Re: [xsl] Why doesn't this simple XSLT (Identity transform) work?

[<ohaya@xxxxxxx>]

Hi Ken,

Also, I think that what was 'throwing me off' was that the "sig:" namespace was implicit.  That was why I was using just "Signature" instead of "sig:Signature".

Thanks again,
Jim


---- ohaya@xxxxxxx wrote: 
> Hi Ken,
> 
> Thanks, not just for the solution, but for the VERY detailed explanation.  I know that I'll have to re-re-read your post, probably several more times, but if I'm understanding, basically the problem was that the match I was using was not matching anything, so that xsl:template was not "catching", and the reason for not matching was because of the namespace.
> 
> Is that right?
> 
> Thanks again,
> Jim
> 
>  
> 
> 
> ---- "G. Ken Holman" <gkholman@xxxxxxxxxxxxxxxxxxxx> wrote: 
> > At 2009-12-01 19:43 -0500, ohaya@xxxxxxx wrote:
> > >It's been awhile since I've worked with XSLT, but I'm having to 
> > >implement one that removes an element (<Signature>) from the 
> > >incoming (SOAP) message.
> > 
> > Actually, you want to remove the element:
> > 
> >   {http://www.w3.org/2000/09/xmldsig#}Signature
> > 
> > ... regardless of the prefix used in the syntax of the input XML.
> > 
> > >I know that this should be simple, and I know that I have written 
> > >similar XSLT before, but for some reason, I can get this to work.
> > 
> > You are forgetting that XSLT matches on the expanded name of a node 
> > and not the specified name of the node.  Prefixes are irrelevant 
> > (other than playing the role of associating the namespace URI string 
> > for the expanded name).
> > 
> > >Here's an example SOAP message:
> > >...
> > >And, here's the XSLT that I'm using:
> > >...
> > 
> > Thank you for providing the plug-and-play.
> > 
> > >What the XSLT seems to be doing is just doing the Identity 
> > >transform, and copying everything from the input message to the 
> > >output, i.e., the "<xsl:template match="//Signature">" is not 
> > >getting processed at all.
> > 
> > Right.  And, BTW, the "//" isn't needed, but that isn't what is wrong.
> > 
> > >I've tried different things for that template match, including just 
> > >"Signature", a "fully-qualified" match term, etc.
> > 
> > You didn't try a qualified name match.  A qualified name has as its 
> > lexical space the specified name for the element and as its value 
> > space the expanded name for the element.  Two qualified names are 
> > compared by their expanded names.  A qualified name is exposed and 
> > written using the specified name and the in-scope namespaces for the 
> > prefix used or not by the specified name.
> > 
> > >I have the impression that the XSLT processing should always use the 
> > >more specific match (i.e., the one above, and not the Identity 
> > >transform), but it doesn't seem to be working :(...
> > 
> > That isn't true in general but happens to be true in this case, you 
> > just haven't named the element properly.
> > 
> > Some of the detail relevant to your situation is that every match 
> > pattern that is more complex than a simple name has the same inferred 
> > priority of 0.5, without any kind of "increasing level of complexity 
> > based on length", just 0.5 full stop.  A simple name has the inferred 
> > priority of 0.  A wild card has the inferred priority of 
> > -0.5.  (There are a couple others not in play here)  Since all of 
> > your template rules that match the Signature element have different 
> > priorities, the one that is highest (the simple name) trumps the 
> > lower one (the element wild card).
> > 
> > >I'm sure that I am missing something really obvious here,
> > 
> > The qualified element name in your XSLT has to match the qualified 
> > element name in the XML (in the value space, not in the lexical 
> > space, thus the expanded names must be equal).
> > 
> > The specified element name in your XSLT has no relation to the 
> > specified element name in the XML (the lexical space).
> > 
> > I hope the solution below illustrates this for you.
> > 
> > . . . . . . . . . . Ken
> > 
> > t:\ftemp>type ohaya.xml
> > <SOAP:Envelope xmlns:saml="urn:oasis:names:tc:SAML:1.0:assertion" 
> > xmlns:samlp="urn:oasis:names:tc:SAML:1.0:protocol" 
> > xmlns:SOAP="http://schemas.xmlsoap.org/soap/envelope/"; 
> > xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd"; 
> > xmlns:env="http://schemas.xmlsoap.org/soap/envelope/";>
> >      <SOAP:Header>
> >          <wsse:Security SOAP:mustUnderstand="1">
> >              <saml:Assertion MajorVersion="1" MinorVersion="1" 
> > AssertionID="ID46a342be-9d3a-437a-8a26-85fcd72a723d" 
> > Issuer="http://foo.com"; IssueInstant="2009-12-01T21:55:13Z">
> >                  <saml:Conditions NotBefore="2009-12-01T21:54:58Z" 
> > NotOnOrAfter="2009-12-01T22:10:28Z"/>
> >                  <saml:AuthenticationStatement 
> > AuthenticationMethod="urn:oasis:names:tc:SAML:1.0:am:unspecified" 
> > AuthenticationInstant="2009-12-01T21:55:13Z">
> >                  .....
> >                  </saml:AuthenticationStatement>
> >               <Signature xmlns="http://www.w3.org/2000/09/xmldsig#";>
> >                    ...
> >               </Signature></saml:Assertion></wsse:Security>
> > </SOAP:Header>
> > <env:Body>
> >          <m:hello xmlns:m="http://services";>
> >              <m:x>123</m:x></m:hello>
> > </env:Body>
> > </SOAP:Envelope>
> > 
> > t:\ftemp>call xslt ohaya.xml ohaya.xsl
> > <?xml version="1.0" encoding="utf-8"?><SOAP:Envelope 
> > xmlns:SOAP="http://schemas.xmlsoap.org/soap/envelope/"; 
> > xmlns:saml="urn:oasis:names:tc:SAML:1.0:assertion" 
> > xmlns:samlp="urn:oasis:names:tc:SAML:1.0:protocol" 
> > xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd"; 
> > xmlns:env="http://schemas.xmlsoap.org/soap/envelope/";>
> >      <SOAP:Header>
> >          <wsse:Security SOAP:mustUnderstand="1">
> >              <saml:Assertion MajorVersion="1" MinorVersion="1" 
> > AssertionID="ID46a342be-9d3a-437a-8a26-85fcd72a723d" 
> > Issuer="http://foo.com"; IssueInstant="2009-12-01T21:55:13Z">
> >                  <saml:Conditions NotBefore="2009-12-01T21:54:58Z" 
> > NotOnOrAfter="2009-12-01T22:10:28Z"/>
> >                  <saml:AuthenticationStatement 
> > AuthenticationMethod="urn:oasis:names:tc:SAML:1.0:am:unspecified" 
> > AuthenticationInstant="2009-12-01T21:55:13Z">
> >                  .....
> >                  </saml:AuthenticationStatement>
> >               </saml:Assertion></wsse:Security>
> > </SOAP:Header>
> > <env:Body>
> >          <m:hello xmlns:m="http://services";>
> >              <m:x>123</m:x></m:hello>
> > </env:Body>
> > </SOAP:Envelope>
> > t:\ftemp>type ohaya.xsl
> > <?xml version="1.0" encoding="utf-8"?>
> > <xsl:stylesheet version="1.0" 
> > xmlns:xsl="http://www.w3.org/1999/XSL/Transform"; 
> > xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"; 
> > xmlns:dp="http://www.datapower.com/extensions";
> >      xmlns:SOAP="http://schemas.xmlsoap.org/soap/envelope/";
> >      xmlns:saml="urn:oasis:names:tc:SAML:1.0:assertion"
> >      xmlns:samlp="urn:oasis:names:tc:SAML:1.0:protocol"
> >      xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd";
> >      xmlns:sig="http://www.w3.org/2000/09/xmldsig#";
> >  >
> >      <xsl:output method="xml"/>
> > 
> >      <xsl:template match="node()|@*">
> >          <xsl:copy>
> >              <xsl:apply-templates select="node()|@*"/>
> >          </xsl:copy>
> >      </xsl:template>
> > 
> >      <xsl:template match="sig:Signature">
> >      </xsl:template>
> > 
> > </xsl:stylesheet>
> > 
> > t:\ftemp>rem Done!
> > 
> > 
> > 
> > --
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> > G. Ken Holman                 mailto:gkholman@xxxxxxxxxxxxxxxxxxxx
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