I see, thanks for explaining
On 8/27/2015 8:30 AM, Clebert Suconic wrote:
> If you set DupsOK, duplicates are ok to be received...
>
>
> The user will receive a message, and update the DB...
>
>
> Say, for instance:
>
>
> Db.update(balance = balance + message.getProperty("sale"));
>
>
> Since it's DupsOK, you could eventually get a duplicate of the
> message, and have an invalid balance generated.
>
>
> You could say users should verify if this was duplicated or not... but
> that's not the usual usage I have seen users doing...
> Any user doing MDB will probably require XA and have the server
> avoiding duplicates for him on that case.
>
>
>
> You may say, there's a way to do that through standalone
> applications... but I have failed to do that in 10 years, and I see
> most of the users through support cases, and consulting engagements
> (when I used to do that before I joined JBoss / RedHat) doing MDBs and XA.
>
>
> I think the best way to help these users is to enable them to batch
> transactions through MDBs, otherwise they will bound to one commit per
> message received.. what makes performance really bad on both their
> endpoints (database) and Message transactions.
>
>
>
> On Thu, Aug 27, 2015 at 11:18 AM, Chris Barrow
> <chris.barrow_at_kaazing.com <mailto:chris.barrow_at_kaazing.com>> wrote:
>
> Hi Clebert,
>
> "DupsOK is ok, but that doesn't guarantee the semantic these users
> have."
>
> Sounds intriguing. Could you explain a bit more, maybe give a
> concrete use case?
>
> Chris
>
>
> On 8/27/2015 8:11 AM, Clebert Suconic wrote:
>>
>> On Thu, Aug 27, 2015 at 10:37 AM, Nigel Deakin
>> <nigel.deakin_at_oracle.com <mailto:nigel.deakin_at_oracle.com>> wrote:
>>
>> Hi Clebert,
>>
>> We should definitely discuss how the JMS 2.0 proposals
>> proposals for batch delivery (since deferred) might work with
>> the new-style MDBs and listener beans.
>>
>> As you know, MDB users can turn off XA transactions using the
>> @TransactionManagement annotation, and can remove the number
>> of network round-trips using an acknowledgement mode of
>> DUPS_OK. Why is this not sufficient?
>>
>>
>> Because users want to have the messages and their Database
>> operations in transaction.
>> I have seen this pattern since my days of consultant.
>>
>> This goes beyond my JBoss. I'm not concerned about any specific
>> usecase from JBoss, but from what I see from users doing on day
>> by day with their messaging systems.
>>
>> DupsOK is ok, but that doesn't guarantee the semantic these users
>> have.
>>
>>
>> Or do you have a specific need to have XA transactions that
>> cover multiple messages?
>>
>>
>>
>> From what I see, EE users will want to have async messages, but
>> will need transactions.. the easiest way to do XA Transactions
>> between JMS and Databases are through EE... for that reason,
>> users are *over-using* MDBs... and XA transaction
>>
>> And that's limiting any improvements done by any messaging provider.
>>
>> A few handful users will write standalone application to batch
>> things properly...
>>
>>
>> So, I think we really should propose a way to batch things
>> through MDBs. At least these users would take full advantage of
>> asynchronous message systems and still do transactions.
>>
>>
>>
>>
>
>
>
>
> --
> Clebert Suconic