Re: [wsbpel] Issue 92 - 92.3 - Allow BPEL specified elements andattributes to be extended - Proposal For Vote

["Yaron Y. Goland" <ygoland@bea.com>]

I think we are saying the same thing. I certainly wouldn't want to 
encourage people to invent extensions that turn while activities into 
switches.

How about if we change the word "change" to the word "expand"?

Extensions that expand the semantics of elements or attributes in
the WS-BPEL namespace MUST either be backwards compatible with the
definitions provided in this specification or MUST be declared as a
mandatory extension. See section 13.7 for information about mandatory
extensions.

	Thanks,
		Yaron

Francisco Curbera wrote:
> This is a very subtle matter, I agree; however, the principle that when you
> find a BPEL element you can safely assume the semantics that the spec
> assigns to it is a sound one. In addition to those semantics (but not
> instead of them) you'll need to consider whatever the extensibility
> elements included are also included. The key point is that an extension may
> "extend" the existing semantics, not replace them. Otherwise you should not
> be writing BPEL.
> 
> I would be ok mentioning this extension principle explicitly, but I am not
> comfortable with the proposal below because it seems to open the door for
> arbitrary 'mutations' of BPEL construct semantics.
> 
> Paco
> 
> 
> 
> 
>                                                                                                                                   
> 
> 
>                       "Yaron Y. 
> Goland"                                                                                           
> 
> 
>                       <ygoland@bea.com>        To:       wsbpeltc 
> <wsbpel@lists.oasis-open.org>                                  
> 
>                                                
> cc:                                                                               
> 
>                       02/28/2005 09:46         Subject:  [wsbpel] Issue 92 - 
> 92.3 - Allow BPEL specified elements and attributes 
> 
>                       PM                        to be extended - Proposal For 
> Vote                                               
> 
>                       Please respond 
> to                                                                                           
> 
> 
>                       
> ygoland                                                                                                     
> 
> 
>                                                                                                                                   
> 
> 
> 
> 
> 
> Section 6.3 of the specification current states that extensions must not
> change the semantics of attributes and elements in BPEL. This rather
> defeats the point of allowing extensions, especially of the mandatory
> variety, whose purpose in life is often to change the semantics of
> things in BPEL. In practice the current restriction isn't enforceable
> since there really is nothing to stop someone from introducing an
> extension that changes existing BPEL semantics. But as a general rule I
> think it's good to avoid unenforceable rules and instead provide
> actionable guidance. With that in mind I propose:
> 
> Section 6.3
> 
> From: Extensions MUST NOT change the semantics of any element or
> attribute from the WS-BPEL namespace.
> 
> To: Extensions that change the semantics of elements or attributes in
> the WS-BPEL namespace MUST either be backwards compatible with the
> definitions provided in this specification or MUST be declared as a
> mandatory extension. See section 13.7 for information about mandatory
> extensions.
> 
>         Thanks,
> 
>                  Yaron
> 
> 
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