Question on reentrant beans

Hi all,
If there is a StatelessSessionBean that has two methods in its remote interface
say
method1() and method2(). In the bean implementation consider that method1() calls
method2(),
now my questions are:
     1) Can this scenario be called as re-entrant.
     2) What is the problem of calling a method in the same bean using "this" keyword.
     3) What problems in the transactions will happen in this scenario.
Thanks in advance,
Chandru

Stefan,
You are mixing terminology.
What you are describing is concurrency (although now that I think about
it, if you somehow manage to associate your two threads with the same
transactional context then you'll possibly create a transaction diamond).
I don't think there is a situation at all when Weblogic will allow a
second thread to access the instance while another thread is still in
the middle of an EJB call. Depending on the concurrency strategy for
entity beans you can get parallel access to instances with the same PKs
but it will not be one and the same instance.
For stateless session beans each call can hit a different available
instance since it doesn't matter which one will do the job.
You can get a reentrant call when from inside an EJB (I haven't dealt
with statefull session EJBs but it's probably very similar) business
method call you either call another EJB business method via the
remote/local interfaces (ejbObject) that will hit the same instance (if
you are in the same transaction you already have the access to that
particular instance so there is no concurrency issue).
Then you are reentering the same instance via the remote/local interface
and it is going to be a reentrant call.
If you simply call the method it is a normal Java method call and the
container doesn't get involved and there you can get recursion.
Dejan
Stefan wrote:
Re-entrance is when the executing thread A gets suspended in the
middle of a method call and thread B calls the same method on the very
same object. When thread A gets to continues two things might happen:
1 The method uses only stack variables and A is able to carry on its
work. 2 If the metod have static variables (not for Java) or uses any
memeber variables thread B might have messed things upp for A (this
situation calls for some sort of synchronisation). In situation 1 we
have a re-entrant method.
method1 calling method1 is called recursion.
Fortunattly having more than one thread operating on one object should
not happen with EJBs. It can happen if your EJB uses som static
methods or singeltons.
Regards
/Stefan

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simon.

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"Michael Jouravlev" <[email protected]> wrote in message
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>
"Eric Temel" <[email protected]> wrote in message
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null

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import java.io.*;
import oracle.jbo.*;
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null

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