Re: [wsbpel] ISSUE # 23 Addendum && Re: [wsbpel] implicite linksof the runtime engine

[Assaf Arkin <arkin@intalio.com>]

Ram Jeyaraman wrote:

>
> CASE 2: Translating a sequence-with-explicit-links-construct into an 
> equivalent flow-with-explicit-links-construct
>
> Let's consider a sequence { a, b, c } with link dependencies b -> x 
> and c -> y, similar to the one, Satish pointed to earlier, in the 
> spec. a, b, c, x, y are all activities. Note, x and y are activities 
> outside the sequence. Translating the sequence to a flow, that is,
>
>      x  y            x    y
>
>      ^  ^            ^    ^
>      |  |         ==>>         |    |
>
> { a, b, c }         { a <- b <- c }
>
> In this case, it does not seem possible to use the same inclusive-OR 
> operation of the implicit join condition rule, on a 
> sequence-with-explicit-links-construct, in order to produce an 
> equivalent flow-with-explicit-links-construct.
>
> In this case, instead of using the implicit join condition rule, if 
> the engine uses an explicit join condition rule of
> (getLinkStatus(AtoB) && (getLinkStatus(XtoB) || getLinkStatus(..) || ..))
> then these constructs are readily exchangeable.

What you ment to say is that C should execute only after B has 
completed. The rules of the sequence is that whether B executed or 
completed immediately (since XtoB is false) does not affect whether or 
not C is executed. However, C cannot execute until after B has 
completed. This could be written as:

( getLinkStatus(BtoC) | true ) & getLinkStatus(YtoC)

arkin

>
> Note: It is also possible for an execution engine to use for CASE 1, 
> the explicit join condition of CASE 2, instead of the implicit 
> inclusive-OR join condition. That is, CASE 1 become a special case of 
> CASE 2. This makes unnecessary the use of implicit join condition for 
> the translation.
>
> peter.furniss@choreology.com: Peter, could you add this as an addendum 
> to issue 23, please? thank you.
>
>
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----------------------------------------------------------------------
Assaf Arkin                                          arkin@intalio.com
Intalio Inc.                                           www.intalio.com
The Business Process Management Company                 (650) 577 4700


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