On Wed, Jan 26, 2011 at 04:37:27AM -0800, Mario Camou wrote:
>
> OK, so I create my own Receiver (perhaps inheriting from
> RuoteAMQP::Receiver) and in there I can do whatever I want. As far as
> "correlation" is concerned, what I need to do is, find out the FEI to which
> to send the incoming data, get the workitem associated with that FEI, and
> plug in the data from the message.
>
> Outbound messages get handled by my own Participant which needs to
> coordinate with the Receiver, perhaps storing the data needed for
> correlation somewhere where the Receiver can find it (perhaps a global Hash
> table, a database, or in the quantum state of the Universe) and associate it
> with the FEI. Correct?
Hello Mario,
yes. If you follow my suggestion, you'll notice that passing the fei avoids the
need to map to a custom correlation id, the fei being the correlation id.
> Also, is there a way of searching through all the stored workitems, to do
> the correlation? So, suppose the message comes with certain fields (for
> example, "source_token" and "message_type") that need to match data inside
> of the workitem (for example, fields called "expected_token" and
> "expected_message_type"). In that case I could either store the
> "expected_token" and "expected_message_type" someplace and associated with
> the FEI, so the Receiver can get at them, or have the Receiver search the
> stored workitems to find the FEI. What would be the preferred way of doing
> this?
Re-working my previous sample :
---8<---
class MarioReceiver
def handle(msg)
correlation_id = extract_correlation_id(msg)
expressions = @engine.processes.collect { |process_status|
process_status.expressions.select { |expression|
expression.class == Ruote::Exp::ParticipantExpression
}
}.flatten
expression = expressions.find { |exp|
exp.h.applied_workitem['fields']['correlation_id'] == correlation_id
}
raise "not found" unless expression
workitem = Ruote::Workitem.new(expression.h.applied_workitem)
reply_to_engine(workitem)
end
end
--->8---
Something like that.
The problem : it goes through all the process instances... The fei as
correlation id method is so much "direct"...
Now I could show you examples of how to store your correlation_id <-> fei
mapping, but oh well...
"expected_token" could easily contain the fei, and "expected_message_type"...
does it matter ? The receiver should just discard irrelevant messages before
even thinking about correlation.
Best regards,
--
John Mettraux - http://jmettraux.wordpress.com
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