Applications Messaging Standard

[Tony Linde]

Yes, I thought we were making different assumptions here.

> about only how to communicate with an existing (running) hub, 

I'd tend to agree with Mark: the messaging standard is about the above. The
standard should include what a hub does to make known that it is running and
how plastic apps find out how to communicate with the hub. And, for now, the
only solution we all agree might work is that the hub writes a file into
some common area (~/.ivoamsg) and that file contains the mode by which
communications with the hub take place.

BUT we're still stuck with the problem of embedded hubs and what happens if
they go away. Personally, I think the simplest solution is to mandate that
hubs can only be stand-alone.

THEN we get onto the issue (if we want to address it - could leave it to the
user to sort out) of how a running plastic app can find and invoke the hub.

T.

> -----Original Message-----
> From: owner-apps at eso.org [mailto:owner-apps at eso.org] On 
> Behalf Of Mark Taylor
> Sent: 16 February 2007 11:24
> To: apps at ivoa.net
> Subject: Re: Applications Messaging Standard
> 
> On Fri, 16 Feb 2007, John Taylor wrote:
> 
> > On 16 Feb 2007, at 09:25, Tony Linde wrote:
> >> Can I ask if we all are talking about the same thing here? 
> What are we
> >> trying to discover at runtime with this file-based mechanism?
> >> 
> >> Where the hub is and how to invoke it?
> >> How to communicate with the hub?
> >> What other plastic apps are running and what they can do?
> >
> > Hi Tony,
> > I believe we are just trying to discover where the hub is 
> and how to invoke 
> > it.
> 
> Not sure if I'm being pedantic here, but I'd say we're talking here
> about only how to communicate with an existing (running) hub, 
> not how to invoke it - invoke to me means start up a process which 
> runs a hub, and that's not what the ~/.ivoamsg file would do.
> Invoking a hub is, to me, an implementation thing.
> 
> >     For instance, if a hub supported xmlrpc as a wire 
> protocol then it would 
> > need to get the URL of its xmlrpc server to the clients, 
> perhaps by writing 
> > this URL into a file in a well-known location.  Thereafter, 
> all the discovery 
> > of other applications and their capabilities takes place by 
> talking to the 
> > hub on this URL.
> 
> .. but I agree with this explanation.
> 
> Mark
> 
> -- 
> Mark Taylor   Astronomical Programmer   Physics, Bristol 
> University, UK
> m.b.taylor at bris.ac.uk +44-117-928-8776 
> http://www.star.bris.ac.uk/~mbt/
> 

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