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Date: Fri, 11 May 2012 14:09:48 -0700
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 <CAARMrHUJ_EfTV6Zm-Q=4xkCBy9=edTRS6ub1COZTB_DfqvSfBA@mail.gmail.com>
Subject: Re: Event Publish and Subscribe ( was perhaps Re: Cloudstack
 Questions )
From: Adrian Cole <adrian@jclouds.org>
To: cloudstack-dev@incubator.apache.org
Cc: Dean <cloud@tizatron.com>
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+1

Makes sense to have pubsub.  Inside the java codebase, we could consider a
clean and idiomatic lib like guava which is easy to unit test.

http://codingjunkie.net/guava-eventbus/

Then, expose out-of-JVM hooks for any of the popular services people use.

-A
On May 11, 2012 1:58 PM, "Dean" <cloud@tizatron.com> wrote:

> Cross reference to:
>
>
> http://mail-archives.apache.org/mod_mbox/incubator-cloudstack-dev/201204.mbox/browser
>
> [ from: Marlon Davids ]
> < munch >
> > 2) How do we monitor VM's that are in Cloudstack when they are in an
> isolated VLAN does
> > anyone have a clever workaround?
> > 3) Has anyone developed a script for parsing and alerting on warning
> events in the
> > management Log yet?
>
> I would like to propose cloudstack consider a pub/sub model for event
> handling to complement API calls like listEvents.
>
> Polling can be problematic and sensitive to scaling.
>
> A simple example would be state change on a physical device.  The admin
> server can simply publish a message on a network socket indicating that the
> device has changed it's state.
>
> If a subscriber was interested in that device, it could make an api call
> to the admin server for state change information for that device only.  The
> admin server may choose to validate that physical device against the
> current state table in the database.
>
> The API would reply that this node changed it's state from Operational to
> Prep For Maintenance.  (or whatever the transition state would be)
>
> The message exchange could be wrapped around vm states, resource
> additions/removals etc.
>
> Using a library like zeromq, a developer can write any number of consumers
> in any language they wanted to subscribe to the Event Bus.
>
> Comments?
>
> --
> -Dean

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