Thanks Jones for your help but still i am some queries
1. How to search for elements which belong to default namespace i.e., i want 
to use XML1 model . I had tried by setting the (default and extension) 
namespaces using the IXMLDOMDocument2_setProperty function.
 i.,e for the following xml document, I want to search the following pattern 
"//tuple"
       <?xml version=\"1.0\"?>
       <presence xmlns=\"urn:ietf:params:xml:ns:pidf\"
              xmlns:ex=\"urn:ietf:params:xml:ns:pidf:ex\" >
       <tuple id='xyz'>
       <status><basic>online</basic><ex:ex>busy</ex:ex></status>
       </tuple>
       <tuple id='xyz1'>
       <status><basic>offline</basic></status>
       </tuple>
       </presence>

"Anthony Jones" wrote:

> 
> "sai" <sai@d...> wrote in message
> news:B2EB7545-DFD0-45B9-A79D-8EBABD18951F@m......
> > I have the following xml files.
> >
> > xml1:
> > <?xml version=\"1.0\"?>
> > <presence xmlns=\"urn:ietf:params:xml:ns:pidf\"
> > xmlns:ex=\"urn:ietf:params:xml:ns:pidf:ex\" >
> > <tuple id='xyz'>
> > <status><basic>online</basic><ex:ex>busy</ex:ex></status>
> > </tuple>
> > <tuple id='xyz1'>
> > <status><basic>offline</basic></status>
> > </tuple>
> > </presence>
> > xml2:
> >   <?xml version=\"1.0\"?>
> > <tns:presence xmlns:tns=\"urn:ietf:params:xml:ns:pidf\"
> > xmlns:ex=\"urn:ietf:params:xml:ns:pidf:ex\" >
> > <tuple id='xyz'>
> > <status><basic>online</basic><ex:ex>busy</ex:ex></status>
> > </tuple>
> > <tuple id='xyz1'>
> > <status><basic>offline</basic></status>
> > </tuple>
> > </tns:presence>
> >
> > 1. If I use the "xml1" xml file and execute the following XPath query
> > "//tuple",  I got the response as 0 nodes matched
> > 2: If I use the "xml2" file and execute the same XPath query as above,
> then
> > I got the response as 2 nodes matched.
> >
> > Q1. I do not see any difference in the xml files and both represent same
> > thing but why do i   get differnet response for the same query. Is is
> > mandatory to write namespace declarations similar to that of in xml file
> > "xml2".
> 
> In XML1 you set the default namespace whereas in XML2 you do not.  Since
> tuple has no namepace alias it is part of the default namespace.  However
> XPath searches are not affected by alias declarations in the document hence
> it will search the no-name namespace.    In XML2 tuple belongs to the
> no-name namespace hence the XPath finds it whereas in XML1 tuple belongs to
> the urn:ietf:params:xml:ns:pidf namespace so it doesn't.
> 
> > Q2. How should be the XPath query for searching for "ex:ex" element? If I
> > use the following XPath query, I am getting the response as 0 nodes
> matched.
> 
> In order to search other namespaces using XPath it needs to be informed of
> them.
> This is done using a secondary property on the DOM which is set via the
> setPropery method on the IXMLDOMDocument2 interface.  E.g.-
> 
> oDOM.setProperty("SelectionNamespaces",
> "xmlns:tns='urn:ietf:params:xml:ns:pidf'
> xmlns:ex='urn:ietf:params:xml:ns:pidf:ex'")
> 
> (I don't know C well enough to port this for you)
> 
> Note that eh alias names uses in the above do not need to match the alias
> names used in the document.  Eg. the following XPath will find the tuple
> nodes in XML1:-
> 
> "//tns:tuple"
> 
> Even though tns isn't used in XML1.
> 
> I suspect that you will also need:-
> 
> oDOM.setProperty("SelectionLanguage", "XPath")
> 
> to ensure MSXML3 is actually using XPath.
> 
> 
> 
> 
> 
> >
> > Thanks in advance for your help.
> 
> 
>