Examplotron

This Version: V 0.6 (29 January 2003)

Latest Version: http://examplotron.org/

This namespace: http://examplotron.org/0/

Previous Version: V 0.5 (20 January 2003)

Examplotron 0.x is a proof of concept including this page, compile.xsl (a XSLT transformation that transforms examplotron documents into Relax NG schemas that validate "similar" documents) and a set of examples.

The description of the namespace version convention I intend to use for examplotron has been posted for discussion on xml-dev.

Note that this release (0.5) is a transitional release between previous releases based on XSLT validation with their own semantic and future releases which will be based on DSDL validation involving Relax NG and Schematron. Examplotron 0.5 is a rewrite of Examplotron 0.4 keeping the same set of features (with a couple of exceptions) under the new architecture to evaluate the changes implied by the move. Future releases will build on this base to resume adding new features.

Editor:

• Eric van der Vlist, Dyomedea

Table of contents

1. Purposes
2. Limitations
3. Tutorial
   1. Getting started
   2. What about the attributes
   3. Occurrences
   4. Namespaces
   5. Assertions
   6. Imports
   7. Place holders
4. Resources
5. To do
6. Acknowledgements
7. History
8. Legal statement

1. Purposes

The purpose of examplotron is to use instance documents as a lightweight schema language-- eventually adding the information needed to guide a validator in the sample documents.

"Classical" XML validation languages such as DTDs, W3C XML Schema, Relax, Trex or Schematron rely on a modeling of either the structure (and eventually the datatypes) that a document must follow to be considered as valid or on the rules that needs to be checked.

This modeling relies on specific XML serialization syntaxes that need to be understood before one can validate a document and is very different from the instance documents and the creation of a new XML vocabulary involves both creating a new syntax and mastering a syntax for the schema.

Many tools (including popular XML editors) are able to generate various flavors of XML schemas from instance documents, but these schemas do not find enough information in the documents to be directly useable leaving the need for human tweaking and the need to fully understand the schema language.

Examplotron may then be used either as a validation language by itself, or to improve the generation of schemas expressed using other XML schema languages by providing more information to the schema translators.

2. Limitations

The obvious limitation of working with sample documents is that while this is very efficient to describe patterns that can be "shown" in a document, this cannot by itself be used to describe abstract "constructed" patterns.

To workaround this limitation, one need to introduce modeling elements or attributes, moving to an hybrid schema language involving both pure "schema by example" and modeling or rules construction.

The current release includes such an attribute (eg:occurs) to provide a control on the number of occurrences of an element (see section "Occurrences" for a detailed description of this attribute).

I plan to consider the addition of other similar elements or attributes to workaround other similar restrictions such as:

• Allowing defining recursive definitions.
• Allowing elements and attributes from other (possibly unknown) namespaces.
• Controlling the occurrences of attributes.
• Allowing documents with different root elements.
• Adding adhoc rules.
• Adding type information.
• Adding documentation.
• Identifying examplotron documents.

3. Tutorial

<?xml version="1.0" encoding="UTF-8"?>
<foo>
	<bar>My first examplotron.</bar>
	<bar>Hello world</bar>
</foo>

   
<?xml version="1.0" encoding="UTF-8"?>
<grammar xmlns="http://relaxng.org/ns/structure/1.0">
  <start>
    <element name="foo">
      <element name="bar">
        <text/>
      </element>
      <element name="bar">
        <text/>
      </element>
    </element>
  </start>
</grammar>

<?xml version="1.0" encoding="UTF-8"?>
<foo>
	<bar true="no longer">My first examplotron.</bar>
	<bar>Hello world</bar>
</foo>

<?xml version="1.0" encoding="UTF-8"?>
<grammar xmlns="http://relaxng.org/ns/structure/1.0">
  <start>
    <element name="foo">
      <element name="bar">
        <attribute name="true"/>
        <text/>
      </element>
      <element name="bar">
        <text/>
      </element>
    </element>
  </start>
</grammar>

<?xml version="1.0" encoding="UTF-8"?>
<foo xmlns:eg="http://examplotron.org/0/">
	<bar eg:occurs="+">Hello world</bar>
	<!-- eg:occurs could also have been set to "*", "." or "?" -->
</foo>

 
<?xml version="1.0" encoding="utf-8"?>
<grammar xmlns="http://relaxng.org/ns/structure/1.0">
  <start>
    <element name="foo">
      <oneOrMore>
        <element name="bar">
          <text/>
        </element>
      </oneOrMore>
    </element>
  </start>
</grammar>
				

<?xml version="1.0" encoding="UTF-8"?>
<foo xmlns:eg="http://examplotron.org/0/" xmlns:bar="http://http://examplotron.org/otherns/">
	<bar:bar eg:occurs="+">Hello world</bar:bar>
	<!-- eg:occurs could also have been set to "*", "." or "?" -->
</foo>

<?xml version="1.0" encoding="utf-8"?>
<grammar xmlns="http://relaxng.org/ns/structure/1.0">
  <start>
    <element name="foo">
      <oneOrMore>
        <element name="bar" ns="http://http://examplotron.org/otherns/">
          <text/>
        </element>
      </oneOrMore>
    </element>
  </start>
</grammar>

<?xml version="1.0" encoding="UTF-8"?>
<foo xmlns:eg="http://examplotron.org/0/"  eg:assert="sum(percent)=100">
<!-- The sum of the values of the "percent" element needs to be equal to 100 -->
	<percent eg:occurs="+">100</percent>
</foo>

<?xml version="1.0" encoding="UTF-8"?>
<grammar xmlns="http://relaxng.org/ns/structure/1.0" 
   xmlns:sch="http://www.ascc.net/xml/schematron">
  <start>
    <element name="foo">
      <sch:assert test="sum(percent)=100"/>
      <oneOrMore>
        <element name="percent">
          <text/>
        </element>
      </oneOrMore>
    </element>
  </start>
</grammar>

<?xml version="1.0" encoding="UTF-8"?>
<foo:foo xmlns:eg="http://examplotron.org/0/"  eg:assert="sum(bar:percent)=100" 
    xmlns:foo="http://examplotron/otherns/foo" xmlns:bar="http://examplotron/otherns/bar">
	<bar:percent eg:occurs="+">100</bar:percent>
</foo:foo>

<?xml version="1.0" encoding="UTF-8"?>
<grammar xmlns="http://relaxng.org/ns/structure/1.0" 
   xmlns:sch="http://www.ascc.net/xml/schematron">
  <start>
    <element name="foo" ns="http://examplotron/otherns/foo">
      <sch:assert xmlns:eg="http://examplotron.org/0/" 
          xmlns:foo="http://examplotron/otherns/foo" 
          xmlns:bar="http://examplotron/otherns/bar" 
          test="sum(bar:percent)=100"/>
      <oneOrMore>
        <element name="percent" ns="http://examplotron/otherns/bar">
          <text/>
        </element>
      </oneOrMore>
    </element>
  </start>
</grammar>

4. Resources

This documentation has been written as a RDDL document and this section will be developed to include more resources related to examplotron.

5. To do

I have been pleasantly surprised after a couple of hours working on examplotron that this simple tool was beginning to be useful while still very simple (or simplistic).

The current version is already a powerful tool that can be used to validate documents.

It can be used as a main validation tool, or as a complement of a more classical validation tool, for instance, to add additional requirements and constraints to existing vocabularies when an application is using a subset of a vocabulary.

This being said, the simplicity of the tools is leaving room for many applications and extensions on which your feedback is welcome:

1. Documentation: develop the resources section.
2. Extension: ability to accurately control the number of occurrences (may already be done using eg:assert).
3. Extension: ability to control text nodes.
4. Extension: ability to define recursive models.
5. Extension: ability to add type information.
6. Extension: ability to explicitly control the occurrences of attributes.
7. Readability: ability to add documentation.
8. Proof of concept: write an examplotron schema for XHTML.
9. Anything else ?

6. Acknowledgements

Many thanks to the many people that have given me hints, ideas or encouragements or even let me think that examplotron could be the best invention since the French baguette.

Note: the French baguette is another very simple invention made only of flour, salt, yeast and water (exactly like examplotron that is made out of XML 1.0, Namespaces in XML 1.0, XPath 1.0 and XSLT 1.0). The Englo-American sliced bread (often used in this context), involving more ingredients and postprocessing is far more complex and does obviously not belong to the same category than examplotron.

Non normative list (by chronological order): Simon St.Laurent, Edd Dumbill, John Cowan, Len Bullard, Rick Jelliffe, Evan Lenz, Dan Brickley, Jonathan Borden, David Mundie, David Carlisle, Murata Makoto, Cyril Jandia, Amelia A. Lewis, Gavin Thomas Nicol, Tim Mueller-Seydlitz, Michael Champion, Wendell Piez...

7. History

8. Legal Statement

Copyright (c) 2001-2003 Eric van der Vlist

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the ``Software''), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

1. The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
2. The name of the authors when specified in the source files shall be kept unmodified.

THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL ERIC VAN DER VLIST BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.