The cast works fine in my case but the problem is that everything is NULL, including the meta-data. Indeed the message is cleaned before the listeners are called... https://github.com/apache/qpid-broker-j/blob/7193e26f6fad83f5ce81fd9ef855edb0fd5594ea/broker-plugins/jdbc-store/src/main/java/org/apache/qpid/server/store/jdbc/AbstractJDBCMessageStore.java#L1670
Olivier -----Original Message----- From: Rob Godfrey <[email protected]> Sent: lundi 9 mars 2020 09:58 To: [email protected] Subject: Re: [Broker-J] Claim-check pattern and MessageDeleteListener On Mon, 9 Mar 2020 at 09:36, VERMEULEN Olivier <[email protected]> wrote: > Hello Rob, > > "Are you looking to have Broker-J trigger the deletion on the blob at > the point at which it believes it no longer needs the message?" > Yes that's exactly what I'm trying to do. > Note that I managed to do it by creating my own vhost, just wanted to > check if there was a less intrusive way of doing it... > I agree that we shouldn't be able to modify the message but today I > can't even read it easily. > What I'm interested in are the headers but from a StoredMessage > instance I have to go through internal classes and package-protected > classes to get > them: > ((InternalMessageMetaData) storedMessage.getMetaData()).getHeader(); > getHeader being package-protected here... > Note that this will only work if the message is an "Internal" message (i.e. the casting here would fail if the message were an AMQP 0-9, AMQP 0-10 or AMQP 1.0 message sent over the wire). The store API is basically built to be as unaware of the form of the message as possible, and the api here is basically designed to allow the store to clean up a message which was potentially stored in multiple queues, but which has now been removed from all of them. As such it's not really designed to make it easy for you to access the headers (or content - since the "content" will include structure for 1.0 messages). > Did I miss something? > No - I think to do this safely we'd have to expose some new API here. -- Rob > > Thanks, > Olivier > > -----Original Message----- > From: Rob Godfrey <[email protected]> > Sent: vendredi 6 mars 2020 17:54 > To: [email protected] > Subject: Re: [Broker-J] Claim-check pattern and MessageDeleteListener > > Hi Olivier > > I'm not entirely sure what your exact idea here is - are you looking > to have Broker-J trigger the deletion on the blob at the point at > which it believes it no longer needs the message? Or maybe to update > the blob store to make clear that the broker no longer needs to retain > a copy of the message? > > Clearly the API is not designed for allowing extensions here - and I > think if we were to try to make it an extension / interception point > then we would have to be careful in limiting what could be done here > (e.g. offering only some read-only view of the message). > > Without such an interception extension mechanism, you are correct I > think that you would need to create a new vhost type (potentially > using a new store type of your own implementation) > > -- Rob > > On Fri, 6 Mar 2020 at 16:37, VERMEULEN Olivier < > [email protected]> > wrote: > > > Hello, > > > > We're trying to implement the claim-check pattern on top of our > > broker > > + dispatch-router topology. > > So we have a blob store and the idea is for each message above 10KB > > to store the payload in it and to only keep an ID in the message. > > The tricky part is the delete of the payload in the blob store, > > especially since some of our use cases are using multicast... > > When looking at the Broker-J source code I found this > > MessageDeleteListener which would be really helpful for this use case: > > > > https://github.com/apache/qpid-broker-j/blob/c018e1ac9d21e9f5eb38d2a > > e7 > > a26a31e63c07fdf/broker-core/src/main/java/org/apache/qpid/server/sto > > re > > /MessageStore.java#L84 > > > > My first question would be, is it ok to use it? > > Second, so far the only way I found to register a new listener is to > > define my own VirtualHost, is there an easier way ? > > > > Thanks, > > Olivier > > ******************************* > > This e-mail contains information for the intended recipient only. 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