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From Fraser Adams <fraser.ad...@blueyonder.co.uk>
Subject Use of subject for routing - moved thread to user list from earlier private discussion.
Date Fri, 29 Aug 2014 13:55:38 GMT
All,
I've moved this thread to the user list. It started out on the back of 
an email conversation between Rob Godfrey. Gordon Sim and and myself 
when I couldn't get my QMF messages routed on the Java Broker.

The original context was that I was sending messages to 
qmf.default.direct and setting the message subject to "broker", this is 
pretty much exactly what the python qpid tools such as qpid-config do.

in AMQP 0.10 this works fine because the subject (which in AMQP 0.10 is 
a user property called qpid.subject) gets treated as the routing key 
when sent to a direct exchange.

When I did my AMQP 1.0 JavaScript qpid-config port I set the AMQP 1.0 
subject (which is now an immutable message property and not an 
application property) to "broker" and sent to 
amqp://guest:guest@localhost:5673/qmf.default.direct


This worked fine with the C++ broker, but with the Java Broker the 
message wasn't routed and in subsequent conversations with Rob and 
Gordon I discovered that the Java Broker doesn't route on direct 
exchanges based on Subject rather it first tries to use to "to" - in 
other words if I sent to 
amqp://guest:guest@localhost:5673/qmf.default.direct/broker it'd work or 
if the to isn't set it uses the application property "routing-key".

So basically this thread is around an inconsistency between the C++ and 
Java Brokers where the C++ Broker continues to route on Subject for AMQP 
1.0 but the Java Broker does not.

Rob and Gordon can fill in if I've missed anything, but it's probably 
best to share this discussion on the user list.

Frase




On 29/08/14 14:03, Rob Godfrey wrote:
> I think in the context of where AMQP 1.0 is now, routing by subject is 
> somewhat counter-intuitive, though when we started we did see the 
> subject field in a routing-key sort of role.
 From my perspective I'd say exactly the opposite, that is routing by 
subject seems entirely intuitive and is also consistent with what 
happened with AMQP 0.10. Given the use of subject as the defacto routing 
key on all of the python tools I don't think I'm alone in feeling that's 
intuitive. I'm pretty sure that the subject is used for routing on topic 
exchanges so I'm not sure why you think its counter-intuitive on derect 
exchanges?

>
> In terms of current behaviour - the legacy filters in the Java Broker 
> just set up the bindings between the queue and the exchange and thus 
> use the same routing as previously described (i.e. they're not 
> currently using subject). Inside the Java Broker an exchange routes 
> based on an abstract notion of the "routingAddress" of a message 
> instance.  In AMQP 0.x that's taken to be the routing key.  In 1.0 it 
> is as I described in my previous mail.
>
> If we collectively (and this discussion should really be on the users 
> list) think that 0.x exchanges should route on subject when routing a 
> 1.0 message then I'm happy to change the default behaviour of the Java 
> Broker - except for the "no name" exchange which will route on "to" 
> because that's what we're defining on the addressing spec.  I'll then 
> probably add options to the exchange implementation so that a user can 
> configure on a per exchange basis to route on something else (except 
> for the non default amq.* exchanges).
>
> -- Rob
>
>
> On 29 August 2014 13:45, Gordon Sim <gsim@redhat.com 
> <mailto:gsim@redhat.com>> wrote:
>
>     On 08/29/2014 11:49 AM, Rob Godfrey wrote:
>
>         For the moment I guess we'll just have to live with the C++
>         and Java
>         Brokers having different ideas about how to route 1.0 messages
>         at exchanges.
>
>
>     The legacy-amqp filters are defined to work on the subject when
>     using the exchange as the source. I thought the java broker
>     supported those?
>
>     If I create a receiving link from amq.direct with a
>     apache.org:legacy-amqp-direct-binding:string of foo, then send a
>     message to amq.direct whose subject is foo, my expectation would
>     be that the receiver will receive that.
>
>

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