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Bug #3120

closed

Streaming not working from JAXP Transformation API

Added by Alex Jitianu about 7 years ago. Updated almost 7 years ago.

Status:
Closed
Priority:
Normal
Assignee:
-
Category:
-
Sprint/Milestone:
-
Start date:
2017-01-30
Due date:
% Done:

100%

Estimated time:
Legacy ID:
Applies to branch:
9.7
Fix Committed on Branch:
9.7, trunk
Fixed in Maintenance Release:
9.7.0.18
Platforms:

Description

Hi,

I'm trying to use Saxon through its API to execute a "streaming" transformation, like in this example:

import java.io.StringReader;
import java.io.StringWriter;

import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.sax.SAXSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;

import net.sf.saxon.TransformerFactoryImpl;

import org.xml.sax.InputSource;

public class Streaming {

  private static String xsl = 
      "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" + 
      "<xsl:stylesheet xmlns:xsl=\"http://www.w3.org/1999/XSL/Transform\"\n" + 
      "    xmlns:xs=\"http://www.w3.org/2001/XMLSchema\"\n" + 
      "    exclude-result-prefixes=\"xs\"\n" + 
      "    version=\"3.0\">\n"
      + "<xsl:mode streamable=\"true\"/>\n" + 
      "    <xsl:template match=\"*:person\"><xsl:value-of select=\"@id\"/></xsl:template>\n" + 
      "</xsl:stylesheet>";
  private static String xml = "<person id='test'/>";

  public static void main(String[] args) throws TransformerException {
    TransformerFactory factory = TransformerFactoryImpl.newInstance();
    Transformer transformer = factory.newTransformer(new StreamSource(new StringReader(xsl)));
    
    InputSource inputSource = new InputSource(new StringReader(xml));
    SAXSource xmlSource = new SAXSource(inputSource);
    StringWriter writer = new StringWriter();
    transformer.transform(xmlSource, new StreamResult(writer));
    
    System.out.println(writer.toString());
  }
}

The following warning appears in the console:

  Requested initial mode  is streamable, but the supplied input is not streamed

which is a hint that the transformation is not ran in "streaming mode". From what I can tell something strange occurs inside net.sf.saxon.s9api.XsltTransformer.transform() :

               if (initialSource instanceof NodeInfo) {
                    controller.setGlobalContextItem((NodeInfo)initialSource);
                } else if (initialSource instanceof DOMSource) {
                    NodeInfo node = controller.prepareInputTree(initialSource);
                    controller.setGlobalContextItem(node);
                    initialSource = node;
                } else {
                    boolean close = (initialSource instanceof AugmentedSource && ((AugmentedSource)initialSource).isPleaseCloseAfterUse());
                    NodeInfo node = controller.makeSourceTree(initialSource, close, getSchemaValidationMode().getNumber());
                    controller.setGlobalContextItem(node);
                    initialSource = node;
                }

When a SAXSource passes through this code it will be transformed into a NodeInfo and because of that, inside net.sf.saxon.Controller.transform(Source, Receiver) a decision is taken to go into net.sf.saxon.Controller.transformDocument() where that warning is generated. Thank you for taking the time to look into this.

Alex

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