Re: [JXPath] Registering namespace prefixes - never mind

I understand now.  Let me read a little more before I reintroduce this
feature.
In XPath 2 there is this notion of in-scope-namespaces.  Are these two
related?

- Dmitri

----- Original Message ----- 
From: "Sudhir Rao" <[email protected]>
To: "Dmitri Plotnikov" <[email protected]>
Cc: <[email protected]>; "Jakarta Commons Developers List"
<[email protected]>; "Jakarta Commons Users List"
<[email protected]>
Sent: Tuesday, January 20, 2004 5:45 PM
Subject: Re: [JXPath] Registering namespace prefixes - never mind


> Dmitri,
>
>        I was looking at it mainly for xml documents. I am not sure how
> this maps out to Java objects (and as I mentioned earlier as I don't
> have a very good idea in that respect). Here is what I feel the issue is
> with xml documents (Chap pointed this out briefly earlier).
>     I have a fairly simple xml document,
>         ===================================
>         |<?xml version="1.0"?>
>     <bk:book xmlns:bk='urn:loc.gov:books'
>          xmlns:isbn='urn:ISBN:0-395-36341-6'>
>         <bk:title>Cheaper by the Dozen</bk:title>
>         <isbn:number>1568491379</isbn:number>
>     </bk:book>
>     |===================================
>
> |    To access say the isbn number I would use the following xpath in my
> code.
>           /bk:book/isbn:number
>     Note that I need to specify the prefixes in my xpath or it won't work.
>
>     Now if I had instead the following document which is identical for
> all practical purposes with the earlier xml except that the prefixes are
> different, it is my opinion that my code still ought to work.
> |        ===================================
>         |<?xml version="1.0"?>
>     <!-- both namespace prefixes are available throughout -->
>     <ck:book xmlns:ck='urn:loc.gov:books'
>          xmlns:idn='urn:ISBN:0-395-36341-6'>
>         <ck:title>Cheaper by the Dozen</ck:title>
>         <idn:number>1568491379</idn:number>
>     </ck:book>
>     |===================================
>
> |    But it doesn't. And that is because the prefixes I am specifying in
> my xpaths are not the same as what is used in the document. I need the
> xpaths being used to stay consistent and I ought to be able to specify
> the namespace mappings. So that when I say "I want to access the xpath
> /||bk:book/isbn:number", I can specify exactly what I mean by bk and
> isbn in this xpath.
>
>     There might be a easier, cleaner way using jxpath, but I am not
> aware of it at this point. If you could specify alternatives that would
> be great. For my purposes I think Xalan might be a better fit for now.
>
> Regards
> Sudhir
> ||
>
> |
> Dmitri Plotnikov wrote:
>
> >Chap, Sudhir,
> >
> >After some profound discussions on the [email protected] mailing
list,
> >I decided to roll back this new feature.  I need to better understand the
> >use case before I introduce this new API.
> >
> >Is the functionality you are referring to intended for use with Java
> >objects?  What is the meaning of a namespace URI in the context of Java
> >objects?  Please, give me as much information about this use case as
> >possible.
> >
> >- Dmiri
> >
> >----- Original Message ----- 
> >From: "Dmitri Plotnikov" <[email protected]>
> >To: <[email protected]>; "Jakarta Commons Users List"
> ><[email protected]>; ""Sudhir Rao"" <[email protected]>
> >Cc: "Jakarta Commons Developers List" <[email protected]>
> >Sent: Saturday, January 17, 2004 8:52 PM
> >Subject: Re: [JXPath] Registering namespace prefixes
> >
> >
> >
> >
> >>Chap,
> >>
> >>I added registration of external namespaces to JXPath. My solution is a
> >>little different from the one proposed by Sudhir.  The main difference
in
> >>the API is that instead of calling registerNamespace directly on
> >>JXPathContext, you call it indirectly like this:
> >>
> >>   JXPathContext context = JXPathContext.newContext(document);
> >>   NamespaceManager nsm = context.getNamespaceManager();
> >>   nsm.registerNamespace ("prefix", "http://www.example.com/ns/sample");
> >>
> >>Take a look at the NamespaceManager interface - you can supply your own
> >>implementation, which could perform very flexible customizations of
> >>namespace lookup.
> >>
> >>Please note that external namespaces are supported with DOM but not
JDOM,
> >>because JDOM B9 at this point requires that all namespaces be explicitly
> >>declared in the XML file itself.
> >>
> >>Chap, Sudhir, if you guys get a chance to try out the new APIs to see if
> >>they address your needs, I will highly appreciate it.
> >>
> >>Thanks,
> >>
> >>- Dmitri
> >>
> >>
> >>----- Original Message ----- 
> >>From: "Sudhir Rao" <[email protected]>
> >>To: <[email protected]>
> >>Cc: <[email protected]>
> >>Sent: Saturday, December 06, 2003 6:41 PM
> >>Subject: Re: [JXPath] Registering namespace prefixes
> >>
> >>
> >>
> >>
> >>>I made some local modifications for this. I am not sure if adding  that
> >>>registerNamespace is the right way to do it, as I am not very familiar
> >>>with the codebase. The changes I did locally were to
> >>>a) Modify org.apache.commons.jxpath.ri.QName.java to include the
> >>>namespace prefix (similar to the one in Apache Axis). Had to tweak it a
> >>>bit to consider the prefix as the namespaceURI however to keep it
> >>>compatible with existing code.
> >>>b) Maintain a HashMap of prefixes to namespace URIs in the TreeCompiler
> >>>class.
> >>>c) Modify the TreeCompiler.qName(..) to populate the namespace URI in
> >>>the QName instance returned.
> >>>d) Add the registerNamespace method to JXPathContextReferenceImpl and
> >>>JXPathContext which in turn call a registerNamespace in Compiler class.
> >>>
> >>>I can send across my changes if someone would like to look into it.
> >>>
> >>>-Sudhir
> >>>
> >>>
> >>>
> >>>>From: Prasad A. Chodavarapu <[email protected]>
> >>>>Subject: [JXPath] Registering namespace prefixes
> >>>>Date: Wed, 3 Dec 2003 12:32:23 -0500
> >>>>Content-Type: text/plain;
> >>>>charset="iso-8859-1"
> >>>>
> >>>>
> >>>>
> >>>>Hi All:
> >>>>
> >>>>Is there a way of registering a namespace prefix upfront in a
> >>>>JXPathContext so that I can then use that prefix in xpath expressions?
> >>>>Here's what I'm looking for, in pseudo-code.
> >>>>
> >>>>JXPathContext domContext = JXPathContext.newContext(document);
> >>>>domContext.registerNamespace
> >>>> (http://www.example.com/ns/sample, "prefix");
> >>>>domContext.getValue("prefix:a/prefix:b");
> >>>>
> >>>>Thanks
> >>>>chap
> >>>>
> >>>>
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