Re: [sca-assembly] [ASSEMBLY-88] Possible duplicate functionality offeredby constrainingType and component - proposed resolution

[Mike Edwards <mike_edwards@uk.ibm.com>]

Anish,

I'll also reply to your other note on
the wider issue here, but I'd like to address the specific point you made
in 
this note.

Done 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

Anish Karmarkar <Anish.Karmarkar@oracle.com>
wrote on 25/11/2008 08:01:04:

> [image removed] 
> 
> Re: [sca-assembly] [ASSEMBLY-88] Possible duplicate functionality
> offered by constrainingType and component - proposed resolution
> 
> Anish Karmarkar 
> 
> to:
> 
> OASIS Assembly
> 
> 25/11/2008 08:02
> 
> Mike Edwards wrote:
> > 
> > This is a proposal to resolve Issue 88.
> > 
> > Summary:
> > - remove constrainingType from the specification
> > - add an attribute to <component/> called @constrained
which is a 
> > boolean value with a default of "false"
> > 
> > - a <component/> with constrained=false is just like a
component today - 
> > no changes
> > - a <component/> with constrained=true requires its implementation
to 
> > follow rules similar to those for
> >   constrainingType - namely:
> > 
> > "When the component using an implementation has @constrained=true
the 
> > implementation's component type
> > MUST contain all the services, references and properties explicitly
> > declared by the component. The component’s
> > references and services can have interfaces specified and can
have 
> > intents specified - the implementation's
> > service interfaces must be the same or a superset and its reference
> > interfaces must the the same or a subset, while
> > any intents present in the componentType must match those declared
by 
> > the component.. An implementation MAY
> > contain additional services, additional optional references 
> > (multiplicity 0..1 or 0..n) and additional optional properties
> > beyond those declared by the component, but MUST NOT contain
additional 
> > non-optional references
> > (multiplicity 1..1 or 1..n) or additional non-optional properties
(a 
> > property with mustSupply=true). (and any such references
> > will not be wired and any such properties will not be configured
by the 
> > component). Any services in the componentType
> > which are not also declared by the component cannot be wired
or promoted"
> > 
> 
> Other than the inability to promote or be a source/target in a wire
> element, what other restriction does this add? What is stated here
is 
> already true regardless of constrainted='true'. For example, the 
> implementation cannot contain non-optional properties that are not
set 
> in the component configuration. This is already true (although we
state 
> this in the opposite way: a component must set the value for a required
> property).
> 
<mje>
Well, ahem, I basically
copied out the material from the existing constrainingType section.
So your question about
what does this add is just as relevant to that existing section - and
is one of the reasons that
I think that this functionality is on the trivial side - and deserves
a minimalist approach of
the kind I propose.

This is what that existing
section actually says:

When an implementation is constrained by
a constrainingType its component type MUST 
contain all the services, references and
properties specified in the constrainingType. [ASM70004]

The constraining type’s references and
services will have interfaces specified and can have 
intents specified. An implementation MAY
contain additional services, additional optional 
references (multiplicity 0..1 or 0..n)
and additional optional properties beyond those declared 
in the constraining type, but MUST NOT
contain additional non-optional references 
(multiplicity 1..1 or 1..n) or additional
non-optional properties (a property with 
mustSupply=true). [ASM70005]

When a component is constrained by a constrainingType via the "constrainingType" attribute,
the entire componentType associated with the component and its implementation is not visible
to the containing composite. The containing composite can only see a projection of the
componentType associated with the component and implementation as scoped by the
constrainingType of the component. Additional services, references and properties provided
by the implementation which are not declared in the constrainingType associated with a
component MUST NOT be configured in any way by the containing composite. [ASM70006]
This requirement ensures that the constrainingType contract cannot be violated by the composite.

I believe that the wording for the proposal matches this existing wording about as
faithfully as possible.

</mje>
> > I believe that this allows a component to control what its
> > implementations MUST look like, which is the idea behind
> > constrainingType.
>
> I'll respond to the idea behind constrainingType in a reply to your
> other email. I don't think this captures it.
>
> -Anish
> --
>
> >
> > Detailed changes:
> >
> >
> >
> > 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
> >
> >
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