Tim Bain created AMQ-6099:
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Summary: Allow broker to read any OpenWire version from KahaDB
Key: AMQ-6099
URL: https://issues.apache.org/jira/browse/AMQ-6099
Project: ActiveMQ
Issue Type: New Feature
Components: KahaDB
Affects Versions: 5.x
Reporter: Tim Bain
The current KahaDB implementation only allows a single OpenWire version to be
read from the store. This works fine during normal operations, but when a user
upgrades to a version of ActiveMQ that uses a different OpenWire version, the
new broker is unable to read any persisted messages from the store because of
the version mismatch, as described in AMQ-5995.
Broker upgrades are going to happen, and the requirement that they be done with
an empty message store, or that the user apply temporary workarounds like
running the old broker in a networked configuration that's not the standard
config for the cluster, leads to a less-than-satisfactory experience during the
upgrade. As much as possible, broker upgrades should be seamless; sometimes
that's not possible, but in this case it seems like code that would be able to
read any version of OpenWire but only write the current one (and that could be
less-efficient with older versions if necessary) wouldn't be all that hard and
would eliminate this problem.
Alternatively, we could create a command-line utility to transform a set of
KahaDB data files from an (offline) broker from one version to another. That's
a little clunkier for the user, but reasonable if it's substantially easier to
implement.
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