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From Fraser Adams <fraser.ad...@blueyonder.co.uk>
Subject Re: how to query a single object with QMF2?
Date Sat, 13 Oct 2012 09:35:18 GMT
Hi Yannan
I wrote a pretty complete Java Implementation of the QMF2 API which you 
can get from the Jira 3675 linked here.

https://issues.apache.org/jira/browse/QPID-3675

I've got absolutely no idea if this has made it into Qpid proper, it's 
marked down as assigned to Ted Ross.

Unfortunately I've had no feedback on this and my only mechanism for 
doing anything with it is via the Jira.

I must admit that I'm a little bit frustrated, I put a load of effort 
into it and I'm simply not sure if there's any take up. I'm not aware of 
any other Java implementation of the QMF2 API though there are a few 
examples of basic QMF2 protocol Map Message passing out there.

To answer your question there is no way to just get the queue names 
without getting the QmfData Map objects. Basically you initially have to 
do getObjects("queue") - or the low-level protocol equivalent.

However once you have retrieved the queue objects you can go through 
them looking for the one with the name that you want (the "name" 
property IIRC).where  you

Once you've found that you can get the _object_id from it (it's just a 
property) and given that then you can then do a query based on the 
_object_id

In the QMF2 API the refresh() method on a QmfConsoleData Object does 
just that - but you need to have done an initial getObjects to get the list.

Technically there's another way - using the API you can set up a "query 
subscription"  can pass the queue name as part of the query and get the 
updates pushed to you. The broker (at least up to 0.12, which is what 
I'm currently using) doesn't actually support the query subscription 
part of the API so I actually emulated it within the Console itself (if 
a query subscription is added the Console subscribes to object updates 
and applies the required filters).


FWIW there's one fairly notable bug in my implementation, basically if 
there are more than 100 management objects the broker sends partial 
updates. The version I've posted to the Jira doesn't support this, 
though the version I'm working on does (I've tested with 1000's of 
connections, queues etc.)

I've not posted any updates 'cause I'm working on some fancy new 
features. Primarily I'm writing a fancy HTML5 web UI to enable full 
management and monitoring of potentially multiple brokers. It's working 
on browsers from IE6 to mobile safari. There's still a fair bit to do 
(I'm working on adding queues remotely at the moment). In support of the 
Web UI I've been writing a full REST API around the QMF2 API.

I'd like to think all of this might be useful to someone, It's been over 
a year of weekends including the original QMF2 API development, but the 
apparent lack of interest is leaving me a little demotivated - I'm 
mainly carrying on because it's useful to me, there aren't any other 
really good UIs for Qpid/QMF that I'm aware of.


Regards,
Frase




On 12/10/12 22:49, yannanlu wrote:
> With the example java code, I am able to query a full list of queue objects
> from a C++ broker. Is there a way to query just a list of names for all the
> queues without their detailed attributes?
>
> How can I query just one object if I know the queue name? Where to look up
> the _objectId for a known queue?
>
> Thanks,
>
> Yannan
>
>
>
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