Re: [sca-assembly] [Issue 95] "wiredByImpl" is an invalid attributefor a Composite Reference

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

Mike,

Apologies for misunderstanding your proposal on the call today. 
Unfortunately, line numbers on a 2007 .doc file don't mean a whole lot 
to me.

IIUIC, what you are proposing is to get rid of the attribute wiredByImpl 
on a composite reference, while retaining the ability to promote a 
component reference that has wiredByImpl='true'.

If this is correct, I think this is problematic. Without the 
wiredByImpl='true', the componentType associated with the composite will 
not contain information about the fact that the reference cannot be 
wired. Higher-level composites won't know the cardinality associated 
with the reference (which is 0..0) and therefore will be free to wire 
it. Unless, the spec says that wiredByImpl='true' automatically becomes 
part of the CT associated with the composite by the virtue of the fact 
that the underlying component reference has wiredByImpl='true'. We allow 
narrowing of constraints when promoting. A 0..0 cannot be narrowed any 
further, so wireByImpl='true' is indeed ripe for defaulting in such cases.

But as it stands I don't think there is any inconsistency in the spec 
(other than the fact that it does not say that you cannot change the 
value of wiredByImpl when promoting).

Currently, wiredByImpl says:
"wiredByImpl : boolean (0..1) - a boolean value, "false" by default, 
which indicates that the implementation wires this reference 
dynamically.  If set to "true" it indicates that the target of the 
reference is set at runtime by the implementation code (eg by the code 
obtaining an endpoint reference by some means and setting this as the 
target of the reference through the use of programming interfaces 
defined by the relevant Client and Implementation specification).  If 
"true" is set, then the reference should not be wired statically within 
a composite, but left unwired."

Which seems right to me. There is implementation code associated with a 
composite reference: it is the code associated with the corresponding 
promoted component reference (however levels deep).

OTOH, the existence of wiredByImpl when we already have the multiplicity 
attribute (on both component reference as well as composite reference) 
always seemed a little strange to me. wiredByImpl is really saying 
multiplicity of 0..0, why not then just say exactly that. I know this 
was discussed during the OSOA days, but I don't recall why addition of a 
new attribute was chosen over 0..0.

I'll be bold and make a proposal to remove wiredByImpl altogether and 
use 0..0 on the multiplicity attribute instead (with the usual narrowing 
rules for promotion).

I'm hoping that, if there was a good argument for choosing wiredByImpl 
over 0..0 in OSOA, someone will bring it up here.

Comments?

-Anish
--

Mike Edwards wrote:
> 
> Raiser:                Mike Edwards
> 
> Target:                Assembly spec: sca-assembly-1.1-spec-cd01-rev3.doc
> 
> Description:
> 
> The current spec has the attribute @wiredByImpl as an attribute of a 
> Composite reference element.
> This cannot be valid, since there @wiredByImpl=true implies that the 
> composite itself will act to wire
> the reference at runtime.  However, this can never happen since there is 
> no active code in the
> composite which could do this.
> 
> It is valid for a reference on a component within the composite to have 
> @wiredByImpl on one of its
> references, but this applies to wiring of the component reference - and 
> NOT to wiring of any
> promotion of that reference.
> 
> Proposal:
> 
> Remove @wiredByImpl from <reference/> within a <composite/>.
> 
> Specifically:
> 
> Line 1337 - remove  wiredByImpl="xs:boolean"?
> 
> Lines 1399 - 1405 - remove
> 
> Lines 3825 - 3826 - remove
> 
> Lines 3971 - 4006 - replace with:
> 
>     <complexType name="ComponentReference">
> 
>             <complexContent>
> 
>                             <sequence>
> 
>                                     <element ref="sca:interface" 
> minOccurs="0" maxOccurs="1" />
> 
>                                     <element name="operation" 
> type="sca:Operation" minOccurs="0"
> 
>                                             maxOccurs="unbounded" />
> 
>                                     <element ref="sca:binding" />
> 
>                                     <element ref="sca:callback" 
> minOccurs="0" maxOccurs="1" />
> 
>                                     <any namespace="##other" 
> processContents="lax" minOccurs="0"
> 
>                                             maxOccurs="unbounded" />
> 
>                             </sequence>
> 
>                             <attribute name="name" type="NCName" 
> use="required" />
> 
>                   <attribute name="autowire" type="boolean" 
> use="optional" />
> 
>                             <attribute name="wiredByImpl" type="boolean" 
> use="optional"
> 
>                         default="false"/>
> 
>                             <attribute name="target" 
> type="sca:listOfAnyURIs" use="optional"/>
> 
>                             <attribute name="multiplicity" 
> type="sca:Multiplicity"
> 
>                                     use="optional" default="1..1" />
> 
>                             <attribute name="requires" 
> type="sca:listOfQNames" use="optional"/>
> 
>                         <attribute name="policySets" 
> type="sca:listOfQNames"
> 
>                                 use="optional"/>
> 
>                             <anyAttribute namespace="##other" 
> processContents="lax" />
> 
>             </complexContent>
> 
>     </complexType>
> 
> 
> 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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