WHAT IS THIS

GNU JAXP includes interfaces and implementations for basic XML processing
in Java, some general purpose SAX2 utilities, and transformation.

The standard distribution includes the full source code.  The current
software is available at:
    http://www.gnu.org/software/classpathx/jaxp

See INSTALL for installation instructions.

JAVA PACKAGES
    
. javax.xml.* ... JAXP 1.3 interfaces
. org.xml.sax.* ... SAX2 (r2pre3, extensions 1.1beta) interfaces
. org.w3c.dom.* ... DOM Level 3 interfaces

. gnu.xml.aelfred2.* ... SAX2 parser + validator
. gnu.xml.dom.* ... DOM Level 3 Core, Traversal, XPath implementation
. gnu.xml.dom.ls.* ... DOM Level 3 Load & Save implementation
. gnu.xml.xpath.* ... JAXP XPath implementation
. gnu.xml.transform.* ... JAXP XSL transformer implementation
. gnu.xml.pipeline.* ... SAX2 event pipeline support
. gnu.xml.util.* ... various XML utility classes
. gnu.xml.libxmlj.dom.* ... libxmlj DOM Level 3 Core and XPath
. gnu.xml.libxmlj.sax.* ... libxmlj SAX parser
. gnu.xml.libxmlj.transform.* ... libxmlj XSL transformer
. gnu.xml.libxmlj.util.* ... libxmlj utility classes

LICENSING

Briefly, most software in this package is distributed under the GNU
General Public License with the "library exception" that  permits its
usage even in statically linked environments.  That licensing is more
permissive than the "LGPL".

See the LICENSE file for more information.

CONFORMANCE
    The primary test resources are at http://xmlconf.sourceforge.net
    and include:

    SAX2/XML conformance tests
	That the "xml.testing.Driver" addresses the core XML 1.0
	specification requirements, which closely correspond to the
	functionality SAX1 provides.  The driver uses SAX2 APIs to
	test that functionality It is used with a bugfixed version of
	the NIST/OASIS XML conformance test cases.
	
	The AElfred2 parser is highly conformant, though it still takes
	a few implementation shortcuts.  See its package documentation
	for information about known XML conformance issues in AElfred2.

	The primary issue is using Unicode character tables, rather than
	those in the XML specification, for determining what names are
	valid.  Most applications won't notice the difference, and this
	solution is smaller and faster than the alternative.

	For validation, a secondary issue is that issues relating to
	entity modularity are not validated; they can't all be cleanly
	layered.  For example, validity constraints related to standalone
	declarations and PE nesting are not checked.

        The current implementation has also been tested against Elliotte
        Rusty Harold's SAXTest test suite (http://www.cafeconleche.org/SAXTest)
        and achieves approximately 93% conformance to the SAX specification
        according to these tests, higher than any other current Java parser.

    SAX2
	SAX2 API conformance currently has a minimal JUNIT (0.2) test suite,
	which can be accessed at the xmlconf site listed above.  It does
	not cover namespaces or LexicalHandler and Declhandler extensions
	anywhere as exhaustively as the SAX1 level functionality is
	tested by the "xml.testing.Driver".  However:

	    - Applying the DOM unit tests to this implementation gives
	      the LexicalHandler (comments, and boundaries of DTDs,
	      CDATA sections, and general entities) a workout, and
	      does the same for DeclHandler entity declarations.
	    
	    - The pipeline package's layered validator demands that
	      element and attribute declarations are reported correctly.
	
	By those metrics, SAX2 conformance for AElfred2 is also strong. 
    
    DOM Level 3 Core Tests
        The DOM implementation has been tested against the W3C DOM Level 3
        Core conformance test suite (http://www.w3.org/DOM/Test/). Current
        conformance according to these tests is 72.3%. Many of the test
        failures are due to the fact that GNU JAXP does not currently
        provide any W3C XML Schema support.

    XSL transformation
        The transformer and XPath implementation have been tested against
        the OASIS XSLT and XPath TC test suite. Conformance against the
        Xalan tests is currently 77%.


GNU libxmlj
========================================================================

libxmlj is an effort to create a 100% JAXP-compatible Java wrapper for
libxml2 and libxslt. JAXP is the Java API for XML processing, libxml2
is the XML C library for Gnome, and libxslt is the XSLT C library for
Gnome.

libxmlj currently supports most of the DOM Level 3 Core, Traversal, and
XPath APIs, SAX2, and XSLT transformations. There is no W3C XML Schema
support yet.

libxmlj can parse and transform XML documents extremely quickly in
comparison to Java-based JAXP implementations. DOM manipulations, however,
involve JNI overhead, so the speed of DOM tree construction and traversal
can be slower than the Java implementation.

libxmlj is highly experimental, doesn't always conform to the DOM
specification correctly, and may leak memory. Production use is not advised.


Usage
------------------------------------------------------------------------

See INSTALL for installation instructions.

To enable the various GNU JAXP factories, set the following system properties
(command-line version shown, but they can equally be set programmatically):

  AElfred2:
   -Djavax.xml.parsers.SAXParserFactory=gnu.xml.aelfred2.JAXPFactory

  GNU DOM (using DOM Level 3 Load & Save):
   -Djavax.xml.parsers.DocumentBuilderFactory=gnu.xml.dom.DomDocumentBuilderFactory

  GNU DOM (using AElfred-only pipeline classes):
   -Djavax.xml.parsers.DocumentBuilderFactory=gnu.xml.dom.JAXPFactory

  GNU XSL transformer:
   -Djavax.xml.transform.TransformerFactory=gnu.xml.transform.TransformerFactoryImpl

  libxmlj SAX:
   -Djavax.xml.parsers.SAXParserFactory=gnu.xml.libxmlj.sax.GnomeSAXParserFactory

  libxmlj DOM:
   -Djavax.xml.parsers.DocumentBuilderFactory=gnu.xml.libxmlj.dom.GnomeDocumentBuilderFactory

  libxmlj XSL transformer:
   -Djavax.xml.transform.TransformerFactory=gnu.xml.libxmlj.transform.GnomeTransformerFactory

When using libxmlj, the libxmlj shared library must be available. In Linux,
this means it must be configured via ldconfig or specified in the
LD_LIBRARY_PATH environment variable. Additionally, you may need to specify
the location of your shared libraries to the JRE using the java.library.path
system property.


Usage with Gcj
------------------------------------------------------------------------

You can create native executables from Java JAXP/XSLT applications
using gcj, GNU JAXP and LibxmlJ like this:

	gcj --output=./yourapplication \
	    --main=your.MainClass \
            --fjni \
	    /path/to/your/application.jar \
	    /path/to/gnujaxp.jar \
	    /path/to/libxmlj.jar \
	    -Djavax.xml.transform.TransformerFactory= \
	        gnu.xml.libxmlj.transform.TransformerFactoryImpl \
            -lxml2 -lxslt -lxmlj

Note that this requires gcj 3.3.

Note that you may have to specify the source codes (the .java files)
for the classes contained in the jar files listed above in order for 
gcj 3.3 to link stuff properly.

The resulting executable will depend on libxmlj.so, which in turn
depends on libxml2.so and libxslt.so.


Missing Features
------------------------------------------------------------------------ 

See BUGS for known bugs.

This implementation should be thread-safe, but currently all
transformation requests are queued via Java synchronization, which
means that it effectively performs single-threaded. Long story short,
both libxml2 and libxslt are not fully reentrant.  

Update: it may be possible to make libxmlj thread-safe nonetheless
using thread context variables.

Update: thread context variables have been introduced. This is very
untested though, libxmll therefore still has the single thread
bottleneck.
