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From: Raul Kripalani <raul@evosent.com>
Date: Wed, 15 May 2013 20:46:08 +0100
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Subject: Re: What is the best approach to do an "asynchronous rendezvous"?
To: "users@camel.apache.org" <users@camel.apache.org>
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Hi Chris,

I like this kind of problems ;-) Do these two messages share a correlation
key?

If yes, you can create a bean which acts like a Repository, accumulating
message bodies or Exchanges under the correlation key. Could be implemented
using Guava's MultiMap, or a DB if you need durable persistence, or a
distributed cache if you require clustering without persistence.

When a message arrives, you query the Repository for a previous message
with the same correlation key. If it exists, you pick it up, do whatever
manipulation is needed, and release the 3rd event. Kind of like a
CyclicBarrier that stores the messages for later usage.

P.S.: You could consider using the Aggregator EIP, but it'll block a thread
until the 2nd event comes through.

Regards,

*Ra=FAl Kripalani*
Enterprise Architect, Open Source Integration specialist, Program
Manager | Apache
Camel Committer
http://about.me/raulkripalani | http://www.linkedin.com/in/raulkripalani
http://blog.raulkr.net | twitter: @raulvk

On Wed, May 15, 2013 at 6:56 PM, Chris Wolf <cwolf.algo@gmail.com> wrote:

> In my process, I have two events that must be completed before the
> third can proceed.
> One event is the arrival of a certain JMS message and the other is the
> arrival of
> a certain file type.  The problem is, I cannot represent this in a
> route pipeline because
> one event may occur before the other and it's totally random from one
> run to another.
>
> In the abstract, I'm thinking one of the EIP patterns, either
> "resequencer" or "scatter-gather"
> applies, but I'm not certain how to do this in a concrete way with
> Camel.  If anyone has
> ideas, that would be great...
>
> Thanks,
>
>
> Chris
>

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