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Subject: ISSUE 22 - When is a RequestContext available?
- From: "Barack, Ron" <ron.barack@sap.com>
- To: "Mike Edwards" <mike_edwards@uk.ibm.com>, "OASIS Java" <sca-j@lists.oasis-open.org>
- Date: Thu, 31 Jan 2008 17:19:41 +0100
Folks,
This conversation indicates a problem with our
terminology, which we need to sort out.
An SCA Component is indeed a configured instance of an Implementation -
and a single
implementation may be used
by multiple Components.
However, in
Simon's original wording, "instance" was not being used in that sense at
all.
In Simon's wording, "instance"
referred to a runtime instance - a particular instantiation of
a particular component. In Java, this would mean a
particular Java object. Simon's wording
was correct in that sense, but it clearly caused confusion for some
folks.
Can I suggest that we use a
term such as "runtime instance" for this case?
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
Simon
Nash/UK/IBM@IBMGB
30/01/2008 21:32
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To
| sca-j@lists.oasis-open.org
|
cc
|
|
Subject
| RE: [sca-j] NEW ISSUE: When is a
RequestContext available? |
|
Sanjay,
Thanks for the pointer and for putting me straight on the
terminology. If
a component is an instance (Appendix C) then just
calling it a component
should be enough, but perhaps "component instance" is
clearer. I agree
that the term "instance of a component" that I was
using is incorrect.
Simon
Simon C. Nash, IBM
Distinguished Engineer
Member of the IBM Academy of Technology
Tel.
+44-1962-815156 Fax +44-1962-818999
"Patil, Sanjay"
<sanjay.patil@sap.com>
30/01/2008 20:21
To
Simon
Nash/UK/IBM@IBMGB,
<sca-j@lists.oasis-open.org>
cc
Subject
RE: [sca-j] NEW
ISSUE: When is a RequestContext available?
The
Appendix C of the Assembly specification is the closest I can think
of for a
glossary of the terms.
The Assembly specification in several places makes
statements on the
lines of - A component is a configured instance of an
implementation. So
I guess a component itself is an instance. So calling a
component
instance as just that (that is - 'the component instance') may be
better
than calling it 'an instance of the component' (which I
believe
incorrectly hints at the possibility of multiple instance of the
same
component). Now there is a possibility of multiple instances of the
same
component in the implementation hierarchy (via
implementation.composite)
of the SCA domain, but I guess you were not
referring to that case.
BTW, I searched the Assembly spec for all
occurrences of the term
'instance' and couldn't find the term used for
indicating 'instance of a
component' anywhere.
I get a feeling that we
are now on the path of splitting hairs :-)
-- Sanjay
>
-----Original Message-----
> From: Simon Nash [mailto:NASH@uk.ibm.com]
> Sent: Wednesday, Jan 30, 2008 11:55 AM
> To:
sca-j@lists.oasis-open.org
> Subject: RE: [sca-j] NEW ISSUE: When is a
RequestContext available?
>
> Sanjay,
> Here's my terminology
model:
> A component is a configuration of an implementation.
>
There can (in general) be many instances of an
> implementation.
Each of
> these instances is configured by the component.
>
Invocations to a component (via a service) are dispatched to
> an
instance
> of the component
> In the above, I said "...instance of
the component" rather than
> "...instance of the implementation" because
the instance has had the
> component's configuration applied to
it
>
> Is there an SCA glossary somewhere that provides approved
> definitions of
> the above terms?
>
>
Simon
>
> Simon C. Nash, IBM Distinguished Engineer
> Member
of the IBM Academy of Technology
> Tel. +44-1962-815156 Fax
+44-1962-818999
>
>
>
> "Patil, Sanjay"
<sanjay.patil@sap.com>
> 30/01/2008 18:12
>
>
To
> Simon Nash/UK/IBM@IBMGB, <sca-j@lists.oasis-open.org>
>
cc
>
> Subject
> RE: [sca-j] NEW ISSUE: When is a
RequestContext available?
>
>
>
>
>
>
>
> Just a nitpick - You have used the term 'an instance of
the
> component'
> a few times below. I would have thought that a
component itself is an
> instance (of an implementation). Perhaps
replacing 'an instance of the
> component' with 'the component instance'
would be more appropriate!
>
> Regarding the issue and the proposal
- both make sense to me.
>
> -- Sanjay
>
> >
-----Original Message-----
> > From: Simon Nash
[mailto:NASH@uk.ibm.com]
> > Sent: Wednesday, Jan 30, 2008 6:11
AM
> > To: sca-j@lists.oasis-open.org
> > Subject: [sca-j] NEW
ISSUE: When is a RequestContext available?
> >
> > RAISER:
Simon Nash
> >
> > TARGET: SCA Java Annotations and APIs
Section 7.1: ComponentContext
> >
> > DESCRIPTION:
>
>
> > The decription of ComponentContext.getRequestContext() says
> in lines
> > 647-648 that it returns null if "... there is no
current
> > request or if the
> > context is unavailable".
The situations where this applies
> > need to be
> >
defined more precisely. Here are some cases where a request
> >
context may
> > or not be available:
> > 1. Within a business
method for a service of the component.
> > 2. Within a property or
reference injection setter method for
> > an instance
> > of
the component.
> > 3. Within a constructor for an instance of the
component.
> > 4. Within an Init or Destroy method for an instance of
the
> component.
> >
> > In case 1, it seems clear
that getRequestContext() will
> always return
> > non-null.
In the other cases, it is not clear what should be
> >
returned.
> >
> > PROPOSAL:
> >
> >
getRequestContext() MUST return non-null for case 1 and
> > SHOULD
return null
> > for cases 2 through 4.
> >
> >
> > 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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