1 Introduction to XML XML stands for Extensible Markup Language. Because it is extensible, XML has been used to create a wide variety of different markup vocabularies.

2 CML: An XML Example

3 GolfML: Another XML Example …

4 Why is XML Important? XML gives us a way to create and maintain structured documents in plain text that can be rendered in a variety of different ways. A primary objective of XML is to completely separate content from presentation. Example: The Asbury Park Press is a structured document containing pages, columns, etc. The news is just plain text (including the images). Newspapers can be rendered on paper or online.

5 Where XML Fits into Other Markup Languages

6 DTDs and XML Documents A DTD (Document Type Definition) or schema specifies the rules for what a legal XML document may contain. An XML document is well-formed if it contains no syntax errors and fulfills all of the specifications for XML code as defined by the W3C. An XML document is valid if it is well-formed and also satisfies the rules laid out in the DTD or schema attached to the document.

7 The Structure of an XML Document: The Prolog The XML declaration is always the first line of code in an XML document. It tells the parser what follows is written using XML. The complete syntax is: <?xml version=“version number” encoding=“encoding type” standalone=“yes | no” ?> The typical declaration is: <?xml version=“1.0” encoding=“UTF-8” standalone = “yes” ?>

8 Closed elements have the following syntax: Content For example: Miles Davis Open elements have the syntax: For example: Element names are case sensitive, must begin with a letter (or _), and may not contain spaces. Elements can be (properly) nested. For example: So What Blue in Green All elements must be nested within a single root element. Comments are enclosed in (like HTML). The Structure of an XML Document: Elements

9 An attribute is a property of an element. They are text strings placed in single or double quotes. The syntax is: The Structure of an XML Document: Attributes

The Element Hierarchy 10

11 Special Character References Special symbols can be inserted into an XML document using either the character reference or entity reference,

12 CDATA Sections Validators can get confused by some XML: > 100 degrees You must separate the file into PCDATA and CDATA. Parsed character data (PCDATA) is text to be parsed by a browser or parser (all the XML code: declarations, elements, attributes, comments). Unparsed character data (CDATA) is text not to be processed by the browser or parser. A CDATA section marks a block of text as CDATA so that parsers ignore any text within it: <![CDATA[ > 100 degrees ]]>

13 Mark Your XML with the Sections You Don’t Want Parsed CDATA section

14 Parsing an XML Document

15 Displaying an XML Document in a Web Browser If it’s well-formed If it’s not well-formed

16 Linking to a Style Sheet

17 Applying Styles to the XML Elements To apply a style sheet to a document, use the syntax: selector {attribute1:value1; attribute2:value2; …} For example: artist {color:red; font-weight:bold}

18 Linking the XML to the Style Sheet The link from the XML document to a style sheet is created using a processing statement. A processing instruction is a command that gives instructions to the XML parser.

19 The XML Document Formatted with the Style Sheet