Re: [sca-assembly] NEW ISSUE: Need definition of compatible for propertytypes

[Anish Karmarkar <Anish.Karmarkar@oracle.com>]

David Booz wrote:
> I do not want to lose the top down use cases.
> 
> Strict type equivalence is the easiest and safest solution.
> 
> The question I'm struggling with conceptually is the degree of coupling 
> between a component def'n and a component implementation. We've gone to 
> great lengths to enable a clean component vs. implementation separation, 
> presumably with the goal of enabling top down development which in turn 
> enables replace-ability, substitute-ability, etc. As an analogy, we 
> reduced coupling between components by enabling subset and superset 
> interface relationships, and a similar argument could be made for the 
> component v. implementation relationship. It will serve us well to 
> remember that this component model is intended primarily for 
> implementing coarse grained services which inherently benefit from loose 
> coupling of all kinds. I'll note that strict type equivalence increases 
> the degree of coupling. Just throwing out some thoughts for discussion.....
> 

This is a good discussion.
Does your opinion change by the fact that properties are always typed 
using XML Schema (at least at the 
composite/component/ComponentType/ConstrainingType level)? I.e., XML 
schema is the canonical type system that provides the necessary looser 
coupling?

-Anish
--

> Dave Booz
> STSM, BPM and SCA Architecture
> Co-Chair OASIS SCA-Policy TC and SCA-J TC
> "Distributed objects first, then world hunger"
> Poughkeepsie, NY (845)-435-6093 or 8-295-6093
> e-mail:booz@us.ibm.com
> 
> Inactive hide details for Mike Edwards ---04/07/2009 04:23:15 
> AM---Folks, Comment inline...Mike Edwards ---04/07/2009 04:23:15 
> AM---Folks, Comment inline...
> 
> 
> From:	
> Mike Edwards <mike_edwards@uk.ibm.com>
> 
> To:	
> sca-assembly@lists.oasis-open.org
> 
> Date:	
> 04/07/2009 04:23 AM
> 
> Subject:	
> Re: [sca-assembly] NEW ISSUE: Need definition of compatible for property 
> types
> 
> ------------------------------------------------------------------------
> 
> 
> 
> 
> Folks,
> 
> Comment inline...
> 
> Yours, Mike.
> 
> Strategist - Emerging Technologies, SCA & SDO.
> Co Chair OASIS SCA Assembly TC.
> IBM Hursley Park, Mail Point 146, Winchester, SO21 2JN, Great Britain.
> Phone & FAX: +44-1962-818014 Mobile: +44-7802-467431
> Email: mike_edwards@uk.ibm.com
> 
> From: 	Anish Karmarkar <Anish.Karmarkar@oracle.com>
> To: 	sca-assembly@lists.oasis-open.org
> Date: 	07/04/2009 06:28
> Subject: 	Re: [sca-assembly] NEW ISSUE: Need definition of compatible 
> for property types
> 
> 
> ------------------------------------------------------------------------
> 
> 
> 
> +1 to raising this issue.
> 
> The correct line number for [1] is 1045.
> 
> Do we really need this feature? Why allow @type or @element on component
> properties?
> *
> <mje>* *
> I am somewhat surprised by Anish making this comment!* *
> One of the usecases of specifying the type of a property on a component 
> is to ensure* *
> that whichever implementation is used for that component conforms to the 
> needs of* *
> the component, when building using a top-down approach. If the type 
> cannot be* *
> specified, then the composite is forced to accept whatever type the 
> implementation* *
> decides to provide and no error would get raised in the case of a 
> mismatch.* *
> </mje>*
> 
> 
> The implementation declares the type of the property, it is
> tricky to allow subtypes and hope that it would get mapped correctly and
> would be allowed by the implementation/implementation language
> (especially when we want to allow multiple C&I types). Do we lose
> anything by removing this?
> *
> <mje>* *
> +1 to disallowing subtypes...* *
> </mje>*
> 
> -Anish
> --
> 
> David Booz wrote:
>  > TARGET: Assembly spec CD03 [1]
>  >
>  > DESCRIPTION:
>  > Line 1036 of CD03 [1] says that if a component specifies a property
>  > type, then that type must be compatible with the type of the same
>  > property in the componentType. What does compatible mean? It might be as
>  > simple as the same type of sub-type (i.e though some form of
>  > inheritance), but it needs to be specified.
>  >
>  > PROPOSAL:
>  > None
>  >
>  > [1]
>  > 
> _http://www.oasis-open.org/committees/download.php/31740/sca-assembly-1.1-spec-cd03.pdf_
>  >
>  >
>  >
>  > Dave Booz
>  > STSM, BPM and SCA Architecture
>  > Co-Chair OASIS SCA-Policy TC and SCA-J TC
>  > "Distributed objects first, then world hunger"
>  > Poughkeepsie, NY (845)-435-6093 or 8-295-6093
>  > e-mail:booz@us.ibm.com
>  >
> 
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