Alex,
XPath 2.0 and XQuery
1.0 will help out, but in the mean time, introducing an XPath function to
retrieve an external document will have the side effect that you would be able
to dynamically build the location path, such as in the example
below:
<from
expression=”bpws:getExternalDocument(concat(‘/mylocation/’,
$myInputVariable/a:myPart/a:myData))”/>
Thus effectively
removing any possibility of static analysis and you also introduce a level of
logic into the fetching of an external document that will probably be better
handled by an external web service. Not to mention the security implications
of a dynamically generated path based on some unknown
input.
Regards
Kristofer
From: Alex Yiu
[mailto:alex.yiu@oracle.com]
Sent: Monday, April 26, 2004 7:09
PM
To: Kristofer Agren
Cc: edwink@collaxa.com; 'Martin Chapman';
'Dieter Koenig1'; wsbpel@lists.oasis-open.org; Alex Yiu
Subject: Re: [wsbpel] Issue - 90 -
Proposal to vote
Hi,
For runtime-include, XPath function is
a good way to go.
When BPEL moves to XPath 2.0 or XQuery 1.0 model,
the function used in XPath / XQuery can be associated with metadata. And,
static analysis will be able to be performed.
Regards,
Alex
Yiu
Kristofer Agren
wrote:
By using an XPath function, unless the BPEL implementation can thoroughly
validate the XPath expressions, you loose the benefit of static analysis and
the business process may fail at run time, for example because the external
document is not valid or the location may be wrong.
Regards,
Kristofer
-----Original Message-----
From: Edwin Khodabakchian [mailto:edwink@collaxa.com]
Sent: Monday, April 26, 2004 3:25 PM
To: 'Martin Chapman'; 'Dieter Koenig1'; 'Kristofer Agren'
Cc: wsbpel@lists.oasis-open.org
Subject: RE: [wsbpel] Issue - 90 - Proposal to vote
+1. Specially given that it is fairly straight forward to create an XPATH
function to emulate this functionality. -Edwin
-----Original Message-----
From: Martin Chapman [mailto:martin.chapman@oracle.com]
Sent: Monday, April 26, 2004 10:55 AM
To: 'Dieter Koenig1'; 'Kristofer Agren'
Cc: wsbpel@lists.oasis-open.org
Subject: RE: [wsbpel] Issue - 90 - Proposal to vote
+1
-----Original Message-----
From: Dieter Koenig1 [mailto:dieterkoenig@de.ibm.com]
Sent: 26 April 2004 08:46
To: Kristofer Agren
Cc: wsbpel@lists.oasis-open.org
Subject: Re: [wsbpel] Issue - 90 - Proposal to vote
Kristofer, the use case for having an external document that
is part of the business process is not clear to me. Why is
this not a literal residing inside of the process definition.
In addition, such document references would create a new
problem as I see no obvious way of recognizing changes of the
external artifacts. Kind Regards DK
"Kristofer Agren"
<kagren@pakalert.
com>
To
<wsbpel@lists.oasis-open.org>
23.04.2004 04:49
cc
Subject
[wsbpel] Issue - 90 -
Proposal to
vote
Hello all,
Here is a proposal to vote for issue 90 (
http://www.choreology.com/external/WS_BPEL_issues_list.html#Issue90):
-----------------
Proposed solution:
Introduce a new form of the <from> element:
<from location="document-location" query="queryString"?/>
The query attribute has the same semantics as the normal query
attribute on the <from> element, i.e. it must be an absolute
location path and select exactly one node. If no query is
specified, the root node of the XML document is selected. The
document-location is a URL (as defined in RFC
2396) that refers to an XML document, and in the case that the
XML document is not valid and/or a single node cannot be
returned, a selectionFailure fault should be thrown by a
compliant implementation. The document that is retrieved from
the URL is considered static in the same way the business
process definition is considered static during execution.
Furthermore, the external document is considered part of the
business processes that reference it, and conversely, the
business process definition should not be considered complete
or valid without the external document. A change in the
external document should be treated in the same way as a
change in the business process definition.
This <from> form can be used in conjunction with all the <to> forms.
-----------------
Regards,
Kristofer Agren
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