RE: Issue 5; GET vs GetLastTradePrice

> -----Original Message-----
> From: Walden Mathews [mailto:[email protected]]
> Sent: Thursday, January 02, 2003 10:37 AM
> To: Newcomer, Eric
> Cc: [email protected]
> Subject: Re: Issue 5; GET vs GetLastTradePrice
> 
> I'd like to get clearer on what that middle ground is.  Last 
> summer I got involved in a project that
> had already decided to use XML in a "document" mode as 
> opposed to a "RPC" mode, but the
> distinction was only skin deep, at least according to my 
> analysis. 

I sometimes suspect that too.  As someone said in one of these recent
threads, it would be hard to distinguish an instance of one from the other
using a protocol analyzer. The distinctions do seem more at the design
pattern level-- do you CONCEIVE of the message as a method invocation with
arguments that gets directly mapped onto a procedure call of some sort, or
do you conceive of it as a business document to be acted on by some
intermediate software that interprets the data and indirectly invokes the
back-end software.  

I'm  seeing this more and more as an engineering question of finding the
optimal degree of coupling in a particular web application than as some huge
meta-question of competing paradigms. The tighter coupling of direct mapping
of method invocations (synchronous or asynchronous) on one system to another
via SOAP messages makes sense in stable, well-managed systems where
performance considerations are paramount; the looser coupling of business
document exchange makes sense in more dynamic, hapharzardly managed systems
where ease of discovery by new "customers" is more important than
performance for existing customers.