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Subject: RE: [wsbpel] Issue 6 - Rough draft of proposal for vote
Ivana, for this purpose, I would define an "end activity" as an activity
directly nested within the flow activity without outgoing links (that is,
without <sources> standard element).
Kind Regards
DK
"Trickovic,
Ivana"
<ivana.trickovic@ To
sap.com> Dieter Koenig1/Germany/IBM@IBMDE
cc
14.09.2004 13:28 Alex Yiu <alex.yiu@oracle.com>,
Axel Martens <amarten@us.ibm.com>,
Dieter Roller/Germany/IBM@IBMDE,
"'edwink@collaxa.com'"
<edwink@collaxa.com>, Frank
Leymann/Germany/Contr/IBM@IBMDE,
"'satisht@microsoft.com'"
<satisht@microsoft.com>,
"'wsbpel@lists.oasis-open.org'"
<wsbpel@lists.oasis-open.org>
Subject
RE: [wsbpel] Issue 6 - Rough draft
of proposal for vote
Hi Dieter,
I do believe that people who use links extensively find term "end
activities" more natural. They design processes in more graph-oriented way
and they structure their processes/activities in such a way that the
outcome you mentioned below would be really a surprise. Other people use
more block-oriented approach. But, how would you define term "end
activity"?
Regards,
Ivana
> -----Original Message-----
> From: Dieter Koenig1 [mailto:dieterkoenig@de.ibm.com]
> Sent: Dienstag, 14. September 2004 08:43
> To: Trickovic, Ivana
> Cc: Alex Yiu; Axel Martens; Dieter Roller; 'edwink@collaxa.com'; Frank
> Leymann; 'satisht@microsoft.com'; 'wsbpel@lists.oasis-open.org'
> Subject: RE: [wsbpel] Issue 6 - Rough draft of proposal for vote
>
>
>
>
>
>
> Hi Ivana, let me construct a new example. I was concerned
> about situations
> like the following.
>
> The number of activities directly nested within the flow activity
> (definition of "concurrent activities") is 6. So if M=6, I
> can specify a "4
> out of 6" condition. This would allow e.g. a, b, d, e to
> cause the flow to
> complete. This may be a surprise because both subgraphs
> {a,b,c} and {d,e,f}
> did NOT finish.
>
> If there would be a notion of "end activities" instead, then
> M would be 2
> and one could specify e.g. "1 out of 2".
>
> flow
> completionCondition="N out of M"
>
> link name=from-a-to-c
> link name=from-b-to-c
> link name=from-d-to-f
> link name=from-e-to-f
>
> any-activity name=a
> source name=from-a-to-c
> any-activity name=b
> source name=from-b-to-c
> any-activity name=c
> target name=from-a-to-c
> target name=from-b-to-c
>
> any-activity name=d
> source name=from-d-to-f
> any-activity name=e
> source name=from-e-to-f
> any-activity name=f
> target name=from-d-to-f
> target name=from-e-to-f
>
> (Embedded image moved to file: pic27589.jpg)
>
>
> Kind Regards
> DK
>
>
>
>
>
> "Trickovic,
>
> Ivana"
>
> <ivana.trickovic@
> To
> sap.com> Dieter
> Koenig1/Germany/IBM@IBMDE,
> Alex Yiu
> <alex.yiu@oracle.com>
> 13.09.2004 18:34
> cc
> Axel Martens
> <amarten@us.ibm.com>,
> Dieter
> Roller/Germany/IBM@IBMDE,
> "'edwink@collaxa.com'"
>
> <edwink@collaxa.com>,
> Frank
>
> Leymann/Germany/Contr/IBM@IBMDE,
>
> "'satisht@microsoft.com'"
>
> <satisht@microsoft.com>,
>
> "'wsbpel@lists.oasis-open.org'"
>
> <wsbpel@lists.oasis-open.org>
>
> Subject
> RE: [wsbpel] Issue 6 -
> Rough draft
> of proposal for vote
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Dieter,
>
> The proposal I sent is using term "concurrent activities"
> instead of "end
> activities". So, M would be the number of activities directly
> nested within
> the flow activity. This term does not take into account links and
> synchronization dependencies between activities. If we take
> your examples,
> in both cases M would be 4. I find the term easier to understand and
> "calculate". As your examples show, term "end activities" is highly
> depended on synchronization dependencies between activities
> and that makes
> it more difficult for "calculation". Do you have any example,
> which shows
> that term "concurrent activities" is not sufficient (or is ambiguous)?
>
> Regards,
>
> Ivana
>
>
> > -----Original Message-----
> > From: Dieter Koenig1 [mailto:dieterkoenig@de.ibm.com]
> > Sent: Montag, 13. September 2004 11:24
> > To: Alex Yiu
> > Cc: Axel Martens; Dieter Roller; 'edwink@collaxa.com';
> Frank Leymann;
> > Trickovic, Ivana; 'satisht@microsoft.com';
> > 'wsbpel@lists.oasis-open.org'
> > Subject: Re: [wsbpel] Issue 6 - Rough draft of proposal for vote
> >
> >
> >
> >
> >
> >
> > Just for completeness (sorry if this has been mentioned
> > somewhere already):
> > for "N out of M", is there a notion of "end activities" in a
> > flow? M would
> > then be the number of such end activities. This would be
> > interesting for a
> > static analysis in order to avoid specification where N > M
> > where one would
> > wait forever.
> >
> > Examples:
> >
> > flow name=flow1 <!-- a flow with two "end activities" -->
> > link name=from-a-to-c
> > link name=from-b-to-c
> > any-activity name=a
> > source name=from-a-to-c
> > any-activity name=b
> > source name=from-b-to-c
> > any-activity name=c
> > target name=from-a-to-c
> > target name=from-b-to-c
> > any-activity name=d
> >
> > flow name=flow2 <!-- a flow with three "end activities" -->
> > link name=from-a-to-b
> > link name=from-a-to-c
> > any-activity name=a
> > source name=from-a-to-b
> > source name=from-a-to-c
> > any-activity name=b
> > target name=from-a-to-b
> > any-activity name=c
> > target name=from-a-to-c
> > any-activity name=d
> >
> > (Embedded image moved to file: pic12343.jpg)
> >
> >
> > Kind Regards
> > DK
> >
> >
> >
> >
> >
> > Alex Yiu
> >
> > <alex.yiu@oracle.
> >
> > com>
> > To
> > "Trickovic, Ivana"
> >
> > 13.09.2004 08:00
> > <ivana.trickovic@sap.com>
> >
> > cc
> > Axel Martens
> > <amarten@us.ibm.com>,
> > Frank
> >
> >
> > Leymann/Germany/Contr/IBM@IBMDE,
> > Dieter
> > Roller/Germany/IBM@IBMDE,
> > Dieter
> > Koenig1/Germany/IBM@IBMDE,
> > "'edwink@collaxa.com'"
> >
> > <edwink@collaxa.com>,
> >
> >
> > "'satisht@microsoft.com'"
> >
> > <satisht@microsoft.com>,
> >
> > "'wsbpel@lists.oasis-open.org'"
> >
> > <wsbpel@lists.oasis-open.org>, Alex
> > Yiu
> > <alex.yiu@oracle.com>
> >
> > Subject
> > Re: [wsbpel] Issue 6 -
> > Rough draft
> > of proposal for vote
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > Hi,
> >
> > Ivana, thanks for sending out this proposal.
> > I believe a number of us (including me) like the
> <completionConditon>
> > construct from your proposal high level speaking.
> >
> > After reading the proposal, I guess we need to work on a
> > number of details.
> > I would like to ask a few questions / mention a few points:
> > Minor syntax and semantics questions:
> > Do we want to allow expression for branch
> > attribute? instead of
> > just a constant integer?
> > We may need to some minor syntax adjustment for
> expression
> > attribute because we have passed Isseu 13 already.
> > If answers to the above question are yes, then
> > the condition
> > syntax may become a choice (xsd:choice) of the
> > following two:
> > <condition
> >
> > expressionLanguage="anyURI"?>boolean-expression</condition>
> > <branchCondition
> >
> > expressionLanguage="anyURI"?>integer-expression</condition>
> >
> > About completionConditionFailure: it looks like a nice
> > idea so far
> > ...
> >
> > About the new "isCompleted()" function: I am not against this
> > function. But, I tend to think there are usually BPEL
> > variables being
> > modifed as the execution result of a flow activity. (See the
> > train-or-plane-and-hotel example). Is it more typical to have
> > completionCondition to be evaluated on those variables?
> > Also, after the completion of the whole flow, it is not
> > uncommon for
> > people to have logic to find out which branch is
> > finished (especially
> > when "or" is involved in the condition). The
> > "isComplete()" function
> > would be available only within the completionCondition
> > within the
> > flow. People may get confused and attempt to use the
> > "isComplete()"
> > function outside the flow. If the completionCondition
> relies on
> > variables, the same logic is applicable outside of the flow.
> >
> > About the IgnoreFault semantics: I recall this
> > ignoreFault idea back
> > to March F2F. With ignoreFault semantics, it
> > essentially introduces
> > two brand new semantics.
> > It turns <flow> into a semi-<scope> like construct
> > It adds this new "ignoreFault" semantics: which
> > catches certain
> > fault and the catching action will not cause any
> > scope to be
> > marked as faulted.
> > I tend to think this "ignoreFault" functionality has
> > quite a heavy
> > weight impact to <flow> and fault handling picture in
> > BPEL. If there
> > is an alternative way to achieve similar business
> > logic, I would go
> > for the alternative way.
> >
> > Quoted from Ivana's email:
> > "Not all activities must complete in order the enclosing flow
> > activity to complete. The way to identify that an
> > enclosed activity
> > did not complete is to propagate faults."
> >
> > I agree with the first sentence. But, I am not sure
> > that propagating
> > fault is the only way to identify an enclosed activity did not
> > complete. I would rather use a scope as an activity
> > enclosed by flow.
> > If we wish to suppress any minor fault which happens
> during the
> > execution of the scope, then we can just add a fault
> > handler. If the
> > fault that happen, the scope will be marked as "faulted".
> >
> > The completeConditon can identify the "incomplete"
> > state of the scope
> > by two ways:
> > completeCondition can be evaluated based on BPEL
> > variables,
> > which are set to "incomplete" state by pre-flow
> > initialization
> > or related fault-handler logic.
> > branch-based condition will interprete a
> faulted scope as
> > "incomplete" branch and will not count them into
> > the required N
> > branches.
> > This will allow us to suppress minor fault with or without the
> > <completionCondition> construct. Please see the
> > following example. It
> > is already legal and working today. It shows how to suppress
> > "foo:barFault" without the <completeCondition> construct
> >
> > <flow>
> > <scope name="A">
> > <faultHandler>
> > <catch faultName="foo:barFault" ... > ... </catch>
> > </faultHandler>
> > <sequence>
> > ... <invoke name="doA" ... /> ...
> > </sequence>
> > </scope>
> > <scope name="B"> ... <!-- similar to A --> ... </scope>
> > </flow>
> >
> > If the invoke of "doA" triggers "foo:barFault", the
> > scope "A" will be
> > marked as faulted. On the other hand, scope "B" will be
> > allowed to
> > continue and complete. After scope "B" is completed,
> > the compensation
> > handler of scope "B" will be installed. And, the
> > overall execution of
> > flow is still considered a normal completion.
> >
> > I hope I have illustrated we can achieve similar logic without
> > introducing a new "ignoreFault" construct and concept to BPEL.
> >
> > What "completionCondition" does should be just
> > providing a way to
> > pro-actively cancel/terminate other flows without
> > waiting to them to
> > complete or to be faulted.
> >
> > About "Cancel-other-flows": (Let me consolidate what I
> > am leaning
> > towards so far.) We need to formal define the notion of a "
> > cancel-other-flows" mechanism. This mechanism is specified and
> > attached to <flow> construct (and future parallel
> > forEach construct).
> > When this mechanism is triggered by one of parallel
> > flows, it will
> > cancel/terminate other parallel flows which are still
> > running, after
> > the triggering flow is completed. If the other flow
> > activties are
> > scope activities, the scope will be marked as cancelled.
> >
> > This mechanism will be triggered upon the
> completionCondition is
> > evaluated to be true.
> >
> > [Note: (a) since this mechanism is triggered by without
> > using any
> > fault directly. This will again decrease the need of
> > "ignoreFault"
> > construct (b) This mechanism will affect the wordings
> > of Issue 135 to
> > an extent.]
> >
> > [Question: again, should we enforce scope-only activity when
> > completionCondition is used? I tend to say yes.]
> >
> >
> > Thank you all for following and reading this email thread!!!
> >
> >
> >
> > Regards,
> > Alex Yiu
> >
> >
> >
> > Trickovic, Ivana wrote:
> >
> > Here is a proposal for the completion condition - it
> > addresses some
> > issues not tackled so far (at least not in case of
> > <completeCondition>). It is a version of the proposal
> > for completion
> > condition for the bundle element. This proposal
> > includes comments
> > from many people including Frank Leymann, Dieter
> Koenig, Dieter
> > Roller and Satish Thatte. It does not mean that they
> completely
> > support the proposal - they may have issues with any
> part of the
> > proposal.
> >
> >
> > Completion condition
> > =====================
> > The current semantics of the flow activity is that it
> > waits for all
> > concurrent activities to complete. The completion also
> > means that an
> > enclosed activity/scope may end abnormally or be
> > skipped (e.g. the
> > join condition of the activity evaluated to false). If
> > a fault is
> > thrown within an enclosed activity/scope and one of the
> > local fault
> > handlers catch the fault (and does not rethrow the fault), the
> > enclosed activity/scope will be deemed to be
> completed (although
> > ended abnormally). If a fault is not caught by any local fault
> > handler (or is rethrown) the flow activity will
> > terminate all active
> > concurrent activities and corresponding fault handler may be
> > initiated.
> >
> > A completion condition for the flow activity is needed
> > for scenarios
> > where not all concurrent activities of a flow activity
> > must complete
> > in order the flow activity to complete. Note: We are
> not talking
> > about "successful completion" of enclosed concurrent
> activities
> > because that would not be consistent with the semantics of the
> > current flow activity.
> >
> > The completion condition may have different flavors, such as:
> > (1) N out of M
> > (2) The two most important requests completed
> > (3) A Boolean condition operating upon process variables
> >
> > Not all activities must complete in order the enclosing
> > flow activity
> > to complete. The way to identify that an enclosed
> > activity did not
> > complete is to propagate faults. We may distinguish
> > between severe
> > faults and those that can be ignored. Severe faults cause the
> > enclosing flow activity (or more precisely, enclosing
> scope) to
> > terminate the flow activity, including all active concurrent
> > activities, and corresponding fault handler may be
> > initiated. Other
> > faults may be ignored - the flow activity is "informed" that a
> > concurrent activity did not complete but still allows
> > other active
> > concurrent activities to continue with execution.
> >
> > Ignore semantics
> > =================
> > Faults thrown within enclosed concurrent
> > activities/scopes and not
> > handled by local fault handlers are rethrown. Enclosing <flow>
> > element decides which of these rethrown faults can be
> > ignored. This
> > new "ignore" semantics should be part of the completion
> > condition and
> > should apply to all enclosed activities. This new
> > semantics does not
> > introduce a new fault handling mechanism. It is needed for
> > identifying how many of the enclosed activities failed.
> >
> >
> > Proposed syntax
> > ================
> > <flow standard-attributes>
> > standard-elements
> > <completionCondition/>?
> > <links>?
> > <link name="ncname">+
> > </links>
> > activity+
> > </flow>
> >
> > <completionCondition>
> > <conditions branch="xsd:integer"?
> > expression=xpath?/>?
> > <ignoreFaults>?
> > <fault name="qname"? value="ncname"?/>*
> > <ignoreAll/>?
> > </ignoreFaults>
> > </completionCondition>
> >
> > Attribute branch is used to specify a condition of
> > flavor "wait for N
> > out of M activities to complete", or more precisely value N.
> > Attribute expression is used to specify a Boolean
> > condition operating
> > upon process variables or a condition of flavor "the two most
> > important requests completed".
> >
> > Both conditions (branch and expression) may be
> > specified at the same
> > time. They will be checked when one instance of the
> > scope activity
> > reaches the end. If at least one condition evaluates
> to true all
> > active instances will be terminated.
> >
> > Element <ignoreFaults> specifies faults that may be
> > ignored. Element
> > fault is used to specify a fault which may be ignored
> > (fault name and
> > fault data may be specified). Element <ignoreAll> would
> > mean that all
> > faults thrown/rethrown by any concurrent activity/scope may be
> > ignored. If this element is specified <fault> element must be
> > omitted.
> >
> > Completion condition failure
> > =============================
> > A new standard fault, e.g.
> completionConditionFailure, should be
> > introduced to notify that the completion condition of a
> > flow activity
> > evaluated to false (note: all concurrent activities have been
> > completed). The fault is thrown in the scope
> enclosing the flow
> > element.
> >
> > Completion condition and links
> > ==============================
> > There should be no difference between a flow activity with a
> > completion condition and a flow activity without completion
> > condition. For example, if the completion condition
> > fails all links
> > leaving the flow activity should have value "false" (or
> > be reverted
> > to a negative status).
> >
> > There are just a few additional rules:
> > (1) Let's assume enclosed activity A is the source of a
> > link. If the
> > completion condition evaluates to true and activity A is not
> > completed it will be terminated and the value of the
> > link will be set
> > to "false".
> > (2) Let's assume enclosed activity A is the source of a
> > link and the
> > activity failed but the fault is "ignored" by the
> enclosing flow
> > activity. The value of the link will be set to "false".
> >
> > New function for completion condition of flavor "the two most
> > important requests completed"
> >
> > ==============================================================
> > ==============================
> > For completion conditions of flavor "the two most
> > important requests
> > completed" standard attribute "name" must be specified for all
> > enclosing activities in order to be able to
> distinguish them. In
> > addition a new function, e.g.
> > isCompleted('activityName') must be
> > introduced. The semantics of the function is: if
> > activity completed
> > successfully the function returns value true.
> >
> > Example
> > <completionCondition expression=
> > "isCompleted('A') AND isCompleted('B')"
> > </completionConditions>
> >
> >
> > Regards,
> >
> > Ivana
> >
> >
> >
> > -----Original Message-----
> > From: Alex Yiu [mailto:alex.yiu@oracle.com]
> > Sent: Samstag, 11. September 2004 00:49
> > To: Axel Martens
> > Cc: 'edwink@collaxa.com'; Trickovic, Ivana;
> > 'satisht@microsoft.com';
> > 'wsbpel@lists.oasis-open.org'; Alex Yiu
> > Subject: Re: [wsbpel] Issue 6 - Rough draft of
> > proposal for vote
> >
> >
> > Hi, Axel,
> >
> > Thanks for liking parts of my proposal so far.
> > Actually, the idea of my proposal is borrowed from a part of
> > presentation from Ivana and Dieter Roller in March
> F2F. I just
> > generalize it to apply to <flow> also.
> >
> > About using links or not:
> > I don't have a huge opposition to Axel's proposal
> > which enriches the
> > semantics of joinCondition evaluation. However, it
> is not that
> > difficult for people to make mistakes in
> > joinCondition. Look at the
> > 2-out-of-3 example. The join condition already gets so
> > complicated.
> > If people make a mistake in their joinCondition, the
> > whole flow can
> > get struck for no good reasons. (The completeCondition
> > approach will
> > less likely to have the whole flow struck. Because,
> it does not
> > introduce a new parallel activity in the flow). But,
> > if this is what
> > Petri-net-oriented and control-link-oriented audience
> > really want, I
> > can accept it in a sense, as long as this is not the
> > only way to
> > achieve similar business logic.
> >
> > About static vs dynamic parallelism:
> > Static parallelism is basically <flow> construct in
> > BPEL. Dynamic
> > parallelism is "parallel forEach" or "bundle". Issue 4
> > and 147 are
> > related issues.
> >
> > http://www.choreology.com/external/WS_BPEL_issues_list.html#Issue4
> >
> > http://www.choreology.com/external/WS_BPEL_issues_list.html#Issue147
> >
> > About "Terminating still running tasks versus
> > proceeding in control
> > flow while those tasks are
> > still running":
> > I am not 100% that I understand your question. Let me
> > try to answer
> > it anyway. The completeCondition is about triggering
> > termination of
> > still-running tasks. The "proceeding in control flow" (if I
> > understand you correctly) will be handled by an
> outter flow. [I
> > guess it is related to (hotel and (train or plane)) flow??]
> >
> > About changes of "forcedTermination" fault handler:
> > If you got a chance to see some recent emails on Issue
> > 135, Satish
> > has recently suggested to remove the notion
> "forcedTermination"
> > fault and replace its fault handler with
> cancelHandler. Frank,
> > Yaron, Edwin and I all agree with this direction. Because,
> > overloading fault with the concept of
> "forcedTermination" is a
> > "false economy" and it creates quite a bit of
> > unnecessary confusion.
> >
> >
> > I don't think we should go back to this route or even further
> > overload the "forcedTermination" fault handler
> > semantics. Because,
> > fault handling is way too generic and the changes you
> > mentioned will
> > create even more confusion. (e.g. Will this change of
> > marking as
> > "completed" apply to all "forcedTermination" fault
> > handler / cancel
> > handler of all scopes? )
> >
> > I guess most of us agree that we should have a new
> > mechanism to kill
> > / do an early completion of a flow in a nice and clean
> > way. However,
> > overloading a standard fault handler does not seem to
> > be the best
> > one. I would rather introduce a construct which is
> > very specific to
> > <flow> or parallel-forEach. For example, this
> > <completeCondition>
> > construct or maybe a new activity called <completeFlow
> > />. I will
> > send out more emails on joint thinking of both Issue 6
> > and Issue
> > 135. Please stay tuned.
> >
> >
> > Thanks!
> >
> >
> >
> > Regards,
> > Alex Yiu
> >
> >
> > Axel Martens wrote:
> >
> > Hi,
> >
> > I like the simplicity of the syntax of Alex's proposal.
> > Although,
> > for me it is quite easy to model in terms of
> > links and join
> > conditions, and I want to keep my proposal alive
> > (because of
> > the
> > minimal changes to BPEL's syntax and semantics),
> > it looks like
> > a
> > nice macro to provide more convenience to the
> customers.
> >
> > Alex, could you shortly explain to me, what do
> > you mean by
> > static
> > and dynamic parallelism? How do you handle the
> > two different
> > cases
> > after evaluating the completeCondition:
> Terminating still
> > running
> > tasks versus proceeding in control flow while
> > those tasks are
> > still running (Sorry, I missed your previous emails)?
> >
> > I agree to Alex's opinion, that we need a
> > mechanism to kill
> > parallel flow nice and clean. This could be done
> > either by a
> > new
> > mechanism which does not throw a fault or by
> > changing the way
> > fault are handled. I have discussed already an
> > example of the
> > second case with Ivana, and I like to tell you,
> > what I have in
> >
> > mind. Look at the following example:
> >
> > <scope name="scopeFlow">
> > ...
> > <flow>
> > <link name="linkA"/>
> > <link name="linkB"/>
> >
> > <scope name="scopeA">
> > ...
> > <invoke name="A" ...>
> > <source linkName="linkA" ...>
> > </invoke>
> > </scope>
> >
> > <scope name="scopeB">
> > ...
> > <invoke name="B" ...>
> > <source linkName="linkB" ...>
> > </invoke>
> > </scope>
> >
> > <throw name="C" faultName="bpws:forcedCompletion"
> > joinCondition="linkA OR linkB"
> > joinEvaluation="immediate">
> > <target linkName="linkA" ...>
> > <target linkName="linkB" ...>
> > </throw>
> >
> > </flow>
> > </scope>
> >
> > First, I explain the situation: In the example
> > above, activity
> > C
> > will be executed if one of the two activities
> A and B was
> > successfully completed. Activity C throws the fault
> > "forcedCompletion". Like each other fault, this
> > forces the
> > scope
> > "scopeFlow" to terminate still running
> > activities. Assume,
> > there
> > was a fault handler defined in this scope which
> > catches the
> > fault
> > "forcedCompletion" (omitted in here), the
> > process continues
> > after
> > scope "scopeFlow". A problem arises, if scope
> "scopeFlow"
> > should
> > be compensated. Because it was exited from a
> > fault handler, no
> >
> > compensation handler was installed.
> >
> > Now, I explain my solution: In the example, I
> > have chosen a
> > new
> > "standard" fault name: "forcedCompletion". The
> > only necessary
> > change is to allow a fault handler that catches
> > this fault to
> > install a compensation handler for the same
> > scope, i.e. to
> > mark
> > the scope "scopeFlow" as "completed" instead
> of "exited".
> >
> > The standard compensation mechanism will only
> undo those
> > ("scoped") activities within the scope, which
> > actually have
> > been
> > successfully completed, i.e. scopeA or scopeB or
> > may be both.
> >
> > Axel.
> > ----------------------------------------
> > Axel Martens
> >
> > Post Doc Researcher
> > Component Systems Group
> > IBM TJ Watson Research Center
> > Hawthorne, NY (USA)
> > Phone: (914) 784-7480
> > E-mail: amarten@us.ibm.com
> >
> >
> >
> > Alex Yiu
> >
> > <alex.yi
> >
> > u@oracle
> >
> > .com>
> > To
> > Alex Yiu
> > <alex.yiu@oracle.com>
> >
> > cc
> > 09/10/20 "Trickovic, Ivana"
> >
> > 04 12:10
> > <ivana.trickovic@sap.com>, Axel
> > AM Martens/Watson/IBM@IBMUS,
> >
> > "'edwink@collaxa.com'"
> >
> > <edwink@collaxa.com>,
> >
> > "'satisht@microsoft.com'"
> >
> > <satisht@microsoft.com>,
> >
> >
> > "'wsbpel@lists.oasis-open.org'"
> >
> > <wsbpel@lists.oasis-open.org>, Alex
> > Yiu <alex.yiu@oracle.com>
> >
> >
> > Subject
> > Re: [wsbpel] Issue 6 -
> > Rough draft of
> > proposal for vote
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > Hi,
> >
> > Here are some examples how to use
> > completeCondition to express
> > similar business logic in Axel's previous email:
> >
> > (A) "Select one out of three" example:
> > <flow>
> > <completeCondition branch="1" />
> > <invoke name="CheckAirlineA" ... />
> > <invoke name="CheckAirlineB" ... />
> > <invoke name="CheckAirlineC" ... />
> > </flow>
> >
> >
> > (B) "Select two out of three" example:
> > <flow>
> > <completeCondition branch="2" />
> > <invoke name="AskRefereeA" ... />
> > <invoke name="AskRefereeB" ... />
> > <invoke name="AskRefereeC" ... />
> > </flow>
> >
> > As you guys can see, the completeCondition
> > declaration is very
> > straight forward and simple. No complicated links and
> > joinCondition usage.
> >
> > (C) "(Plane or Train) and Hotel" example: It
> > would become two
> > flow constructed (nested).
> >
> >
> > <assign> ... <to variable="planeResult"></assign>
> > <!-- initialize "planeResult" with NOT-OK value -->
> > <assign> ... <to variable="trainResult"></assign>
> > <!-- initialize "trainResult" with NOT-OK value -->
> > <flow name="checkIterinary">
> > <flow name="PlaneOrPlane">
> > <completeCondition>
> > fn:planeOK(planeResult) or
> > fn:trainOK(trainResult)
> > </completeCondition>
> > <invoke name="CheckPlane"
> > outputVariable="planeResult"
> > ... />
> > <invoke name="CheckTrain"
> > outputVariable="trainResult"
> > ... />
> > </flow>
> > <invoke name="checkHotel" />
> > </flow>
> > <switch name="bookingSwitch">
> > <case>
> > <condition>
> > (fn:planeOK(planeResult) or
> > fn:trainOK(trainResult))
> > and fn:hotelOK(hotelResult)
> > </condition>
> > <invoke name="invokeBooking" ... />
> > </case>
> > <otherwise>
> > <invoke name="writeInformation" ... />
> > </otherwise>
> > </switch>
> >
> >
> > Please note that regardless whether we pick a
> > link-oriented
> > approach or completeCondition approach:
> > The initialization of result variables are needed
> > because of potential cancellation of one
> > of the invoke
> > between train and plane
> > The "fn:*()" represents the logic to
> > determine whether a
> > traveling resource is available. They are
> > used in either
> > the transitionCondition of links or the
> > condition of
> > switch/case.
> > As you guys see, we don't need declare to six
> links. The
> > completeCondition and case-condition are much
> simpler and
> > easier to understand.
> >
> > I attach a diagram to illustrate the above flows.
> >
> > I guess we can still more time in terms of
> refiniment of
> > joinCondition evaluation. However, I don't think
> > that should
> > be the only approach to achieve complete
> > condition related
> > logic.
> >
> >
> > Thanks!!!
> >
> > Regards,
> > Alex Yiu
> >
> >
> >
> >
> > Alex Yiu wrote:
> >
> > Hi,
> >
> > +1 to what Ivana said in general.
> >
> > Few points to add:
> > Axel's proposed enhancement to control
> > links evaluation
> > works to an extent for static parallelism (e.g.
> > <flow>). However, control links do not
> work well in
> > dynamic parallelism (e.g. "parallel forEach" or
> > "bundle"). I think the notion of
> completeCondition
> > (borrowed from Ivana and DK) is general
> > enough and it
> > should be applied to both static and dynamic
> > parallelism. A general completeCondition
> > mechanism will
> > be easier for BPEL users to learn.
> > Even in a pure static parallelism case,
> > completeCondition has much better code
> > clarity. It is
> > more declarative and easier for BPEL users to
> > understand. It will eliminate
> significant amount of
> > joinCondition programming, which may be
> > error prone. (I
> > will send another email later to show how
> > completeCondition can be used to express the same
> > semantics of Axel's example).
> > In one of my previous emails, I also
> tried to use a
> > "macro" way to illustrate how outstanding
> > running flows
> > can be cancelled by throwing a fault
> > within a scope. The
> > illustration has the same compensation handler
> > installation problem that Ivana has
> > pointed out. The
> > "illustraction macro" does NOT carry a
> > desirable and
> > intended semantics. We need to create /
> > describe a new
> > mechanism to cancel parallel flow without
> > throwing a
> > fault. (That was discussed briefly between
> > Edwin and me
> > at Oracle).
> >
> > Thanks!
> >
> >
> > Regards,
> > Alex Yiu
> >
> >
> >
> > Trickovic, Ivana wrote:
> > Axel,
> >
> > I find the idea interesting. In fact, I was
> > discussing the
> > completion condition issue with Dieter Koenig
> > during the last
> > f2f meeting and his suggestion was also to try
> > to resolve this
> > issue using links. And we identified that
> > several changes need
> > to be done, including removing restriction for
> > jonCondition,
> > that "the join condition is evaluated as soon as
> > all incoming
> > links of the activity are determined" - so definitely
> > "immediate" semantics needs to be introduced.
> >
> > I have the following comments on your proposal.
> > 1. In your proposal you are using a fault
> > (bpws:forcedTermination) to terminate all
> active parallel
> > branches. But this changes the outcome of the
> > flow activity.
> > It will always end abnormally and compensation
> > handler (if it
> > is defined) will never be installed. Although
> completion
> > condition has evaluated to true and needed
> > activities have
> > completed the enclosing flow activity will end
> > abnormally. Is
> > this really intended semantics?
> >
> > 2. Your proposal does not address some pain points. For
> > example, in case of "N out of M", N<M there
> many possible
> > "variations":
> > (A) One enclosed activity may experience
> problems but the
> > <flow> activity may succeed
> > (B) One of enclosed activities may experience a
> > severe error,
> > which may have impact on the <flow> activity
> > The question is what to do with running
> > activities? In the
> > latter case, reasonable behavior would be: if
> > one enclosed
> > activity does not succeed other running
> > activities should be
> > cancelled and the flow activity should try to
> > recover. In the
> > former case, we should allow active parallel
> > activities to
> > complete their work. This is not supported in
> > your proposal.
> >
> > Regards,
> >
> >
> >
> > Ivana
> >
> >
> >
> > [stuff deleted]
> >
> >
>
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