This suggestion is related to 241 and 204.
For more consistency across event handlers and forEach, if we allow
variables to be declared in the EH's associated scope:
"For cross-reference redundancy and clarity, these variables referenced
by
variable attribute or <fromPart> element may be optionally
declared in the
associated scope explicitly. If explicitly declared, variable types
used in
declaration MUST be exact matches of the correponding definitions in
WSDL."
then it would make sense to allow the optional explicit declaration of a
counter variable (in a scope associated with forEach) as well.
Any opinion?
Kind Regards
DK
Alex
Yiu
<alex.yiu@oracle.
com> To
wsbpeltc
07.03.2006 05:44
<wsbpel@lists.oasis-open.org>
cc
Alex Yiu
<alex.yiu@oracle.com>,
Danny van der
Rijn
<dannyv@tibco.com>, Mark
Ford
<mark.ford@active-endpoints.com>
Subject
[wsbpel] Issue 241 - Proposal
for
Vote
Hi all,
Here is the formal proposal for voting for Issue 241:
PDF version: (9 page)
http://www.oasis-open.org/apps/org/workgroup/wsbpel/download.php/17023/wsbpel-specification-draft.241_proposal_v2b.pdf
MS-Word version: (9 page of changes on top of whole spec)
http://www.oasis-open.org/apps/org/workgroup/wsbpel/download.php/17024/wsbpel-specification-draft.241_proposal_v2b.doc
90% of changes are same as the draft that I sent out last week with some
extra clarification and cleaning up syntax in the direction of voting
decision of Issue 242.
Please let me know ahead of time, if you guys have any idea of friendly
amendments or fine-tuning of wordings.
Thanks!
Regards,
Alex Yiu
Alex Yiu wrote:
Hi all,
Here is the proposal draft for Issue 241.
PDF version of 9 pages which contain the changes
http://www.oasis-open.org/apps/org/workgroup/wsbpel/download.php/16945/wsbpel-specification-draft.241_proposal_draft.pdf
MS-Word version of changes applied to the whole spec text (based
on a
very recent version from CVS):
http://www.oasis-open.org/apps/org/workgroup/wsbpel/download.php/16944/wsbpel-specification-draft.241_proposal.doc
Note:
[1]
One more normative changes we need to make (but not a part of the
PDF) is to amend/clarify resolution of Issue 123 in a very minor
way
as follow:
From: "This resolution follows the same scoping rules as variable
and
correlationSet resolution."
To: "This resolution follows the same scoping rules as
correlationSet
resolution."
[2]
In this proposal, I did try to clean up some syntactic issue of
<onEvent> not directly related to issue 242. (e.g. making
variable
attribute optional because of <fromPart>).
I do intend to come up a consolidated proposal based on the
(directional) decision of Issue 242. Because there are a number of
places in desc text of <onEvent> (not just syntax) needs to
be
fine-tuned a bit more after syntactic decisions are made. Here are
two syntactic decisions need to be made:
[a] moving <correlationSets> "inline" declaration to the
associate
scope (regardless of decision of [b] below: whether the associated
scope is collapse into <onEvent>). [Currently, I tend to
say we
should move declaration to make the syntax more consistent with
other
scope-related syntax]
[b] core decision for Issue 242: whether to collapse scope syntax
into <onEvent> syntax. Namely, we have 3 choices here:
(i) Yes, we collapse. The syntax is based XSD extend. Example:
---------------------------
<onEvent ... partnerLink="..." variable="..."
isolated="..." name="...">
<partnerLinks> ... </partnerLinks>
<variables> ...
</variables> <correlationSets> ...
</correlationSets>
... main activity
<correlations> ... </corelations>
<fromPart ... />*
</onEvent>
---------------------------
(ii) Yes, we collapse. Its syntax is NOT derived scope. (That
means
we need to main a separate, duplicated, different and yet similar
grammar rule.) Example:
---------------------------
<onEvent ... partnerLink="..." variable="..."
isolated="..." name="...">
<correlations> ... </corelations>
<fromPart ... />*
<partnerLinks> ... </partnerLinks>
<variables> ...
</variables> <correlationSets> ...
</correlationSets>
... main activity
</onEvent>
---------------------------
(iii) No. We do not collapse. Instead, we choose the
"extend-by-containment" approach. Example:
---------------------------
<onEvent ... partnerLink="..." variable="...">
<correlations> ... </corelations>
<fromPart ... />*
<scope ... isolated="..." name="...">
<partnerLinks> ... </partnerLinks>
<variables> ...
</variables> <correlationSets> ...
</correlationSets>
... main activity </scope>
</onEvent>
---------------------------
Further analysis (from my viewpoint):
The main reason that I heard from proponents of collapse
seems
to be elminiating forward-reference pattern (i.e. a
resource is
declared after reference in source code order). IMHO, that
is a
commonly used situation in a lot of programming language.
Furthermore, you can see later that this situation cannot be
elminated even if we decide to collapse those syntax.
The syntax order in (i) just seems very odd and unnatural
and
make the source code visualization much harder. And,
forward-reference still happens for variable and
partnerLink.
For the syntax in (ii), forward-reference still happens for
variable and partnerLink. The interleaving syntax
(highlighted
blue and brown) make it harder for people to learn and
remember
what is exactly <onEvent> is about. Moreover, we will
be forced
to duplicated grammar rule for tScope for no compelling
reasons. Make BPEL source code syntax analyser
implementation
more difficult.
For the syntax in (iii), I personally prefer the most.
Because,
the syntax groups syntax common to <scope> and
specific to
<onEvent> in a clean and easy-to-learn way.
<onEvent> syntax is
the outer syntax, while <scope> is the inner syntax.
It does
not require any XSD grammar rule duplication. And, it makes
use
of another common and useful design pattern -
"extend-by-containment".
Ideally, I want to submit a proposal (potentially with Danny) that
resolve both Issue 241 and 242. That will minimize any risk
inconsistent and "leftover" editing issue in that section.
[3]
For Issue 245, assuming it is opened. I agree with Danny and Mark
there. This proposal draft contains an attempt to clean up Section
12.5.7 which is also a part of "Event Handlers" section.
Thanks!
Regards,
Alex Yiu
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