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Subject: RE: [wsbpel] implicite links of the runtime engine (was: Implicit <sequence> macro)


+1, BPEL is an abstract virtual machine, it should have the minimum constructs necessary to express the universe of supported programs; if there is no "if-then-else" because "switch" has all the expressive power (and then some) of "if-then-else",  then there should not be a "sequenence" by the same reasoning. 

-Maciej

> -----Original Message-----
> From: Assaf Arkin [mailto:arkin@intalio.com]
> Sent: Tuesday, June 17, 2003 2:46 PM
> To: Eckenfels. Bernd
> Cc: wsbpel@lists.oasis-open.org
> Subject: Re: [wsbpel] implicite links of the runtime engine (was:
> Implicit <sequence> macro)
> 
> 
> I agree.
> 
> If the distinction was made between doings thing in order or in 
> parallel, then I understand why you need two different 
> activities. But 
> we wouldn't need links or serializable scopes. Currently the flow 
> activity covers all the cases from strictly serialized to strictly 
> concurrent and all shades in between, making the sequence activity 
> nothing more than a convinience. You need to support the 
> complexity of 
> synchronized activities to support the flow activity, that's not easy 
> but if you have the capability you might as well use it all the way.
> 
> So the sequence activity does need to justify its existence, and it 
> needs a generic rational so we can decide what to do with 
> other existing 
> or proposed "simplifications" to the language.
> 
> arkin
> 
> Eckenfels. Bernd wrote:
> 
> >Hello Satish,
> >
> >  
> >
> >>I honestly don't think <sequence> needs to justify its existence.
> >>Concurrency with synchronization can emulate sequentiality 
> but that is
> >>clearly a convoluted and expensive way to do the simplest kind of
> >>orchestration.
> >>    
> >>
> >
> >This may be true from the standpoint of writing bpel by 
> hand, but for sure it is a non issue for implementation. 
> Depending on your internal runtime data model, a sequence is 
> only an additional complication, provided the fact, that you 
> need to offer a implementation for flow, anyway. And since a 
> sequence does not forbid to have links in and out, it also 
> means your engine has to support the notion of 
> synchronisation, anyway.
> >
> >So we should make clear in the spec, that it is only a 
> shortcut, for skipping those links inside a sequential flow, 
> but all other properties will apply, anyway.
> >
> >Greetings
> >Bernd
> >
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> >
> 
> 
> 
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