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

[David Booz <booz@us.ibm.com>]

The fact that we're XML schema based is helpful, but not sufficient to really reduce the coupling. I'll point you back at what we've done with WSDL interface super-setting and subsetting. WSDL portTypes have schema semantics (i.e. not language specific, abstract, extensible, etc) but we still felt it necessary to reduce coupling even further.

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

Anish Karmarkar <Anish.Karmarkar@oracle.com> wrote on 04/14/2009 02:04:51 AM:

> [image removed]
>
> Re: [sca-assembly] NEW ISSUE: Need definition of compatible for property types
>
> Anish Karmarkar
>
> to:
>
> David Booz
>
> 04/14/2009 02:05 AM
>
> Cc:
>
> sca-assembly
>
> 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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