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Struts & Hibernate
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| | | Accessing Different DBs from State less EJB | Accessing Different DBs from State less EJB 2003-11-02 - By J�rn �lmheim
Back
Hi.
You're on the right track here, Christophe, but not quite there.
The problem is as you correctly observe with transactions, but the problem
is with the database driver. This data base driver only one-phase commit,
and what you need when you use more than one resource in a transaction is
of course two-phase commit.
Anil: Switch to a database driver that supports XA connections (two-phase
commit), and that will solve your problem.
Best regards,
J�rn �lmheim
Senior Software Developer
Statoil ASA.
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| | Christophe Thepaut |
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| | 02.11.2003 09:55 |
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| Subject: Re: Accessing Different DBs from State less EJB
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Hi
Using the abstract factory with a DAO will not help. These patterns only
allow you to choose different databases with no or little changes on the
client side (SQL statements). Here your databases are DB2. You're fine
about it.
What you need here is to manage transactional behaviours. The exception is
pretty clear about it: An illegal attempt to use multiple resources that
have only one-phase capability has occurred within a global transaction.
Either you manage your transactions using EJBs (session beans in your case)
or a transactional middleware.
If you go with EJBs then you need to choose between Container Managed
Transaction and define transactional demarcation in the ejb-jar.xml
descriptor or Bean Managed Transaction and define transaction
programmatically using JTA. Beware that you can not use both. You need to
choose one or another and stick with it.
If you go with a transactional middleware such as BEA Tuxedo for instance
(IBM must have one but I can't recall) then you can not manage transactions
using EJBs.
What is a little scary about your issue here is that transactional
management should have been defined by your Architect in a Software
architecture document or/and in a Design Model.
Good luck.
Christophe
SCEA for J2EE
From: An interest list for Sun Java Center J2EE Pattern Catalog
[mailto:J2EEPATTERNS-INTEREST@(protected)] On Behalf Of Anil Kumar
Sent: Sunday, November 02, 2003 7:22 AM
To: J2EEPATTERNS-INTEREST@(protected)
Subject: Re: Accessing Different DBs from State less EJB
Ashraf,
Iam implementing DAO the same way as you told. I am following the core
J2EE design
patterns.
Thanks
Anil
ashraf galal <ashrafwg@(protected)> wrote:
Anil;
you must implement it usaing the abstract factory pattern.
the pattern looks like the following class diagram:
I hope this might help you.
Best wishes
Ashraf Galal
EAI Senior Architect
(416)804-8359
>From: Anil Kumar
>Reply-To: An interest list for Sun Java Center J2EE Pattern Catalog
>To: J2EEPATTERNS-INTEREST@(protected)
>Subject: Accessing Different DBs from State less EJB
>Date: Sat, 1 Nov 2003 21:45:41 -0800
>
>Hi,
>
>I had a Stateless session Bean and DAO to access 4 databases. But as
per my requirement I have to get data from different databases one
after other in EJB.
>I am getting data from First DB then when it is trying to create the
statement for second DB its throwing the error.
>
>WTRN0062E: An illegal attempt to use multiple resources that have
only one-phase capability has occurred within a global transaction.
>
>I am using Websphere application server (WSAD) with
COM.ibm.db2.jdbc.app.DB2Driver
>(JDBC 2.0) Database is DB2.
>
>
>Please help me out
>
>Thanks a lot
>Anil
>
>
>
>
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