Re: [xmlblaster] Some QOS Questions

[Marcel Ruff <ruff at swand.lake.de>]

Adam Williams wrote:

> As I'm figuring the ins-n-outs of xmlBlaster I'm trying to put together
> a presentation on the topic.  I've posted the slides I have so far
> concerning QOS at ftp://kalamazoolinux.org/pub/pdf/xmlBlaster.pdf  I'd
> appreciate it if someone would take a look and offer their opinion on
> the accuracy, although there isn't much there yet.
>
> But I've come up with a few questions that the documentation seems iffy
> about -
>
> 1 - Does the sender of the message actually set the "<sender></sender>"
> tags or are these added when the message is recieved?
If the sender has set the <sender> attribute it will be respected 
(especially important
for cluster setup), if no <sender> is given, xmlBlaster will set in when 
a message arrives.

> 2 - Does the priority tags really have any effect?  On the order the
> messages are delivered, etc...?
Yes. But priority only has impact on queues. If a queue is empty, the 
prio does not
help. If a queue has many messages, a high prio message overtakes all 
others.

> 3 - On a published message the examples in XMLQoS show an XPATH
> statement in the <destination> tags.  Is this actually used?  I though
> XPATH queries were run against the keys of queued messages?
This is currently not implemented. The problem is that authentication
is plugin based (as almost everything in xmlBlaster). If the authentication
plugin used is LDAP, the XPath query fails as ldap has its own query syntax.
The destination query is delegated to the plugin to query the user info 
available
there.
Approaches to address this issue need to be discussed.

regards,

Marcel

>