Applications Messaging Standard

[Alasdair Allan]

Doug Tody wrote:
> Alasdair Allan wrote:
>> Doug Tody wrote:
>>>    o	Separate protocol from implementation.  That is, we should be
>>>    	able to implement a message bus/hub in different languages such
>>> 	as Java or C, or layer the protocol on top of an existing robust
>>> 	messaging infrastructure such as D-Bus, MPI, PVM, ActiveMQ,
>>> 	Ice, CORBA, etc.  It is fine to have a simple hub (or two)
>>> 	developed as part of the standard, which doesn't queue messages,
>>> 	guarantee delivery, and so forth.
>>
>> Yes, but. Surely the entirely point is that one application that  
>> supports this messaging protocol can talk (possibly via some sort  
>> of messaging hub, although we shouldn't entirely rule out peer-to- 
>> peer at this stage), if we're required to support all of these  
>> that isn't possible. What's the point of having a standard that  
>> doesn't let one application that supports it talk to another  
>> application that supports it?
>
> The point is not to "support" all the mentioned messaging  
> technologies,
> but rather to define a simple messaging protocol which is sufficiently
> independent of implementation to be possible to implement on top of
> any sufficiently general messaging infrastructure.

Well sure, but that's not a application messaging standard at that  
point.

The problem I have with this is that (as a user) if I have two  
applications that claim to implement this protocol they might not be  
able to talk to one another because either they (or an intervening  
hub if there is one) don't speak the same protocol. In practice the  
entire point is for the user to be able to fire up two 3rd party  
applications and they "just work" without any prior knowledge of each  
other, or the user having to understand the one speaks IVOA  
Applications Messaging Standard via XML-RPC and the other via Jabber,  
and finding and then running a Hub implementation that speaks both.

Al.