Moving to XML Weft Technology Ltd
<?XML!>

Moving to XML

Author and presenter: Simon Brooke, Technical Director, Weft Technology Ltd.

The full text of this presentation is online at <URL:http://www.weft.co.uk/library/inet2001/xml/>

Changes to the presentation since your handouts were printed are highlighted like this.

Simon Brooke
Weft Technology Ltd, 21 Main Street, Auchencairn, Scotland.

What we're going to do today

How we're going to get there

Breaks

Nearest WCs, how to get to coffee?

Before we start: what do you know

We've got a lot of ground to cover... Just so I can know which bits to concentrate on and which bits to skip, what do you know about...

nothing a little can do it expert
HTML        
Java        

Before we start: Namespace

[get participants to write their names on bits of paper. Make sure there are not two in the class with the same name. If there are, get them to add something to their names to disambiguate]

A brief chautauqua on language

Words

We can recognise words as belonging to a language because we know them... (sometimes, we can recognise words as belonging to a language even when we don't know them, because they sound right).

Sentences

Language

Words

Although language families have rules about what can be in a word and what can't, it's much harder to tell whether a word is valid or not, unless we know which language we're looking at.

Sentences

Meta-Language [1]

Meta-Language [2]

HTML [1]

HTML [2]

Well Formedness

What is XML

Key Features

A universal, application-independent framework for the communication of semantically rich structured information between software agents.

Differences from HTML

Extensible: what does this mean for you?

Extensible: a simple example [1] 

<?xml version="1.0"?>
<!DOCTYPE meeting PUBLIC "-//WEFT//DTD MEETING 0.1//EN" 
        "meeting.dtd">
<meeting id="June Board Meeting">
  <venue>
    28 Forth Street, Edinburgh
  </venue>
  <invitees>
    <attendee attendance="required" 
        meeting-role="convenor">
      <name>
    Simon Brooke
      </name>
      <position>
    Technical Director
      </position>
    </attendee>
    <attendee attendance="required">
      <name>Angela Stormont</name>
      <position>
    Communications Director
      </position>
    </attendee> 
  </invitees>
</meeting>

Extensible: a simple example [2]

Strictly parsed: what does this mean for you? [1]

Documents which are not well-formed will not be handled by an XML application. At all.

Strictly parsed: what does this mean for you? [2]

Differences from SGML

A bit about the other bits

A bit about the other bits [ii]: XLink

A bit about the other bits [iii]: XPath and XPointer

A bit about the other bits [iv]: XSL-T

Digression: Visual Appearance and Stylesheets [i]

If people are interested, you can open the stylesheet for this presentation, slideshow.css, in a text editor.

Visual Appearance and Stylesheets [ii]

Visual Appearance and Stylesheets [iii]: Status of XSL

Visual Appearance and Stylesheets [iv]: XSL Summary

Visual Appearance and Stylesheets [v]: What about CSS?

A bit about the other bits [v]: XML Schemas

Digression: Dialects of XML

What is a Document Type Definition?

What about Schemas? (Schemata?)

More about Schemas [i]: benefits

More about Schemas [ii]: examples

The pattern specification seems to have changed at some stage in the drafting process. The examples given in Learning XML don't work with Daniel Potter's tutorial applet. Treat all tutorials with care and refer back to the formal specification!

More about Schemas [iii]: conversion

Do I have to use a DTD or Schema?

What DTDs and Schemas are available?

Who will write DTDs and Schemas? [i]

Who will write DTDs and Schemas? [ii]

A bit about the other bits [vi]: SOAP

XML in your context

Applications which benefit greatly from XML

At present, only where the audience is controlled

Applications which will benefit little from XML

XML in action: content syndication

What is content syndication

History of Syndication

Standards for Syndication

Offering Syndication

Incorporating Syndication [i]

Incorporating Syndication [ii]: Sample code 

<!-- sidebar sections: show title and top eight entries -->
  <xsl:template match="rss">
    <h2>
      <xsl:apply-templates select="channel/title" />
    </h2>
    <xsl:for-each select="channel/item">
      <xsl:if test="9 > position()">
	<p>
	  <a>
	    <xsl:attribute name="href"><xsl:value-of 
	      select="link"/> 
	    </xsl:attribute>
	    <xsl:apply-templates select="title" />
	  </a>
	</p>
      </xsl:if>
    </xsl:for-each>
  </xsl:template>

Internet Europe news

T-Online to launch premium services

Home Office denies seven-year rule

EU keeps eye out for web monopolies

EU website to promote internet safety

Lycos Europe says it is open to a takeover

Lycos Europe open to Terra or Bertelsmann takeover

Election 2001: Tory manifesto embraces freedom of the Net

Lycos Europe Open to Terra or Bertelsmann Takeover

Sample XSL code Moreover Internet Europe headlines, processed with this XSL 22nd May 2001

Aggregation

Worked Example: a meeting arranger system

Creating an example document (quite easy)

This is a good opportunity for a whiteboard and some interaction! If possible, get the participants to do an example for themselves.

Creating the DTD and/or Schema (hard, but we'll use a trick)

Again, if possible, get the participants to actually do this.

Viewing it: creating a style-sheet (harder)

Using it: applications

Now we need to write applications which will:

Specifying

The Structure of an XML document

Overall Structure

Processing Instructions

XML Namespaces

xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

Elements [i]

Syntactically, an element is what is delimited by its tags.

Elements [ii]

Attributes

When to use which 

    <meeting id="June Board Meeting">
      <agenda>
        <item proposer="Simon Brooke">
          <title>
            Adoption of new project management
            procedures manual
          </title>
        </item>
        <item proposer="Angela Stormont">
          <title>
            Transfer of shares
          </title>
        </item>
      </agenda>
    </meeting>

Exercise period [i]

Creating

Building XML applications: tools and technologies

Why Java?

Other languages for building XML applications

Tools, components and toolkits

Transformation engines

Apply XSL stylesheets to transform a document from one representation to another.

What we will be using today

Apache Xalan
XSL processor contributed to the Apache Foundation by IBM closely related to IBM's LotusXSL processor
Apache Xerces
XML parser contributed to the Apache Foundation by IBM; based on IBM's XML4J parser
SAX
Simple API for XML, by David Megginson and others
DOM
The W3C Document Object Model API
W3C Jigsaw
HTTP Server and Servlet Server developed by W3C
Jacquard
A toolkit of useful bits for sticking it all together. By me. Not neccesarily the best but it's what I know and use.

Constructing the document

The Document Object Model

The DOM: what is a Document?

A document is just a document.

The DOM: what is an Element?

The DOM: what is a Text?

Create a document object 

    DocumentImpl doc = new DocumentImpl();

Add a root ('content') element 

    doc.appendChild( new ElementImpl( doc, "eventsdiary"));
    Element content = doc.getDocumentElement();

Add further elements recursively as required 

    Enumeration e = events.elements();

    while ( e.hasMoreElements())
        content.appendChild( new 
        EventElement( doc, ( Context) e.nextElement()));

Let's see that again [i] the source 

public class DayView extends DocumentGeneratorImpl
{
    /** generate a document containing all the details of this session
     *  in this context */
    public Document generate( ServiceContext context) 
    throws DataStoreException, SQLException
    {
    DocumentImpl doc = new DocumentImpl();
    String day = context.getValueAsString( "day");
    uk.co.weft.dbutil.Calendar when = new uk.co.weft.dbutil.Calendar();

    if ( day == null)   // default to today
        day = new java.sql.Date( when.getTime().getTime()).toString();
    else
        when.setTime( java.sql.Date.valueOf( day));
    
    doc.appendChild( new ElementImpl( doc, "eventsdiary"));
    Element content = doc.getDocumentElement();

    content.setAttribute( "date", when.toString());

    String q = "select EVENT.Actor, EVENT.Event, " +
        "CATEGORY.Description as Type, " +
        "LOCATION.Description as Location, " +
        "EVENT.EventDate, EVENT.StartTime, EVENT.EndTime, " +
        "LOCATION.Description as Location, " +
        "EVENT.Description " +
        "from EVENT, CATEGORY, LOCATION " +
        "where EVENT.EventDate = '" + day + "'" +
        "and EVENT.Location = LOCATION.Location " +
        "and EVENT.Category = CATEGORY.Category " +
        "order by EventDate, StartTime";        

    Connection c = context.getConnection();
    Statement s = c.createStatement();
    ResultSet r = s.executeQuery( q);

    Contexts events = new Contexts( r);

    Enumeration e = events.elements();

    while ( e.hasMoreElements())
        content.appendChild( new 
        EventElement( doc, ( Context) e.nextElement()));

    s.close();
    context.releaseConnection( c);

    return doc;
    }
}

Let's see that again [ii]: the event element

The event element is a simple wrapper round a context element: 

/** an XML element representing a single event. This uses
 *  ContextElement which knows how to construct a DOM element node by
 *  taking values out of a context, so all we need to do is tell it
 *  which value names to treat as attributes and which as children */
class EventElement extends ContextElement
{
    /** The name of this particular element type */
    protected static String name = "event";

    public EventElement( DocumentImpl doc, Context source)
    {
    super( doc, name, source);
    }

    /** return a String array of the names of my properties to output
     *  as attributes */
    protected String[] getAttrNames()
    {
    String[] attrNames = 
    { "event", "type", "location", "starttime", "endtime", "actor"};

    return attrNames;
    }

    /** return a String array of the names of my properties to output
     *  as children */
    protected String[] getChildNames()
    {
    String[] childNames = { "description"};

    return childNames;
    }
}

Let's see that again: [iii] the context element

Let's see that again: [iv] the output 

<?xml version="1.0"?>
 <eventsdiary
  date="Jul 18, 2000">
  <event
   actor="simon"
   endtime="5:30:00 PM"
   event="19"
   location="Yokohama, Japan"
   starttime="9:00:00 AM"
   type="Otherwise unavailable">
   <description>
    Lecture, Java XML, all day
   </description>
  </event>
 </eventsdiary>

Should be online here (login required). HTML formatted view here

Exercise period [ii]

We may skip this one if time's short or the group is struggling!

Transforming

Beginning XSL-T [i] The 'stylesheet' 

    
<?xml version="1.0"?>
<xsl:stylesheet version=1.0
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

<!-- Basic XSL stylesheet for day view of events diary.  -->

  <xsl:output indent="yes" method="html" 
          doctype-public="-//W3C//DTD HTML 4.0 Transitional//EN"/>

  <xsl:template match="eventsdiary">
    <html>
      <head>
    <title>
      Diary for <xsl:value-of select="@date" />
    </title>
    <link rel="StyleSheet" href="/styles/jacquard.css" type="text/css" 
      media="screen"/>
      </head>
      <body>
    <h1>
      Diary for <xsl:value-of select="@date" />
    </h1>
    <table>
      <tr>
        <th rowspan="2">
        Who
        </th>
        <th rowspan="2">
        Where
        </th>
        <th colspan="2">
        When
        </th>
        <th rowspan="2">
        What
        </th>
        <th rowspan="2">
        Details
        </th>
        <th rowspan="2">
        <a href="event">Add</a>
        </th>
      </tr>
      <tr>
        <th>
          Starts
        </th>
        <th>
          Ends
        </th>
      </tr>
      <xsl:apply-templates select="event" />
    </table>
      </body>
   </html>
  </xsl:template>

  <xsl:template match="event">
    <tr>
      <td>
    <xsl:value-of select="@actor"/>
      </td>
      <td>
    <xsl:value-of select="@location"/>
      </td>
      <td>
    <xsl:value-of select="@starttime"/>
      </td>
      <td>
    <xsl:value-of select="@endtime"/>
      </td>
      <td>
    <xsl:value-of select="@type"/>
      </td>
      <td>
    <xsl:value-of select="description"/>
      </td>
      <td>
    <a>
      <xsl:attribute name="href">event?event=<xsl:value-of 
        select="@event"/>
      </xsl:attribute>
      Edit
    </a>
      </td>
    </tr>
  </xsl:template>

</xsl:stylesheet>

Beginning XSL-T [ii] The 'stylesheet' tag 

<?xml version="1.0"?>

<xsl:stylesheet version=1.0 
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

Beginning XSL-T [iii] comments 

<!-- Basic XSL stylesheet for day view of events diary.  -->

Beginning XSL-T [iv] output specifier 

  <xsl:output indent="yes" method="html" 
          doctype-public="-//W3C//DTD HTML 4.0 Transitional//EN"/>

Beginning XSL-T [v] declaring a template 

  <xsl:template match="eventsdiary">

This template matches every instance of the element eventsdiary which is found in the document being processed. As eventsdiary is the root element of the document type we're interested in, there will only be one. 

    <html>
      <head>
        <title>

As you can see, what is in the template is just the HTML markup that will be output (if we were outputting XML, it would be XML, of course)... 

      Diary for <xsl:value-of select="@date" />

with scattered among it special xsl tags which cause things to be spliced into the output. This one says 'use the value of the data attribute of the current element' 

        </title>
      </head>
      <body>
        <h1>
          Diary for <xsl:value-of select="@date" />
        </h1>
        <table>
          <tr>
            <th rowspan="2">
              Who
            </th>
            <th rowspan="2">
              Where
            </th>
            <th colspan="2">
              When
            </th>
            <th rowspan="2">
              What
            </th>
            <th rowspan="2">
              Details
            </th>
            <th rowspan="2">
              <a href="event">Add</a>
            </th>
          </tr>
          <tr>
            <th>
              Starts
            </th>
            <th>
              Ends
            </th>
          </tr>
          <xsl:apply-templates select="event" />

This is the important one. It says "apply the templates in this stylesheet to all the instances of event elements which are children of the current node". 

        </table>
      </body>
   </html>
  </xsl:template>

Beginning XSL-T [vi] other useful bits 

<xsl:template match="section[ @slot='main']">

This template will match only section elements which have an attribute named slot whose value is main 

  <p>
    <xsl:call-template name="toc"/>

paste in the output of the named template called toc. 

  </p>
  <xsl:apply-templates select="section">
    <xsl:sort select="title"/>

Apply templates in this stylesheet to sections which are children of this section, sorted alphabetically by their title sub-element 

  </xsl:apply-templates>
</xsl:template>

<xsl:template name="toc">

This is the named template which was called earlier. Most templates are not named: they are applied automatically if their patterns match an element 

  <xsl:for-each select="section">

for-each iterates over matching elements in turn 

      <xsl:sort select="title"/>
        <a>
              <xsl:attribute name="href">#<xsl:value-of select="title"/>
                </xsl:attribute>

xsl:attribute allows us to construct the value of an attribute of the enclosing tag 

          <xsl:value-of select="title"/>
      </a> |
  </xsl:for-each>
</xsl:template>

XSL-T elements: reprise

xsl:output
allows us to define how we want the output to be formatted
xsl:template
defines what should be output for elements matching a given pattern
xsl:apply-templates
applies the templates to the elements which match its pattern
xsl:call-template
calls a template with a particular name, overriding the pattern-matching system
xsl:for-each
produces output iteratively, overriding the pattern-matching system
xsl:sort
orders the result of its enclosing element (an xsl:apply-templates or an xsl:for-each)
xsl:value-of
produces the value of the thing matched by its pattern
xsl:attribute
outputs an attribute for the output element which encloses it

There are a few more XSL elements, but these will do most things for you.

Beginning XSL-T [vii]: Patterns

*
matches any element
foo
matches any element whose type is foo
foo | bar
matches any element whose type is foo or bar
foo/bar
matches any bar element with a foo parent
foo//bar
matches any bar element with a foo ancestor
foo[ @bar='baz']
matches any foo element which has a bar attribute which has the value baz
foo[1]
matches any foo element which is the first foo child of its parent
foo[ position() = 1]
matches any foo element which is the first child of its parent
[ position() < 5]
matches any element which is the first, second, third or fourth child of its parent
text()
matches any text element.

This is just the basics. The full definition is here

XSL-T: A deceptively simple language

Exercise period [iii]

Communicating

Just a bit about transport

Parsers

Parsing is quite compute-intensive - don't do it if you don't have to!

More about parsers [i] types

More about parsers [ii] types

Parsing from XML into the database

Identifying the data to store

Other things to bear in mind

Parsing: very simple worked example

Sample XML document 

<?xml version="1.0"?>
<workshop tutor="Simon Brooke" 
  title="Parsing XML" venue="small">
  <attendee name="Jon Smith" age="37" 
    sex="M" country="UK" />
  <attendee name="Jane Doe" age="42" 
      sex="F" country="US" />
</workshop>

those who were here yesterday will probably recognise this from the 'WORKSHOP' database - I'm using this because I can't predict what your 'MEETING' databases will look like

Sample Java class 

import java.io.*;		// to read things from the user
import java.sql.*;		// to talk to the database
import uk.co.weft.domutil.*;	// things to convert elements to namespaces
import uk.co.weft.dbutil.*;	// things to store namespaces in databases
import org.w3c.dom.*;		// interrogates a DOM tree...
import org.apache.xerces.dom.*;	// using Apache's DOM implementation
import org.apache.xalan.xslt.*;	// Apache's XSL processor
import org.apache.xerces.parsers.DOMParser;
				// and Apache's XML parser


public class ParseExample
{
    static Context connectionContext = new Context();
				// a context to hold database
				// connection details

    /** walk down a document tree looking for nodes we recognise */
    public static void walk( Node node)
	throws SQLException, DataStoreException
    {
	if ( node.getNodeType() == Node.ELEMENT_NODE)
	    {
		Element elt = ( Element) node;

		System.out.println( "Considering element of type " +
				    elt.getTagName());

		if ( elt.getTagName().equals( "workshop"))
		    handleWorkshop( elt);
		else
		    {
			NodeList children = elt.getChildNodes();

			for ( int i = 0; i < children.getLength(); i++)
			    walk( children.item( i));
				// recurse down through the children
		    }
	    }
    }


    /** handle a workshop element; extract its attribute (and
     *  actually, it's text-only child) values, and store them in the
     *  database. Then look for attendees.*/
    protected static void handleWorkshop( Element elt) 
	throws SQLException, DataStoreException
    {
	Object key = null;

	Context c = ( Context)connectionContext.clone(); 
				// construct a new namespace with just
				// the database connection details in
				// it
	ContextElement.populateContext( elt, c);
				// fill it with values from the element

	TableDescriptor workshopDescriptor = 
	    TableDescriptor.getDescriptor( "WORKSHOP", "Workshop", c);
				// get a descriptor on the WORKSHOP table

	Contexts rows = workshopDescriptor.match( c);
				// try to match that against what's
				// already in the table

	if ( rows != null && rows.size() > 0)
	    {			// there was a match
		key = ( ( Context)rows.get( 0)).getValueAsInteger( "Workshop");
				// get its primary key value
		System.out.println( "Found workshop " + key.toString());
	    }
	else
	    {
		key = workshopDescriptor.store( c);
				// store it and get its primary key value
		System.out.println( "Created workshop " + key.toString());
	    }

	NodeList children = elt.getChildNodes();

	for ( int i = 0; i < children.getLength(); i++)
	    {			// look through the children for my attendees
		Node child = children.item( i);

		if ( child.getNodeType() == Node.ELEMENT_NODE &&
		     ( ( Element) child).getTagName().equals( "attendee"))
		    {
			handleAttendee( ( Element)child, key);
		    }
	    }
    }

    /** handle an attendee element by finding or storing it in the
     *  database, and fixing up the link table */
    protected static void handleAttendee( Element elt, Object workshopKey)
	throws SQLException, DataStoreException
    {
	Object attendeeKey = null;

	Context c = ( Context)connectionContext.clone(); 
				// construct a new namespace with just
				// the database connection details in
				// it
	ContextElement.populateContext( elt, c);
				// fill it with values from the element

	TableDescriptor attendeeDescriptor = 
	    TableDescriptor.getDescriptor( "ATTENDEE", "Attendee", c);
				// get a descriptor on the ATTENDEE table

	Contexts rows = attendeeDescriptor.match( c);
				// try to match that against what's
				// already in the table

	if ( rows != null && rows.size() > 0)
	    {			// there was a match
		attendeeKey = 
		    ( ( Context)rows.get( 0)).getValueAsInteger( "Attendee");
				// get its primary key value
		System.out.println( "Found attendee " + 
				    attendeeKey.toString());
	    }
	else
	    {
		attendeeKey = attendeeDescriptor.store( c);
				// store it and get its primary key value
		System.out.println( "Created attendee " + 
				    attendeeKey.toString());
	    }

	String q = "insert into ATTENDANCE ( Attendee, Workshop) values ("
	    + attendeeKey.toString() + ", " + workshopKey.toString() + ")";

	Connection conn = c.getConnection();
	Statement s = conn.createStatement();
				// set up a database connection

	s.executeUpdate( q);	// run the statement
	System.out.println( "Inserted link into link table");

	s.close();		// close it...
	c.releaseConnection( conn);
				// and release it back into the pool
    }

    /** prompt the user for input; if we get any, return it */
    protected static String maybeGetFromUser( BufferedReader in, String prompt,
				       String val) throws IOException
    {
	System.out.print( prompt + " ] ");

	String s = in.readLine();

	if ( s != null || s.length() == 0)
	    val = s.trim();
	
	return val;
    }

    /** start me up... */
    public static void main(String args[]) 
    {
	BufferedReader in = new 
	    BufferedReader( new InputStreamReader( System.in));

				// get from the user the name of the
				// database driver to use
	try
	    {
		Class.forName( 
		      maybeGetFromUser( in, "Database Driver", 
					"sun.jdbc.odbc.JdbcOdbcDriver"));

				// get from the user the details
				// needed to connect to the database
		connectionContext.put( "db_url", 
			       maybeGetFromUser( in, "Database URL", 
						 "jdbc:odbc:workshop"));
		connectionContext.put( "db_username", 
			       maybeGetFromUser( in, "Database Username", 
						 "nobody"));
		connectionContext.put( "db_password", 
			       maybeGetFromUser( in, "Database Password", 
						 "doesntmatter"));


		DOMParser p = new DOMParser();
			
		p.parse( maybeGetFromUser( in, "URL of XML to handle", 
						 "file:workshop.xml"));

		walk( p.getDocument().getDocumentElement());

		System.exit( 0); // all satisfactory
	    }
	catch ( Exception e)
	    {
		System.out.println( "Failed: " + e.getClass().getName() +
				    ": " +e.getMessage());
		System.exit( 1); // whoops
	    }
    }
}

Exercise period [iv]

References

XML

news:comp.text.xml
Newsgroup for XML - recommended

FAQs, Directories and Resources

Extensible Markup Language (XML): http://www.oasis-open.org/cover/xml.html
A useful and authoritative overview of the technology; another good place to start.
Frequently Asked Questions about the Extensible Markup Language: http://www.ucc.ie/xml/
The most superior FAQ. Everyone seriously interested in XML should start here.
SCHEMA.NET: The XML Schema Site: http://www.schema.net/
Cafe con Leche XML News, and Resources: http://metalab.unc.edu/xml/index.html
DEVELOPERLIFE.COM brought to you by Nazmul Idris.: http://developerlife.com/
xmlTree - The leading directory of XML content on the Web: http://www.xmltree.com/

News

Welcome to XMLNews.org: http://www.xmlnews.org/
Mulberry Technologies, Inc.: XSL-List -- Open Forum on XSL: http://www.mulberrytech.com/xsl/xsl-list/
XMLephant: News: http://www.xmlephant.com/pages/News/
XML.ORG - A good XML Portal: http://www.xml.org/
XML.com - Another good XML portal: http://www.xml.com/pub

Standards

Authoritative sources of standards documents, mostly from the World Wide Web Consortium (W3C)

Core standards

The Annotated XML Specification: http://www.xml.com/axml/testaxml.htm
The standard annotated by one of the editor's personal comments -- very revealing!
Extensible Markup Language (XML) 1.0: http://www.w3.org/TR/1998/REC-xml-19980210
XML Linking Language (XLink): http://www.w3.org/TR/WD-xlink#addressing

Resource Description Framework

W3C Resource Description Framework: http://www.w3.org/RDF/
java tutorial help resource only at gamelan.com: http://www.gamelan.com/journal/techfocus/090199_rdf1.html
UKOLN: DC-dot, A Dublin Core Generator: http://www.ukoln.ac.uk/metadata/dcdot/
Dublin Core Metadata Initiative / Documents / Proposed Recommendations / Dublin Core Element Set, Version 1.1: http://purl.org/DC/documents/rec-dces-19990702.htm
Dublin Core Metadata Initiative: http://purl.org/dc/index.htm
UKOLN Metadata Resources - DC: http://www.ukoln.ac.uk/metadata/resources/dc/
UKOLN Metadata Resources - DC: http://www.ukoln.ac.uk/metadata/resources/dc/
Welcome to XMLNews.org: http://www.xmlnews.org/

XSL

XSL Transformations (XSLT) Specification: http://www.w3.org/TR/WD-xslt

DocBook

The nwalsh.com Home Page - XSL DocBook Stylesheets: http://nwalsh.com/docbook/xsl/
XSL DocBook Stylesheets: http://nwalsh.com/docbook/xsl/

WML

WAP WAP Binary XML (WBXML) Encoding Specification: http://www.w3.org/TR/wbxml/
Welcome to WAP School: http://www.refsnesdata.no/wap/default.asp
Nokia WAP Developer Forum: Nokia WAP Toolkit: http://www.forum.nokia.com/wapforum/main/1,6668,1_1_3_2,00.html

RSS: Rich Site Summary

Tutorials

My Netscape Network: http://my.netscape.com/publish/
Using RSS News Feeds - Webreference.com: http://www.webreference.com/perl/tutorial/8/

Feed Directories

Webfeeds: http://www.stirbitch.com/cgi-bin/agg/sources.pl
Moreover... Top stories: http://w.moreover.com/
StartsHere Channel List: http://theweb.startshere.net/channels.phtml
Open Directory - Computers: Internet: WWW: Web Portals: Netscape Netcenter: My Netscape Network: http://dmoz.org/Computers/Internet/WWW/Web_Portals/Netscape_Netcenter/My_Netscape_Network/

Internet Alchemy : Internet Alchemy : RSSMaker: http://internetalchemy.org/rss/index.phtml
xmlTree - The leading directory of XML content on the Web: http://www.xmltree.com/rss/index.htm

XML.COM - Standards List Sorted by Date: http://www.xml.com/xml/pub/standate/
W3C Scalable Vector Graphics (SVG): http://www.w3.org/Graphics/SVG/
VML - the Vector Markup Language: http://www.w3.org/TR/1998/NOTE-VML-19980513
Vector (infinitely zoomable) graphics for the Web, with implications especially for maps and technical diagrams.
News Industry Text Format: http://www.nitf.org/
Meta Content Framework Using XML: http://www.w3.org/TR/NOTE-MCF-XML/
'Content about content' - i.e. information for search and indexing engines and other software agents which must make some sense of the document.
Audio, Video, and Synchronized Multimedia: http://www.w3.org/AudioVideo/
The SMIL standard. I believe SMIL has implications not just for the Web, but for all sorts of presentation media including digital television.
XHTML 1.0: The Extensible HyperText Markup Language: http://www.w3.org/TR/WD-html-in-xml/
Backwards compatibility: implementing HTML in XML. Only very well written HTML is going to work!
XML Catalog proposal: http://www.ccil.org/~cowan/XML/XCatalog.html
XHTML 1.0: The Extensible HyperText Markup Language: http://www.w3.org/TR/xhtml1/
Template Resolution in XML/HTML: http://www-uk.hpl.hp.com/people/ak/doc/trix.html
eXtensible Server Pages (XSP) Layer 1: http://java.apache.org/cocoon/xsp/WD-xsp.html
Workflow Management Coalition: http://www.aiim.org/wfmc/mainframe.htm
DSML.ORG: The Standards Effort to Link Directories with XML: http://www.dsml.org/

Turorials

Info for Newcomers to XML at XMLINFO: http://www.xmlinfo.com/newcomers/
Producing HTML tables with XSLT: http://www.cogsci.ed.ac.uk/~dmck/xslt-tutorial.html
A Tutorial in XML and XSL Authoring: http://pdbeam.uwaterloo.ca/~rlander/XML_Tutorial/
Java & XML: 1 + 1 > 2: http://www.sun.com.au/sjug/pres/xml/JavaAndXML/seminar.html#Slide3
The WDVL: XML Tutorials: http://www.wdvl.com/Authoring/Languages/XML/Tutorials/
Generally Markup: XML Resources: http://pdbeam.uwaterloo.ca/~rlander/XML_Tutorial/
developerWorks : XML : Education: http://www.software.ibm.com/developer/education/xmlintro/xmlintro.html
SGML/XML: Using Elements and Attributes: http://www.oasis-open.org/cover/elementsAndAttrs.html
Producing HTML tables with XSLT: http://www.cogsci.ed.ac.uk/~dmck/xslt-tutorial.html
Welcome to XML School: http://www.refsnesdata.no/xml/
Practical XML : An introduction to XML and XSL stylesheets: http://www.kst.com/articles/2000/January/practical_xml1/index.php
Crane Softwrights Ltd. - Training: http://www.CraneSoftwrights.com/training/index.htm#ptux-dl
developerWorks : XML : Education: http://www-4.ibm.com/software/developer/education/xmlintro/xmlintro.html
RSS Tutorial: http://my.netscape.com/publish/help/mnn20/quickstart.html#rsssyntax
XML DTD Tutorial: http://www.xml101.com/dtd/

Software resources

Editors

Editing SGML with Emacs and PSGML - Table of Contents: http://rainbow.ldeo.columbia.edu/documentation/programs/psgml/psgml_toc.html#SEC2
A GNU Emacs mode for SGML files: http://www.lysator.liu.se/projects/about_psgml.html
This is what I use and recommend (I personally use XEmacs rather than GNU Emacs)
SoftQuad XMetaLhttp://www.softquad.com/index_main.html
Mulberry Technologies -- tdtd Emacs Major Mode for SGML and XML DTDs: http://www.mulberrytech.com/tdtd/
Download Morphon XML Editor 1.0b41: http://www.lunatech.com/products/morphon-xml-editor/download/

Browsers

Jumbo: http://ala.vsms.nottingham.ac.uk/vsms/java/jumbo/
Doczilla: http://www.doczilla.com/download/index.html
XML Viewer : another alphaWorks technology: http://www.alphaworks.ibm.com/tech/xmlviewer
InDelv: http://www.indelv.com/

XML to HTML on the fly

IBM XML Web Site, Education - Accessing XML on the Client: http://www.software.ibm.com/xml/education/client/client.html
Apache Cocoon: http://xml.apache.org/cocoon/
Apache is the world's most widely used Web server. This is the Apache project's server-side XML to HTML conversion strategy, important for serving XML documents while many browsers are still unable to interpret it. Implemented as a Java Servlet, may work with other Servlet enabled Web servers (but then does anyone serious use anything other than Apache anyway?)

XML Database integration

DB2XML A tool for transforming relational databases into XML documents: http://www.informatik.fh-wiesbaden.de/~turau/DB2XML/index.html
Tamino - The Information Server for Electronic Business, Software AG: http://www.softwareag.com/tamino/
A database which claims to store XML directly. Whether this means that it's really an object-oriented database underneath I'm not sure.
ODBC2XML: Merging ODBC data into XML documents: http://members.xoom.com/_XOOM/gvaughan/odbc2xml.htm
pgxml homepage: http://www.morinel.demon.nl/pgxml/
My favourite database engine, Postgres,
XML Lightweight Extractor : another alphaWorks technology: http://alphaworks.ibm.com/tech/xle

Conversion tools and filters

RTF2XML: http://www.xmeta.com/omlette/
Tool for converting RTF to XML, written in Omnimark
OmniMark Technologies Corporation: http://www.omnimark.com/
A programming language for manipulating data streams, useful in writing conversion filters from other formats into XML.

Quick ways to produce DTDs

DTDGenerator Frontend: http://www.pault.com/Xmltube/dtdgen.html
DB2XML A tool for transforming relational databases into XML documents: http://www.informatik.fh-wiesbaden.de/~turau/DB2XML/index.html
schematron: http://www.ascc.net/xml/resource/schematron/schematron.html
Widely recommended as a very powerful and elegant solution, knows about schemas as well as DTDs.
XMLschema.com: http://apps.xmlschema.com/

Structured Search tools

Downloading sgrep: http://www.cs.helsinki.fi/~jjaakkol/sgrep/download.html
Probably the most powerful simple tool for manipulating SGML and XML documents

Software collections and directories

xml.apache.org: http://xml.apache.org/
XMLSOFTWARE.COM: The XML Software Site: http://www.xmlsoftware.com/
This (commercial) site tries to keep track of XML related software tools which are available. Likely not to effectively index open source tools in the longer term.
Free XML software: http://www.stud.ifi.uio.no/~larsga/linker/XMLtools.html#SC_XSL

IBM Developers: XML : Overview: http://www.ibm.com/developer/xml/
eXtensible Server Pages (XSP) Layer 1: http://java.apache.org/cocoon/xsp/WD-xsp.html
OpenXML: http://www.openxml.org/
Major open source project to provide XML tools in Java
PHP3: Manual: XML Parser Functions: http://www.php.net/manual/ref.xml.php3
PHP is a server-side scripting language -- probably the best of the open source ones available. This manual section shows how the PHP project intends to handle XML at the server side, and is thus an alternative to Apache's Cocoon technology.
XML Authority Product Overview: http://www.extensibility.com/xml_authority/xml_ath_specs.htm
eidon products - Solutions for Structured Documents: http://www.eidon-products.com/
Dynamic XML for Java : another alphaWorks technology: http://www.alphaworks.ibm.com/tech/dynamicxmlforjava
XML Products Evaluation Form: http://www.bluestone.com/scripts/SaApps/SaCGI.exe/XMLevaluate.class
XML Script - XML tools for E-commerce: http://www.xmlscript.org/
SAX: The Simple API for XML: http://www.megginson.com/SAX/
Activated Intelligence Rocks Your Java World!: http://www.activated.com/
W4F, the World Wide Web Wrapper Factory: Welcome: http://db.cis.upenn.edu/W4F/
JDOM: Who We Are: http://www.jdom.org/credits/index.html

Commentry and background

XML, Java, and the future of the Web: ftp://sunsite.unc.edu/pub/sun-info/standards/xml/why/xmlapps.html
Scientific American: Feature Article: XML and the Second Generation Web: May 1999: http://www.scientificamerican.com/1999/0599issue/0599bosak.html
An extremely clear and well written article
DevEdge Online - Metadata: http://developer.netscape.com/tech/metadata/index.html
Netscape's official take on metadata.
XML.COM - XML support in IE5: http://www.xml.com/xml/pub/1999/03/ie5/first-x.html
XML.com sets out to be a newsletter on XML and related developments. It's contributors are in general exceptionally well informed. In this article Tim Bray (who works closely with Netscape) reviews Microsoft IE5's XML compatibility.
CNET News.com - Taking sides on XML: http://www.news.com/News/Item/0,4,37072,00.html
XML, Java, and the future of the Web: ftp://sunsite.unc.edu/pub/sun-info/standards/xml/why/xmlapps.html
XML Namespaces: http://www.jclark.com/xml/xmlns.htm
The Last Page: XML's Achilles Heel (Web Techniques, June 1999): http://www.webtechniques.com/archives/1999/06/lastpage/

XML EDI and e-Commerce stuff

A number of competeing proposals are being developed to do automatic businessto business transfer of invoices, orders,et cetera...

CNET.com - News - Services & Consulting - Big-name chemical firms join business e-commerce trend: http://news.cnet.com/news/0-1008-200-1579569.html?tag=st

Collaborative initiatives

The OBI Consortium: http://www.openbuy.org/
A solid business community consortium
Welcome to RosettaNet: http://www.rosettanet.org/
Probably the most incompetent and unprofessional Web site I've ever seen. This organisation claims to be the hub of EDI in XML development, but their Web site gives no comfort whatever regarding their competence.
Biztalk - Letting computers speak the language of business: http://www.biztalk.org/
Microsoft's tame e-Commerce consortium.
FpML.org: http://www.fpml.org/
JP Morgan - PriceWaterhouseCoopers initiative, apparently mainly aimed at financial services.
Electronic Business XML (ebXML) Home Page: http://www.ebXML.org/

Suppliers

DEDIOUX - Dynamic EDI Objects Using XML: http://www.americancoders.com/OpenBusinessObjects
ariba.com - welcome: http://www.ariba.com/
Welcome To OpenLink Software: http://www.openlinksw.com/virtuoso/

Stories

XML Applications Stand Up To EDI: http://www.techweb.com/wire/story/TWB19990416S0002
XML Applications Stand Up To EDI: http://www.techweb.com/se/directlink.cgi?INW19990419S0014
News story about Dell Computer's XML
CNET News.com - IBM links business software, e-commerce: http://www.news.com/News/Item/0,4,35128,00.html
News story about IBM's XML e-Commerce

WAP/WML

WAP WAP Binary XML (WBXML) Encoding Specification: http://www.w3.org/TR/wbxml/
wml-tools: http://www.pwot.co.uk/wml/
www.kannel.org: http://www.kannel.org/

XML Icon Gallery.: http://www.iol.ie/~alank/xml/icons.htm