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| nathanw |
 Posted: Wed Jan 30, 2013 9:12 am Post subject: Java Compute Node - evaluateXPath |
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Knight
Joined: 14 Jul 2004
Posts: 550
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Ok this has been implemented in the past and not by me I am just trying to find out why suddenly post V8 upgrade that the evaluateXPath function in a java compute node is failing in V8 when it worked in V6
The code snippet within the node is as follows (de-sensitised)
| Code: |
MbMessage inMessage = contact admin.getMessage();
MbMessage outMessage = new MbMessage(inMessage);
MbMessageAssembly outAssembly = new MbMessageAssembly(contact admin, outMessage);
String transferMnemonics= (String) inMessage.getRootElement().getFirstElementByPath("filepath").getValue();
String fileName = (String) inMessage.getRootElement().getFirstElementByPath("filename").getValue();
outMessage.getRootElement().getLastChild().detach();
MbElement outRoot = outMessage.getRootElement();
MbElement outBody = outRoot.createElementAsLastChild("XMLNSC");
// This block has changed to include file name in the trigger call
outMessage.evaluateXPath("/?is04_service_request/?@xmlns:xsi[set-value('http://www.w3.org/2001/XMLSchema-instance')]");
outMessage.evaluateXPath("/is04_service_request/?$action/?@step[set-value(1)]" ); |
the error being received is (again de-sensitised)
| Code: |
2013-01-30 14:19:01.705552 5451 UserTrace BIP2231E: Error detected whilst processing a message in node 'NODENAME'.
The message broker detected an error whilst processing a message in node 'NODENAME'. The message has been augmented with an exception list and has been propagated to the node's failure terminal for further processing.
See the following messages for details of the error.
2013-01-30 14:19:01.705580 5451 RecoverableException BIP2230E: Error detected whilst processing a message in node 'NODENAME2'.
The message broker detected an error whilst processing a message in node 'NODENAME2'. An exception has been thrown to cut short the processing of the message.
See the following messages for details of the error.
2013-01-30 14:19:01.705588 5451 RecoverableException BIP4359E: XPath query ''/?is04_service_request/?@xmlns:xsi[set-value('http://www.w3.org/2001/XMLSchema-instance')]'' has an undefined namespace prefix ''xmlns''
All namespace prefixes in an XPath expression must be mapped to a namespace URI. The prefix quoted in the error message is not mapped.
If you created the XPath expression using the XPath Expression Builder in the Toolkit:
- Open the XPath Expression Builder.
- Expand the 'Namespace Settings' section.
- Add the prefix and its URI to the list.
- Redeploy the message flow.
If you supplied the XPath expression in a monitoring profile through a configurable service:
- Add a 'prefixMapping' element to the monitoring profile.
- Update the configurable service that contains the monitoring profile. |
So folks do we know of any changes in V8 that could have affected this?
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| lancelotlinc |
| Posted: Wed Jan 30, 2013 9:33 am Post subject: |
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Jedi Knight
Joined: 22 Mar 2010
Posts: 4941
Location: Bloomington, IL USA
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There is an APAR out related to the XERCES component of the WMB runtime about it running out of memory and generating errors like this. You'll need to open a PMR to get the APAR as the fix isn't scheduled for GA until next quarter. I don't have my notes any more about it, so I can't give you the number.
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| nathanw |
| Posted: Thu Jan 31, 2013 2:14 am Post subject: |
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Knight
Joined: 14 Jul 2004
Posts: 550
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lancelotinc
thanks for the reply if you can find any info linking this i would be grateful
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| kimbert |
| Posted: Thu Jan 31, 2013 4:54 am Post subject: |
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Jedi Council
Joined: 29 Jul 2003
Posts: 5542
Location: Southampton
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I don't think this is caused by that APAR. It looks like a simple configuration issue. Are you 100% sure that this worked OK in v6? Because there haven't been any major changes in this area for a long time.
Regardless, the error message is very specific about how to fix it - you need to declare all of the prefixes that your XPath expression uses. If v6 was allowing you to omit some of them then that was probably a defect in v6. |
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| mqjeff |
| Posted: Thu Jan 31, 2013 4:57 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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| kimbert wrote: |
| you need to declare all of the prefixes that your XPath expression uses. If v6 was allowing you to omit some of them then that was probably a defect in v6. |
This is done by creating an MbXPath object, and setting the namespace prefixes on that object before executing the query.
Using xpath for this simple a task, however, seems a bit unnecessary. |
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| nathanw |
| Posted: Fri Feb 01, 2013 6:29 am Post subject: |
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Knight
Joined: 14 Jul 2004
Posts: 550
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as an update talking about this with IBM the initial response was they were not sure if this was a XPATH expression issue or an underlying issue with the XPATH engine itself.
@kimbert I agree about the defect in V6 as we have had similar points to ponder in the past where we have had to change a line of esql in V8.
I am looking at the expression side of things as well as waiting for response from IBM
Thanks for all your inputs so far
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| kimbert |
| Posted: Fri Feb 01, 2013 9:24 am Post subject: |
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Jedi Council
Joined: 29 Jul 2003
Posts: 5542
Location: Southampton
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| Quote: |
| talking about this with IBM the initial response was they were not sure if this was a XPATH expression issue or an underlying issue with the XPATH engine itself. |
It's 'neither of the above'.
The XPath specification requires that every namespace prefix is mapped to a URL. It doesn't say how this mapping should be done. The WMB Java API does it in the way described by mqjeff above. |
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| nathanw |
| Posted: Tue Feb 05, 2013 4:11 am Post subject: |
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Knight
Joined: 14 Jul 2004
Posts: 550
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As an update
"We" have coded a work around to this issue.
The original code was
| Code: |
| outMessage.evaluateXPath("/?is04_service_request/?@xmlns:xsi[set-value('http://www.w3.org/2001/XMLSchema-instance')]"); |
This was changed to be
| Code: |
| outMessage.evaluateXPath("/?is04_service_request"); |
The process now works with the javanode initiating the application trigger to read the file.
I can only assume that V6 worked the same way but ignored the second portion whereas V8 reads the entire portion and was trying to use the data and failing as it was not a real "link"
As ever thanks for the advice chaps.
I have informed IBM of the change and that if they have anything further to add then they should let us know.
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| kimbert |
| Posted: Tue Feb 05, 2013 5:16 am Post subject: |
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Jedi Council
Joined: 29 Jul 2003
Posts: 5542
Location: Southampton
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| Quote: |
| I can only assume that V6 worked the same way but ignored the second portion whereas V8 reads the entire portion and was trying to use the data and failing as it was not a real "link" |
I cannot work out why you are assuming that. The error message was very specific: you did not provide bindings for all of the namespace prefixes in the query. WMB v8 is applying that rule strictly - as v6.1 should have done.
What am I missing? ( Vitor and mqjeff: polite answers only, please ) |
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| mqjeff |
| Posted: Tue Feb 05, 2013 5:18 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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| kimbert wrote: |
| What am I missing? ( Vitor and mqjeff: polite answers only, please ) |
If I phrase it in the form of a question, is it still an answer? |
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| Vitor |
| Posted: Tue Feb 05, 2013 5:31 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| kimbert wrote: |
| What am I missing? ( Vitor and mqjeff: polite answers only, please ) |
That hurts. As the truth often does.
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| fjb_saper |
| Posted: Tue Feb 05, 2013 10:48 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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| kimbert wrote: |
| Quote: |
| I can only assume that V6 worked the same way but ignored the second portion whereas V8 reads the entire portion and was trying to use the data and failing as it was not a real "link" |
I cannot work out why you are assuming that. The error message was very specific: you did not provide bindings for all of the namespace prefixes in the query. WMB v8 is applying that rule strictly - as v6.1 should have done.
What am I missing? ( Vitor and mqjeff: polite answers only, please ) |
Don't think you're missing anything at all. As I remember V7 already worked the correct way. So this might be strictly a V6 problem... 
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| rekarm01 |
| Posted: Wed Feb 06, 2013 2:04 am Post subject: Re: Java Compute Node - evaluateXPath |
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Grand Master
Joined: 25 Jun 2008
Posts: 1415
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| nathanw wrote: |
| Code: |
| outMessage.evaluateXPath("/?is04_service_request/?@xmlns:xsi[set-value('http://www.w3.org/2001/XMLSchema-instance')]"); |
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'@' is the wrong axis-specifier to use for namespace declarations. Use 'namespace::' instead.
| kimbert wrote: |
| Regardless, the error message is very specific about how to fix it - you need to declare all of the prefixes that your XPath expression uses. |
The XML namespace standard prohibits an explicit declaration for the 'xmlns' prefix itself. MbXPath should not require adding a namespace prefix for it.
It's more likely that the error is indirectly due to the wrong axis-specifier. The 'xmlns' prefix is meant only for namespace declarations, not for other attributes. |
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| kimbert |
| Posted: Wed Feb 06, 2013 5:45 am Post subject: |
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Jedi Council
Joined: 29 Jul 2003
Posts: 5542
Location: Southampton
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| Quote: |
| The XML namespace standard prohibits an explicit declaration for the 'xmlns' prefix itself. MbXPath should not require adding a namespace prefix for it. |
That's a very good point - thanks.
| Quote: |
| It's more likely that the error is indirectly due to the wrong axis-specifier. The 'xmlns' prefix is meant only for namespace declarations, not for other attributes. |
Right - so the error message is insisting on the 'xmlns' prefix only because the axis specifier says that this is a normal attribute. That's a theory worth following up on. |
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