Dan
Thank you for time, this correction and your kindness. I don’t really understand your sentence : Serial AsyncEventListener's have their own concept of a primary, and the primary dispatches all events until it fails. I would be please to read your explanation if you have few moments. Best regards Paul From: Dan Smith [mailto:[email protected]] Sent: 19 January 2017 19:26 To: [email protected] Cc: Udo Kohlmeyer <[email protected]>; Michael Stolz <[email protected]>; [email protected] Subject: Re: Send an asynchronous event to one client among many One minor correction - even serial AsyncEventListener's are only fired on a single node for each event. Serial AsyncEventListener's have their own concept of a primary, and the primary dispatches all events until it fails. In this case I do think the parallel AsyncEventListener is probably the better option so you can scale out. -Dan On Thu, Jan 19, 2017 at 11:13 AM, Paul Perez <[email protected] <mailto:[email protected]> > wrote: Hi Url That is a very good idea I will test it and let you know. Thank you everyone I really appreciate your help and your comments. Sent from my mobile phone Paul Perez Pymma On Jan 19, 2017, at 19:00, Udo Kohlmeyer <[email protected] <mailto:[email protected]> > wrote: Hi there Paul. We will assume that you are using partitioned regions. In partitioned regions you have the notion of "primary" and "redundant" data copies. Any CUD (create,update,destroy) operations will ALWAYS only happen on the primary node. Which means that with an AsyncEventListener, it will only ever "fire" on the primary data node. So no, you will not have the AsyncEventListener fire 3 times. With a replicate region, the AsyncEventListener will fire 3 times. The concept of serial vs parallel just means the amount to threads/executors that each AsyncEventListener will use. With serial, there will only be 1. With parallel you could have many threads, but once again an event will only ever be processed by one of the AsyncEventListener threads. (if you are using partitioned regions). You can try this out if you want. --Udo On 1/19/17 10:42, Paul Perez wrote: Hello Michael I did not see your answer before replying to Udo so may be in my last email I made mistakes and wrote wrong things. We also though about AsyncEventListeners but we found a difficulty in. Geode documentation says: “You can configure an AsyncEventQueue to be either serial or parallel. A serial queue is deployed to one Geode member, and it delivers all of a region’s events, in order of occurrence, to a configured AsyncEventListener implementation. A parallel queue is deployed to multiple Geode members, and each instance of the queue delivers region events, possibly simultaneously, to a local AsyncEventListener implementation.” Let’s say that for scalability reason we have 3 members in our aggregation system, and we implement the aggregation process in the Listener. We understand that it will be invoked 3 times. And since an aggregation is not a stateless process the aggregation will be wrong. May be I’m wrong and I did not understand the documentation. I would be very happy with that. Please let me know Best regards Paul From: Michael Stolz [mailto:[email protected]] Sent: 19 January 2017 16:55 To: [email protected] <mailto:[email protected]> Cc: [email protected] <mailto:[email protected]> ; [email protected] <mailto:[email protected]> Subject: Re: Send an asynchronous event to one client among many Instead of hopping out to a client, you could get horizontal scale and asynchronous processing by using an AsyncEventListener in the servers. That will take care of multi-threading and queuing and all the plumbing, and you just go ahead and write your processing code and deploy it as AsyncEventListeners. This gives you guaranteed ordering semantics for each key as well. I *think* it even gives you a notion of H/A so that if the primary fails the queued messages will be processed by a secondary. (I know the WAN Gateway does and it uses pretty much the same plumbing under the covers). -- Mike Stolz Principal Engineer, GemFire Product Manager Mobile: 631-835-4771 <tel:(631)%20835-4771> On Thu, Jan 19, 2017 at 11:21 AM, Udo Kohlmeyer <[email protected] <mailto:[email protected]> > wrote: Hi there Paul, Firstly, your use case looks really interesting and hope to see a few more posts on how you use Geode further. Keep us informed we like to hear what you guys are doing with GEODE! :) The subscription or CQ (continuous query) paradigm is, as stated, a 1:1 relationship. When a client registers interest on a region that client will be notified. This is more of a topic semantic rather than a queue semantic. Although this is not the first time I've heard the request for this kind of functionality. To best explain why GEODE, currently, implements the 1:1 relationship has got to do with guaranteed delivery and in-order delivery. If we use a queue semantic, with multiple clients being able to process data in a balanced manner, we end up with potential out-of-order processing of messages. In addition to that it now becomes significantly harder to track and n deal with client failures and the potential replaying of messages. But that said, I have seen other users resolve this problem and could detail some approaches in a later correspondence if you'd like. --Udo On 1/19/17 03:39, Paul Perez wrote: Hello All, As explained in a previous email, we try to use Geode to process and aggregate a stream of Traces. Our requirement is to process billions of simple traces every day. We imagine the aggregation process in many steps. One: traces are generated by a tiers tools and stored in a first geode region Two: once a trace put in the first region we use the async event feature to invoke a client that executes the first aggregation steps. Then the result will be put in a second region. Three: the second aggregation step is in the same way, when traces are put in the second region, then an asynchronous event is sent to the client to execute the second part of the aggregation etc.… For scalability purposes, we plan to use many clients that could receive the events and execute the aggregation and put the results back to Geode. Consequently, as far as we understand the documentation, when an entry is put in a region, each client that registered an interest receives an event and aggregate the trace. So, the trace will be aggregated many times. My question is: If many clients are registered, could we configure the region to send randomly, the event to one client only. A subsidiary question: Do we have the same behaviour with the function execution feature or it could be an alternative in that case Thank you for your help Best regards Paul
