[Engine-devel] Issue with XML namespaces in engine-setup

[Juan Hernandez]

On 04/11/2012 09:51 AM, Ofer Schreiber wrote:
> 
> 
> ----- Original Message -----
>> Hello,
>>
>> The code that we use in engine-setup to modify JBoss AS XML
>> configuration files uses the following pattern:
>>
>> datasourceStr = '''
>>     <datasource ...>
>>        ...
>>     </datasource>
>> '''
>>
>> xmlObj.addNodes("//datasource:subsystem/datasource:datasources",
>> datasourceStr)
>>
>> This looks correct but is in fact generating a incorrect XML
>> document,
>> as the tags being added are not associated to a namespace. The
>> resulting
>> XML file will be correct, but the temporary representation in memory
>> is
>> not. This causes problems if you later, before writing out the
>> modified
>> file, try to use xpath expressions matching the added nodes: there
>> will
>> be no match.
>>
>> I would suggest that we change the pattern to something like this:
>>
>> datasourceStr = '''
>>   <any_dummy_tag xmlns="urn:jboss:domain:datasources:1.0">
>>     <datasource ...>
>>        ...
>>     </datasource>
>>   </any_dummy_tag>
>> '''
>> datasourceNodes =
>> libxml2.parseDoc(datasourceStr).getRootElement().children
>>
>> xmlObje.addNodes("//datasource:subsystem/datasource:datasources",
>> datasourceNodes)
>>
>> This way both the representation in memory and the resulting file are
>> correct.
>>
>> Le me know what you think.
> 
> As long as it work, I have no problem with that, sounds the right thing to do.
> btw- why would you want to use xpath on the "in memory" xml? (In your specific case I mean, not in general)

The specific case is that in the Fedora 17 JBoss AS RPM the default
standaonle.xml file doesn't contain a <datasources> tag, so I wanted to
do something like this:

1. Check if the datasources tag is there, if not add it.
2. Add the new datasource tag, like we do now.

Step 2 fails: the xpath that we use in xmlObj.addNodes doesn't match the
datasources tag added in step 1 because the in memory XML is not using
the right namespace.

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