Re: [ebxmlms-general] Connectionpooling and transactions

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By the time we were designing Hermes, Hibernate is not that well=20
considered... (yes, the other way to interpret this is, we are quite=20
closed in terms of employing other libraries). I think your opinion is a=20
good one.

Regards,
Patrick Yee
Center for E-Commerce Infrastructure Development

Making E-Commerce Everyday Commerce

R. van Kuijk (Ronald) wrote:

>Hmm... I missed the option to redirect file persistence to a database. I=
'll have a look. With 'still it is not transaction-aware' you mean that t=
he filepersistence is not really transaction aware? There are some 'in vm=
-locking mechamisms' in there but no real commit/rollback etc. Would that=
 be needed? Kind of difficult, but I'll see.
>
>Ok, another question. I have a fairly clear picture of the front-end mes=
sageserver, messageservicehandler etc and how the command parsing works. =
In addition to that, I dug a little bit deeper into hermes again especial=
ly the DBTableManager classes etc. If it is possible I'd like to get some=
 info on the architectural choices that were made to come to such a solut=
ion. It looks like it is some persistence mapping, for which there curren=
tly are very nice out-of-the-box solutions (think hibernate). IMVVHO (it =
is a very, very humble one) this would also be a nice change and would ma=
ke it possible to support more databases.=20
>
>I'll try to work something out which makes it possible to store messages=
 in either a file or a database (configurable?)
>
>
>-----Oorspronkelijk bericht-----
>Van: ebx...@li... [mailto:ebxmlms-general=
-ad...@li...] Namens Patrick Yee
>Verzonden: woensdag 6 juli 2005 4:02
>Aan: ebx...@li...
>Onderwerp: Re: [ebxmlms-general] Connectionpooling and transactions. was=
: Problems after lost connection to database
>
>Now, Hermes supports a custom way (API) to redirect the file persistence=
=20
>to database. However, still it is not transaction-aware. So we may need=20
>to modify that API as well. What do you think?
>Regards, -Patrick
>
>
>Ronald van Kuijk wrote:
>
> =20
>
>>Sounds interesting. But with regard to this immediately a second questi=
on comes to mind. There is
>>also a transactionmechanism in place which does a kind of xa over a dat=
abase and a filesystem.
>>This makes it almost impossible to use the default JTA for this, which =
would make the hermes core
>>even smaller. For our company, storing the messages in a DB as a blob i=
s not a problem since we
>>require clustering and failover any way. It is in fact even a requireme=
nt unless there would be a
>>JTA compatible filesystem persistency layer (JCA?)).
>>
>>Replacing the DBConnectionPool with a standard based solution can be do=
ne by me, since I've done
>>it before and probably have the code somewhere. DBCP does not have to b=
e provided then, since all
>>servlet engines and j2ee servers contain one. But regarding the file pe=
rsistency I'd like to get a
>>response from more users since that is another issue.
>>
>>Comments?
>>
>>
>>Patrick Yee probeerde me het volgende duidelijk te maken:
>>=20
>>
>>   =20
>>
>>>There is no strict reason for using our own implementation. So it woul=
d
>>>be good to have some contribution to port Hermes to make use of other
>>>database pool, like DBCP.
>>>Regards, -Patrick
>>>
>>>Regards, -Patrick
>>>
>>>
>>>Mattias J wrote:
>>>
>>>  =20
>>>
>>>     =20
>>>
>>>>Yes, why not include for example Jakarta Commons DBCP?
>>>>
>>>>At 2005-06-27 09:29, you wrote:
>>>>
>>>>    =20
>>>>
>>>>       =20
>>>>
>>>>>I guess the problem is that you have implemented your own
>>>>>databasepool, without sophisticated recovery mechanism.
>>>>>Our own application use javax.sql.DataSource, to get a connection. I
>>>>>guess there is a recovery mechanism in that solution, as our own
>>>>>application runs fine when the connection gets back.
>>>>>Is there anyway to use javax.sql.DataSource instead of your
>>>>>implementation of the connection pool? I guess my question is more t=
o
>>>>>why you are using your own implemtation, are you using some extra
>>>>>stuff, I can't get from javax.sql.DataSource?
>>>>>
>>>>>Regards Kenneth
>>>>>
>>>>>      =20
>>>>>
>>>>>         =20
>>>>>
>>>>>>From: Patrick Yee <kc...@ce...>
>>>>>>To: ebx...@li...
>>>>>>CC: tr...@ho...
>>>>>>Subject: Re: [ebxmlms-general] Problems after lost connection to
>>>>>>database
>>>>>>Date: Sun, 26 Jun 2005 19:19:35 +0800
>>>>>>
>>>>>>We have not implemented a sophisticated recovery mechanism in the
>>>>>>database connection pool. The only mechanism we have done is,
>>>>>>whenever a connection is proved to be bad, we will not put it back
>>>>>>to the connection pool. Actually there was a suggestion some time
>>>>>>ago that we can do a "select *" on some tables before we use the
>>>>>>pooled database connection. We think that will create certain
>>>>>>performance issue, and so we shelved that idea. Of course, if you
>>>>>>want it, you can just patch the database connection pool classes an=
d
>>>>>>implement any advanced recovery mechanism as you like. :-)
>>>>>>Regards, -Patrick
>>>>>>
>>>>>>
>>>>>>Kenneth Pedersen wrote:
>>>>>>
>>>>>>        =20
>>>>>>
>>>>>>           =20
>>>>>>
>>>>>>>Hi
>>>>>>>
>>>>>>>If I loose the connection to my database for a short time
>>>>>>>(1-2minutes), MSH do not operate properly afterwards.
>>>>>>>
>>>>>>>When the connection is lost this occurs in the MSH_client.log:
>>>>>>>
>>>>>>>2005-06-21 09:13:34,384 DEBUG [Thread-8]: =3D>
>>>>>>>DbConnectionPool.getConnection
>>>>>>>2005-06-21 09:13:34,384 DEBUG [Thread-8]: <=3D
>>>>>>>DbConnectionPool.getConnection
>>>>>>>2005-06-21 09:13:34,384 ERROR [Thread-8]: [10002] Unknown error
>>>>>>>Exception: java.sql.SQLException
>>>>>>>Message: I/O Error: Connection reset by peer: socket write error
>>>>>>>2005-06-21 09:13:34,384 DEBUG [Thread-8]: =3D> Transaction.rollbac=
k
>>>>>>>(txID: #2321)
>>>>>>>2005-06-21 09:13:34,384 ERROR [Thread-8]: [10315] Cannot rollback
>>>>>>>DB changes
>>>>>>>Exception: java.sql.SQLException
>>>>>>>Message: Invalid state, the Connection object is closed.
>>>>>>>2005-06-21 09:13:34,384 DEBUG [Thread-8]: =3D>
>>>>>>>DbConnectionPool.freeConnection
>>>>>>>2005-06-21 09:13:34,384 DEBUG [Thread-8]: <=3D
>>>>>>>DbConnectionPool.freeConnection
>>>>>>>2005-06-21 09:13:34,384 DEBUG [Thread-8]: <=3D Transaction.rollbac=
k
>>>>>>>2005-06-21 09:13:34,384 DEBUG [Thread-8]: =3D>
>>>>>>>MessageServiceHandler.getNextUndeliveredMessage
>>>>>>>2005-06-21 09:13:34,384 DEBUG [Thread-8]: =3D>
>>>>>>>MessageServer.getUndeliveredMessages
>>>>>>>2005-06-21 09:13:34,384 DEBUG [Thread-8]: =3D>
>>>>>>>DbConnectionPool.getConnection
>>>>>>>2005-06-21 09:13:34,384 DEBUG [Thread-8]: =3D>
>>>>>>>DbConnectionPool.createConnection
>>>>>>>2005-06-21 09:13:35,352 ERROR [Thread-8]: [10306] Cannot create DB
>>>>>>>connection Exception: java.sql.SQLException Message: Network error
>>>>>>>IOException: Connection refused: connect
>>>>>>>2005-06-21 09:13:35,352 DEBUG [Thread-8]: =3D> Transaction.rollbac=
k
>>>>>>>(txID: #2323)
>>>>>>>2005-06-21 09:13:35,352 DEBUG [Thread-8]: <=3D Transaction.rollbac=
k
>>>>>>>2005-06-21 09:13:35,352 DEBUG [Thread-8]: =3D>
>>>>>>>MessageServiceHandler.getNextUndeliveredMessage
>>>>>>>2005-06-21 09:13:35,352 DEBUG [Thread-8]: =3D>
>>>>>>>MessageServer.getUndeliveredMessages
>>>>>>>2005-06-21 09:13:35,352 DEBUG [Thread-8]: =3D>
>>>>>>>DbConnectionPool.getConnection
>>>>>>>2005-06-21 09:13:35,352 DEBUG [Thread-8]: =3D>
>>>>>>>DbConnectionPool.createConnection
>>>>>>>
>>>>>>>
>>>>>>>After the connection is restored MSH do not seem to get a proper
>>>>>>>connection.
>>>>>>>This occurs then in the MSH_Client.log:
>>>>>>>
>>>>>>>2005-06-21 09:13:42,384 ERROR [Thread-8]: [10306] Cannot create DB
>>>>>>>connection
>>>>>>>Exception: java.sql.SQLException Message: Network error
>>>>>>>IOException: Connection refused: connect
>>>>>>>2005-06-21 09:13:42,384 DEBUG [Thread-8]: =3D> Transaction.rollbac=
k
>>>>>>>(txID: #2338)
>>>>>>>2005-06-21 09:13:42,384 DEBUG [Thread-8]: <=3D Transaction.rollbac=
k
>>>>>>>2005-06-21 09:13:42,384 DEBUG [Thread-8]: =3D>
>>>>>>>MessageServiceHandler.getNextUndeliveredMessage
>>>>>>>2005-06-21 09:13:42,384 DEBUG [Thread-8]: =3D>
>>>>>>>MessageServer.getUndeliveredMessages
>>>>>>>2005-06-21 09:13:42,384 DEBUG [Thread-8]: =3D>
>>>>>>>DbConnectionPool.getConnection
>>>>>>>2005-06-21 09:13:42,384 DEBUG [Thread-8]: =3D>
>>>>>>>DbConnectionPool.createConnection
>>>>>>>2005-06-21 09:13:43,384 ERROR [Thread-8]: [10306] Cannot create DB
>>>>>>>connection
>>>>>>>Exception: java.sql.SQLException
>>>>>>>Message: Network error IOException: Connection refused: connect
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>When i try to send a message through MSH i get this:
>>>>>>>hk.hku.cecid.phoenix.message.handler.RequestException:
>>>>>>>Failed to send query to MSH.
>>>>>>>HTTP response code =3D 200
>>>>>>>HTTP response message =3D OK
>>>>>>>   at
>>>>>>>hk.hku.cecid.phoenix.message.handler.Request.expectMapResponse(Unk=
nown
>>>>>>>Source)
>>>>>>>   at
>>>>>>>hk.hku.cecid.phoenix.message.handler.Request.sendMessageServiceHan=
dlerConfig(Unknown
>>>>>>>Source)
>>>>>>>   at
>>>>>>>hk.hku.cecid.phoenix.message.handler.Request.register(Unknown Sour=
ce)
>>>>>>>   at hk.hku.cecid.phoenix.message.handler.Request.<init>(Unknown
>>>>>>>Source)
>>>>>>>   at hk.hku.cecid.phoenix.message.handler.Request.<init>(Unknown
>>>>>>>Source)
>>>>>>>   at
>>>>>>>com.mysupply.ebxi.msh.MessageManager.sendMessage(MessageManager.ja=
va:149)
>>>>>>>
>>>>>>>
>>>>>>>And of course I can not receive any messages through MSH either.
>>>>>>>
>>>>>>>Does anybody have the same problems, after a lost database
>>>>>>>connection? The other part of my application that uses MSH, is
>>>>>>>right back in action when the database connection is restored, but
>>>>>>>not MSH.
>>>>>>>
>>>>>>>The app is running on jboss-4.0.1 (Tomcat 5.0.28), Java
>>>>>>>jdk1.5.0_01. The database is Microsofts MSSQL 2000. The driver for
>>>>>>>MSSQL is JTDS 1.0.
>>>>>>>I have added this:
>>>>>>><check-valid-connection-sql>select * from
>>>>>>>some_table</check-valid-connection-sql>
>>>>>>>to my datasource file: mssql-ds.xml which is deployed along with
>>>>>>>msh.war.
>>>>>>>
>>>>>>>Everything is working fine, for days, until I loose the database
>>>>>>>connection for a few minutes.
>>>>>>>
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