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Subject: RE: [sca-j] ISSUE 21 - Clarify Request Scope lifetime
- From: Mike Edwards <mike_edwards@uk.ibm.com>
- To: "OASIS Java" <sca-j@lists.oasis-open.org>
- Date: Wed, 19 Mar 2008 13:05:55 +0000
Folks,
I think the concept here is less a "conversation"
or a "session" but rather a "shared context", with
rules about
the physical scope of the sharing and
its time duration. It is the sharing aspect that makes it different.
Conversations today only affect a single
interaction (and in principle really only apply to the service
provider). The new concept here
is sharing across a range of components.
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
19/03/2008 10:59
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Subject
| RE: [sca-j] ISSUE 21 - Clarify Request
Scope lifetime |
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Dave,
I always thought that SCA's conversation was the equivalent of a session.
If we are going to invent a session concept as well, we need to think
very carefully about the relationship between these.
Simon
Simon C. Nash, IBM Distinguished Engineer
Member of the IBM Academy of Technology
Tel. +44-1962-815156 Fax +44-1962-818999
David Booz <booz@us.ibm.com>
18/03/2008 14:00
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| RE: [sca-j] ISSUE 21 - Clarify Request
Scope lifetime |
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+1 to dropping request scope.
...with a word of caution. We have not yet created constraints in
the
assembly model which force developers/architects to place boundaries on
composites (with the exception of composites that are used as
implementations). Any semantic which can only be obtained through
collocation of components in a composite will turn out to be overly
constraining as it will force developers and assemblers to aggregate
components which otherwise might not need to be aggregated.
I would hope that we could explore these new ideas from the perspective
of
a session concept, and I mean session in a generic form. I would
also hope
that we could avoid the temptation to tie this semantic too tightly with
composites. I'm thinking about components which cooperate to provide
coarse grained business services with some shared runtime context called
a
session. We will have to debate how much of the session is visible
to the
business logic. We will have to debate system managed vs. application
managed session correlation. Other technologies have been here. WS
RM has
this idea baked into it. CORBA has activity session.
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
sca-j@lists.oasis-open.org
03/17/2008 08:59
cc
AM
Subject
RE: [sca-j]
ISSUE 21 - Clarify
Request Scope
lifetime
Michael,
Yes, I'm OK with the idea of dropping request scope.
The conversation propagation idea is interesting - possibly it is part
of a
wider consideration of sets
of components within a composite acting in a coordinated or unified way,
that may apply to a number
of things beyond conversations.
Perhaps this is going to turn into some mechanics that apply to composites
as a whole. Intents at the
composite level that are meaningful to the composite itself -and which
has
specific implications on the
components within the composite. An example might be the idea that
all
conversations between
components within the composite are shared.
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
"Michael Rowley"
<mrowley@bea.com>
To
13/03/2008 18:31
Mike Edwards/UK/IBM@IBMGB,
<sca-j@lists.oasis-open.org>
cc
Subject
RE: [sca-j] ISSUE 21 - Clarify
Request Scope lifetime
Mike,
You are absolutely right. The resolution was only w.r.t. java components.
Given that, I will agree with Dave B that in this case the
conversation-propagation idea is a little bit different from request scope
semantics. Nonetheless, I think it would be close enough to warrant
getting rid of the request scope.
Michael
From: Mike Edwards [mailto:mike_edwards@uk.ibm.com]
Sent: Thursday, March 13, 2008 10:44 AM
To: sca-j@lists.oasis-open.org
Subject: RE: [sca-j] ISSUE 21 - Clarify Request Scope lifetime
Folks,
Unless I've got the wrong end of the stick here, I think that the SCA Java
TC is acting ultra vires.
Dave posed a question about a composite exposing two services, one
conversational one non,
conversational.
Michael responded saying that the Java F2F decided that a component cannot
offer both a
conversational and non-conversational service.
Now, I can agree that the SCA Java TC decided that a Java implementation
could not offer both a
conversational and a non-conversational service. However, to extend
this
idea to apply to all
components, using whatever implementation type, I think must be a decision
of the SCA Assembly
TC.
If the Java TC really wants to limit ALL components to only expose either
conversational or non conversational
services, but never both, then I think the TC must get an appropriate issue
raised in the Assembly TC. I suspect
that the other C&I TCs would need to be consulted also.
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
"Michael Rowley"
<mrowley@bea.com>
To
13/03/2008 14:30
"David Booz" <booz@us.ibm.com>,
<sca-j@lists.oasis-open.org>
cc
Subject
RE:
[sca-j] ISSUE 21 - Clarify
Request
Scope lifetime
At the F2F we resolved that a component is not allowed to offer both a
conversational and non-conversational service.
Michael
-----Original Message-----
From: David Booz [mailto:booz@us.ibm.com]
Sent: Wednesday, March 12, 2008 10:35 PM
To: sca-j@lists.oasis-open.org
Subject: RE: [sca-j] ISSUE 21 - Clarify Request Scope lifetime
What if the composite exposes two services, one conversational and one
non-conversational? Would the conversational service act as in 3
and
the
non-conversational service as in 4? That's not clear from your text.
While it seems desireable to be able to answer yes to the second
question,
I'll observe that it means that components in that composite will run
differently (different context) depending on the inbound service. This
is
another divergence from request scope.
...and while I have your attention...regrets for the call tomorrow.
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
"Michael Rowley"
<mrowley@bea.com>
To
03/12/2008 10:14
"Barack, Ron"
<ron.barack@sap.com>,
PM
"OASIS Java"
<sca-j@lists.oasis-open.org>
cc
Subject
RE: [sca-j] ISSUE
21 - Clarify
Request Scope lifetime
During the F2F it was observed that the request scope is similar to the
conversation scope, except that it automatically propagates around the
local components of a composite. Perhaps it would be simpler to take
advantage of this similarity and also expand on conversation scopes. If
an
entire conversation can be marked as conversational, it could mean that
all
of the components within the composite work within the same
conversation.
This is also something that BEA has had customers ask for on its own
right.
However, if we did this, the request-scope could be removed, since
basically same semantics could be achieved by having a composite that
has
been marked as "local" be also marked as conversational.
The rules that we discussed at the F2F were:
1. Composite can be marked to propagate conversations through all
components within the composite ("propagatesConversation").
2. Request scope goes away.
3. If the composite service has a conversational interface, then if the
composite is marked as "propagatesConversation" then the conversation
of
the composite's client will be propagated throughout all of the
components
within the composite.
4. If the composite service has a non-conversational interface, then if
the
composite is marked as "propagatesConversation", then (unless
step 3
applies) a new conversation will be started on each operation of
the
composite service and propagated throughout the components within the
composite.
5. Marking a composite as "propagatesConversation" acts as if
all the
components have been marked as "propagatesConversation". Marking
a
component with "propagatesConversation" means that any conversationID
passed into the component through a service will be passed with any call
on
a intra-composite wire from the component.
If this were to happen, it would probably have to be done in either the
policy or assembly TC.
Michael
From: Barack, Ron [mailto:ron.barack@sap.com]
Sent: Thursday, January 31, 2008 11:26 AM
To: OASIS Java
Subject: [sca-j] ISSUE 21 - Clarify Request Scope lifetime
http://www.osoa.org/jira/browse/JAVA-21
Von:: Michael Rowley [mailto:mrowley@bea.com]
Gesendet: Montag, 21. Januar 2008 21:24
An: OASIS Java.
Betreff: [sca-j] NEW ISSUE: Clarify Request Scope lifetime
RAISER: Michael Rowley
TARGET: SCA Java Component Implementation Specification section
titled "Request Scope"
DESCRIPTION:
The section currently starts with the following sentence:
"The lifecycle of request scope extends from the point a request
on a
remotable interface enters the SCA runtime and a thread processes
that request until the thread completes synchronously processing
the
request."
From this description, it is not clear whether the request scope
lasts through a remotable call to another component that happens
to
be local. In one possible interpretation it would depend
on the
binding. A call through a web service binding would be seen
as
changing threads, and therefore would be a new request scope. The
same call through an SCA binding might be assumed to remain within
the thread and therefore be within the same scope.
It is probably a bad idea for the scope to depend on the binding
that
is used, and it may even be a bad idea for the scope to depend
on
whether a call through a remotable interface _happens_ to be
local.
PROPOSALS:
1) Have the request scope be only for a single remotable operation
call. From that operation, any request scope component that
is
reached through only local-service calls would reach the same
component instance. Calls through a remotable interface would
introduce a new request scope.
2) Alternately, the request scope could last from the time a
request
"enters the SCA runtime" until it is done, but with the
clarification
that the "SCA Runtime" is domain-wide. As long
as a call is made
to
another SCA component within the same domain (irrespective of the
binding used) it is part of the same request scope.
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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
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