[TAP] sync vs async

[Mark Taylor]

On Mon, 2 Mar 2009, Patrick Dowler wrote:

> In cases where it works, sync is easier for the client, but I think we  agree 
> that it cannot be made robust in the general case. Async handles the general 
> case; this is why async is required. For the small extra work and utility, it 
> was deemed it simpler for everyone if sync was also required (plus the oddity 
> about VOSI requests noted above).

I'll note SAMP's experience for information here:

Considering experience from the PLASTIC model in which the only way to 
receive a message response was synchronous, we decided for (PLASTIC's
successor) SAMP that the server (hub) had to provide asynchronous 
communications because of the greater robustness and scalability 
that approach gives.
However, considering that for some use contexts synchronous use 
would be adequate and a great deal easier for clients, we added 
a synchronous facade, at not much implementation cost, for those 
who wish to use it.

I'm not necessarily saying that the cases are similar enough to
warrant drawing conclusions from one to the the other, but I 
think this line of thinking made sense for SAMP, and I think 
it makes sense for TAP.

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/