[xml] question about xpath filtering

[Ottavio Campana <o campana videotec com>]

Hello,

 

I need to filter the response of a SOAP web-service. Since SOAP is based on XML, I am thinking about using libxml2, but I am not able to understand how to write an XPATH rule to achieve the desired result.

 

At the end of the message you'll find an example of the response, where two NotficationMessages are sent, one has a topic tns1:RuleEngine/LineDetector/Crossed , the other one has topic tns1:RuleEngine/CellMotionDetector/Motion .

 

I am trying to write the following XPATH expressions:

·         match any NotficationMessage whose topic is tns1:RuleEngine/LineDetector/Crossed

·         match any NotficationMessage whose topic is tns1:RuleEngine//.

·         match any NotficationMessage whose topic is everything but tns1:RuleEngine//.

 

All the examples I found match on tag attributes, not the inhalt of subtags.

 

So I'm asking.

1)      are this kinds of matching doable with libxml2?

2)      can you please give me a hint about writing the XPATH expressions?

 

Thank you for your help

 

Ottavio

 

 

<?xml version="1.0" encoding="UTF-8"?>

  <SOAP-ENV:Envelope

    xmlns:SOAP-ENV="http://www.w3.org/2003/05/soap-envelope"

    xmlns:wsa="http://www.w3.org/2005/08/addressing"

    xmlns:wstop="http://docs.oasis-open.org/wsn/t-1"

    xmlns:wsnt="http://docs.oasis-open.org/wsn/b-2"

    xmlns:tet="http://www.onvif.org/ver10/events/wsdl"

    xmlns:tns1="http://www.onvif.org/ver10/topics"

    xmlns:tt="http://www.onvif.org/ver10/schema">

    <SOAP-ENV:Header>

      <wsa:Action>  http://www.onvif.org/ver10/events/wsdl/PullPointSubscription/PullMessagesResponse

      </wsa:Action>

    </SOAP-ENV:Header>

    <SOAP-ENV:Body>

      <tet:PullMessagesResponse>

        <tet:CurrentTime>

          2008-10-10T12:24:58

        </tet:CurrentTime>

        <tet:TerminationTime>

          2008-10-10T12:25:58

        </tet:TerminationTime>

        <wsnt:NotificationMessage>

          <wsnt:Topic Dialect="http://www.onvif.org/ver10/tev/topicExpression/ConcreteSet">

            tns1:RuleEngine/LineDetector/Crossed

          </wsnt:Topic>

          <wsnt:Message>

            <tt:Message UtcTime="2008-10-10T12:24:57.321Z">

              <tt:Source>

                <tt:SimpleItem Name="VideoSourceConfigurationToken"

                               Value="1"/>

                <tt:SimpleItem Name="VideoAnalyticsConfigurationToken"

                               Value="2"/>

                <tt:SimpleItem Value="MyImportantFence1" Name="Rule"/>

              </tt:Source>

              <tt:Data>

                <tt:SimpleItem Name="ObjectId" Value="15" />

              </tt:Data>

            </tt:Message>

          </wsnt:Message>

        </wsnt:NotificationMessage>

        <wsnt:NotficationMessage>

          <wsnt:Topic Dialect="http://www.onvif.org/ver10/tev/topicExpression/ConcreteSet">

           tns1:RuleEngine/CellMotionDetector/Motion

          </wsnt:Topic>

          <wsnt:Message>

            <tt:Message UtcTime= "2010-10-20T12:24:57.628">

              <tt:Source>

               <tt:SimpleItem Name="VideoSourceConfigurationToken" Value="1"/>

               <tt:SimpleItem Name="VideoAnalyticsConfigurationToken" Value="1"/>

               <tt:SimpleItem Name="Rule" Value="MotionInDefinedCells"/>

              </tt:Source> 

              <tt:Data>

               <tt:SimpleItem Name="IsMotion" Value="true"/>

              </tt:Data>

            </tt:Message>

          </wsnt:Message>

        </wsnt:NotficationMessage>

      </tet:PullMessagesResponse>

    </SOAP-ENV:Body>

</SOAP-ENV:Envelope>