pburleson
Jan 31st, 2005, 09:07 AM
I posted this to the Spring User Mailing List, but got no responses. I'm hoping posting it here will hopefully generate something:
I think these questions are mostly targeted at Colin since I think he
wrote the ejbtest app, but feel free to provide answers if you have them.
I've been battling with our app config for a few days trying to get
our Message Driven Beans to deploy with JBoss (everything works fine
with Weblogic). The way we have our app setup is most of the code
(including the files that define our Spring context ) in one jar. That
jar is shared by our webapp and our ejb jar inside an EAR. The webapp
deploys fine and the ContextLoaderListener there fires up our Spring
context and it wires up the JtaTransactionManager which we use in
conjunction with the TransactionProxyFactoryBean to do transaction
declarations on our services. These services are backed by DAOs backed
by Hibernate. The web part of our app runs fine, transactions occur
like they should.
The problem comes up when we send a message to one of our MDBs. It's
at that point that ejbCreate() gets called and since we are using
AbstractJmsMessageDrivenBean defined to use our application's context
definition file, it starts to create a bean factory for the Message
Driven Bean to use that contains all the beans our web app uses. We
get an exception when the JtaTransactionManager tries to find the
UserTransaction object at java:/comp/UserTransaction because JBoss
doesn't have one there for EJB modules.
While searching around for a solution to this problem I ran across a
post by Colin in the forums mentioning the ejbtest app in CVS that
uses EJBs with a service layer backed by both ContainerManaged and
Spring managed transactions. I was intrigued.
First thing I really like was that the Web app and the EJB layer share
the same Application context. That definitely seems like a more
efficient solution. It also explains why the app deploys on JBoss
since the JtaTransactionManager is only initialized when the Web App
does and is available later from the same bean factory the EJBs get to
use. I also noticed that the HibernateSessionFactory definition goes
ahead and defines the JBoss Jta lookup.
So, first, it appears this solution only works (at least on JBoss) if
the EJBs are deployed in the same EAR as the web app. How would you go
about using this if you wanted to deploy just the EJB part on a remote
server? The JtaManager would no longer be able to lookup the
UserTransaction at the same location on JBosss. I guess you could
configure that location in that case, but we are trying to create a
Jar that doesn't need to be changed for any deployment, is that an
achievable goal?
Second, I'm guessing the JtaTransactionManager is smart enough to know
when a CMT transaction is already going on and join it for the
TransactionProxyFactoryBean created services? As well as hibernate
knowing when to delegate the transaction management to Jta. But does
that mean for an Message Driven bean the transaction starts for the
call of the onMessage() and I would have to commit manually between
service method calls if I lookup service beans from the context and
call their methods and want their actions to commit?
I definitely think I am going to change our deployment to share the
factory since most of the time the MDBs will be co-located with the
web app. But I still want to solve the problem of being able to deploy
the same core jar in a standalone setting with just the MDBs and no
webapp.
Thanks,
Patrick
I think these questions are mostly targeted at Colin since I think he
wrote the ejbtest app, but feel free to provide answers if you have them.
I've been battling with our app config for a few days trying to get
our Message Driven Beans to deploy with JBoss (everything works fine
with Weblogic). The way we have our app setup is most of the code
(including the files that define our Spring context ) in one jar. That
jar is shared by our webapp and our ejb jar inside an EAR. The webapp
deploys fine and the ContextLoaderListener there fires up our Spring
context and it wires up the JtaTransactionManager which we use in
conjunction with the TransactionProxyFactoryBean to do transaction
declarations on our services. These services are backed by DAOs backed
by Hibernate. The web part of our app runs fine, transactions occur
like they should.
The problem comes up when we send a message to one of our MDBs. It's
at that point that ejbCreate() gets called and since we are using
AbstractJmsMessageDrivenBean defined to use our application's context
definition file, it starts to create a bean factory for the Message
Driven Bean to use that contains all the beans our web app uses. We
get an exception when the JtaTransactionManager tries to find the
UserTransaction object at java:/comp/UserTransaction because JBoss
doesn't have one there for EJB modules.
While searching around for a solution to this problem I ran across a
post by Colin in the forums mentioning the ejbtest app in CVS that
uses EJBs with a service layer backed by both ContainerManaged and
Spring managed transactions. I was intrigued.
First thing I really like was that the Web app and the EJB layer share
the same Application context. That definitely seems like a more
efficient solution. It also explains why the app deploys on JBoss
since the JtaTransactionManager is only initialized when the Web App
does and is available later from the same bean factory the EJBs get to
use. I also noticed that the HibernateSessionFactory definition goes
ahead and defines the JBoss Jta lookup.
So, first, it appears this solution only works (at least on JBoss) if
the EJBs are deployed in the same EAR as the web app. How would you go
about using this if you wanted to deploy just the EJB part on a remote
server? The JtaManager would no longer be able to lookup the
UserTransaction at the same location on JBosss. I guess you could
configure that location in that case, but we are trying to create a
Jar that doesn't need to be changed for any deployment, is that an
achievable goal?
Second, I'm guessing the JtaTransactionManager is smart enough to know
when a CMT transaction is already going on and join it for the
TransactionProxyFactoryBean created services? As well as hibernate
knowing when to delegate the transaction management to Jta. But does
that mean for an Message Driven bean the transaction starts for the
call of the onMessage() and I would have to commit manually between
service method calls if I lookup service beans from the context and
call their methods and want their actions to commit?
I definitely think I am going to change our deployment to share the
factory since most of the time the MDBs will be co-located with the
web app. But I still want to solve the problem of being able to deploy
the same core jar in a standalone setting with just the MDBs and no
webapp.
Thanks,
Patrick