XML

Lauren Pisciotta

Zackary Zweber

History

Extensive Markup Language was developed in 1996 by an 11 member group with James Clark as the leader

Interestingly this group never met face to face, but rather communicated by email and teleconferencing

The technology is based off SGML from the 80’s

The designers simply took the best parts of SGML and merged it with the ease of use of HTML

Functional Paradigm

XML is a meta-language - a language for defining languages

In general, FP languages excel at language definition and implementation

Using OO design for XML tends merely to make our lives more difficult and our programs less clear

Comparable to HTML

Makes use of tags, words are between <brackets>

XML uses the tags only to delimit pieces of data, and leaves the interpretation of the data completely to the application that reads it

If you see a <p> in XML it doesn’t mean it’s a new paragraph, it could be anything

XML and Java

Functions are to FP what objects are to OOP

Both are platform independent

Both use data structures

Data Structuring

XML is a set of rules for designing text formats that let you structure your data

XML is NOT a programming language, and you don't have to be a programmer to use it or learn it

XML makes it easy for a computer to generate data, read data, and ensure that the data structure is unambiguous

XML avoids common pitfalls in language design: it is extensible, platform-independent, and it supports internationalization and localization

XML as text

An advantage to storing XML as text allows it to be opened in any text editor rather than just the original program

The rules of XML are more strict than HTML. A forgotten “>” in XML would cause errors allowed in HTML

The specifications in XML don’t allow applications to “second guess” what the programmer was trying to do

Bigger by design

Since XML is a text format and it uses tags to delimit the data, XML files are nearly always larger than comparable binary formats

Although binary would save space, with modern technology it isn’t necessary to make files tiny

The XML FamilyXML 1.0 – defines tags and attributes

XLink – adds hyperlinks

XPointer – pointing in XML documents(similar to a URL except points parts in the document)

CSS – Style sheet language, used in HTML also

XSL – Used for advanced style sheets

DOM – set of function calls to manipulate XML files

XML Schemas 1&2 – define XML-structure format

Modularity

XML allows you to define a new document format by combining and reusing other formats

XML provides a namespace mechanism to eliminate confusion when combining formats

XML Syntax

• Case sensitive• Everything must have a close </> <p>New paragraph (illegal in XML)

<p>New paragraph </p> (legal)• Proper nesting needed <b><i>Hello World</b></i> (illegal)• White space is not truncated • <!– This is a comment -->

Other things

XML is license free, so you don’t have to pay anybody to use it

It is platform independent, so you can create it with a variety of programs

Finally, it’s well supported, so when if you run into trouble there are lots of places to turn for help

Choosing XML is comparable to choosing SQL for a database

Hello World

 

<?xml version="1.0" encoding="ISO-8859-1"?>

<?xml-stylesheet type="text/xsl" href="HelloWorld.xsl" ?>

<!-- Hello World in XML -->

<text><string>Hello, World</string></text>

Real World Examples

• http://www.bondmovies.com/board/markers.xml

<?xml version="1.0" encoding="ISO-8859-1" ?> <markers>  <marker lng="-76.80784463882446" lat="42.08592980608292" title="thuffner" text="Where I live." type="yellow" />   <marker lng="4.49615478515625" lat="50.86144411058923" title="StonyArc" text="StonyArc DEV House" type="red" />   <marker lng="-117.96707153320312" lat="33.58716733904656" title="Perminisconious" text="My house is not underwater" type="yellow" />   <marker lng="-89.03785407543182" lat="42.20704003634335" title="JohnConner" text="Heres where I some what live" type="red" />   <marker lng="-118.44121634960175" lat="34.06879158520567" title="Shindig" text="At least, near here. ^.^" type="red" />   <marker lng="-95.32699584960937" lat="29.757224408272662" title="goldfinger1356" text="Goldfinger1356" type="red" />   <marker lng="-73.64417374134064" lat="45.59338068769037" title="Rob" text="The place where it all started" type="red" />   <marker lng="-73.49344432353973" lat="40.80126266614006" title="zmost22" text="Come Visit Me" type="red" />   <marker lng="-88.05485129356384" lat="41.69379273847097" title="Agent0007" text="Idlewood Dr" type="red" />   <marker lng="-82.01654434204101" lat="39.953438023308465" title="Jack Wade" text="Jack Wade" type="red" />   </markers>

QuickStart XML Tutorial

http://www59.homepage.villanova.edu/zackary.zweber/xml.htm