Re: [wsbpel] A possible issue concerning the definition of IMA scope

["Monica J. Martin" <Monica.Martin@Sun.COM>]

> yiu:
> Hi, Ron,
> Besides 10.4.1, another relevant part of IMA and message exchange 
> handling is in section 12.2:
> ------------------------
>
>
>       12.2. Message Exchange Handling
>
> When the primary activity and the event handlers of a <scope> complete 
> then all Web service interactions dependent on partner links or 
> message exchanges declared inside of the <scope> need to be completed. 
> An /orphaned IMA/ occurs when an IMA using a partner link or message 
> exchange, declared in the completing <scope> or its descendants, 
> remains open.  ....
> ------------------------
>
> If we do a brief update in 10.1.4

Correction (typo): 10.4.1

> from:
> -----------------------
> Further if an open IMA goes out of scope prior to being closed
> -----------------------
> to:
> -----------------------
> Further if an open IMA goes out of scope *(known as an orphaned IMA)* 
> prior to being closed
> -----------------------

mm1: Alex, perhaps we would also add a small revision (see **...**).

Section 10.4.1
"An open IMA (known as an orphaned IMA) describes the state of a Web Service operation **and its bounds** from the point that a requestresponse IMA starts execution until an associated <reply> activity completes successfully."

We may also consider one sentence that is explicit regarding named and default messageExchange.
"Unless expressed otherwise, a default messageExchange follows the scoping rules a named messageExchange."

Note that I avoided 'and its scope' to alleviate any confusion (if possible). We have received questions about both.

>   from:
> -----------------------
> (see section 12. Scopes for other details of bpel:missingReply).
> -----------------------
> to:
> -----------------------
> (see section *12.2 Message Exchange Handling* for other details of 
> bpel:missingReply *and orphaned IMA*).
> -----------------------
>
> then, it may improve ease of understanding.
>
>
> Please see more inline:
>
> Ron Ten-Hove wrote:
>
>> An IMA has associated with it three scopes, two of which are 
>> associated with its identity:
>>
>>     * The scope in which the IMA itself is defined
>>     * The scope of its partnerLink
>>     * The scope of its messageExchange name (including default name,
>>       of course)
>>
>> This leads to a question: when we speak of the "scope of an IMA", 
>> what precisely do we mean? Section 10.4.1 doesn't really answer this, 
>> and I've heard good arguments for a variety of definitions for IMA scope:
>>
>>    1. Its the scope of the activity, the same of any other activity.
>>    2. Its the scope of the partner link. IMAs are special, and must
>>       be paired with a <reply>, so the association between the IMA
>>       and <reply> logically belongs to the partnerLink. It follows
>>       that the IMA belongs to the partnerLink, and thus its scope.
>>    3. Its the scope of the messageExchange name shared between the
>>       IMA and the <reply>. This name (even if it is the default name)
>>       indicates the association between the IMA and the <reply>, and
>>       thus the IMA logically belongs to the ME name's scope.
>>    4. Both 2 & 3 are correct, with the scope closest to the root
>>       (process) scope being the correct choice if the partnerLink and
>>       messageExchange are not in the same scope. (They both must be
>>       enclosing scopes for both the IMA and the <reply> activities.)
>>
>
> *[AYIU]*: I have not found the exact usage of term "scope of an IMA". 
> But I do find the usage of "an open IMA goes out of scope". I hope my 
> above suggestion make it easier to read and understand.
>
> I think the answer is definitely not choice #1. The answer will be the 
> fifth one, as indicated in section 12.2: the closest scope to the IMA 
> activity, if partnerLink and messageExchange are declared in different 
> scopes.
>
> Because, <reply> activities need _both_ partnerLink and 
> messageExchange (maybe implicit) to match an IMA.
>
>> As an illustrative (and abbreviated) example:
>>
>>process
>>   partnerLink foo
>>   messageExchange bar
>>   sequence
>>      scope X
>>         ...
>>         receive partnerLink foo messageExchange bar
>>         ...
>>      ...
>>      reply partnerLink foo messageExchange bar
>>  
>>
>> Case 1 would deem this to be an invalid process, for when scope X 
>> completes, it will hold an open IMA, causing a bpel:missingReply 
>> fault. In cases 2-4, this would be considered valid, since the 
>> <receive> IMA belongs to the process scope.
>>
> *[AYIU]*: The above example is definitely a valid process.
>
>> My question for the TC is this: what is the scope of an IMA? Have I 
>> missed the appropriate text in the spec that clarifies this, should 
>> we add a clarification, presumably in section 10.4.1? If 
>> clarification is necessary, what will our definition of IMA scope be?
>>
>> -Ron
>
>
> *[AYIU]*:
> I tend to think the description in description in 12.2  is clear 
> enough. IMHO, we may not need any new big paragraph. A refinement of 
> cross reference should be good enough.
>
>
> Thanks!
>
>
> Regards,
> Alex Yiu
>
>