2. ICS-FORTH 1 May 22, 2001 Christos Georgis The extensible markup language: An introduction to XML What is a XML document ? How do we check its validity ? How do we display its content ?

3. ICS-FORTH 2 May 22, 2001 Christos Georgis What Is XML ? XML stands for EXtensible Markup Language XML is a markup language much like HTML XML was designed to describe data XML tags are not predefined in XML: you must define your own tags XML uses a DTD (Document Type Definition) to describe the data XML with a DTD is designed to be self describing XML uses a CSS (Cascading Style Sheets) to display information

4. ICS-FORTH 3 May 22, 2001 Christos Georgis Vincent van Gogh 1853 Holland 1890 France The Starry Night 1889 Oil on Canvas 29 36 1/4 Museum of Modern Art, NewYork An Example XML Document element content xml-declaration end-tag start-tag root element

5. ICS-FORTH 4 May 22, 2001 Christos Georgis Vincent van Gogh 1853 Holland 1890 France The Starry Night 1889 Oil on Canvas 29 36 1/4 Museum of Modern Art, NewYork An Example XML Document attribute nameattribute value

6. ICS-FORTH 5 May 22, 2001 Christos Georgis “Well Formed” vs “Valid” XML Documents XML (document) with correct syntax is Well Formed XML  All XML elements must have a closing tag  XML tags are case sensitive  All XML elements must be properly nested  All XML documents must have a root tag  Attribute values must always be quoted XML (document) validated against a DTD is Valid XML  A DTD defines the legal elements of an XML document Vincent van Gogh 1853 Holland ………

7. ICS-FORTH 6 May 22, 2001 Christos Georgis An Example XML DTD Declaring zero or more occurrences of the same element (*) Declaring zero or one occurrences of the same element (?) GROUP: element with children (sequences) Elements with only character data

8. ICS-FORTH 7 May 22, 2001 Christos Georgis XML DTD Building Blocks Elements  Elements are the main building blocks of both XML and HTML documents  Tags are used to markup elements (e.g. … )  Elements are nested and may define a specific sequence Attributes  Attributes provide extra information about elements (other than their content and type)  Attributes are always placed inside the starting tag of an element Attributes always come in name/value pairs ( e.g. 36 1/4 )  May be applied to one specific instance of a given element Entities  Entities are variables used to define common text

9. ICS-FORTH 8 May 22, 2001 Christos Georgis XML DTD Elements

10. ICS-FORTH 9 May 22, 2001 Christos Georgis XML DTD Attributes and Entities

11. ICS-FORTH 10 May 22, 2001 Christos Georgis Viewing XML Documents with IE 5.0

12. ICS-FORTH 11 May 22, 2001 Christos Georgis Displaying XML with CSS

13. ICS-FORTH 12 May 22, 2001 Christos Georgis What is CSS ? CSS stands for Cascading Style Sheets Styles define how to display HTML/XML elements Styles are normally stored in Style Sheets Styles were added to HTML 4.0 to solve a problem External Style Sheets can save you a lot of work External Style Sheets are stored in CSS files Multiple style definitions will cascade into on  cascading order

14. ICS-FORTH 13 May 22, 2001 Christos Georgis CSS Syntax Use of External Style Sheets Grouping Basic syntax artifact, artist, artwork, name, title { font-family: Arial; font-size: 16pt; display: block; } title { font-family: Palatino; font-size: 16pt; font-weight: bold; text-align: center; color: #6699CC; }...

15. ICS-FORTH 14 May 22, 2001 Christos Georgis CSS Display Properties Background properties (color, image, position) Text properties (color, alignment, direction, letter-spacing) Font properties (family, size, style, weight) Border properties (color, style, width) Margin properties Padding properties Classification properties (visibility, inline, block) Pseudo-elements (:before, :after)