RE: [xsl] Writing out to and reading back from an XML file

[Chris Loschen <closchen@xxxxxxxxxxxxxxxxxx>]

At 02:28 PM 8/1/2004, you wrote:
> It's not clear how you are "writing out" the file.

I'm using xalan:write like so:

        <xalan:write file="BillHeader.xml">


> If you're using XSLT 2.0 xsl:result-document, the spec is quite clear that
> it's an error to try and read and write the same resource in a single
> transformation. The reason is that XSLT doesn't define the sequence in which
> operations are performed. A processor could try and read the file before it
> has been written.

I'm stuck with XSLT 1.0 for now, unfortunately. But the other problem isn't
a problem, because we're talking about persisting the data in one transform
and reading it back in during subsequent transforms.


> More to the point, I don't see why you are trying to do this. With the help
> of the xx:node-set() extension in XSLT 1.0, you can create a temporary tree
> in memory and use it more than once. You don't have to write it out in
> serial form to filestore, and then reread and reparse it.

That would be fine if I were doing all of this in a single transform, but 
I'm not --
I'm doing several thousand transforms, each one on a small piece of the
larger document. That is, I'm running a transform on one <Bill> at a time.
So I can't just refer back to another piece of the same transform -- that's why
I think I need to persist the information so I can get back at it later on.


> This expression:
>
>    string(namespace::$uri)
>
> should give you an XPath syntax error.

Yes, indeed it does. What I was hoping for was that the namespace axis
would return the URI as a string, which I could then manipulate as such to
take care of the translated spaces, but that's clearly not the case

> I can't correct it for you because I
> have no idea what you thought it might mean.

I hope that's more clear -- thanks so much for your help (and for your 
book, which
I use constantly!).


> Michael Kay
>
> > -----Original Message-----
> > From: Chris Loschen [mailto:closchen@xxxxxxxxxxxxxxxxxx]
> > Sent: 01 August 2004 19:07
> > To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> > Subject: [xsl] Writing out to and reading back from an XML file
> >
> > Hi again all,
> >
> > I posted this the other day, but made the mistake of burying
> > the question
> > down inside an email on
> > another subject. Of course, it's also a summer weekend...
> > Nevertheless, I
> > still can't figure out a
> > usable workaround, and I'd appreciate any insights anyone might have.
> >
> > Here's the situation: I have a very large file which I need
> > to parse piece
> > by piece, so I'm looping through
> > <BillHeader> and <Bill> (many times) and finally
> > <BillTrailer> elements. In
> > each case, the XSLT is run
> > on a single <BillHeader>, <Bill>, or <BillTrailer> rather than on the
> > entire XML document, which could be
> > several hundred megabytes. So far, so good, but as it turns out, the
> > <BillTrailer> output needs to replicate
> > most of what's in the <BillHeader> output. The solution I'm
> > trying to use
> > is to write out the <BillHeader>
> > normally, but also to an XML document which can then get
> > called back in
> > when we get to the <BillTrailer>.
> >
> > The file is getting written out more or less as expected, and
> > has the good
> > data, but then the later process
> > can't find the file again. The cause appears to be that my
> > filesystem has
> > spaces in the names (d--n that
> > Windows!) so the file isn't getting written out to c:\Documents and
> > Settings\ etc. but to c:\Documents%20and%20Settings
> > etc. -- I have a complete tree built up on my C drive with all of the
> > spaces replaced with %20s. Then the
> > later process looks in the current directory and the file isn't there.
> >
> > I've tried to get the URI of the current directory as a
> > string so I could
> > then replace the spaces with %20s and
> > use that as the base URI of the document() function, but
> > wasn't able to
> > make that work -- here's the
> > code I tried:
> >
> > <xsl:variable name="header"><!-- not working -->
> >          <!--<xsl:variable name="base">
> >                  <xsl:variable name="uri">
> >                          <xsl:value-of select="document('')/invoice"/>
> >                  </xsl:variable>
> >                  <xsl:call-template name="translate-space">
> >                          <xsl:with-param name="base"
> > select="string(namespace::$uri)"/>
> >                  </xsl:call-template>
> >          </xsl:variable>
> >          <xsl:variable name="file">
> >                  <xsl:value-of
> > select="concat($base,'/BillHeader.xml')"/>
> >          </xsl:variable>
> >          <xsl:value-of select="document($file)"/>-->
> > </xsl:variable>
> >
> > <xsl:template name="translate-space">
> >          <xsl:param name="base"/>
> >          <xsl:choose>
> >                  <xsl:when test="contains($base,' ')">
> >                          <xsl:call-template name="translate-space">
> >                                  <xsl:with-param name="base"
> > select="concat(substring-before($base,'
> > '),'%20',substring-after($base,' '))"/>
> >                          </xsl:call-template>
> >                  </xsl:when>
> >                  <xsl:otherwise>
> >                          <xsl:value-of select="$base"/>
> >                  </xsl:otherwise>
> >          </xsl:choose>
> > </xsl:template>
> >
> > I was getting ClassCast exceptions, probably (I'm not sure)
> > from the place
> > where I try to cast the namespace as a string
> > and then it still couldn't find the document. I also tried
> > setting up a
> > shortcut to the other file from the current directory but
> > that didn't work either -- the file still wasn't found.
> >
> > So, I think I understand what's happening, but I don't have a
> > way around it
> > -- any suggestions out there? Thanks!
> >
> >
> > Yours,
> >
> > Chris Loschen
> > closchen@xxxxxxxxxxxxxxxxxx
> > 781-718-3017 (cell)

Yours,

Chris Loschen
closchen@xxxxxxxxxxxxxxxxxx
781-718-3017 (cell)