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From Eric Plowe <eric.pl...@gmail.com>
Subject Re: sending notifications through data replication on remote clusters
Date Mon, 10 Mar 2014 14:31:42 GMT
You should be able to achieve what you're looking for with a trigger vs. a
modification to the core of Cassandra.

http://www.datastax.com/dev/blog/whats-new-in-cassandra-2-0-prototype-triggers-support




On Mon, Mar 10, 2014 at 10:06 AM, DE VITO Dominique <
dominique.devito@thalesgroup.com> wrote:

> > On 03/10/2014 07:49 AM, DE VITO Dominique wrote:
> > > If I update a data on DC1, I just want apps "connected-first" to DC2
> > > to be informed when this data is available on DC2 after replication.
> >
> > If I run a SELECT, I'm going to receive the latest data per the read
> conditions (ONE, TWO, QUORUM), regardless of location of the client
> connection. If using > network aware topology, you'll get the most current
> data in that DC.
> >
> > > When using Thrift, one way could be to modify CassandraServer class,
> > > to send notification to apps according to data coming in into the
> > > coordinator node of DC2.
> > >
> > > Is it "common" (~ the way to do it) ?
> > >
> > > Is there another way to do so ?
> > >
> > > When using CQL, is there a precise "src code" place to modify for the
> > > same purpose ?
> >
> > Notifying connected clients about random INSERT or UPDATE statements
> that ran somewhere seems to be far, far outside the scope of storing data.
> Just configure your client to SELECT in the manner that you need.
> >
> > I may not fully understand your problem and could be simplifying things
> in my head, so feel free to expand.
> >
> > --
> > Michael
>
> First of all, thanks for you answer and your attention.
>
> I know about SELECT.
> The idea, here, is to avoid doing POLLING regularly, as it could be easily
> a performance nightmare.
> The idea is to replace POLLING with PUSH, just like in many cases like
> SEDA architecture, or CQRS architecture, or continuous querying with some
> data stores.
>
> So, following this PUSH idea, it would be nice to inform apps connected to
> a preferred DC that some new data have been replicated, and is now
> "available".
>
> I hope it's clearer.
>
> Dominique
>
>
>

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