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https://issues.apache.org/jira/browse/BOOKKEEPER-312?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13431729#comment-13431729
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Sijie Guo commented on BOOKKEEPER-312:
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@Mridul,
{quote}
There are package info files on each package to give general idea of what it
does.
It will be less overwhelming if you split effort along these lines as opposed
to try to take everything in.
{quote}
thanks for providing these informations.
as I mentioned, splitting the patches would speed up reviewing. If it is
difficult for you to split, I am OK to review, but it might take more time to
finish it :-(
> Implementation of JMS provider
> ------------------------------
>
> Key: BOOKKEEPER-312
> URL: https://issues.apache.org/jira/browse/BOOKKEEPER-312
> Project: Bookkeeper
> Issue Type: Sub-task
> Reporter: Mridul Muralidharan
> Attachments: hedwig-client-jms.patch, hedwig-client-jms.patch.1,
> hedwig-client-jms.patch.2, hedwig-client-jms.patch.3,
> hedwig-client-jms.patch.4, hedwig-client-jms.patch.5
>
>
> The JMS provider implementation conforming to the 1.1 spec.
> The limitations as of now are :
> 1) No support for Queue's : Hedwig currently does not have a notion of JMS
> queue's for us to leverage.
> 2) No support for noLocal : Hedwig DOES NOT conform to JMS model of
> connection -(n)-> session -(n)-> publisher/subscriber. Each session has a
> hedwig connection.
> Currently I am simulating noLocal, but this IS fragile and works for the
> duration of connection - ONLY until the message id is still in a LRUCache. As
> mentioned before, this is a kludge, and not a good solution.
> 3) Note that everything is durable in hedwig - so we do not support
> NON_PERSISTENT delivery mode.
> 4) Calling unsubscribe on a durable subscription will fail if it was NOT
> created in the current session.
> In hedwig, to unsubscribe, we need the subscription id and the topic ...
> To simulate unsubscribe(), we store the subscriberId to topicName mapping
> when a create* api is invoked. Hence, if create* was NOT called, then we have
> no way to infer which topic the subscription-id refers to from hedwig, and so
> cant unsubscribe.
> The workaround is - simply create a durable subsriber just as a workaround of
> this limitation - the topicName will be known to the user/client anyway.
> 5) Explicit session recovery is not supported.
> Reconnection of hedwig session (either explicitly or implicitly by underlying
> client implementation) will automatically trigger redelivery of
> un-acknowledged messages.
> 6) Because of the above, setting the JMSRedelivered flag is almost impossible
> in a consistent way.
> Currently, we simulate it for redelivery due to provider side events :
> rollback of txn, exception in message listener (primarily).
> At best we can simulate it with a kludge - at risk of potentially running out
> of resources ... this is being investigated : but unlikely to have a clean
> fix.
> 7) Hedwig only supports marking all messages until seq-id as received : while
> JMS indicates ability to acknowledge individual messages.
> This distinction is currently unsupported.
> 8) JMS spec requires
> "A connection's delivery of incoming messages can be temporarily stopped
> using its stop() method. It can be restarted using its start() method. When
> the connection is stopped, delivery to all the connection’s MessageConsumers
> is inhibited: synchronous receives block, and messages are not delivered to
> MessageListeners."
> We honor this for undelivered messages from server - but if stop is called
> while there are pending messages yet to be delivered to a listener (or
> buffered in subscriber for receive), then they will be delivered irrespective
> of stop().
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