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Subject: Re: [sca-assembly] ISSUE 6 - alternate proposal - Version 2 final tweaks


There's still a typo at the end of new section 3.0.1

"on each wire created implied by the @target attribute."

It should read

"on each wire created by the @target attribute."



Dave Booz
STSM, SCA and WebSphere Architecture
Co-Chair OASIS SCA-Policy TC
"Distributed objects first, then world hunger"
Poughkeepsie, NY (845)-435-6093  or  8-295-6093
e-mail:booz@us.ibm.com
http://washome.austin.ibm.com/xwiki/bin/view/SCA2Team/WebHome


                                                                           
             Mike Edwards                                                  
             <mike_edwards@uk.                                             
             ibm.com>                                                   To 
                                       "OASIS Assembly"                    
             11/26/2007 04:34          <sca-assembly@lists.oasis-open.org> 
             AM                                                         cc 
                                                                           
                                                                   Subject 
                                       Re: [sca-assembly] ISSUE 6 -        
                                       alternate proposal - Version 2      
                                       final tweaks                        
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           





Folks,


A couple of minor tweaks to address comments by Michael Rowley and Simon
Nash.  Simon raises an issue about using roles (Assembler, Deployer) as
conformance
targets.  I suggest that we review this point under ASSEMBLY-11 - Define
Conformance
Targets.


Introduce a new subsection into the specification, to follow line 330:

3.0.1 Specifying the Target Service(s) for a Reference

A reference may define one or more target services which satisfy the
reference.  The target service(s) may be defined in the following ways:


1) Through a value specified in the @target attribute of the reference:
element

2) Through a target URI specified in the @uri attribute of a binding
element which is a child of the reference element

3) Through the setting of one or more values for binding-specific
attributes and/or child elements of a binding element which is a child
of the reference element

4) Through the specification of @autowire="true" for the reference (or
through inheritance of that value from the component or composite
containing the reference)

5) Through the promotion of a component reference by a composite reference
of the composite containing the component (the target service is then
identified by the configuration of the composite reference).

Some combinations of these different methods are not allowed:

If @autowire="true" applies to the reference, the autowire procedure is
only used to find a target service if no target is identified by any of the

other ways listed above.  It is not an error if autowire="true" applies to
a reference and a target is also defined through some other means.

If a reference has a value specified for one or more target services in its

@target attribute, the child binding elements of that reference MUST NOT
identify target services using the @uri attribute or using binding specific

attributes or elements.

If a binding element has a value specified for a target service using its
@uri attribute, the binding element MUST NOT identify target services using

binding specific attributes or elements.

It is possible that a particular binding type MAY require that the address
of a target service uses more than a simple URI.  In such cases, the @uri

attribute MUST NOT be used to identify the target service - instead,
binding
specific attributes and/or child elements must be used.

Where the reference has a value specified in its @target attribute, all the

binding types identified by the child binding elements are available for
use
on each wire created implied by the @target attribute..


3.0.1.1 Multiplicity and the Valid Number of Target Services for a
Reference

For references with multiplicity 0..1 or 0..n, it is valid for the
reference to have no target service defined.

For references with multiplicity 0..1 or 1..1, it is an error for the
reference to have more than 1 target service defined.

For references with multiplicity 1..1 or 1..n, it is an error for the
reference to have no target service defined.

For references with multiplicity 0..n or 1..n, it is valid for the
reference to have 1 or more target services defined.

The assembler or the deployer of a composite MUST ensure that references
are properly configured according to these rules.

For the error cases identified above, an error MUST be generated by the SCA

runtime before the reference is invoked by the component implementation.

Some errors can be detected at deployment time.  For example, where a
composite is used as a component implementation, wires and target services
cannot be added to the composite after deployment.  As a result, for
components which are part of the composite, both missing
wires and wires with a non-existent target can be detected at deployment
time through a scan of the contents of the composite.  In these cases, an
error SHOULD be generated by the SCA runtime at deployment time.

Other errors can only be checked at runtime.  Examples include cases of
components deployed to the SCA Domain.  At the Domain level, the target of
a wire, or even the wire itself, may form part of a separate deployed
contribution and as a result these may be deployed after the original
component is deployed.  In these cases, the SCA runtime MUST generate an
error before the reference is invoked by the component implementation.


For the cases where it is valid for the reference to have no target service

specified, the component implementation language specification defines the

programming model for interacting with an untargetted reference.

Where a component reference is promoted by a composite reference, the
promotion is treated from a multiplicity perspective as providing 0 or more

target services for the component reference, depending upon the further
configuration of the composite reference.  These target services are in
addition to any target services identified on the component reference
itself,
subject to the rules relating to multiplicity described in this section.


----------------------------------------------------------------------

Replace lines 274 - 280 with the following:

"A reference may identify one or more target services which satisfy the.
reference.  This can be done in a number of ways, which are fully described

in section "3.0.1 Specifying the Target Service(s) for a Reference".

Replace lines 1424 - 1430 with the following:

"A reference may identify one or more target services which satisfy the
reference.  This can be done in a number of ways, which are fully described

in section "3.0.1 Specifying the Target Service(s) for a Reference".

Replace lines 2372 - 2383 with the following:

uri  - has the following semantic

The uri attribute can be omitted.

For the binding of a reference, the uri attribute defines the target URI
of the reference.  This can be either the componentName/serviceName for
a wire to an endpoint within the SCA domain, or the accessible address
of some service endpoint either inside or outside the SCA domain (where
the addressing scheme is defined by the type of the binding).

The circumstances under which the uri attribute can be used are
defined in section 3.0.1 Specifying the Target Service(s) for a
Reference


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








Unless stated otherwise above:
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Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU













Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number
741598.
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU













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