RE: [OJB-developers] More JCA

[Matthew B. <ma...@so...>]

Summary: I will be cleaning up the code tonight for another round, this will
include proper connection and transaction contract fulfillment including
only LocalTransaction Support. I'll need assistance on the XA
implementation.

No, the issue is related to JCA.

Please read the JCA spec section 5.5.4. Especially the part "Connection 
Sharing and Multiple Connection Handles". Then, for example, try look at the

JCA-compliant JDBC wrapper provided with JBoss as an example how to get 
around the problem.

Another approach is to do it after the book. That is, support resource 
sharing for real. However, this implies supporting and testing all kinds of 
scenarios such as interleaving of multiple transactions on the same 
connection, joining of transaction, thread-safety and more. Also, many of
the 
issues are related to XA. For example local transactions have no concept of 
XID, so it's pretty much impossible to do transaction interleaving here. 
Resource sharing from a XA point of view is described in the JTA spec
section 
3.4.6.


> Ok, I have the spec and a JCA book I'm using. I'll nail this one.

Well, using logical JNDI names is the standard way to access external 
resources in EJB 2.0. There's also several good reasons why to actual do it.

Here's a description how to declare resource references in Jboss: 
http://www.jboss.org/online-manual/HTML/ch07s02.html

Also, not doing this and you might get grilled by unpleasant EJB individuals

when the stuff reaches out to the hardcore J2EE community. I actually once 
got death threats from a J2EE developers when I said that EJB was the
perfect 
anti-pattern. Well, I guess one can't compare this with not using resource 
references in ejb-jar.xml :-) However, just take it as a hint then.

> ok this is just the indirection from using the name I bound the resource
too. No problem will add to my example. I don't want any death-threats :)

What JCA's did you look at?

Commercial JDO product, just looked at the sample ejb.

In a managed environment the connection manager of the application server 
controls the pool. OJB should only create connections when told to do so by 
the server.

> Agree, but wondered about all the calls to new database vs current
database.

Okay. But, if you could look at the connection related stuff and make sure
it 
is compliant with the spec, that would be nice. Because, it's your code and 
you know best how the connection handling part of it is supposed to work.

> yep, will do.

Well, there are several issues around XA, but of course it can be done. 
However, I'll need to try get some connector stuff running in this Trifork 
application server first. Thereafter I'll go for the XA stuff, probably in 
the very near future, say in a couple of weeks.

> hopefully the jca piece is portable. Why did you guys choose Trifork? What
are the advantages of that application server?

However, if you can get a robust JCA version up running with local 
transactions that would be a major step also! XA it only needed in the more 
advanced transaction scenarios where several resource adapters are involved.

I guess most "normal" people don't need these features right away, but I 
could be wrong of course.

> Yah, XA is advanced, and we will need it in about 6 months. I really want
to learn all about it as well, but time is not on my side.

What about the non-CCI ODMG factory interface and the BMT stuff we talked 
about, do you intent to look at this also, or what is your plan?

> I'm going to implement the non-CCI ODMG factory as well as the PBroker
factory, and the BMT stuff.

regards,
Matthew