It's easy to get lost when talking about XML. It has grown into a
huge topic, inspiring so many technologies and branching into new
areas. Anywhere there is information, you'll find XML, or at least hear
it scratching at the door. So priority number one is to get a broad
view, ask the big questions, so that you can find your way through the
dense jungle of standards and concepts.
There are a few
questions that come to mind. What is XML? We will attack this from
different angles. It's more than the next generation of HTML. It's a
general-purpose information storage system. It's a markup language
toolkit. It's an open standard. It's a collection of standards. It's a
lot of things, as you'll see.
Where did it come from? It's good
to have a historical perspective. You'll see how XML evolved out of
preceding efforts like SGML, HTML, and the earliest presentational
What can I do with XML? A practical question, again
with several answers: store and retrieve data, ensure document
integrity, format documents, and support many cultural localizations.
And the following section answers the other question, what can't I do
with XML? You need to know about the limitations, in case it isn't a
good fit with your problem.
How do I get started? Without any
hesitation, I hope. I'll describe the tools you need to get going with
XML and test the examples in this book. From authoring, validating,
checking well-formedness, transforming, formatting, and writing
programs, you'll have a lot to play with.
So now, let us dive
into the big questions. At the end, you should know enough to decide
where to go from here. Future chapters will describe topics in more
detail, such as core markup, quality control, style and presentation,
programming interfaces, and internationalization.