Struggling with XML? Can't figure out the difference between an entity and a namespace? Fear not - our XML series has all the answers. This introductory article discusses the origins and design goals of XML, the basic rules of XML markup, and how to use elements and attributes in an XML document.
Before beginning any development effort with XML, you should make sure that you have the right development environment and tools.
The first - and most important - development tool is the XML editor. Since XML is a set of rules which allow for the description of textual data, XML documents can be created with any text editor (just like HTML.) On a UN*X system, both vi and emacs can handle XML documents, while Notepad remains one of my favourites under Windows. If you prefer something a little more user-friendly, take a look at XMLSpy, a powerful and full-featured XML editor, at http://www.xmlspy.com, or XMetaL at http://www.xmetal.com/
Both Microsoft Internet Explorer 5.0 and Netscape Navigator 6.0 come with built-in XML support, and can read and display an XML document in a hierarchical tree view. Since most systems come with either or both of these installed, you don't need to look very far if you need a tool to simply display an XML document. In addition to these, both Opera and the W3C's Amaya browser now have support for XML documents.
It should be noted at this point that since one of the primary purposes of XML is to describe data - not present it - browser support is not an essential requirement for XML usage. Since XML is an open standard, it can be used to package data into structures that are easily transferable from one system to another. Consequently, you don't need to constrain yourself to a browser to validate XML data - James Clark's expat parser, at http://www.jclark.com/xml/expat.html, and Tim Bray's Lark parser, at http://www.textuality.com/Lark/, will both do the job for you.
In addition to the general-purpose tools listed above, there are a huge number of specialized little programs floating around the Web. As this series narrows its focus, I'll be identifying the tools most suited for specific applications; however, if you can't wait, drop by http://www.garshol.priv.no/download/xmltools/, a frequently-updated list of free XML software, and download to your heart's content.
This article copyright Melonfire 2001. All rights reserved.