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From Rob Godfrey <rob.j.godf...@gmail.com>
Subject Re: [Qpid Java Broker] What happens if 2 brokers have the same JDBC url
Date Wed, 30 Nov 2016 15:25:31 GMT
On 30 November 2016 at 15:19, Adel Boutros <Adelboutros@live.com> wrote:

> Hello,
>
>
> Following the discussion regarding the JDBCMessageStore, I would like to
> ask what would happen in the below scenario:
>
>
Bad things :-)


>
> Let's say we have 2 brokers running with the same JDBC message store
> configured (Same JDBC url for both). One of the broker is hidden and is
> thus not accessible for consumers or producers while the other is visible.
>
>
> Can I see queues created on one broker on the other without any restart?
>
>
No - the broker relies entirely on in memory state while it is running. It
only reads from the database on restart (except for reloading messages
which have "flowed to disk"... but again this is based on an in-memory
record of the message existence).


> Can messages received on the first be visible on the 2nd without any
> restart?
>
>
No - as above the broker state is the in-memory state.  The broker assumes
that it is the only thing updating the persistent state... updating the
persistent state outside of the broker process will cause a failure due
these expectations not being met (just as if deleting a file from a derby
or BDB store would).


> Are there any locks issues which will make the above scenario fail?
>
>
No - since the JDBC store can't really make any assumptions about what
locking mechanisms are available on a JDBC store, it relies on the broker
to be properly configured.

Hope this helps,
Rob


>
> Regards,
>
> Adel
>

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