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From: Danushka Menikkumbura <danushka.menikkumbura@gmail.com>
Date: Fri, 29 Mar 2013 03:01:16 +0530
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Subject: Re: AMQP Support for WS-Messenger
To: dev@airavata.apache.org
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Hi Suresh,

The AMQP exchanges fit the Airavata notification model quite nicely.
Basically we can map elements in the workflow tracking schema to the
Header/Topic exchanges (or even to Direct/Fanout exchanges). For an
example, we can define a topic (MyTopic) and associate few message types in
the schema with it so that whoever subscribes to MyTopic would receive
those messages. Furthermore we can let subscribers have durable
subscriptions so that the messages will get stored and forwarded in case
the subscriber in on an unreliable network. Likewise we can make use of the
rich set of building blocks available in AMQP model to have a very robust
notification framework.

RabbitMQ has a nice article [1] about the AMQP model that explains
different types of exchanges, etc nicely. I suggest you read the "Exchanges
and Exchange Types" section.

[1] - http://www.rabbitmq.com/tutorials/amqp-concepts.html

Thanks,
Danushka


On Thu, Mar 28, 2013 at 1:48 AM, Suresh Marru <smarru@apache.org> wrote:

> Hi Danushka,
>
> Good thinking, I agree with you for the most part. There are few other
> concrete use cases I can suggest, but let me get your thoughts on a
> particular example:
>
> Currently WS-Eventing is used to track workflow progress. In reality its
> not so much of the eventing spec, but the Airavata Information Model which
> is currently based on Workflow Tracking schema [1]. As you can see form the
> Web Based XBaya discussion, if a light weight java script based workflow
> GUI has to monitor progress and show real-time status (like the current
> color coded), would you say AMQP has any additional advantages? Or if you
> were to design from scratch, what would you pick which can build upon a
> pre-defined information model.
>
> Suresh
> [1] -
> https://svn.apache.org/repos/asf/airavata/trunk/modules/commons/workflow-tracking/src/main/resources/schemas/workflow_tracking_types.xsd
>
> On Mar 27, 2013, at 4:07 PM, Danushka Menikkumbura <
> danushka.menikkumbura@gmail.com> wrote:
>
> > Hi,
> >
> > When I go through [1], I get the impression that what we really need is
> an
> > extensible event bus that can provide notification push/pull
> functionality
> > so that a gateway developer has the flexibility to come up with his own
> > protocol for receiving notifications. At a very higher level the
> messenger
> > would have two main layers, the routing layer and the transport layer. We
> > would have the routing rules defined in the routing layer that makes
> > notifications available to different transports, such as WS-Notification,
> > WS-Eventing, file, mail, AMQP, JMS, etc or any other custom type
> developed
> > as you wish.
> >
> > Along the line of AMQP, basically the requirements could be twofold.
> >
> > 1. AMQP broker semantics to support pub/sub behavior
> > 2. AMPQ wire-level format
> >
> > I am not quite sure which makes AMQP more appealing to the scientific
> > community, specially in environments like XSEDE. Furthermore, I would
> like
> > to know a typical scenario, either real or hypothetical that could
> exploit
> > the capabilities of AMQP.
> >
> > [1] - https://issues.apache.org/jira/browse/AIRAVATA-339
> >
> > Thanks,
> > Danushka
>
>

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