[xsl] Creating Forward/Backward HTML links from multi-file XSL processing

[Randolph Kahle <randy.kahle@xxxxxxxxxxxxx>]

I am using XSL to translate a set of XML documents into a corresponding 
set of HTML documents. I am stuck trying to figure out how to create <a 
> ... </a> links in HTML that display forward and backward pointers 
through the web pages.

Each XMl document represents one "topic" in a class.

The file class.xml is:

<<<<<

<?xml version="1.0" encoding="iso-8859-1" ?>

<!DOCTYPE class
[
<!ENTITY pINTRODUCTION    SYSTEM  "introduction.xml" >
<!ENTITY pOVERVIEW        SYSTEM  "overview.xml" >
<!ENTITY pOVERVIEW2       SYSTEM  "overview2.xml" >
]>

<class>
    &pINTRODUCTION;
    &pOVERVIEW;
    &pOVERVIEW2;
</class>

>>>>>

Each topic has the following (partial) structure:

<<<<<

<topic>
    <!-- Used to link topics together -->
    <menu>
        <file>overview</file>
        <display>overview</display>
        <next>overview2</next>
        <prior>introduction</prior>
    </menu>
    <course>Course Name</course>
    <section>Overview</section>
    <title>Overview</title>
    <abstract></abstract>

<!--- removed -->

</topic>

>>>>>

Notice that I embed knowledge of the <next/> and <prior/> topic names 
into each topic file. This has allowed me to use the following code to 
create forward/backward pointers:

<<<<<

    <div id="navigation">
      <xsl:variable name="menu-prior" select="menu/prior"/>
      <xsl:value-of select="menu-prior"/>
      <xsl:if test="(menu/prior) or (menu/next)">
          <ul>
          <xsl:if test="menu/prior">
              <li><a href="{menu/prior}.html">prior</a></li>
          </xsl:if>
          <xsl:if test="menu/next">
              <li><a href="{menu/next}.html">next</a></li>
          </xsl:if>
          </ul>
      </xsl:if>
    </div>

>>>>>

Is there a better solution to this? I would prefer to keep the meta 
information about topic sequence out of each topic file.

Basically, as I understand it, I need to point backward one sibling 
topic and forward one sibling topic and detect the end cases where 
there is no forward/backward sibling.

I am stumped. Would someone mind helping me with the XPath construct(s) 
to do this?

Regards,

Randy



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