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:  

 

 

 

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 

 

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