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From Gordon Sim <g...@redhat.com>
Subject Re: python proton reactor "dynamic message selection"?
Date Thu, 16 Nov 2017 19:56:13 GMT
On 16/11/17 17:30, James Sears wrote:
> Is there a way - using the python proton reactor API - to do what I'd call dynamic message
selection?
> 
> By this I mean I'd like my application to do something like this:
> 
> 1. receive message M1 on queue Q1 with unique correlation_id N.
> 2. send message M2 to topic T1 with correlation_id N and reply_to queue Q2.
> 3. receive messages - M3, M4, etc - to Q2 and use a message selector with correlation_id
N.
> 4. messages to Q2 would eventually reach their expiry_time.
> 5. remove message selector on Q2 with correlation_id N.
> 5. event back to step 1.
> 
> Is this sort of thing possible with proton reactor?
> 
> Just that I'm not sure how I'd be able to create and then remove selectors that are no
longer required.

Selectors are set when you create a receiver[1]. You can only remove 
them by closing the receiver (and then optionally opening again with a 
different selector (or no selector).

However, without fully understanding your use case, I'd suggest maybe 
using a different reply queue for specific messages rather than trying 
to use selectors for that. You can have reply queues created dynamically 
on demand (e.g. [2])

[1] 
https://git1-us-west.apache.org/repos/asf/qpid-proton/repo?p=qpid-proton.git;a=blob;f=examples/python/selected_recv.py;h=dc062d5f54dda321f9b4b7de7489a58f3a462a4b;hb=HEAD

[2] 
https://git1-us-west.apache.org/repos/asf/qpid-proton/repo?p=qpid-proton.git;a=blob;f=examples/python/client.py;h=86f2c76a7bbe03e563ab0e44a5d1ecff296fdd4d;hb=HEAD#l35


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