How To Use XML

Authors: Henk Hangyi, Pierre van Rooden
Date: 2003-02-12

This software is OSI Certified Open Source Software. OSI Certified is a certification mark of the Open Source Initiative.

The license (Mozilla version 1.0) can be read at the MMBase site. See http://www.mmbase.org/license

Table of Contents

1. Introduction
2. A very simple XML could be the following
3. DTD Layout
4. XPath
5. More information

1. Introduction

XML stands for "EXtensible Markup Language"

XML is a mark-up language
XML describes data
XML uses a DTD(Document Type Definition) for describing the data-structure within the document.
XML is developed with a DTD, so it should be self explaining.
XML Layout [todo: what is meant with this]

2. A very simple XML could be the following

Within MMBase is a security framework, in which different security implementations can be used. In this way it is possible to adapt MMBase to the needs of the environment in which it runs. Currently there are a few different implementations ready. The context security and the cloud security are the most advanced schemes available.

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE root SYSTEM "definition.dtd">
<root></root>

This XML uses "utf-8" as encoding and uses definition.dtd to validate the XML file for correctness.

3. DTD Layout

The simple XML document which is shown above, could be described by a DTD like:

<!ELEMENT root #PCDATA)>

The element allows only the use of <root> tags in the document. The PCDATA indicates that text may be entered within the <root> tag. [todo: There should be more text here but it seems to be missing. The DTD needs some more work. ]

4. XPath

With the use of XPath is it possible to denote a certain location in a xml file. The location can be enclosed in an element or a field of an element. For XPath / counts as the root of the document. To separate elements you should use a '/' between those elements. In the case that you point to a field inside an element you should use 'element[@fieldname]'

5. More information

For more information on how to read DTDs, see:

For more information on XML, see:

W3 Schools:http://www.w3schools.com/xml/default.asp
Zvon: http://www.zvon.org/xxl/XMLTutorial/General/book.html

For more information on XPath, see:

Zvon: http://www.zvon.org/xxl/XPathTutorial/General/examples.html

This is part of the MMBase documentation.

For questions and remarks about this documentation mail to: documentation@mmbase.org