Let's forget the 2PC stuff for now...Here is a scenaro:
[APP/VM-1] <-> [EJB-1,EJB-2,...EJB-n/JBOSS/VM2] <-JDBC-> [DataStore-1]
Each method of each of the EJBs forms a transaction by themselves if noone
else issues explicit transaction control a la "begin,commit,abort".
APP takes on this role. APP decides the set of EJBs' methods will form 1
transaction. Same problem, replace APP with say a servlet running in a
Servlet Container in a different VM and you still need the solution where it
is possible to obtain a transaction from a separate VM.
Sure, you could move the all the APP transaction control into one single
method of one single EJB...but that's not always desirable, I believe...
Anh
----- Original Message -----
From: "David Jencks" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Saturday, June 16, 2001 11:34 AM
Subject: Re: [JBoss-user] Obtaining a transaction from outside JBoss in
another VM Plan
> Hi,
> I think the advice to stay away from distributed transactions is universal
> design advice. Basically using distributed transactions just about
> guarantees bad performance, as resources get tied up waiting for the 2pc
to
> make its way to all those other machines or vms not once but twice. If at
> all possible, if you need things to happen on several machines, use
> transactional messaging (jms, jbossmq) to break the work up into pieces
> that can be all done on one machine + 1 resource manager + 1 message to
the
> next machine. I don't know what jboss/jbossmq actually does in this
> scenario, however with a db and a message que as your transactional
> resources the db (the slow part) could use 1pc:
>
> 1. prepare message commit
> 2. 1pc on db
> 3. commit message.
>
> This should be roughly as fast as 1pc to the db, since jbossmq is running
> in the same vm as the rest of jboss.
>
> I learned the most about this subject from the (pre ejb) book "High
> Performance Client Server" by Loosley and Douglas, isbn 0-471-16269-8
>
> david jencks
>
> On 2001.06.16 12:57:44 -0400 Phan Anh Tran wrote:
> > We are at design time for a real system. Your suggestion "don't use it"
> > is
> > that due to JBOSS specific implementation issues or is it a universal
> > design advice?
> >
> > Do you have a copy of Vlada talk? Thanks.
> >
> > Anh
> >
> > ----- Original Message -----
> > From: "marc fleury" <[EMAIL PROTECTED]>
> > To: <[EMAIL PROTECTED]>
> > Sent: Saturday, June 16, 2001 3:24 AM
> > Subject: RE: [JBoss-user] Obtaining a transaction from outside JBoss in
> > another VM Plan
> >
> >
> > > yes anatoly ackerman finished an integration of Tyrex (real DTM) in
> > JBoss.
> > >
> > > We truly truly discourage the use of DTx (even Vlada matena had a full
> > talk
> > > on that). So my question is "are you at design time" (in which case
> > don't
> > > use it) or is this "real life".
> > >
> > > marcf
> > >
> > > |-----Original Message-----
> > > |From: [EMAIL PROTECTED]
> > > |[mailto:[EMAIL PROTECTED]]On Behalf Of Phan Anh
> > > |Tran
> > > |Sent: Saturday, June 16, 2001 3:11 AM
> > > |To: [EMAIL PROTECTED]
> > > |Subject: [JBoss-user] Obtaining a transaction from outside JBoss in
> > > |another VM Plan
> > > |
> > > |
> > > |When does JBOSS plan to support the obtaining and using a transaction
> > from
> > > |another VM? 2.2.3? 2.3? Anytime in the near future?
> > > |
> > > |[App/VM1] <-> [EJB1,EJB2,.../JBOSS/VM2]
> > > |
> > > |App needs to setup and control the transactions, so in essence, my
> > > |App needs
> > > |to be able to obtain a UserTransaction via JNDI from a separate VM.
I
> > > |believe this feature is not supported right now, but I would like to
> > > |understand when the feature is planned to be incorporated into JBOSS?
> > > |Thanks.
> > > |
> > > |Anh
> > > |
> > > |
> > > |
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