Re: [sca-j] ISSUE 4 - Proposed spec text for dependency reinjection

Folks,

I've taken Simon's text and cast it
into a Word document so that edits and comments can be more

easily tracked.  I've then made
a few edits and comments, which I hope improve the text and deal

with one significant problem relating
to the handling or reinjected arrays/collections:

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:  

Simon Nash/UK/IBM@IBMGB

31/01/2008 15:24

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Subject

[sca-j] ISSUE 4 - Proposed spec text
 for dependency reinjection

Here's my attempt to merge the contents of the v5
spreadsheet with 

Michael's original text.  There's bit more work still to do to capture
the 

decisions we made regarding callback injection and reinjection.

- - - - begin spec words - - - -

References MAY be reinjected after the initial creation of a component
if 

the reference target changes due to a change in wiring that has occurred

since the component was initialized.  In order for reinjection to
occur, 

the following MUST be true:

1) The component MUST NOT be STATELESS or REQUEST scoped.

2) The reference MUST use either field-based injection or setter 

injection. References that are injected through constructor injection MUST

NOT be changed.  Setter injection allows for code in the setter method
to 

perform processing in reaction to a change.

3) If the reference has a conversational interface, then reinjection MUST

NOT occur while the conversation is active.

 

If a reference target changes and the reference is not reinjected, it MUST

continue to work as if the reference target was not changed.

 

If an operation is called on a reference where the target of that 

reference has been undeployed or has become unavailable, the SCA runtime

SHOULD throw InvalidServiceException.  It the target of the reference
is 

changed, the reference MAY continue to work, depending on the runtime and

the type of change that was made.  If it doesn't work, the exception

thrown will depend on the runtime and the cause of the failure.

A ServiceReference that has been obtained from a reference by 

ComponentContext.cast() corresponds to the reference that is passed as
a 

parameter to cast().  If the reference is subsequently reinjected,
the 

ServiceReference MUST continue to work as if the reference target was not

changed.  If the target of a ServiceReference has been undeployed
or has 

become unavailable, the SCA runtime SHOULD throw InvalidServiceException.

If the target of a ServiceReference is changed, the reference MAY continue

to work, depending on the runtime and the type of change that was made.
If 

it doesn't work, the exception thrown will depend on the runtime and the

cause of the failure.

 

A reference or ServiceReference accessed through the component context
by 

calling getService() or getServiceReference() MUST correspond to the 

current configuration of the domain.  If the target has been undeployed
or 

has become unavailable, the result SHOULD be a reference to the undeployed

or unavailable service, and attempts to call business methods SHOULD throw

InvalidServiceException.  If the target has changed, the result SHOULD
be 

a reference to the changed service.

 

The rules for reference reinjection also apply to references with a 

multiplicity of 0..N or 1..N.  This means that in the cases listed
above 

where reference reinjection is not allowed, the array or Collection for

the reference MUST NOT change their contents.  In cases where the
contents 

of a reference collection MAY change, then for references that use setter

injection, the setter method MUST be called for any change to the 

contents.  The injected collection MAY be the same collection object
as is 

currently used by the component, but with some change to its contents.

- - - - end spec words - - - -

    Simon

Simon C. Nash, IBM Distinguished Engineer

Member of the IBM Academy of Technology

Tel. +44-1962-815156  Fax +44-1962-818999

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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Issue_4_Resolution_01.doc