Some systems (e.g. MQTT) allow for the last message on any given topic to be retained and then replayed to any new subscriber. This model can work well: it encourages the design of a topic space where you just need to know the last message (i.e. the latest state of that particular resource).
Paul On 4 July 2013 13:14, Afkham Azeez <[email protected]> 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: **[email protected]* <[email protected]>* 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 > [email protected] > https://mail.wso2.org/cgi-bin/mailman/listinfo/architecture > > -- Paul Fremantle CTO and Co-Founder, WSO2 OASIS WS-RX TC Co-chair, VP, Apache Synapse UK: +44 207 096 0336 US: +1 646 595 7614 blog: http://pzf.fremantle.org twitter.com/pzfreo [email protected] wso2.com Lean Enterprise Middleware Disclaimer: This communication may contain privileged or other confidential information and is intended exclusively for the addressee/s. If you are not the intended recipient/s, or believe that you may have received this communication in error, please reply to the sender indicating that fact and delete the copy you received and in addition, you should not print, copy, retransmit, disseminate, or otherwise use the information contained in this communication. Internet communications cannot be guaranteed to be timely, secure, error or virus-free. The sender does not accept liability for any errors or omissions.
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