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Subject: RE: [sca-j] ISSUE 21 - Clarify Request Scope lifetime



I would prefer to describe the idea on the table as replacing request
scopes with the more general concept of conversation propagation.  I
would not want to get rid of request scopes if we didn't have something
to replace them with.

I agree that conversation propagation should not have to be specified as
a composite-wide concept.  I think you should be able to specify
conversation propagation on an individual component.  I _think_ that
specifying it on a composite is almost the same as specifying it on all
of the components within it.

I also agree is like other technologies concepts of "session" or "shared
context".

Michael

-----Original Message-----
From: David Booz [mailto:booz@us.ibm.com] 
Sent: Tuesday, March 18, 2008 10:00 AM
To: sca-j@lists.oasis-open.org
Subject: RE: [sca-j] ISSUE 21 - Clarify Request Scope lifetime

+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:
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Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6
3AU











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