RE: [sca-assembly] Issue 17 proposal

["Michael Rowley" <mrowley@bea.com>]

I assume that the QName resolution issue comes up when the including
composite and the included composite are in different contributions.  I
suspect that the semantics that users would prefer would be for QNames
to be resolved in the context of the contribution of the _included_
composite.  

This way the contribution of the included composite could contain that
composite and all of its related artifacts.  The contribution of the
including composite would only need to import the namespace of the
composite that it includes.

[Sentences including "included" and "including" get very convoluted
:-(.]

Michael

-----Original Message-----
From: Anish Karmarkar [mailto:Anish.Karmarkar@oracle.com] 
Sent: Tuesday, February 05, 2008 3:52 PM
To: Scott Vorthmann
Cc: OASIS Assembly
Subject: Re: [sca-assembly] Issue 17 proposal

I missed the other half. Thanks for pointing that out. For some reason I

thought issue 24 [1] dealt with that. AFAICT, 17 and 24 are the same.

SCA does not define a component model a la WSDL 2.0. All we have is 
Infoset. Not sure what you were thinking wrt to a formal proposal. I 
would be interested in seeing it. Wrt Qname resolution, my inclination 
is to say that all the resolutions happen in the context of the 
including composite. When u do an include there is no encapsulation, 
everything belongs to the including composite. The including composite 
defines the scope (property names, target names etc -- target names in 
either composite can freely mix service names from both composites) and 
the resolution mechanism. IOW, given a composite that contains one or 
more sca:include elements, there exists an equivalent composite without 
any sca:include elements whose characteristics are exactly the same. The

rules in my proposal are for mapping a composite with include elements 
to one without.

Given that we don't have a formal component model a la WSDL 2.0, maybe 
equivalence rules is how we should state it in the spec.

Comments?

-Anish
--

[1] http://www.osoa.org/jira/browse/ASSEMBLY-24

Scott Vorthmann wrote:
> Anish,
> 
> I think the proposal as you've laid it out is reasonably sound, but I 
> think it addresses only half of issue 17 as captured.  I don't see 
> anything in your proposal to define when QNames, etc. are resolved.
(I 
> regard this as the thornier half of 17.)  Further, since your proposal

> defines include at something like an XML Infoset level, it almost 
> exacerbates the QName problem... how would you require that "QNames
have 
> already been resolved" if include is happening at this low level?
> 
> My suggestion is that we need to define include at the level of
naming, 
> not at the level of XML.  In essence, we'd be saying that wire
elements 
> (including those implied by "target=") in either composite can freely 
> mix component/service names from either composite.  Something similar 
> would be required for property names.  This achieves the goal of 
> include, and makes the XML issues moot.  I'd be happy to make a more 
> formal proposal along these lines, but perhaps we could have a little 
> discussion first.
> 
> Scott
> 
> On Feb 5, 2008, at 12:31 AM, Anish Karmarkar wrote:
> 
>> I took an action to provide a proposal to resolve issue 17 [1]. Here 
>> it is.
>>
>> The proposal in this email was discussed as an errata for SCA 1.0 in
>> OSOA, but it was decided that it resulted in too much change to be
>> considered an errata and therefore not implemented. The proposal
below
>> was worked on by several folks in OSOA including Henning Bloom, Dave
>> Booz, Scott Vorthmann (hope I didn't miss anyone). But it should not
be
>> construed that they agree with all the aspects of this proposal.
>>
>> I. Current problems with the spec:
>>
>> 1) inclusion is not defined recursively. I.e., it does not say what
is
>> supposed to happen if an included composite contains an include
(which
>> the spec says is allowed).
>> 2) It is defined as a textual include, which it most certainly isn't.
>> 3) Attributes (namespace decl, 'local' etc) on the included composite
>> are completely ignored.
>> 4) The current wording also says (through an example) that the
composite
>> resulting from the inclusion must be complete. This isn't true if
there
>> is recursive inclusion. Only a deployable composite needs to be
complete.
>>
>> II. Proposal:
>>
>> 1) Attributes 'targetNamespace', 'name', 'constrainingType' and
'local'
>> on the included composite are thrown away. For constraints on 'local'
>> see #4 below.
>> Rationale: composite inclusion results in losing the
>> encapsulation/scoping. Element children of the included composite are
>> now part of the including composite and are scoped to the the
including
>> composite. Therefore, the attributes 'targetNamespace' and 'name' of
the
>> included composite have no relevance.
>> 2) All NS decl on the included composite are inherited by the each of
>> the child elements of the included composite if they are inscope (not
>> overridden).
>> Rationale: Element and attributes are (and can be) of type xs:QName.
>> This requires inscope NS decl/binding.
>> 3) Attribute 'autowire', if specified on the included composite, is
>> included on all containing component elements unless the containing
>> component already specifies that attribute.
>> Rationale: By sticking autowire on the composite it is inherited by
the
>> contained composites. It is a nice short cut. The intention of the
>> creator of the composite is to autowire the components, therefore
this
>> should be retained on inclusion.
>> 4) If the included composite has the value 'true' for the attribute
>> 'local' then the including composite must have the same value for the
>> 'local' attribute. If not, that is considered an error.
>> Rationale: This is based on the assertion that local="true" is a
>> constraint, and that constraints must not be arbitrarily removed.
>> Components which are not required to be collocated, can be
collocated,
>> where as the converse is not necessarily true.
>> 5) Attributes 'requires' and 'policySet', if present on the included
>> composite, are "merged" with corresponding attribute on the
containing
>> component, service and reference elements. "merge" here means a set 
>> union.
>> Rationale: since they are constraints that must not be overridden,
they
>> are merged.
>> 6) Extension attribute ,if present on the included composite, must
>> follow the rules defined for that extension. Authors of attribute
>> extensions on the composite element must define rules for inclusion.
>> Rationale: depending on the extension, there may be various ways to
deal
>> with attribute extensibility. It does not seem right to define a one
>> size fits all. Perhaps a default behavior may be appropriate.
>>
>> III. Note
>>
>> This proposal does *not* address the issue of xml:base occurring on
the
>> <composite> element of the included composite. I think it is
important,
>> but given the fact that artifacts in SCA (composites, bindings etc)
are
>> identified by QNames, this is less of a problem.
>>
>> IV. Wording changes:
>>
>> Word document with change bars for relevant parts of section 6.6
(WD02)
>> attached. Note that I have not modified/added examples to demonstrate
>> the changes. We might want to add additional examples to illustrate
the
>> changes.
>>
>> Comments?
>>
>> -Anish
>> -- 
>>
>> [1] http://www.osoa.org/jira/browse/ASSEMBLY-17
>> <assembly-issue-17-proposal.doc><ATT8019818.txt>
> 
> 
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