+1
Ron Ten-Hove wrote:
Dieter Koenig1 wrote:
I have not yet fully understood the issue 301.
My picture is as follows:
A. Variables and partner links are allowed to be declared but not used
- Note this is also true for correlation sets and message exchanges
Agreed.
B. Variables and partner roles of partner links are *used* when their value
is *read*
- Variables are used when they are referenced in <from> / <invoke> /
<reply>
- Partner roles of partner links are used when they are referenced in
<from> / <invoke>
C. Variables and partner roles of partner links can be uninitialized
- If they are *used* anyway then
uninitializedVariable/uninitializedPartnerRole is thrown
Questions:
1. Do we have agreement on A. & B. & C.?
2. If yes (1.), which part is left unclear by the spec?
The expected behaviour is unspecified. Consider the following:
<assign>
<copy>
<from partnerLink="foo" endpointReference="partnerRole"/>
<to partnerLink="bar"/>
</copy>
</assign>
when the source partnerLink "foo" is uninitialized. According to
section 8.1 (Variables):
An attempt
during process execution to read a variable or, in the case of a
message type variable, a part of a variable before it is initialized
MUST result in the standard bpel:uninitializedVariable
fault.
There is no equivalent language discussing how uninitialized
partnerLinks are to be handled. The <copy> could cause a fault
(but what kind?), or the copy could uninitialize the partnerRole of the
partnerLink named "bar", and wait until the process attempts to
reference the partnerRole of "bar" (and throws a
uninitializedPartnerRole fault).
The specification does not answer these questions; implementors must
choose, presumably by suiting their own tastes. Do we want to have such
variability in implementations? As it stands, given the scenario
outlined above, we could have three different behaviours, all for good
reasons:
- The <copy> throws an uninitializedVariable fault. (The
entire partnerLink is uninitialized)
- The <copy> throws an uninitializedPartnerRole fault (the
<from> role isn't initialized)
- The <copy> doesn't throw a fault at all.
Are we happy with this variability? This seems worthy of opening an
issue to discuss.
-Ron
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