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Subject: Re: [wsbpel] Issue 37 - Proposal for vote
Below you say "An instance can receive messages for receive activities marked with a createInstance="no" attribute if and only if the message is correlated to the receive activity." When you say 'correlated' do you mean correlated via a correlation set or through some unspecified mechanism that is known to the message infrastructure? Put another way, is it ever legal to have a receive with createInstance="no", a single uninitialized correlation set and initiate="yes"? For example, imagine a new instance is created. Further imagine that the new instance has been assigned a unique URI and that this unique URI has been communicated through an out of band mechanism to other web services. Finally, imagine that the new instance contains within it a receive activity with createInstance="false", an uninitialized correlation set and initiate="yes". My expectation was that if another web service should send a message directly to the instance's uniquely assigned URI and if the message matched the portType/operation described in the receive then the instance would receive the message and initiate the correlation set. Is your understanding different? Thanks, Yaron Satish Thatte wrote: > Yuzo, > > Issue 37 does not relate to process instance creation as far as I can tell, only > to correlation set initiation and matching. Instantiation continues to be > controlled by the createInstance attribute. Note that correlation sets can be > initiated at arbitrary points since they can be declared and initiated inside > arbitrarily nested scopes of running instances. Uninitiated sets cannot > therefore in general cause process instantiation. > > > Define a correlated message relative to a receive activity to mean that > > A. The receive activity has at least one correlation set with initiate="no", > > B. Every correlation set for the receive activity with initiate="no" is already > initialized, and > > C. The message contains property values matching those initialized correlation > sets. > > In other words, the routing infrastructure has every reason to associate that > message with that receive activity in that instance. > > > The rule on which the correlation mechanism has been designed has two parts. > > 1. A receive activity can receive an uncorrelated message only if the receive > activity is marked with a createInstance="yes" attribute. In this case the > receive activity occurs in a new instance of the process. > > > 2. An instance can receive messages for receive activities marked with a > createInstance="no" attribute if and only if the message is correlated to the > receive activity. > > > All of this is reflected in the current specification, though probably not this > explicitly. The ambiguity you pointed out in Issue 37 relates narrowly to the > "multi-start activity" case. In this case, the multiple start activities may > have no correlation set with initiate="no" and thus they may all fail the A > condition for correlated message delivery. And yet for all but one of them, the > message delivery needs to occur based on the correlated message rules rather > than the createInstance rules. > > > Thus the problem is in condition A above. In my view a good way to approach > this is to address it via the createInstance attribute. Add another value: > createInstance="yes | no | alternate" where the alternate value signals the > multi-start case. We could then explain that in the case > createInstance="alternate" the setting of initiate is "yes" for the receive that > follows rule 1 and "no" for the receives that follow rule 2. Therefore we > should reserve the use of the initiate attribute for receives with > createInstance="no" and disallow it for the "start activities". > > > Regards, > > Satish > > > ________________________________ > > From: Yuzo Fujishima [mailto:fujishima@bc.jp.nec.com] > Sent: Wed 3/10/2004 6:29 PM > To: Eckenfels. Bernd; wsbpel@lists.oasis-open.org > Subject: Re: [wsbpel] Issue 37 - Proposal for vote > > > > Bernd, > > Thank you for your comments. > > == As for part-2: > > I am personaly not hesitant to drop part-2. I propsed part-2 in respect > of the TC discussion at the September F2F. > > == As for correlateOrCreate: > > I think the following rule should be natural. > * If there is a pending receive/onMessage activity that references a > matching initiated correlation set, then the message is delivered > to that activity. > * If not, if there is a receive/onMessage activity that specifies > matching partner link, port type, operation, the message is delivered > to that activity, possibly triggering creation of a new process instance > and/or initiating correlation sets. > * An activity can receive at most one message per run. That is, it must > be started twice (e.g. by using while activity) to receive two messages. > This excludes the possibility of delivering another message to a start activity > that actually triggered the creation of the instance. > > Example: > > process p1 > flow > receive r1 partnerLink="pl1" portType="pt1" operation="op1" > correaltion set="cs" > receive r2 partnerLink="pl2" portType="pt2" operation="op2" > correaltion set="cs" > > Event 1. Message m1 that has properties (partnerLink=pl1, portType=pt1, > operation=op1, > cs=v1) arrives. An instance i1 of p1 is created, m1 is delivered to r1 of i1, > and cs of i1 is set to v1. > Event 2. Message m2 that has properties (pl2, pt2, op2, v2) arrives. Because r2 > of i1 > is now waiting for a message with properties (pl2, pt2, op2, v1), m2 cannot > be delivered to it. A new instance i2 is created, m2 is delivered to r2 of i2, > and cs of i2 is set to v2. > Event 3. Message m3 that has value (pl2, pt2, op2, v1) arrives. Because r2 of i1 > is waiting for a message with matching properties, m3 is delivered to it. > Event 4. Message m1' that has value (pl1, pt1, op1, v1) arrives. > Because r1 of i1 already received a message, m1' cannot be delivered to it. > A new instance i3 is created and m1' is delivered to r1 of i3. > > Note: If the events occur in the order of Event 1 then Event 4, skipping Event 2 > and 3, > a conflictingReceive will result because r2's of both i1 and i3 wait for a > samely specified > message (pl2, pt2, op2, v1). > > Sincerely, > > Yuzo Fujishima > NEC Corporation > > ----- Original Message ----- > From: "Eckenfels. Bernd" <B.Eckenfels@seeburger.de> > To: <wsbpel@lists.oasis-open.org> > Sent: Thursday, March 11, 2004 2:24 AM > Subject: RE: [wsbpel] Issue 37 - Proposal for vote > > > > Hello, > > > > I like part-1 if it would be enough, but it does not solve the problem of > "correlateOrCreate" type of receives, which might be > > desireable? > > > > > > Part-2 allows this feature again, but I dont realy see a big change to the > current attribute, then. The same semantic could be > > achieved by changing the default value of initiate to yes. > > > > A more radical solution would be to use another construct like pick, if you > want to pick multiple possibilities to initiate the > > instance and the correlation. So this would be part-1, all correrlations are > initiated if none exist, and by the use of control flow > > you have to ensure that no receive is activated before its expected correlation is. > > > > Mit freundlichen Grusen > > Bernd Eckenfels > > Chief Architect > > -- > > SEEBURGER AG - Edisonstr.1 , D-75015 Bretten, Germany > > Fax: +49 (0)7252 96-2400 - Phone: +49 (0)7252 96-1256 > > mailto:b.eckenfels@seeburger.de - http://www.seeburger.de > > > > > > -----Original Message----- > > From: Yuzo Fujishima [mailto:fujishima@bc.jp.nec.com] > > Sent: Wednesday, March 10, 2004 12:04 PM > > To: wsbpel@lists.oasis-open.org > > Subject: [wsbpel] Issue 37 - Proposal for vote > > > > > > Dear WSBPEL members: > > > > In hope of expediting the discussion, I would like to propose a resolution > > for Issue - 37 - Initiating Correlation Set More Than Once. > > http://lists.oasis-open.org/archives/wsbpel/200307/msg00070.html > > > > The proposed resolution has two parts. The second part is viable only when > > the first part is accepted. In my opinion, the first part should accomodate > > the multiple start activity scenario and the second part lends itself to > > avoid inadvertent errors. > > > > Proposed resolution part-1: > > Abolish the "initiate" attribute of the "correlation" element. A correlation > > set is initiated by the first activity that references it and completes. > > All the pending and future activities in the same process instance > > referencing the same correlation set will not receive any messages that > > do not match the correlation set. > > > > Proposed resolution part-2: > > Introduce "noInitiation" attribute with default value "false" to the > > correlation element. If the attribute is set to "true", the correlation > > set must be already initiated when the referencing activity starts. If the > > correlation set is not initiated, the bpws:correlationViolation fault must > > be thrown. > > > > Sincerely, > > > > Yuzo Fujishima > > NEC Corporation > > > > > > To unsubscribe from this mailing list (and be removed from the roster of the > OASIS TC), go to > http://www.oasis-open.org/apps/org/workgroup/wsbpel/members/leave_workgroup.php. > > > > > > To unsubscribe from this mailing list (and be removed from the roster of the > OASIS TC), go to > http://www.oasis-open.org/apps/org/workgroup/wsbpel/members/leave_workgroup.php. > > > > > > > > > To unsubscribe from this mailing list (and be removed from the roster of the > OASIS TC), go to > http://www.oasis-open.org/apps/org/workgroup/wsbpel/members/leave_workgroup.php. > > > > > To unsubscribe from this mailing list (and be removed from the roster of the > OASIS TC), go to > http://www.oasis-open.org/apps/org/workgroup/wsbpel/members/leave_workgroup.php. >
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