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General questin on queues |
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AlexeiSkate |
Posted: Sat Jun 22, 2002 9:02 am Post subject: General questin on queues |
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Centurion
Joined: 10 Apr 2002 Posts: 123
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Hello,
Is a queue nothing more than a table in the database ?
When you define a queue, is the queue stored in the UDB2 database ? Can MQSeries defines queues in another database like Oracle and still manages them using the MQSeries Explorer ?
thanks,
Alex |
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jhalstead |
Posted: Sat Jun 22, 2002 9:22 am Post subject: |
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 Master
Joined: 16 Aug 2001 Posts: 258 Location: London
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Nothing nearly so glamourous I'm afraid, each queue has a file within which the data is store... however databases are just files aren't they...
Jamie |
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AlexeiSkate |
Posted: Sat Jun 22, 2002 9:40 am Post subject: |
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Centurion
Joined: 10 Apr 2002 Posts: 123
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Yes, but are these files allocated on the UDB2 used by the Configuration Manager and Broker Manager ?
I was in a meeting where there was some confusion as to what was an MQSeries queue. Someone described the MQSeries queues as being nothing more than tables in a database and then asked me if the queues can be created on Oracle instead. I didn't know the answer. |
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kolban |
Posted: Sun Jun 23, 2002 3:53 pm Post subject: |
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 Grand Master
Joined: 22 May 2001 Posts: 1072 Location: Fort Worth, TX, USA
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A queue is a logical repository for messages. How the "logical" concept of a queue is implemented is vendor specific. Some JMS vendors do map logical queues to physical tables.
IBM's MQSeries implements queues as individual files on the file system. When you put a message in a queue, the message data is actually place in a file in the file system (not always ... non-persistent messages may only be stored in memory ...).
Some other IBM products such as WMQI, DO store information in databases for their own operational and configuration purposes but this has nothing to do with a logical "queue".
Again, I always recommend to people to think of the queue as a logical container that holds and manages messages. Queues can't/don't exist without something to manage them and hence the queue manager (compare to tables not existing without a database).
MQSeries uses the platform file system for storing the messages (implementing the queues). On Unix, it is the unix file system. On Windows, it is NTFS and on S/390, it is VSAM. |
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nimconsult |
Posted: Mon Jun 24, 2002 12:10 am Post subject: |
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 Master
Joined: 22 May 2002 Posts: 268 Location: NIMCONSULT - Belgium
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MQ Series has the same level of reliability as a database in term of storing persistent data. This reliability is based on a proprietary implementation and not on a popular database management system such as DB2 or Oracle.
MQ Series behaves with persistent messages in a way which is similar to DB2: the messages are stored in proprietary files (just like DB2 table contents) and recovery is ensured by a mechanism of logging and unit of work management (just like DB2 logging and unit of work management).
These is no way to tell MQ Series to use an external database management system instead of its own proprietary file and log management. _________________ Nicolas Maréchal
Senior Architect - Partner
NIMCONSULT Software Architecture Services (Belgium)
http://www.nimconsult.be |
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