Hi Azeez, If it is sequential, when a node has left and rejoined, he can get the missing messages (Ok well given they are stored somewhere).
Might be useful with deployments etc. But if we do not have a usecase, then no need. --Srinath On Fri, Jul 12, 2013 at 2:44 PM, Afkham Azeez <az...@wso2.com> wrote: > Message ID does not have to be sequential for our use cases. Just a UUID > would do. > > > On Fri, Jul 12, 2013 at 2:08 PM, Srinath Perera <srin...@wso2.com> wrote: > >> Hazecast has an atomic Long ( >> http://www.hazelcast.com/javadoc/com/hazelcast/core/AtomicNumber.html) >> we can use that as the messageID and that way we can detect all missing >> messages as Suho mentioned (need to check the performance though) >> >> --Srinath >> >> >> On Sun, Jul 7, 2013 at 2:53 PM, Sriskandarajah Suhothayan >> <s...@wso2.com>wrote: >> >>> >>> >>> On Sat, Jul 6, 2013 at 2:56 PM, Supun Malinga <sup...@wso2.com> wrote: >>> >>>> Hi Azeez, >>>> >>>> Totally +1 for the approach. >>>> I can suggest some improvement if you haven't already done. >>>> Several components in carbon platform will be using the hazelcast based >>>> clustering impl. We should have some mechanism to embed the usage of the >>>> each cluster message into the message itself. >>>> For eg. depsync messages will have the message type : depsync >>>> cluster initialization/coordination messages will have >>>> message type: cluster >>>> etc. >>>> (I'm aware there is some kind of identification via the cluster message >>>> class, but I'm talking about embedding into api level.) >>>> >>>> So with this (message type), as the next step, we can have some rules >>>> on which messages to re-play. >>>> For eg: depsync messages, we can only re-play the latest (here we might >>>> need to embed a timstamp into the message also). >>>> WDYT? >>>> >>>> +1 >>> We could have normal and reliable messaging APIs. >>> >>> +1 for cluster messages to have UUIDs for reliable messaging. >>> >>> IMHO the reliable messaging can also be implemented with the hazelcast >>> cache, where we can store those messages in the cache and when a member >>> joins/rejoins it can read the missed messages from the cache. but for this >>> we have to use sequence numbers. >>> >>> This is just my thought, not sure how feasible it is. >>> >>> Suho >>> >>> thanks, >>>> >>>> >>>> >>>> >>>> On Sat, Jul 6, 2013 at 2:30 PM, Afkham Azeez <az...@wso2.com> wrote: >>>> >>>>> I have implemented a simple replay mechanism based on message UUIDs. >>>>> >>>>> >>>>> On Thu, Jul 4, 2013 at 5:44 PM, Afkham Azeez <az...@wso2.com> wrote: >>>>> >>>>>> There could be a situation where when a cluster message is sent, a >>>>>> member momentarily leaves the cluster, but joins immediately. This >>>>>> generally could happen when the nodes slow down under load, or due to >>>>>> intermittent network failures. However, this could lead to failures >>>>>> because >>>>>> crucial cluster messages may not be received by members. >>>>>> >>>>>> To overcome this, or reduce the probability of loss of such messages, >>>>>> we can replay a certain number of messages when a member joins. On the >>>>>> sender side, messages over a particular time period can be buffered, and >>>>>> then replayed when new members join. However, we should ensure that the >>>>>> messages are idempotent, and messages should declare whether they are >>>>>> idempotent or not. If a message is not idempotent, we will not replay it. >>>>>> All the messages we have at the moment are idempotent, AFAIK. >>>>>> >>>>>> How does this approach sound? >>>>>> >>>>>> -- >>>>>> *Afkham Azeez* >>>>>> Director of Architecture; WSO2, Inc.; http://wso2.com >>>>>> Member; Apache Software Foundation; http://www.apache.org/ >>>>>> * <http://www.apache.org/>** >>>>>> email: **az...@wso2.com* <az...@wso2.com>* cell: +94 77 3320919 >>>>>> blog: **http://blog.afkham.org* <http://blog.afkham.org>* >>>>>> twitter: >>>>>> **http://twitter.com/afkham_azeez*<http://twitter.com/afkham_azeez> >>>>>> * >>>>>> linked-in: **http://lk.linkedin.com/in/afkhamazeez* >>>>>> * >>>>>> * >>>>>> *Lean . Enterprise . Middleware* >>>>>> >>>>> >>>>> >>>>> >>>>> -- >>>>> *Afkham Azeez* >>>>> Director of Architecture; WSO2, Inc.; http://wso2.com >>>>> Member; Apache Software Foundation; http://www.apache.org/ >>>>> * <http://www.apache.org/>** >>>>> email: **az...@wso2.com* <az...@wso2.com>* cell: +94 77 3320919 >>>>> blog: **http://blog.afkham.org* <http://blog.afkham.org>* >>>>> twitter: >>>>> **http://twitter.com/afkham_azeez*<http://twitter.com/afkham_azeez> >>>>> * >>>>> linked-in: **http://lk.linkedin.com/in/afkhamazeez* >>>>> * >>>>> * >>>>> *Lean . Enterprise . Middleware* >>>>> >>>>> _______________________________________________ >>>>> Architecture mailing list >>>>> Architecture@wso2.org >>>>> https://mail.wso2.org/cgi-bin/mailman/listinfo/architecture >>>>> >>>>> >>>> >>>> >>>> -- >>>> Supun Malinga, >>>> >>>> Senior Software Engineer, >>>> WSO2 Inc. >>>> http://wso2.com >>>> http://wso2.org >>>> email - sup...@wso2.com <sup...@wso2.com> >>>> mobile - 071 56 91 321 >>>> >>>> _______________________________________________ >>>> Architecture mailing list >>>> Architecture@wso2.org >>>> https://mail.wso2.org/cgi-bin/mailman/listinfo/architecture >>>> >>>> >>> >>> >>> -- >>> *S. Suhothayan >>> * >>> Associate Technical Lead, >>> *WSO2 Inc. *http://wso2.com * >>> <http://wso2.com/>* >>> lean . enterprise . middleware >>> >>> *cell: (+94) 779 756 757 | blog: http://suhothayan.blogspot.com/ >>> twitter: http://twitter.com/suhothayan | linked-in: >>> http://lk.linkedin.com/in/suhothayan* >>> * >>> * >>> >>> _______________________________________________ >>> Architecture mailing list >>> Architecture@wso2.org >>> https://mail.wso2.org/cgi-bin/mailman/listinfo/architecture >>> >>> >> >> >> -- >> ============================ >> Srinath Perera, Ph.D. >> http://people.apache.org/~hemapani/ >> http://srinathsview.blogspot.com/ >> >> _______________________________________________ >> Architecture mailing list >> Architecture@wso2.org >> https://mail.wso2.org/cgi-bin/mailman/listinfo/architecture >> >> > > > -- > *Afkham Azeez* > Director of Architecture; WSO2, Inc.; http://wso2.com > Member; Apache Software Foundation; http://www.apache.org/ > * <http://www.apache.org/>** > email: **az...@wso2.com* <az...@wso2.com>* cell: +94 77 3320919 > blog: **http://blog.afkham.org* <http://blog.afkham.org>* > twitter: **http://twitter.com/afkham_azeez*<http://twitter.com/afkham_azeez> > * > linked-in: **http://lk.linkedin.com/in/afkhamazeez* > * > * > *Lean . Enterprise . Middleware* > > _______________________________________________ > Architecture mailing list > Architecture@wso2.org > https://mail.wso2.org/cgi-bin/mailman/listinfo/architecture > > -- ============================ Srinath Perera, Ph.D. Director, Research, WSO2 Inc. Visiting Faculty, University of Moratuwa Member, Apache Software Foundation Research Scientist, Lanka Software Foundation Blog: http://srinathsview.blogspot.com/ Photos: http://www.flickr.com/photos/hemapani/ Phone: 0772360902
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