October 2006 - jboss-dev-forums - Jboss List Archives

[Design of Messaging on JBoss (Messaging/JBoss)] - Unnecessarily pulling messages

by timfox

When a channel deliveries messages to a receiver that can only accept x messages, the channel delivers as many messages as it can until the receiver returns null to signify it doesn't want any more. There is a problem with this in a clustered setup, when pulling messages from a remote queue. The channel will deliver as many messages it can from the local queue, and then, if the receiver is still ready, in some situations will start pulling messages from a remote queue. So what can happen is the local queue pulls a message from the remote queue then offers it to the receiver which returns null because it is now full, so we have unnecessaily retrieved a message. But the receiver knows it is full after accepting the last message. So I suggest we add a flag on simple delivery to signify "receiver now full", this prevents the channel having to try delivery only to find it is rejected. Any other solutions ideas? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3977556#3977556 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=3977556

19 years, 6 months

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[Design of JBoss jBPM] - Status of web console enhancements

by david.lloyd＠jboss.com

Right now I'm working on the new search mechanism for the web application. There are some items in the requirements (all of: the original, Tom's reworked one, and my reworked one on top of that) that I'm not 100% sure about, even now, so I'm still kinda thinking about those things. But the main recurring factor is that we need a good search/navigation system, and that's what I have in progress right now. A search mechanism is specified not only by the console requirements, but also the BAM application (which seems to overlap in functionality with the web console to a degree that remains to be seen). The idea is to have a search mechanism that is very reusable. In this way, I hope to solve the problem with having multiple, similar searches by reducing the amount of effort required to create and maintain the different searches. As far as implementation, I've come to the conclusion that the only real practical alternative is to use criteria queries to specify first the search results, and then add on any specified filter criteria. To attempt to maintain named queries for every kind of search would be hugely complicated. Next will be to start integrating the search page into the pages of the web application, which should be the easy part, if I've done my job right. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3977550#3977550 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=3977550

19 years, 6 months

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[Design of JBossCache] - Re: Issues with shunned node rejoining a cluster

by bstansberry＠jboss.com

"manik.surtani(a)jboss.com" wrote : How do we detect a shun? Do we have a JGroups notification for this? The org.jgroups.ChannelListener interface provides a callback when the channel is disconnected. That either happens with a shun or during a cache stop(), so the listener can know the difference by knowing if it's stopping. Re: merging state, I'm not sure what the answer to this is. Probably the way to think it through is to identify in what cases the reconnected node holds state that's worth preserving. Then see if those cases justify the cost of merging vs. doing things like invalidating tx's and just wiping clean. Once we figure out how to do a merge for the non-shunning case we'll have a better idea of the cost of a merge. I'll realize the above paragraph is a bunch of mush :( View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3977545#3977545 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=3977545

19 years, 6 months

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[Design of JBoss jBPM] - Re: MessageService and JMS

by mteira

Thanks for the tip Tom. That led me to understand what are the previous* fields in the Command subclasses supposed to be for. Anyway, if I understand correctly, every command in the Composite list should accept the result of the previous command execution, providing a field with previous{Class name of the previous result command}. So, to be able to compose a command with a NewProcessInstance and a signal to make it shake, I need SignalCommand to provide a previousProcessInstance field and be able to use it to get the root token of the newly created process instance to signal it. Is that the way to proceed? Regards. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3977542#3977542 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=3977542

19 years, 6 months

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[Design of JBoss jBPM] - Re: MessageService and JMS

by tom.baeyens＠jboss.com

take a look at the composite command. that gives you the option of wrapping multiple commands in one command. could be what you're looking for. alternatively, we could consider adding a transitionName as part of the NewProcessInstanceCommand. if it is diff from null, then a signal is given with the given command. probably we would need to look at an elegant solution for the default transition... View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3977536#3977536 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=3977536

19 years, 6 months

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[Design of Messaging on JBoss (Messaging/JBoss)] - Round Robin router race

by timfox

Just wanted to clarify something. In http://jira.jboss.org/jira/browse/JBMESSAGING-491 was one thread calling close() and another calling handle() concurrently? I wasn't sure of this from the description in the JIRA task. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3977531#3977531 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=3977531

19 years, 6 months

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[Design of JBossCache] - Re: Issues with shunned node rejoining a cluster

by manik.surtani＠jboss.com

1) At the moment, you are correct, an exception is thrown. This should propagate up to the caller though. 2) Yes again; state is transferred when new buddies join (or shunned ones rejoin). No assumptions are made as to the fact that the buddy may already have some state. 3) We need to think about what the correct behaviour here should be. You are correct in that the current behaviour is incorrect. 4) Agreed. The thing is, 1) How do we detect a shun? Do we have a JGroups notification for this? 2) How can we transparently deal with the merge? Simple case of wiping the joiner's in-memory cache? :( View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3977492#3977492 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=3977492

19 years, 6 months

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[Design of JBoss jBPM] - Re: MessageService and JMS

by mteira

After the previous changes, I was able to create new ProcessInstances for an already deployed ProcessDefinition called 'Async' using a JMS standalone client, basically doing: NewProcessInstanceCommand npic = new NewProcessInstanceCommand(); | npic.setProcessName("Async"); | //Setup for JMS session and producer using JNDI (omitted) | ObjectMessage om = session.createObjectMessage(); | om.setObject(npic); | producer.send(om); The process instances are created, and I can see them into the Oracle database I'm using as datasource. But now, I'm a little confused about how to start those process instances: My first attempt was to add to the 'start-state' node the attribute async with value 'true'. But it seems that's not valid under the DTD as I got that error while trying to deploy such process definition. So, I guess that perhaps I should send a SignalCommand targetting that newly created process instance. To do so, it seems that I need to know the tokenId I want to signal (and it looks logical to me), but how could I know it from my JMS client. What I'm going after is to be able to run the complete process inside the JBoss threads. I just want to launch it from the JMS client. Why the start-state node can not be run asynchronously? Is that a design limitation? Shouldn't I receive some feedback from my NewProcessInstanceCommand to know at least what ProcessInstance id I've launched (in order to send signals to that process instance tokens, for example) ? What's the previousToken for, in the SignalCommand class ? Regards. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3977488#3977488 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=3977488

19 years, 6 months

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[Design of Messaging on JBoss (Messaging/JBoss)] - Re: Server side HA and failover

by timfox

"bstansberry(a)jboss.com" wrote : Question: | | What is the 'cluster topology' the client needs to track? Is it the set of JBoss Messaging servers; i.e. there's only one topology? Or does it vary by service (e.g. queue/topic), i.e. the topology for Queue A is different from Queue B because A is deployed on some nodes on B some other ones. This is an interesting question. Currently all queues and topics share the same topology. I'm not sure how much value add there is in supporting multiple topologies. What do others think? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3977486#3977486 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=3977486

19 years, 6 months

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[Design of Messaging on JBoss (Messaging/JBoss)] - Re: Server side HA and failover

by timfox

Hmmm.. Come to think of it we could probably allow movement of queues as long as there are no unacked messages in any delivery lists for those queues, then we could safely move them. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3977485#3977485 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=3977485

19 years, 6 months

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jboss-dev-forums October 2006