Using extension functions to query data files

[Peregrine.Stone@xxxxxxxx]

I am using Xalan C++ v1.5 on OpenVMS and am  trying to create extension 
functions that will return data from an RMS file (no SQL available).
This works fine and I can read all the data I want one record at a time; 
however I have a problem trying return a results list from a search.

The following is basically what i am doing now

XSL
<xsl:template match="query"/> 
 <query>
     <key><xsl:value-of select="@data-item"/></key>
     <data><xsl:value-of 
select="external:get_data(@key,@data-item)"/></data>
  </query>
</xsl:template>

XML-in
<xml>
 <query match="12-34" data-item="A"> 
 <query match="12-567" data-item="A">
 <query match="12-897" data-item="A">
 <query match="12-345" data-item="A">
</xml>

XML-out
<query> 
 <key>12-34</key>
 <data>XYZ</data>
</query>

The disadvantage with this method is that the XML must contain all the 
keys for the records I require.

The following code fragments should indicate what I am trying to do

XSL
<xsl:template match="query"/>
  <xsl:for-each select="external:do_query(@match,@data-item)"/>
    <query>
     <key><xsl:value-of select="@current-key"/></key>
     <data><xsl:value-of select="@current-data)"/></data>
     </query>
  </xsl:for-each>
</xsl:template>

XML-in
<xml>
  <query key="12-*" data-item="A"> 
</xml>

XML-out
<query> 
 <key>12-34</key>
 <data>XYZ</data>
</query>

The XML contains only the a query statement. This implies that do_query 
can modify the (nodeset) source xml to add the following node(s)
<current current-key="12-34" current-data="XYZ"/>


Is this possible, or is there a better way? Xalan does not seem to allow 
the addition of nodes to a nodeset within an extension function.

The following (test code [derived from Saxon range]) returns an error when 
run

                               XalanDOMString ws("12-34");
 XPathExecutionContext::BorrowReturnMutableNodeRefList 
result(executionContext);
                               XalanText* wNode = 
context->getOwnerDocument()->createTextNode(ws);
 result->addNode(static_cast<XalanNode*>(wNode));

                             return 
executionContext.getXObjectFactory().createNodeSet(result);


The alternative of course is that I try an implement a loop for all seach 
matches in the xslt with appropriate extension functions that use 
createString() and return single nodes only.


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