Web service standards question - mandatory vs optional

[Alasdair Allan]

Martin Hill wrote:
> For example, the optional 'describing itself in VO terms' (ie returning
> VOResource) is surely necessary to make the VO work, yet I don't see how
> heartbeat is mandatory to making the VO work!  For mission critical
> systems yes, but the VO is hardly mission critical.  Where are the
> heartbeats going to go?  What is monitoring them?  What alarms will be
> raised and where when a heartbeat fails?

Depends what you're using the VO for, remember some of us are talking to
real time systems. If I want to data mine your service for useful
information I want to know how robust/reliable it is, I can get this from
the HeartBeat and Will's proposed statistics gathering services (to find
the history). I (my agent) won't do this everytime, but if a service
becomes unreliable my software might want to try and find a more reliable
alternative. From an agent(ish) point of view all of this should happen
autonomously without user intervention. This is what I'm going to be using 
HeartBeat and associated information for...
 
> I suspect 'heartbeat' is not what is being meant, and this is really a
> 'getStatus' or 'getAvailability' in which case we ought to rename it. A
> 'heartbeat' is a pushed status message over a regular period (like
> monitoring a casualty's heartbeat), and there may be a case of having
> this in some services so we should not use the wrong term.

I reather like the name actually... :)

Al.