XMPP as VOEvent transport

[Andrew Drake]

Hi John,

On Thu, 24 Sep 2015, John Swinbank wrote:
> A new thread on this, since I don’t want the discussion of VTP to 
>turn into a more general-purpose discussion of how one could or should 
>transport VOEvents. However, I was interested to hear that Svom is 
>pressing forwards with XMPP as a distribution mechanism: I’m aware of 
>that being discussed several years ago, but hadn’t seen any news in 
>some time (I’m out of the loop; sorry).

We started using XMPP at Caltech in 2005 (to distribute GCN notices as 
VOEvents) and continued using it up until this year. This has always been 
the way CRTS has distributed VOEvents. We also had VTP services running, 
but stopped running them long ago.
The MOA project has also used this transport method for the past
five or six years. I believe a MOA PhD student recently did their
Thesis on this topic.

> I’d be curious to know what the latest status of this is. Is there 
>code available? A “getting started” document describing how it works? 
>Any thoughts on scaling to large numbers of events, or large event packet 
>sizes, or bulk distribution? Does it help address issues regarding event 
>authenticity?

It is scalable and secure. However, it was obviously not designed with 
transporting VOEvents in mind, so it is as flexible as a standard
we have complete control over, like VTP. That is to say, for example,
I'm not sure that one could include a fits image as a payload.
With XMPP we always used Pubsub (XEP-0060, 
http://www.xmpp.org/extensions/xep-0060.html).
I'm sure Jean-Paul can give a more up to date account of code, etc.

cheers,
        Andrew