[NEW ISSUE] Need Assembly level definition for "AllowsPassByReference"

Raiser:        
       Mike Edwards        

Target:        
       SCA Assembly Specification

Description:

<Raised at the request of the SCA
J TC following discussion at the Nov 11-13 F2F meeting>

The SCA Java Common Annotations &
APIs specification defines a annotation that can be used to

mark Java interfaces - @AllowsPassByReference.

The purpose of this annotation is to
indicate that for a remotable interface, where the client and the

service implementation happen to run
in the same operating system process, the SCA runtime is

permitted to avoid the pass-by-value
semantics of remotable interfaces and can in fact simply 

pass the request parameters and the
response through references (ie pass-by-reference

semantics).  This offers the prospect
of a significant performance boost for service invocations

between clients and service implementations
that happen to run within the same process.

The AllowsPassByReference annotation
places requirements on BOTH the client and the service

implementation about how the request
and response data is handled.  Originally, it was thought that

this annotation could be (in effect)
private to the Java specifications, but it is now realized that it is

really part of the wire contract between
client and implementation and in principle could apply

between components implemented using
different technologies (envisage different implementation

types that have runtime containers that
can all share the use of a Java VM, for example, so that in

principle components with different
implementation types can still be "local" to one another.

In these circumstances, there is a need
to define the sematics of "AllowsPassByReference" as 

part of the Assembly specification,
so that there is the potential for it to be interpreted by multiple

implementation specifications.  It
is acknowledged that it may not be applicable to all 

implementation types (eg BPEL), but
in such cases the use of normal pass-by-value semantics

should always be usable.

This issue requests that a normative
definition of "AllowsPassByReference" is added to the

Assembly specification in the section
that deals with Interfaces.

Proposal:

None at present

Yours,  Mike.

Strategist - Emerging Technologies, SCA & SDO.

Co Chair OASIS SCA Assembly TC.

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