Re: [xmlblaster] Deliver-once semantics and synchronous message query

[Martin Stjernholm <mast at roxen.com>]

Thanks for the quick answer.

Marcel Ruff <mr at marcelruff.info> wrote:

> you can access any server side queue (callback-queue, history-queue,
> subject-queue)
> with a synchronous call with get().

I'm pleased to hear that.

> This is described in
>  http://www.xmlblaster.org/xmlBlaster/doc/requirements/engine.qos.queryspec.QueueQuery.html

If I understand that page correcly, I have two alternatives: Either a
plain GET command on the administrative telnet port, or with the query
variables encoded on the same form inside a <querySpec> tag in the QoS
of (for instance) an xmlrpc call to xmlBlaster.get.

If the latter is correct, then I suggest mentioning the <querySpec>
tag in the example of "all available get QoS" on the interface.get
requirement page.

> Your XmlRpc client would login and subscribe to all interested
> topics, its callback queue is filled but because you don't establish
> a callback server they are never delivered.

Ah, interesting. I misunderstood the docs on this; I thought it wasn't
possible to subscribe without providing a callback. The combination
of:

1.  interface.subscribe: "Messages are asynchronous accessed with the
    subscribe() method", and
2.  "Clients have to establish a callback server instance to allow
    asynchronous callbacks." (same page)

led me to believe that subscriptions primarily was a tool to achieve
asynchronous communication. Rather, they are primarily for setting up
a queue, and the asynchronous callback is optional (which makes more
sense imho).