Re: Can this be done with ActiveMQ? (durable virtual topic with selector on STOMP with network of brokers)

[Attila Nagy]

Even on activemq.org you can find the terms durable topic and queue. I 
think this is a compact way to represent that I want to store/get my 
messages even when the consumer is offline.

BTW, I'm afraid you haven't read my mail to the end, or the message 
didn't get through.
I'll try to conclude it: I would like to post to a virtual topic in a 
network of brokers and consume from this topic (queues) with different 
clients -with durable subscriptions, but I hope you won't mind there is 
no durable subscription for queues- with different selectors, and I 
would like to get only those messages to those queues, which the 
selectors match.

This works when the consumer is online (consuming from the queue), but 
when I remove it, nothing will get into the queue.

Or the other way around: all messages got into the queue even when the 
consumer is offline, but the consumer receives messages in very slow 
batches when I use a selector.
Without a selector, the full speed can be achieved.

These are two problems, though.

On 11/04/2013 04:56 PM, Aleksandar Ivanisevic wrote:
The only thing that is durable is a consumer, topic per se can not be
durable. Also how is a queue durable? Perhaps you mean a queue with
persistent messages on it?

To have a durable consumer to a topic you need to create a durable
subscription, either through the console or by sending a client-id and
activemq.subscriptionName headers when connecting.

Attila Nagy <b...@fsn.hu> writes:

Hi,

I'm struggling with AMQ 5.9.0 to achieve my goals: durable virtual
topics with selectors on STOMP, with a network of four brokers
(connected with SSL connectors, with ACLs and certificate
authentication/authorization both on client and server side).

In english: I want to publish messages to a -more, but I think it's
irrelevant here- (virtual) topic from machines spread in many data
centers to AMQ servers in two DCs (2x2 machines, fully meshed). Any
publisher or consumer can connect to any of the servers.
The messages in the topic have several headers and I would like to
filter them into durable queues.
So for example Publisher1..10 publishes Type1..10 messages, but
Consumer1 only consuming Type1, Consumer2 consuming Type1-3 and so on
from durable queues.
To protect the queues, I would like to deliver only the messages
matching the consumer's selector, and publish the message with a TTL
set, so if the consumer for the given queue is away for an extender
period of time, the messages should be dropped.

Seems to be fun, but I can't get it to work.

The two behaviours I could get -so far with only one machine and only
one publisher/consumer (one queue):
- everything works nicely, the queue gets only the relevant messages,
but it's not durable. If there is a consumer, it gets the messages,
but if nobody listens, nothing gets to the queue.
- the queue gets all of the messages (not just the ones, the selector
would allow) and is durable. However, the consumer gets the messages
in bursts, like around 130 messages per second and nothing for about a
minute, then another 130 messages and nothing for a minute, while the
queue is full with messages.

The configuration I use is:
http://pastebin.com/d8rkB0Yc

The difference between the two, described above is the selectorAware
true setting, commented out in the pastebin config.

I use a python client, publish to /topic/VirtualTopic.radius and
consume from /queue/Consumer.radiusmq.VirtualTopic.radius with the
following code snippet:
     conn.connect(headers={'client-id':'radiusmq'})
     conn.subscribe(headers={
'destination':'/queue/Consumer.radiusmq.VirtualTopic.radius',
                             'ack':'client',
                             'id':1,
                             'activemq.prefetchSize':1000,
                             'selector':"Xsystem = 'wired' AND ("
                             "Xstatustype = 'STOP' OR "
                             "Xstatustype = 'INTERIM_UPDATE')",
                             }
                    )

I have some graphs about the latter case, if helps, however, I would
like to get the former working, but with a durable queue.

Thanks,