- From: Steve Ross-Talbot <steve@pi4tech.com>
- Date: Mon, 27 Jun 2005 08:28:45 +0100
- To: "Martin Chapman" <martin.chapman@oracle.com>
- Cc: "'Gary Brown'" <gary@pi4tech.com>, "'WS-Choreography List'" <public-ws-chor@w3.org>
The bugzilla entry for 1108 says: "When an isolated sub-choreography terminates unsuccessfully, does this mean that any changes made to variables bound from its parent choreography are made visible - or are they discarded. The text in 2.4.5 only talks about the variables being made visible for read and write after the choreo has completed - but does not indicate whether that only means successful completion." The resolution for 1459 states: Proposed Text: Section 2.4.5 contains the following bullet point: " When isolation is set to "true", changes to the Variable information MUST be visible for read or for write to its sibling Choreographies only after this Choreography has completed " This should be extended to include the text: "An isolated choreography cannot directly or indirectly perform another isolated choreography." I would have thought that this closes 1108 also. Cheers Steve T On 21 Jun 2005, at 11:55, Martin Chapman wrote: > > ignore previous, hit send key premature - must be a fat finger day. > > Gary, > > I can't find any mention of 1108 in the minutes/irc log. It also wasn't > on > the agenda or on my outstanding issues list. > > The only discussion on isolation was issue 1459, and we should verify > whether > that resolution also resolves 1108 (or verify that 1108 is a dupl of > 1459). > > > Martin. > > >> -----Original Message----- >> From: Martin Chapman [mailto:martin.chapman@oracle.com] >> Sent: Tuesday, June 21, 2005 11:47 AM >> To: 'Gary Brown'; 'Steve Ross-Talbot'; 'WS-Choreography List' >> Subject: RE: Issue 1108 - proposal >> >> >> Gary I cant find any mention of 1108 in the f2f minute >> >>> -----Original Message----- >>> From: public-ws-chor-request@w3.org >>> [mailto:public-ws-chor-request@w3.org] On Behalf Of Gary Brown >>> Sent: Tuesday, June 21, 2005 9:36 AM >>> To: Martin Chapman; 'Steve Ross-Talbot'; 'WS-Choreography List' >>> Subject: Re: Issue 1108 - proposal >>> >>> >>> >>> Hi Martin, >>> >>> This was discussed at the f2f and I thought it was agreed that >>> the proposal >>> would be adopted. >>> >>> The only objection at the time from Nick was that he thought >>> BPEL did it the >>> same way as the current approach in CDL, but then when we >>> checked, it was >>> found that BPEL was inline with approach outlined in the proposal. >>> >>> Regards >>> Gary >>> >>> ----- Original Message ----- >>> From: "Martin Chapman" <martin.chapman@oracle.com> >>> To: "'Steve Ross-Talbot'" <steve@pi4tech.com>; >>> "'WS-Choreography List'" >>> <public-ws-chor@w3.org> >>> Sent: Monday, June 20, 2005 10:18 PM >>> Subject: RE: Issue 1108 - proposal >>> >>> >>> >>> For some reason this seems to have fallen through the cracks >>> so lets put it on next weeks agenda. >>> >>> Martin. >>> >>>> -----Original Message----- >>>> From: public-ws-chor-request@w3.org >>>> [mailto:public-ws-chor-request@w3.org] On Behalf Of Steve >>>> Ross-Talbot >>>> Sent: Tuesday, May 10, 2005 6:46 PM >>>> To: 'WS-Choreography List' >>>> Subject: Issue 1108 - proposal >>>> >>>> >>>> >>>> Martin, >>>> >>>> here is a possible way forward. >>>> >>>> Cheers >>>> >>>> Steve T >>>> >>>> Begin forwarded message: >>>> >>>>> Resent-From: public-ws-chor@w3.org >>>>> From: "Gary Brown" <gary@pi4tech.com> >>>>> Date: 20 April 2005 09:13:02 BST >>>>> To: <public-ws-chor@w3.org> >>>>> Subject: PROPOSAL related to: Example showing problem with current >>>>> isolation semantics in CDL >>>>> >>>>> We should clearly state in the spec that nested isolation >>>>> choreographies are not permitted. >>>>> >>>>> Proposed Text: >>>>> >>>>> Section 2.4.5 contains the following bullet point: >>>>> >>>>> " When isolation is set to "true", changes to the Variable >>>> information >>>>> MUST be visible for read or for write to its sibling Choreographies >>>>> only after this Choreography has completed " >>>>> >>>>> This should be extended to include the text: >>>>> >>>>> "An isolated choreography cannot directly or indirectly perform >>>>> another isolated choreography." >>>>> >>>>> Regards >>>>> Gary >>>>> >>>>> ----- Original Message ----- >>>>> From: Gary Brown >>>>> To: public-ws-chor@w3.org >>>>> Sent: Tuesday, April 19, 2005 12:56 PM >>>>> Subject: Example showing problem with current isolation >>> semantics in >>>>> CDL >>>>> >>>>> Hi >>>>> >>>>> After the recent discussion on isolation being inherited from the >>>>> enclosing choreography, I wanted to outline the following >>> example to >>>>> show how simply changing the isolation attribute of an enclosing >>>>> choreography can significantly change the behavior of the >>>>> choreography. >>>>> >>>>> <choreo A> >>>>> >>>>> <variable name="var1" /> >>>>> <variable name="var2" /> >>>>> <choreo B isolation=true > >>>>> >>>>> <assign value "x" to "var1" /> >>>>> <assign value "x" to "var2" /> >>>>> </choreo> >>>>> <choreo C isolation=true > >>>>> >>>>> <assign value "y" to "var1" /> >>>>> <assign value "y" to "var2" /> >>>>> </choreo> >>>>> >>>>> <parallel> >>>>> <perform choreo B> >>>>> <bind var1/> >>>>> <bind var2/> >>>>> </perform> >>>>> >>>>> <perform choreo C> >>>>> <bind var1/> >>>>> <bind var2/> >>>>> </perform> >>>>> </parallel> >>>>> </choreo> >>>>> >>>>> If choreo A is not isolated, then choreo B and C are >>>> isolated in their >>>>> own right - and therefore because they are both accessing common >>>>> variables, I assume that one or the other of the performs >> will wait >>>>> until the other has completed - so in fact they will be >>> performed in >>>>> sequence. [If this assumption is not true, then I need to have an >>>>> explanation of the behavior when two sub-choreos have the same >>>>> isolated variable - at what point do they wait?] >>>>> >>>>> Therefore the result would be that both variables would >>> have the same >>>>> value - either 'x' or 'y' depending on the order in which the >>>>> sub-choreos were actually performed. >>>>> >>>>> However, if we now make choreo A isolated, the isolated >>>> attribute on B >>>>> and C is now ignored, as the isolation is inherited from the parent >>>>> choreography (as described at the last f2f). >>>>> >>>>> This now means that because the variables 'var1' and 'var2' >>>> are within >>>>> the same isolation scope, when the two sub-choreos are performed, >>>>> there is no waiting/blocking. This means that the result of the >>>>> overall choreography is non-deterministic, the variables >> could have >>>>> any combination of 'x' or 'y'. >>>>> >>>>> The problem is that a sub-choreography may be defined on >>> the basis of >>>>> having isolation semantics - and this is effectively >>> overridden when >>>>> performed from an already isolated choreography. Whereas if nested >>>>> isolation was supported, the semantics of the >>>> sub-choreographies would >>>>> be preserved, regardless of the isolation status of the enclosing >>>>> choreography. >>>>> >>>>> This example is showing a simple example, but in a real example the >>>>> isolation of a top level choreography could have unforeseen >>>>> consequences on a sub-choreography that is many levels of nesting >>>>> removed from the isolated choreography. A case of a small change >>>>> having a significant impact on bahavior. >>>>> >>>>> Regards >>>>> Gary >>>> >>>> >>>> >>> >>> >>> >>> >>> >>> >>> >> > > > > >
Received on Monday, 27 June 2005 07:28:57 UTC