The issue of composability is pretty important. If we take two 
orchestrations in some language, lets call them A and B and compose 
them, using some well defined operator to do it, then does the result, 
we shall call it C, have the same behavioral types as A and B and 
something else. That is does composition preserve behavioral typing or 
not.

Why is this important? Well supposing we have a behavioral type for 
some process call X and one for a process called Y. If both X and Y 
have good liveness properties (they terminate and have no livelocks and 
deadlock) can we assert that X+Y does the same or do we have to test 
the heck out of it and hope.

In WS-CDL we can do this formally. No idea what happens to two BPEL 
processes - maybe Frank can tell us.

Cheers

Steve T

On 22 Jul 2006, at 13:58, Alexis Richardson wrote:

> Absolutely - then the question becomes: what is the compositionality 
> in both cases.
>
> Intuitively, you cannot always weave together two 'hows'.  Does 
> choreography help by delimiting each 'how' with a composable 'what'?   
> (like a type system for behaviour). 
>
> Steve, Frank, any comments?
>
>
>
>
> On 7/21/06, Phil Ayres <[EMAIL PROTECTED] > wrote:Alexis,
>>
>>  I think I need to refine this a little, as my brain did a loop trying
>>  to get so abstract!
>>
>>  >
>>  > - the choreography is the 'what'
>>  > - the orchestration is the 'how'
>>  >
>>  Maybe I'll add a few words for my simple brain...
>>
>>  - choreography is the 'what to do - decide yourself how and when to 
>> do it'
>>  - orchestration is the 'what to do - I'll tell you what and when to 
>> do it'
>>
>>  Cheers
>>  Phil
>> http://improving-nao.blogspot.com/
>>
>>
>>
>
>  
>   





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