data with ServletB?
I have tried follow methods:
1) appA and appB could not share HttpSession, so I could not transfer data through session
2) I write a new sigleton java class called AppBroker, servletA get AppBroker's instance, and set some data into the it. ServletB could not get the same instance of the AppBroker, because the appA and appB use different class loader.
tell me how to?

thanks reply, but
1. static class can not solve the problem, it is same
as my sigleton class method, as different web app use
different class loaderhmm... at least in tomcat this seems not be true since i can use static classes in one webapp that are available in another web app on the same host/servlet runner.
Maybe if you build your own classloader than the "scope" of the static class is limited to that classloader (for my understanding this shouldn't be the case since i think it depends on the instance of the jvm and not of the classloader..?!).
2. rmi and object serialization are too expensive!
I am working on how to use jndi to solve this problem.
And I think this maybe a Sevlet specification's
shortcoming: maybe a Local Method as EJB local
interface need been introduced into servlet spec.
could you suggestion other methods?none at the moment. i guess the basic methods are listed.
Maybe there's just one left, a really ugly one. Depending on what kind of data and how often you have to exchange you could think of building a file-based queue, i.e. a dir where you drop files in an read out from the other web app (maybe based on a file/directory listener). But this would only be an appropriate way to go for kind of email and messaging systems i guess...

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Hi
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Dear,
Hi
oracle 10.2
I have following case. One table which is reloaded on daily basis named DELTA. Second table DELTAH i want to use as the store of DELTA's previous loads.
Before every load of DELTA i want put data from it to DELTAH.
DELTA is partitioned by list by column f1 with three partitions. DELTAH is partitioned by list by job_id, where job_id is load identifier. DELTA and DELTAH have same columns.
I wanted to do something like exchange partition to fill DELTAH with DELTA data. But with the given structure i can't use exchange partition.
Now i can
1. Change partitioning of DELTAH to range-list, so it has range partitions by job_id and list subpartitions by f1 (like in DELTA). So i can exchange partitions of DELTA with subpartitions of DELTAH.
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(c) have you any triggers or integrity constraints in your DELTAH
(d) are you deleting from DELTAH (or you will never delete from DELTAH)?
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If the answer to both (c) and (d) is no, then I would suggest finally to do
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select ...Hope his helps
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