Full HTML for

Basic foilset An Introduction to XML

Given by Nancy McCracken,Ozgur Balsoy, Tom Scavo at Basic Information Track Computational Science Course CPS616 on Spring Semester 1999. Foils prepared May 19 99
Outside Index Summary of Material

Overview of XML and its relationship to HTML and SGML
XML extensible tags: DTD
Some simple examples
XSL and XLL
XML tools
Details on writing XML
Example showing the use of XML to store a simple database

Table of Contents for full HTML of An Introduction to XML

 Denote Foils where Image has important information
Denote Foils where HTML is sufficient
1 An Introduction to XML
2 Outline
3 References
4 Overview of HTML
5 Beyond HTML
6 What is XML?
7 Logical vs. Visual Design
8 What is SGML?
9 SGML Example
10 SGML Example (cont'd)
11 XML is SGML Lite
12 XML Design Goals
13 Origins of XML
14 "Hello World!" in XML
15 XML Language Elements
16 Document Type Definition
17 XML must be "well-formed"
18 XML Example
19 XML Example (cont'd)
20 XML Example (cont'd)
21 XML Example (cont'd)
22 XML tag structure
23 XML tag details
24 Syntactic details
25 Document Type Definition
26 Document Type Definition
27 DTD definitions
28 Document Type Definition
29 Document Type Definition
30 Element Declarations
31 Element Declarations
32 Element Declarations
33 Attributes
34 Attribute Types
35 Entities
36 XML Example - the DTD
37 XML Example - the XML document
38 Additional XML/DTD Topics
39 Extensible Style Language
40 Document Formatting (XSL)
41 Document Formatting (XSL)
42 XSL Processing Overview
43 Document Formatting (XSL)
44 Extensible Link Language
45 Uses of XML
46 Software Tools
47 Conclusions

Outside Index Summary of Material

HTML version of Basic Foils prepared May 19 99

Foil 1 An Introduction to XML

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
Nancy McCracken,
Ozgur Balsoy, Tom Scavo
Northeast Parallel Architectures Center at Syracuse University
111 College Place, Syracuse, NY 13244
http://www.npac.syr.edu/XML
HTML version of Basic Foils prepared May 19 99

Foil 2 Outline

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
Overview of XML and its relationship to HTML and SGML
XML extensible tags: DTD
Some simple examples
XSL and XLL
XML tools
Details on writing XML
Example showing the use of XML to store a simple database
HTML version of Basic Foils prepared May 19 99

Foil 3 References

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
XML Complete, Steven Holzner [McGraw-Hill, 1998, ISBN 0-07-913702-4]
"XML, Java, and the future of the Web", Jon Bosak, Sun Microsystems, 1997
"Weaving a Better Web", S. Mace, U. Flohr, R. Dobson, T. Graham, Byte, March 1998, pp.58-68
NPAC's XML Resources page, http://www.npac.syr.edu/projects/tutorials/XML/
HTML version of Basic Foils prepared May 19 99

Foil 4 Overview of HTML

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
HTML = Hypertext Markup Language
  • the lingua franca of the World Wide Web
  • HTML is a simple language well suited for hypertext, multimedia and the display of small and reasonably simple documents
HTML 2.0 spec completed in Nov 95
HTML+ and HTML 3.0 never released
HTML 3.2 (Jan 97) added tables, applets, and other capabilities (approximately 70 tags)
  • this is what most people are familiar with today
HTML 4.0 spec released in Dec 97
HTML version of Basic Foils prepared May 19 99

Foil 5 Beyond HTML

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
Limitations of HTML:
  • Extensibility: HTML does not allow users to specify their own tags or attributes in order to parameterize or otherwise semantically qualify their data.
  • Structure: HTML does not support the specification of deep structures needed to represent database schema or object-oriented hierarchies.
  • Validation: HTML does not support the kind of language specification that allows applications to check data for structural validity when it is imported.
HTML version of Basic Foils prepared May 19 99

Foil 6 What is XML?

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
XML = eXtensible Markup Language
XML is a subset of Standard Generalized Markup Language, but unlike the latter, XML is specifically designed for the web
How XML fits into the new HTML world:
  • XML describes the logical structure of the document.
  • CSS (Cascading Style Sheets) or other style language describes the visual presentation of the document.
  • The DOM (Document Object Model) allows scripting languages, such as JavaScript to access document objects.
  • DHTML (Dynamic HTML) allows a dynamic presentation of the document.
HTML version of Basic Foils prepared May 19 99

Foil 7 Logical vs. Visual Design

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
The logical design of a document (content) should be separate from its visual design (presentation)
Separation of logical and visual design
  • promotes sound typography
  • encourages better writing
  • is more flexible
XML can be used to define the logical design, while the XSL (Extensible Style Language) is used to define the visual design.
HTML version of Basic Foils prepared May 19 99

Foil 8 What is SGML?

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
SGML = Standard Generalized ML
A SGML document carries with it a grammar called a Document Type Definition (DTD). The DTD defines the tags and the meaning of those tags
Presentation is governed by a style sheet written in the Document Style Semantics and Specification Language (DSSSL)
Note that HTML is a fixed SGML application, a hard-wired set of about 70 tags and 50 attributes, and does not need to have a DTD.
HTML version of Basic Foils prepared May 19 99

Foil 9 SGML Example

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
A simple SGML document with embedded DTD: <!DOCTYPE DOCUMENT [ <!ELEMENT DOCUMENT O O (p*,BIGP*)> <!ELEMENT p - O (#PCDATA)> <!ELEMENT BIGP - O (#PCDATA)> ]> <DOCUMENT> <p>Welcome to <BIGP>XML Style! </DOCUMENT>
HTML version of Basic Foils prepared May 19 99

Foil 10 SGML Example (cont'd)

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
A corresponding DSSSL style sheet: <!DOCTYPE style-sheet PUBLIC "-//James Clark//DTD DSSSL Style Sheet//EN"> (root (make simple-page-sequence)) (element p (make paragraph)) (element BIGP (make paragraph font-size: 24pt space-before: 12pt))
HTML version of Basic Foils prepared May 19 99

Foil 11 XML is SGML Lite

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
XML is also an SGML application, but since XML is extensible (XML is also a metalanguage), every XML document must be accompanied by its DTD
XML is a compromise between the non-extensible, limited capabilities of HTML and the full power and complexity of SGML
XML offers "80% of the benefits of SGML for 20% of its complexity"
  • XML designers tried to leave out all the SGML that would be rarely used on the web
  • Note that XML specification is 30 pages and the SGML specification is 500 pages.
XML allows you to define your own tags and to describe nested hierarchies of information.
HTML version of Basic Foils prepared May 19 99

Foil 12 XML Design Goals

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
1) XML shall be usable over the Internet
2) XML shall support a variety of applications
3) XML shall be compatible with SGML
4) It shall be easy to write programs that process XML documents
5) Optional features in XML shall be kept to the absolute minimum, ideally zero
6) XML documents should be human-legible and reasonably clear
7) Design of XML should be prepared quickly
8) Design of XML shall be formal and concise
9) XML documents shall be easy to create
10) Terseness in XML markup is of minimal importance
HTML version of Basic Foils prepared May 19 99

Foil 13 Origins of XML

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
First draft of XML spec released by W3C in Nov 96 (four other drafts published in 1997)
The first XML parser (written in Java) released by Microsoft in July 97
Microsoft released version 1.8 of its XML parser (which supports XML 1.0) in Jan 98
W3C finalized the XML 1.0 spec in Feb 98
First XML-aware beta versions of NC and IE5.0 released in June 98
Sun announced Java Standard Extension for XML (XML API) in March 99
HTML version of Basic Foils prepared May 19 99

Foil 14 "Hello World!" in XML

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
An XML document with external DTD: <?xml version="1.0"?> <!DOCTYPE greeting SYSTEM "hello.dtd"> <greeting>Hello World!</greeting>
An XML document with embedded DTD: <?xml version="1.0"?> <!DOCTYPE greeting [ <!ELEMENT greeting (#PCDATA)> ]> <greeting>Hello World!</greeting>
HTML version of Basic Foils prepared May 19 99

Foil 15 XML Language Elements

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
Document Type Definition (DTD), which defines the tags and their relationships
Extensible Style Language (XSL) style sheets, which specify the presentation of the document
Extensible Link Language (XLL), which defines link-handling details
HTML version of Basic Foils prepared May 19 99

Foil 16 Document Type Definition

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
The DTD specifies the logical structure of the document; it is a formal grammar describing document syntax and semantics
The DTD does not describe the physical layout of the document; this is left to the style sheets and the scripts
It is no mean task to write a DTD, so most users will adopt predefined DTDs
DTDs can be written in separate files to facilitate re-use.
Content-providers, industries and other groups can collaborate to define sets of tags.
HTML version of Basic Foils prepared May 19 99

Foil 17 XML must be "well-formed"

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
For the data contained in an XML document to be parsed correctly, its markup must be well-formed, meaning that properly nested and nonabbreviated starting and ending tags are used.
  • This well-formedness provides the encapsulation mechanism allowing designated sections of the data to be accessed programmatically.
  • It is important to remember that XML is a markup language, not a programming language
Scenario #1: the server offers the XML document without its DTD, the parser does a syntax check, and the DTD follows if the XML document is "well-formed"
Scenario #2: the server checks the XML document against its DTD ("validity") before sending the document to the client
HTML version of Basic Foils prepared May 19 99

Foil 18 XML Example

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
Another example which could be used for URL exchanges between network capable applications: <LINK> <TITLE>XML Recommendation</TITLE> <URL> http://www.w3.org/TR/REC-xml </URL> <DESCRIPTION> The official XML spec from W3C </DESCRIPTION> </LINK>
HTML version of Basic Foils prepared May 19 99

Foil 19 XML Example (cont'd)

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
A document may have many such links: <DOCUMENT> <LINKS> <LINK>...</LINK> <LINK>...</LINK> ... </LINKS> </DOCUMENT>
HTML version of Basic Foils prepared May 19 99

Foil 20 XML Example (cont'd)

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
Now write a DTD for this document: <!ELEMENT DOCUMENT (LINKS)> <!ELEMENT LINKS (LINK)*> <!ELEMENT LINK (TITLE,URL,DESCRIPTION)> <!ELEMENT TITLE (#PCDATA)> <!ELEMENT URL (#PCDATA)> <!ELEMENT DESCRIPTION (#PCDATA)>
PCDATA stands for "parsed character data"
HTML version of Basic Foils prepared May 19 99

Foil 21 XML Example (cont'd)

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
Store the DTD in a file (links.dtd) and write an XML document based on this DTD: <?XML version="1.0"?> <!DOCTYPE DOCUMENT SYSTEM "links.dtd"> <DOCUMENT> <LINKS> <LINK>...</LINK> <LINK>...</LINK> ... </LINKS> </DOCUMENT>
Note that you need an XML compiler to generate regular HTML in Netscape browsers - Internet Explorer 5.0 has a compiler built in.
HTML version of Basic Foils prepared May 19 99

Foil 22 XML tag structure

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
In XML terminology, a pair of start and end tags is an element.
XML documents allow only one root element.
XML documents must have a strict hierarchical structure.
  • All start tags must have an end tag.
  • Any element must be properly nested within another. <LI> XML requires <B><I>proper nesting</I></B>.</LI>
Empty tags are allowed as elements in XML documents.
  • An empty tag is a start and end tag together and is identified by a trailing / after the tag name. <LI>XML requires empty tags, such as <BR/>.</LI>
  • A start tag and end tag with nothing in-between can also be considered an empty tag. <IMG SRC="face.gif"></IMG>
HTML version of Basic Foils prepared May 19 99

Foil 23 XML tag details

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
All attribute values must be within single or double quotes. <FONT COLOR="#FF00CC"> quoted attribute </FONT>
HTML version of Basic Foils prepared May 19 99

Foil 24 Syntactic details

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
XML tags are case-sensitive. (<H1> is not the same as <h1>.
White space in the data between tags is relevant. But within the markup itself and within quoted attribute values, white space is normalized (removed).
XML allows you to specify different character set encodings. <?xml version=`1.0' encoding=`UTF-8' ?>
Predefined entities:
  • < replaced by <
  • & &
  • > >
  • ' `
  • " "
HTML version of Basic Foils prepared May 19 99

Foil 25 Document Type Definition

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
An optional, but powerful feature of XML that provides a formal set of rules to define a document structure
Defines the elements that may be used, and dictates where they may be applied in relation to each other; therefore specifies the document hierarchy and granularity
Comprises a set of declarations that define a document structure tree
Declarations stored either at the top of each document that must conform to the rules, or alternatively, and more usually, in separate data files, referred by a special instruction at the top of each document.
HTML version of Basic Foils prepared May 19 99

Foil 26 Document Type Definition

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
Each DTD element must either be a container element, or be empty (a place holder). Container elements may contain text, child elements, or a mixture of both.
DTD also specifies the names of attributes, and dictates which elements they may appear in. For each attribute it specifies whether it is optional or required.
DTD tree describing a book as containing a number of Chapter elements, with each chapter containing either a number of Paragraph elements, or a single Sections element
A particular document tree has a node for each actual chapter and paragraph present, and may omit some of the optional elements
HTML version of Basic Foils prepared May 19 99

Foil 27 DTD definitions

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
A DTD allows you to create new tags by writing grammar rules which the tags must obey. The rules specify which tags and attributes are valid and their context.
A DTD element declaration looks like: <!ELEMENT person(name, email*)>
  • ELEMENT is the type
  • person is the element declaration
  • (name,email*) is the element content model
  • name and email are the children of person and define the hierarchy of the document.
  • Note that this is called a grammar rule because it could have been written in BNF: person ::= (name, email*)
HTML version of Basic Foils prepared May 19 99

Foil 28 Document Type Definition

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
Each declaration must follow markup format <!...>, and can only use the one of the following keywords:
  • ELEMENT (tag definition)
  • ATTLIST (attribute definitions)
  • ENTITY (entity definition)
  • NOTATION (data type notation definition)
Declarations are grouped within a DTD <!DOCTYPE MYDTD [ <!-- The MYDTD appears here --> <!......> ]>
HTML version of Basic Foils prepared May 19 99

Foil 29 Document Type Definition

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
Declarations stored externally and shared by different documents linked as: <!DOCTYPE MYDTD SYSTEM "EXTRNL.DTD" [ <!-- Some of MYDTD appears here --> <!......> ]>
HTML version of Basic Foils prepared May 19 99

Foil 30 Element Declarations

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
Keyword ELEMENT Introduces a new element <!ELEMENT title .........>
Element name must begin with a letter, and may additionally contain digits and some punctuations, i.e. `.', `-', `_', and `:'
If an element can hold no child elements, and also no text, then it is known as empty element and denoted by EMPTY
An element declared to have a content .of ANY may contain all of the other elements declared in the DTD
<!ELEMENT p ANY> <!ELEMENT image EMPTY>
Empty element usage: <image></image> or <image/>
HTML version of Basic Foils prepared May 19 99

Foil 31 Element Declarations

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
A model group is used to define an element that has mixed content or element content.
A model group is bounded by brackets, and contains at least one token.
When a model group contains more than one content token, the child elements are controlled using two logical connector operators; sequence connector `,', and choice connector `|'
<!ELEMENT element1 (a, b, c)> indicates a is followed by element b, which in turn is followed by c.
<!ELEMENT element2 (a | b | c)> indicates either one can be selected.
Combinations are possible: (a,b,(c|d)), or ((a,b,c) | d)
HTML version of Basic Foils prepared May 19 99

Foil 32 Element Declarations

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
Quantity indicators can also be used.
  • `?' indicates an element is optional or cannot repeat
  • `+' indicates an element is required and may repeat
  • `*' indicates an element is optional, and also repeatable
Document text is indicated by the keyword PCDATA (Parsable Character Data) <!ELEMENT emph (#PCDATA|sub|super)*> <!ELEMENT sub (#PCDATA)> <!ELEMENT super (#PCDATA)> <emph>H<subɮ</subɬ is water.</emph>
HTML version of Basic Foils prepared May 19 99

Foil 33 Attributes

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
The rules for attribute declarations follow a similar structure to elements. <!ATTLIST person gender (male|female)#IMPLIED >
  • ATTLIST is the type
  • person is the element
  • gender is the attribute declaration
  • (male|female)#IMPLIED is the attribute definition
The keywords following an attribute definition can be
  • #IMPLIED attribute is optional
  • "unknown" string in quotes is the default attribute
  • #REQUIRED attribute is required
  • #FIXED if attribute is present, it is assigned a fixed value
HTML version of Basic Foils prepared May 19 99

Foil 34 Attribute Types

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
Enumerated types (male|female|unknown)
CDATA type is character data - may include markup <!ATTLIST form method CDATA #FIXED `POST'>
Tokenized types include the following tokens with special meanings:
  • ID requires that the attribute have a unique value
  • IDREF is rquired to match an ID attribute within the same document
HTML version of Basic Foils prepared May 19 99

Foil 35 Entities

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
The DTD of an XML document can contain entity declarations. These are like constants in other languages.
  • An entity declaration specifies replacement text for the entity including some macro-preprocessing capability. <!ENTITY % pub "Éditions Gallimard"> <!ENTITY rights "All rights reserved"> <!ENTITY book "La Pest: Albert Camus, &#sA9; 1947 %pub; . &rights;">
  • This entity would have replacement text for book: La Peste: Albert Camus, c 1947 Editions Gallimard. &rights; where c would be copyright symbol, and E has accent mark.
HTML version of Basic Foils prepared May 19 99

Foil 36 XML Example - the DTD

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
Create a DTD file for an address book named "ab.dtd"
<!ELEMENT addressBook (person)+>
<!ELEMENT person (name, email*, link?) >
<!ATTLIST person id ID #REQUIRED >
<!ATTLIST person gender (male|female)#IMPLIED >
<!ELEMENT name (#PCDATA|(family,given))>
<!ELEMENT family (#PCDATA)>
<!ELEMENT given (#PCDATA)>
<!ELEMENT email (#PCDATA)>
<!ELEMENT link EMPTY > <!ATTLIST link manager IDREF #IMPLIED subordinates IDREFS #IMPLIED >
HTML version of Basic Foils prepared May 19 99

Foil 37 XML Example - the XML document

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
<?xml version="1.0"?> <!DOCTYPE addressBook SYSTEM "ab.dtd"> <addressBook> <person id="B.WALLACE" gender="male"> <name> <family>Wallace</family> <given>Bob</given> </name> <email>bwallace@megacorp.com</email> <link> manager="C.TUTTLE"/> </person> <person id="C.TUTTLE" gender="femail"> <name> <family>Tuttle</family> <given>Claire </given </name> <email>ctuttle@megacorp.com</email> <link subordinates="B.WALLACE"/> </person> </addressBook>
HTML version of Basic Foils prepared May 19 99

Foil 38 Additional XML/DTD Topics

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
Encoding, internalization and languages
Entities: Internal and External, the constants and macro-processing of XML
Processing instructions - allow documents to contain instructions for applications
Using a language such as Java to write a parser for XML documents.
W3C is considering draft proposals for schemas that would allow you an easier syntax to write DTD grammar rules.
HTML version of Basic Foils prepared May 19 99

Foil 39 Extensible Style Language

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
XSL is to XML as Cascading Style Sheets (CSS) are to HTML
Like a CSS, an XSL style sheet describes the presentation of the XML document
Advanced layout features of XSL include: rotated text, multiple columns, and independent regions
Development of XSL lags behind XML
HTML version of Basic Foils prepared May 19 99

Foil 40 Document Formatting (XSL)

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
Content of XML documents is intended to be easily read by both people and software, but raw XML data is not suitable for viewing by people who are not interested in structure.
To publish information held in XML format it is necessary to replace the tags with appropriate text styles.
Extensible Style Language (XSL) meets this requirement.
HTML version of Basic Foils prepared May 19 99

Foil 41 Document Formatting (XSL)

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
A style rule is used to assign a style to a particular XML element.
It is possible to embed a style rule within an attribute: <p xsl::font-size="9pt" xsl::color="blue">A blue, 9pt paragraph.</p>
The problem with this approach is that the rule must be repeated each time the element is used. The style sheets are developed to solve this problem so that rules are grouped together, and can be shared by multiple files.
HTML version of Basic Foils prepared May 19 99

Foil 42 XSL Processing Overview

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
In general, XSL first specifies how to process the source tree to get a result tree.
The pattern of a template rule is matched with the source tree and replaces it with the template.
The result tree is then processed with formatting to achieve a document suitable for display, printing, speech or other media.
XSL and XML may have their own namespaces for rules.
HTML version of Basic Foils prepared May 19 99

Foil 43 Document Formatting (XSL)

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
General Structure <?xml-stylesheet href="article.stl" type="text/xsl"?> <!DOCTYPE article .........> <article> ... </article>
Each style sheet has a root element called xsl. It may contain any combination of Rule and Stylerule elements.
<xsl> <rule>...</rule><rule>...</rule><stylerule>...</stylerule> </xsl>
HTML version of Basic Foils prepared May 19 99

Foil 44 Extensible Link Language

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
XLL supports simple links (like HTML) plus:
  • Location-independent naming
  • Bidirectional links
  • External links
  • N-ary hyperlinks
  • Aggregate links and link types
  • Transclusion
XLL components: Xlink and XPointer
HTML version of Basic Foils prepared May 19 99

Foil 45 Uses of XML

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
XML can be used as Electronic Data Interchange (EDI):
  • Applications requiring client to mediate between two heterogeneous databases
  • Applications that attempt to redistribute processing load from server to client
  • Applications requiring client to present multiple views of same web document
  • Applications that perform or require detailed, domain-specific search results
HTML version of Basic Foils prepared May 19 99

Foil 46 Software Tools

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
An XML parser (in Java or C++) and an XSL parser are available from Microsoft and IBM
Internet Explorer 5.0 supports XML
An HTML browser may be retrofitted with an XML plugin or applet, but if XML is to survive, full-fledged XML browsers must be developed
HTML version of Basic Foils prepared May 19 99

Foil 47 Conclusions

From An Introduction to XML Basic Information Track Computational Science Course CPS616 -- Spring Semester 1999. *
Full HTML Index
Coupled with XSL, DOM, and a scripting language, XML provides a powerful alternative to HTML
Search engines may make better use of XML documents
Prediction: XML will replace HTML!
Few browsers support XML at this time
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