[XALANJ-2406] Unexpected namespace mappings using identity Transformer with DOM flavour

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Fix Version/s: The Latest Development Code
• Component/s: DOM, Serialization
• Xalan info: PatchAvailable
• Assignee: Unassigned
• Reporter: Brian Minchau
• Reviewer: Christine Li
• Created: 09/Oct/07 17:34
• Updated: 09/Oct/07 21:40

Description

This isn't exacly a bug, but it is against the serialization "philosophy".

The serializer stage tries to write out a minimal set of namespace mappings. For example if <a> has child <b> and both elements have the namespace node that maps prefix "prex" to URI "uri-x" then it tries to serializer the document as:
<a xmlns:prex='uri-x'><b/></a>
rather than as:
<a xmlns:prex='uri-x'><b xmlns:prex='uri-x' /></a>

It isn't that the second form is wrong, it is just that due to the XML standard <b> inherits its parent namespace nodes or mappings. The problem with the second form is that things can get pretty messy when there are a number of namespace nodes and also a deep ancestor tree. Messy and potentially a preformance problem with large (lots of characters) output XML.

Here is a testcase showing this problem:

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.Transformer;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.dom.DOMSource;
import org.w3c.dom.Node;
import org.xml.sax.InputSource;

import java.io.*;
import java.util.Properties;

public class Test {

private static final String XML_SOURCE =
"<doc xmlns:foo='foo'>" +
"<a xmlns:foo='foo'/>" +
"</doc>";

public static void main(String[] args) throws Exception

{ DocumentBuilderFactory dfactory = DocumentBuilderFactory.newInstance(); dfactory.setNamespaceAware(true); DocumentBuilder docBuilder = dfactory.newDocumentBuilder(); Node xmlDOM = docBuilder.parse(new InputSource(new StringReader(XML_SOURCE))); String key = "javax.xml.transform.TransformerFactory"; String value = org.apache.xalan.processor.TransformerFactoryImpl.class.getName(); Properties props = System.getProperties(); props.put(key, value); System.setProperties(props); Transformer t = TransformerFactory.newInstance().newTransformer(); t.transform(new DOMSource(xmlDOM), new StreamResult(System.out)); }

}

Expected result:
<?xml version="1.0" encoding="UTF-8"?><doc xmlns:foo="foo"><a/></doc>
Actual result:
<?xml version="1.0" encoding="UTF-8"?><doc xmlns:foo="foo"><a xmlns:foo="foo"/></doc>