namespace: Proper xpath for libxml2

Question

I am trying to use xpath1, on the following SOAP XML file:

• https://raw.githubusercontent.com/mrjeffstevenson3/mmimproc/master/data/testdata/examcard/SR_ADULT_007.ExamCard

I tried a simple one:

% ./xpath1 SR_ADULT_007.ExamCard "//SOAP-ENC:Array[@id='ref-297']"
XPath error : Undefined namespace prefix
Error: unable to evaluate xpath expression "//SOAP-ENC:Array[@id='ref-297']"
Usage: ./xpath1 <xml-file> <xpath-expr> [<known-ns-list>]
where <known-ns-list> is a list of known namespaces
in "<prefix1>=<href1> <prefix2>=href2> ..." format

However my XPath perl command seems to contradict the above:

% xpath -e "//SOAP-ENC:Array[@id='ref-297']" SR_ADULT_007.ExamCard > /dev/null
Found 1 nodes in SR_ADULT_007.ExamCard:
-- NODE --

What did I misunderstood from libxml2/xpath/namespace convention ?

Answer 1

The correct syntax for xpath1 example is simply (thanks Conal!):

% ./xpath1 SR_ADULT_007.ExamCard "//SOAP-ENC:Array[@id='ref-297']" SOAP-ENC=http://schemas.xmlsoap.org/soap/encoding/
Result (1 nodes):
= element node "http://schemas.xmlsoap.org/soap/encoding/:Array"