Hi David,

I was referring to case 1 when the transaction is inflowed into a second server. For JTS the type of transaction we create is a ServerTopLevelAction and this in its ctor calls back to the remote server:
https://github.com/jbosstm/narayana/blob/master/ArjunaJTS/jts/classes/com/arjuna/ats/internal/jts/orbspecific/interposition/resources/arjuna/ServerTopLevelAction.java#L121 If the transport can do that without the TMs assistance then that works for me :)

I don't think we should optimize for case 2. The incidents where a transaction is created and not used should be really low.


On 1 February 2016 at 15:43, David M. Lloyd <david.lloyd@redhat.com> wrote:
I was thinking about this a bit.  It seems to me that there are two "levels" of this that could be explored:

1. A transaction was made available to the server, but the EJB on the server does not use the caller's transaction context, so the EJB code never actually has to inflow the transaction.  The EJB code would be able to make this determination without any help from the TM.

2. A transaction was made available, and the EJB resumed it, but no resources were actually enlisted, or perhaps resources were enlisted but not actually used, resulting in the same effect but relying on the TM to provide this information.

I guess when you refer to a callback from Narayana, (2) is what you're referring to?  When would this information be available?  Maybe as some special result of suspending the transaction?

On 01/29/2016 12:27 PM, David M. Lloyd wrote:
That's an interesting idea.  So in effect, the remote EJB would tell the
caller "you sent me a transaction ID, but in the end, I didn't use it"?
  I would need to think about how this might work in the presence of
multiple concurrent invocations on the same transaction.

Either way though, I think it would still be beneficial for clients to
be able to explicitly annotate a client method (or otherwise establish a
policy) such that it causes transactions to be propagated (or not), or
to enforce transaction-related preconditions.  The interceptor that
implements this feature doesn't actually have protocol awareness: it
just examines the current environment, and decides whether to attach the
transaction to the invocation context.

On 1/29/16 10:42 AM, Tom Jenkinson wrote:
One option that I would favour is to go down the JTS route where the
subordinate calls back on the parent to tell it to register it in the
transaction. This could be a new JBoss Remoting API that I can invoke
from Narayana. The call would not necessarily be a remote call, it would
invoke back into the JBR transport to tell it that when it returns to
the parent it needs to enlist (or not).

On 29 January 2016 at 15:47, David M. Lloyd <david.lloyd@redhat.com
<mailto:david.lloyd@redhat.com>> wrote:

    As you may know, WildFly supports a feature wherein an EJB client
    is invoking an EJB on a remote server has the option to propagate its
    local transaction to the remote server, treating the remote server
as a
    subordinate and coordinating the transaction's two-phase commit among
    the resultant graph of servers.  This feature has always been
limited in
    that, when enabled, transactions are always propagated, regardless of
    the peer EJB's transaction policy, or of whether the peer even has a
    transaction manager.

    So, for the invocation rework which I anticipate will be included in
    WildFly 11, I've introduced a new client-side annotation intended
to be
    associated with the EJB interface which informs the client library
    to do for transaction propagation for that interface.  In addition, I
    intend to configuration strategies which will allow the default
mode to
    be specified in various ways (per-thread, globally, and by target
    interface/method all come to mind), for cases where the EJB's remote
    interface cannot be easily modified for some reason.  I expect to
    broaden these configuration strategies to apply to all client-side
    interface/methods configuration items [3].

    The first part of this change is the addition of a new annotation
    @ClientTransaction [1], which accepts as a value an enum called
    ClientTransactionPolicy [2].  The latter specifies whether a local
    transaction is required or forbidden for the method or interface, and
    also specifies whether the transaction is propagated or not

    I've added copious amounts of JavaDoc in order to establish
exactly what
    the behavior of each mode is, as well as to specify how each mode
    interacts with the various modules that are configured via the
    javax.ejb.TransactionAttributeType enum.





    [2] (raw)


    [3] for a list, see:


    - DML
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