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From Antoine Chevin <antoine.che...@gmail.com>
Subject Re: Accessing queues with '/' in name in Rest API [qpid java broker 6.0.4]
Date Thu, 02 Mar 2017 14:11:58 GMT
Thank you Rob for the very detailed answer.
I saw in the code
(org.apache.qpid.server.protocol.v1_0.Session_1_0#remoteLinkCreation)that
the exchange lookup is skipped if the address starts with a '/'.
I intend to use a '/' in the beginning because I don't want the exchange
lookup.
Do you think it is a good approach?

Thank you,
Regards,
Antoine

-----Original Message-----
From: Rob Godfrey [mailto:rob.j.godfrey@gmail.com]
Sent: jeudi 2 mars 2017 11:09
To: users@qpid.apache.org
Subject: Re: Accessing queues with '/' in name in Rest API [qpid java
broker 6.0.4]

On 2 March 2017 at 10:46, Antoine Chevin <antoine.chevin@gmail.com> wrote:

> Thank you Rob for the answer. Yes it really helps!
> I noticed that addresses in the form <exchange-name>/<routing-key> are
> also used with AMQP 1-0. Is it expected?
>
>
It is part of how the Java Broker maps the AMQP 0-x Exchange/Binding/Queue
model into the AMQP 1.0 address space, yes.

In short when the Java Broker receives a message to an address X it first
looks to see if there is an exchange X, then if there is a queue X, then if
X contains a / it looks to see if the part before the / is an exchange
name, and if so it sends to that exchange with the part after the / being
used as the routing key.

When the Java Broker receives a request to consume from an address X it
first looks to see if there is a Queue X, then if there is an Exchange X
(in which case it creates a temporary queue and binds with an empty binding
key), and then if X contains a / and the part before the X is an exchange
name it will create a temporary queue and bind that to the exchange with
the binding key being the part of X after the /.

Note the asymmetry on send and consume that on send it first looks for an
exchange and on consume it first looks for a queue.

(There are a few more rules for the globalAddressDomains and for system
addresses like $management, but the above is the general rule).

-- Rob


> Thank you,
> Regards,
> Antoine
>
> On 1 March 2017 at 20:25, Olivier Mallassi
> <olivier.mallassi@gmail.com>
> wrote:
>
> > Rob, all
> >
> > Thank you rob for this. Could you please share more details
> > regarding not using the "/"?
> >
> >
> So there are a couple of reasons why I think not using a / makes sense:
>
> 1) Because of exactly the REST / encoding issue that you ran into -
> using characters that often need escaping can cause a lot of issues in
> config files, parameters etc...  depending upon where the queue name
> might be used you may end up encoding that / one, two or even more
> times... this gets messy fast
>
> 2) Because in AMQP addressing we've been imaging the / as a separator
> when using some sort of topological address scheme for addressing in
> federated networks... for instance you might have a queue for orders
> in you dongle department of your widget division of your company
> foo.com... and you might expose that address as
> //foo.com/widget/dongle/orders  whereas someone connected directly to the
broker would just see the queue as "orders"
> (though they could also address it by its full "global" name).  The
> Java Broker already makes some allowance for this with the notion of
> "globalAddressDomains" which you can set on the virtual host.  For any
> domain <foo> in the list of defined globalAddressDomains, the
> virtualhost will accept messages sent <foo>/M as if it were sent to M
> (and the same with consuming).
>
> Also note that for the Java Broker an address of the form <exchange
> name>/<routing key> can be used to send / receive via AMQP 0-x
> exchange/routing-key semantics.
>
> Hope this helps,
> Rob
>
>
> > On our side we are using amqp 1.0 that, AFAIU, promotes the "complex"
> > addressing plans
> > The benefit for us would be
> > - alignements between our http and amqp naming conventions. It is a
> > nice to have but can help lisibility
> > - use "URL" to route messages. Like the samples with the
> > linkroutepattern
> >
> > Not sure these are good ideas btw. Any feedback is welcomed
> >
> > Regards
> >
> > On Wed, 1 Mar 2017 at 18:16, Rob Godfrey <rob.j.godfrey@gmail.com>
> wrote:
> >
> > > In general I'd advise against using the '/' character in queue
> > > names if possible... however if you must, then you need double
> > > encode the name, so "a/b" would become "a%252Fb"
> > >
> > > Hope this helps,
> > > Rob
> > >
> > > On 1 March 2017 at 17:31, Antoine Chevin
> > > <antoine.chevin@gmail.com>
> > wrote:
> > >
> > > > Hello,
> > > >
> > > > I created a queue with a '/' in the name. How can I access it in
> > > > the
> > rest
> > > > api?
> > > > I tried to encode the '/' with %2F but I still get a 422 "too
> > > > many
> > > entries
> > > > in path for REST servlet queue."
> > > > Can you please help?
> > > >
> > > > Regards,
> > > > Antoine
> > > >
> > >
> >
>

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