[SR-Users] presence_xml and xpath

[Daniel-Constantin Mierla]

Hello,

On 12/6/10 6:09 PM, Andreas Granig wrote:
> Hi Daniel,
>
>>> How is this actually supposed to work? What I'd like to do in the end is
>>> extracting for example the "none" from the "basic"-tag by specifying
>>> "xpath:/presence/tuple/status/basic", which also returns an empty string
>>> now, also when appended with "/text()".
>> the problem is in between IETF and XML guys :-)
>>
>> xpath require to use a prefix for namespaces. The SIMPLE guys liked to
>> set a default one without prefix.
>>
>> For this case, try:
>>
>> modparam("presence_xml", "xml_ns", "pidf=urn:ietf:params:xml:ns:pidf")
>>
>> then:
>>
>> xlog("L_INFO",
>> "tmp2=$xml(x=>xpath:/pidf:presence/pidf:tuple/pidf:status/pidf:basic)\n");
> Got it. But what if it gets a bit more difficult than that? :)
>
> I've an xml document where the namespace for some elements changes, like
> this:
>
> <?xml version="1.0" encoding="utf-8"?>
> <presence xmlns="urn:ietf:params:xml:ns:pidf" entity="sip:foo at mydomain.com">
>    <tuple id="86ae65b7-42de-4399-b635-295caad13aac">
>      <status>
>        <basic>none</basic>
>        <geopriv xmlns="urn:ietf:params:xml:ns:pidf:geopriv10">
>          <location-info>
>            <location xmlns="http://www.opengis.net/gml">
> [snip]
>
> As you can see, the "geopriv" element changes the namespace from "pidf"
> to "pidf:geopriv10". Even giving the full namespace
> (".../urn:ietf:params:xml:ns:pidf:geopriv10:geopriv") to capture the
> "geopriv" element results in
>
> ERROR: presence_xml [pv_xml.c:310]: unable to evaluate xpath expression
> [/pidf:presence/pidf:tuple/pidf:status/urn:ietf:params:xml:ns:pidf:geopriv10:geopriv/83]
>
> Any ideas are highly appreciated :)

you can define many xml_ns parameters, each with different prefix. I 
guess the inner xmlns overwrites the other one in your sample xml 
document, so you have to use different prefix for that nodes:

modparam("presence_xml", "xml_ns", "pidf=urn:ietf:params:xml:ns:pidf")
modparam("presence_xml", "xml_ns", "geop=urn:ietf:params:xml:ns:pidf:geopriv10")

Try a path like:
/pidf:presence/pidf:tuple/pidf:status/geop:geopriv/...

Hope it works.

Daniel


-- 
Daniel-Constantin Mierla
Kamailio (OpenSER) Advanced Training
Jan 24-26, 2011, Irvine, CA, USA
http://www.asipto.com