XSLT not executing java function(using SAXON)

dved · January 15th, 2008, 07:42 PM

Hi,

I am using saxon in XSLT to use my java extensions. XSLT calls a java function by passing a nodeset into it.

Java function grabs the nodeset. Since nodeset for java nothing but string , it appends the <xml version..> line and parse something like this:
public String buildAndParseNodeset(String is){

String newIs="<?xml version=\"1.0\" encoding=\"UTF-8\"?>" +is;
            DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory.newInstance();
            DocumentBuilder docBuilder = docBuilderFactory.newDocumentBuilder();
            StringReader reader = new StringReader( newIs );
            InputSource inputSource = new InputSource( reader );

             Document doc = docBuilder.parse(inputSource);
             NodeList listOfTmPoints = doc.getElementsByTagName("ns1:TmPoint");

....

return st;

}

At the end this will return a string(a HTML ) which will be inserted in xslt.

The whole problem is when I use this program as a standalone java application, it works good.

BUT when I use it in my XSL it gives me a fatal error something like this:(Content is not allowed in prolog)

C:\Users\Deep\Desktop\saxonsa8-9-0-4j>java -cp .;/c:/Users/Deep/Desktop/saxonsa8
-9-0-4j/saxon8.jar net.sf.saxon.Transform -TJ template.xml generateTable.xsl
Loading com.ercot.tpo.ParseNodeSet
Looking for method buildAndParseNodeset in Java class class com.ercot.tpo.ParseN
odeSet
Number of actual arguments = 1
Trying method display: name does not match
Trying method buildAndParseNodeset: name matches
Method is static
Method has 1 argument; expecting 1
Found a candidate method:
    public static java.lang.String com.ercot.tpo.ParseNodeSet.buildAndParseNodes
et(java.lang.String)
Trying method hashCode: name does not match
Trying method getClass: name does not match
Trying method wait: name does not match
Trying method wait: name does not match
Trying method wait: name does not match
Trying method equals: name does not match
Trying method toString: name does not match
Trying method notify: name does not match
Trying method notifyAll: name does not match
[Fatal Error] :1:1: Content is not allowed in prolog.
** Parsing error, line 1, uri null
Content is not allowed in prolog.
<html xmlns:parse="java:com.ercot.tpo.ParseNodeSet">
   <head>
      <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
   </head>
   <body>
      <table id="tbl" border="0" cellpadding="0" cellspacing="0" style="border:b
lack solid 1px;border-left:0px" class="copyacross right"></table>
   </body>
</html>
C:\Users\Deep\Desktop\saxonsa8-9-0-4j>

If any one has any idea please let me know what m I doing wrong.

Thanks

Thanks
Dved

mhkay · January 15th, 2008, 08:16 PM

A "node-set" in XSLT (you're using XSLT 1.0 terminology, but never mind) is a set of nodes, that is, it's the tree representation of some XML data. Your Java method is expecting a string in the form of unparsed lexical XML. You seem to be expecting that the system will work this out for itself, and "unparse" the data (that is, serialize it) to meet the expectations of your function. Well, it doesn't. There is no reason why the string should be well-formed XML, so it's not surprising that the XML parser throws it out.

Why are you trying to parse it anyway? You don't need to, it's already been parsed. For that matter, why are you using an extension function to do something that would be much better done in XSLT?

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

dved · January 15th, 2008, 08:46 PM

Well,

This is to be done due to performance issues. I dont have whole picture why it needs to be done but this is how it should be done.

I got the point about the node-set. But then what should I do. Inorder to get a document handle I do this. I am novice in using Java. Please let me know how do i get handle to the node-set in java function.

If I dont get a document handle I can not traverse the nodes one by one. If I can, let me know.

Also the question I have is: When a nodeset is passed from XSL(using java function), is it in a specific datastructure. What I mean is will my java function will be like public string myFunction(Nodeset ns){..}

Please let me know how to go about writing this program.

Thanks a lot for your suggestions.

Thanks
Dved