Re: Regarding notifications

[Daniel Jemiolo <da...@us.ibm.com>]

Hi,

I don't think you'll like this answer, but this is actually the "desired 
behavior" from a WS-N standpoint. Each new call to subscribe() creates a 
new subscription (ws-resource), and that subscription will notify its 
subscribers whenever a message is published to its topic. There is no 
default policy to prevent duplicate consumer reference and topic 
combinations among the subscription manager's subscriptions, and it would 
hard to police this anyway given that two EPRs can point to the same 
consumer.

That said, it should be possible to introduce a (WSN-defined) policy that 
checks for duplicate consumer references and either throw a fault or 
return the existing subscription EPR when it happens. the only thing you'd 
have to watch for on the second scenario is duplicate calls to WSRL 
Destroy when you wanted to end the subscription(s). 

I'm not familiar enough with how pubscribe works to tell you how to 
introduce such a policy, or if you can override one or more methods in the 
implementation to create the behavior. The JavaDocs don't include any info 
on their implementation classes, and there is no API for adding/affecting 
subscription policies.

Dan



"Muni Reddy" <na...@gmail.com> wrote on 06/30/2006 04:31:45 AM:

>  Hi Dan,
> 
> Thanks for your reply.
> 
> Yes, both notification messages have the same topic value since I have
> subscribed for "Comment" property twice from the same consumer.
> 
> 
> 
> I am using filesystem example. I didn't add manageability capability 
topics.
> 
> 
> 
> My requirement is whenever changes happen to resource properties; I want
> notifications from the notification producer.
> 
> 
> 
> The problem is, if the same consumer sends request to subscribe again 
for
> the same property which has subscribed earlier, the notification 
producer is
> sending notification twice to the same consumer for the same property 
when
> change happens to that property.
> 
> 
> 
> I was surprised why subscription manager is allowing subscription twice 
for
> the same property (let say "Comment") from the same consumer endpoint?
> 
> 
> 
> Is there any way to allow consumer to subscribe only once for one
> topic/property?
> 
> 
> 
> - Naga Muni Reddy
> 
> 
> 
> 
> On 6/30/06, Daniel Jemiolo <da...@us.ibm.com> wrote:
> >
> > Hi,
> >
> > Without seeing your project, it's tough to say, but I'm guessing that
> > perhaps "Comment" is a resource property, and the two notifications 
you're
> >
> > getting are:
> >
> > 1. the WSRP ResourcePropertyValueChangeNotification
> >
> > 2. the same notification for the topic representing the manageability
> > capability defining "Comment"
> >
> > The way WSDM defines its capability topics and the way WSRP defines
> > property change topics kind of clash in this regard, and that can 
result
> > in two notifications. Is this what's happening? Or do both 
notification
> > messages have the same topic value?
> >
> > Dan
> >
> >
> >
> >
> > Dan Jemiolo
> > IBM Corporation
> > Research Triangle Park, NC
> >
> >
> > +++ I'm an engineer. I make slides that people can't read. Sometimes I 
eat
> > donuts. +++
> >
> >
> >
> > "Muni Reddy" < nagamuni.reddy@gmail.com> wrote on 06/29/2006 06:44:55 
AM:
> >
> > > Hi,
> > >
> > > I have implemented muse filesystem example.
> > >
> > > I have subscribed for a "Comment" topic and getting notification 
also
> > from
> > > the notification producer when a change happens to "Comment" topic.
> > Again, I
> > > have subscribed for a "Comment" topic from the same consumer and 
getting
> > > notifications twice, but I want notification only once for one 
topic.
> > >
> > >
> > >
> > > Is there any way to avoid duplicate subscription from same consumer 
for
> > the
> > > same topic?
> > >
> > > What is soap request to get all topics which are subscribed for
> > > notifications?
> > >
> > >
> > >
> > > Please let me know on this
> > >
> > > Regards,
> > > Muni
> >
> >
> > ---------------------------------------------------------------------
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> >
> >
> 
> 
> -- 
> Regards,
> Naga Muni Reddy.D


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