layering (Was) Re: [esb-dev] jca done (I think)

[Bill Burke]

I think JBoss ESB could get the most bang for the buck by layering their 
connector implementations:

1. A plain class/Java bean that does JMS, FTP, Email, etc...  Refactor 
and steal code from JBoss app server and old Rosetta base.

2. Write inflow and outbound JCA adapters for the connectors JBoss is 
going to write (FTP, email etc.)

3. Extend adapters written in step #2 to be "ESB Aware".  For instance, 
a JMS inflow activation could register an outbound EPR to JUDDI to 
enable listeners.

#1 gives you flexibility to repackage things as needed.

#2 drives traffic and interest to the JBoss ESB site.  Many people may 
not be interested in the ESB message abstraction, but they will be 
interested in resource adapters.

#3 Gives you flexibility and integration with Java EE (EJB and 
@Resource).  You could define an ESB outbound connection deployment and 
inject it into a EJB as a resource.  People can write their own MDBs to 
drive their own action pipellines and business logic.

Bill Burke wrote:
> We could inject an implementation of ServiceInvoker that invokes 
> directly on the pipeline.
> 
> The BIG problem though is EPR publishing.  JCA is not bi-directional. 
> Outbound and inflow are two separate things.  Don't know enough about 
> outbound JCA yet, but we could possibly have a callback method or object 
> that creates a JCAOutput EPR.  I'll read more into it.
> 
> Bill
> 
> Kurt T Stam wrote:
>> Well it'd be nice if we had JCA for listeners too no? It's to bad a
>> gateway isn't a listener that takes extra params and we'd be done..
>>
>> Bill Burke wrote:
>>> Kurt, I don't understand what you mean with "can we use JCA within the
>>> ESB", can u elaborate?  I have a qa/junit test that uses the JMS
>>> adapter as a <jca-gateway>.  See the wiki on where it is.
>>>
>>> Yes, you can use what I did to write gateways if that's what you're
>>> asking.
>>>
>>> Kurt T Stam wrote:
>>>> Cool.
>>>>
>>>> Hey can we use JCA within the ESB now too (I mean this work was 
>>>> specific
>>>> to a gateway right?)
>>>> , or is that still something you're working on?
>>>>
>>>> --K
>>>>
>>>> Bill Burke wrote:
>>>>> Kevin Conner wrote:
>>>>>> Kurt T Stam wrote:
>>>>>>> 1. So now we can use XA Txs spanning DB and JMS resources?
>>>>>> We should be able to, the XA transaction should encompass them both.
>>>>>>
>>>>>>> 2. I'm guessing we'd still be using the old JmsGateway when
>>>>>>> running in
>>>>>>> bootstrapper mode?
>>>>>> Weston had intended to develop a standalone implementation of JCA
>>>>>> which
>>>>>> would have been perfect for the standalone ESB.  Not sure what will
>>>>>> happen to that now.
>>>>>>
>>>>>> Using JCA will necessitate the full blown app server or the esb
>>>>>> profile.
>>>>>>
>>>>> As I've said before, the JBoss Embeddable project *already* includes
>>>>> JCA and can run inside Junit tests, Tomcat standalone, and plain Java
>>>>> apps.   Eventually I'll get around to refactoring it to run in other
>>>>> application servers.
>>>>>
>>>>> The JCA rewrite will continue.  Supposedly Adrian was really itching
>>>>> to get back to it anyways.  If he doesn't pick it up, I definately
>>>>> will. Really the brunt of the JCA rewrite is to pojitize it and remove
>>>>> any MBean dependencies or at least, make them "aspectized".
>>>>>
>>>>> The JCA integration I did with ESB should really be moved to the JCA
>>>>> project as it is an abstraction for any inflow container.  MDB could
>>>>> be written on top of it.  It has a bridge interface that would allow
>>>>> you to plug in other JCA implementations, well, at least in theory.  I
>>>>> have no idea if  any other app server has an SPI or even an API we
>>>>> could hack into.  If we can't do that, we could probably still embed
>>>>> our own JCA implementation into another application server.
>>>>>
>>>>>
>>>>>
>>>>>>> 3. How does 'transacted' work? I mean an mdb has: supports,
>>>>>>> requiresNew,
>>>>>>> required, none.
>>>>>> MDB only supports Required and NotSupported transaction types as they
>>>>>> have no calling context.  I would assume that the transacted 
>>>>>> attribute
>>>>>> would be equivalent.
>>>>>>
>>>>> The JCA integration layer I did is really a mini MDB container, so
>>>>> yes, that's what it means.
>>>>>
>>>>> Bill
>>>>>
>>
> 

-- 
Bill Burke
JBoss, a division of Red Hat Inc.