[Haskell-cafe] Re: HXT Namespaces and XPath

Hi Uwe I read your reply multiple times, but I am still confused. I think either I misunderstand you or I did not explain myself properly in the first mail.

Hi Mads,

...

In HXT, namespace prefixes bound by an XML document are valid in the context of an XPath. How do avoid that?

An example program will clarify:

simpleXml :: String simpleXml = "http://www.w3.org/2003/05/soap-envelope\"/>"

nsEnv :: [(String, String)] nsEnv = [ ("s" , "http://www.w3.org/2003/05/soap-envelope") ]

evalXPath :: String -> String -> [XmlTree] evalXPath xpath xml = runLA ( xread >>> propagateNamespaces >>> getXPathTreesWithNsEnv nsEnv xpath ) xml

Here:

evalXPath "//s:Body" simpleXml == evalXPath "//soap:Body" simpleXml

Even though I only mentions the prefix "s" (and not "soap") in the function nsEnv.

When working with namespaces in XML, the prefixes are not longer significant. After namespace propagation every name in the XML document is identified by a qualified name. This is a pair consisting of the namespace URI and the local part. The prefixes become irrelevant.

This is my point. Prefixes are relevant in the current implementation of HXT.

A namespace aware XPath expression needs a namespace environment, as given in the example, to construct these qualified names for the names in the XPath expression. So the results of both evalXPath calls in your example must be the same.

Yes, but in the namespace environment I give to getXPathTreesWithNsEnv I only mention the prefix s, yet I am still able to evaluate the xpath "//soap:Body". Furthermore "//s:body" and "//soap:Body" gives the same results. Why? I think another example will clarify my point. The code: simpleXmlOne, simpleXmlTwo :: String simpleXmlOne = "http://foo.org\"/>" simpleXmlTwo = "http://foo.org\"/>" nsEnv :: [(String, String)] nsEnv = [ ("notFoo" , "http://notfoo.org") ] evalXPath :: String -> [XmlTree] evalXPath xml = runLA ( xread >>> propagateNamespaces >>> getXPathTreesWithNsEnv nsEnv "//a:Foo" ) xml Now notice that simpleXmlOne and simpleXmlTwo are equivalent. Yes, they have a different prefix for "http://foo.org", but the documents means the same. And as you write yourself, "... the prefix is no longer releavant ..." Yet: evalXPath simpleXmlOne /= evalXPath simpleXmlTwo Hope that clarifies things. Regards, Mads