A. Dogac Grenoble Ecole de Managenent MEDFORIST Workshop1 Grenoble Ecole de Management MEDFORIST Workshop XML in Brief Asuman Dogac Middle East Technical

A. Dogac Grenoble Ecole de Managenent MEDFORIST Workshop

1

Grenoble Ecole de ManagementMEDFORIST WorkshopXML in Brief

Asuman DogacMiddle East Technical UniversityAnkara [email protected]


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XML

Extensible Markup Language has become the “universal” standard for representing data

XML started out as a standard data exchange format for the Web

Yet, it has quickly become the fundamental instrument in the development of Web-based online information services and electronic commerce applications

Almost all recent electronic commerce standards are based on XML


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XML

A subset of SGML (Standard Generalized Markup Language); it is defined by World Wide Web Consortium

HTML enables a universal method of displaying data; XML provides a universal method of describing data

Provides the ability to describe data in an open text-based format and deliver it using standard http protocol


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XML

At present, many applications on the Web use XML for hosting large amounts of structured and semi-structured data

Representation of information in XML documents has been increasing at an astonishing pace

According to Meta Group, by 2003, about 65% of corporate data will be stored in an XML format


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XMLXMLMessagingMessaging

Internet

ElectronicData

Interchange

LargeEnterprise

XML: The Unifying Technology

Mail, Phone,FAX, Email

Small, MediumEnterprise


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Browse Browse the Webthe Web

Program Program the Webthe Web

Maturity of Web Infrastructure

Technology

Technology

Web Services

Web Services

XMLXML

ProgrammabiliProgrammabilityty

HTMLHTML

Web PagesWeb Pages

PresentatioPresentationn

StandardStandard

FTP,FTP, EE-mail, Gopher

-mail, Gopher

TTCCP/IPP/IP

ConnectivitConnectivityyInnovation

Innovation


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XML helps address the challenge The data is self-describing

e.g. the meaning of the data is included: identifiers surround every bit of data, indicating what it means

Far more flexible method of representing transmitted information e.g. batched orders sent together can have different

fields and format without breaking apps on each end Open, standard technologies for moving,

processing and validating the data e.g. the XML parser can automatically parse, validate,

and feed the information to an application, instead of every application having to include this functionality


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XML: An Example

“Electronic Commerce”, “100”, “Turban”, “25”, “Addison-Wesley”

Data stream in a typical interface…

<BOOK><TITLE> Electronic Commerce </TITLE><QUANTITY> 100 </QUANTITY><AUTHOR>Turban</AUTHOR><PRICE>25</PRICE><PUBLISHER>Addison-Wesley</PUBLISHER>

</BOOK>

Same data stream in XML…


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Mark up (or Tagging)

XML uses textual markups to define data

An XML document is comprised of a collection of tagged elements each containing a start tag (<tagname>), an end tag (</tagname>), and the content between the two tags

Example:<PONumber> 1234ABCD </PONumber>


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Tagging Data in XML

<PONumber> 1234ABCD </PONumber> Considering the content only, it is not possible to

understand what 1234ABCD stands for The tag name PONumber intuitively tells that the

content is a purchase order number Similarly, an XML element might be tagged as

name, gender, birth date, salary, price,… XML is extensible in the sense that users can create

their own vocabularies, the tag names are neither predefined nor limited


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Adding Structure to data

Tagged elements may be nested to any depth to provide structured data, or may be repeated to represent a list of values

A valid XML document usually contains a single root element, which constitutes the top-level of nesting

In other words, a valid XML document represents a tree of elements


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Giving Meaning and Structure to Data<PurchaseOrderRequest>

<PONumber>1234ABCD </PONumber>

<PurchaseOrderDate>20030601</PurchaseOrderDate>

<LineItem>

<ItemEAN_Identification no=9344 />

<QuantityOrdered> 16 </QuantityOrdered>

<UnitPrice> 95 <UnitPrice>

</LineItem>

<LineItem> … </LineItem>

</PurchaseOrderRequest>

Start TagStart Tag

An Element

An Attribute

Another Element

End Tag

Data


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Giving Structure to Data

PurchaseOrderRequest

PurchaseOrderDatePONumber LineItem

ItemEAN_Identification QuantityOrdered UnitPrice


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Document Type Definition (DTD) The principle purpose of the DTD is to declare the

hierarchy of document elements A document type definition defines:

The name of the elements, The content model of each element, How often and in which order elements may appear, If the end-tags can be shortcut, The possible presence of attributes and their default

values, The names of the entities


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An Example DTD

<?xml version=“1.0” encoding=“UTF-8”?><!DOCTYPE simple [<!ELEMENT PurchaseOrderRequest (PONumber,

PurchaseOrderDate, LineItem+)><!ELEMENT LineItem (ItemEAN_Identification,

QuantityOrdered, UnitPrice)><!ELEMENT ItemEAN_Identification(#PCDATA)><!ELEMENT QuantityOrdered (#PCDATA)><!ELEMENT UnitPrice (#PCDATA)><! --This is a comment line to state that the other

elements are skipped --> ...]>


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DTDs

A DTD specifies the structure of an XML element by specifying the names of its sub-elements and attributes

Sub-element structure is specified using the operators * : set with zero or more elements + : set with one or more elements ?: optional | : or

All values are assumed to be string values, unless the type is ANY in which case the value can be an arbitrary XML fragment


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XML Namespaces

Namespaces are a simple and straightforward way to distinguish names used in XML documents, no matter where they come from

The only reason namespaces exist, is to give elements and attributes programmer-friendly names that will be unique across the whole Internet


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Example<h:html xmlns:xdc="http://www.xml.com/books"

xmlns:h="http://www.w3.org/HTML/1998/html4">

<h:head><h:title>Book Review</h:title></h:head>

<h:body> <xdc:bookreview> <xdc:title>XML: A Primer</xdc:title>

<h:table> <h:tr align="center">

<h:td>Author</h:td><h:td>Price</h:td>

<h:td>Pages</h:td><h:td>Date</h:td></h:tr>

<h:tr align="left">

<h:td><xdc:author>Simon St. Laurent</xdc:author></h:td>

<h:td><xdc:price>31.98</xdc:price></h:td>

<h:td><xdc:pages>352</xdc:pages></h:td>

<h:td><xdc:date>1998/01</xdc:date></h:td>

</h:tr> </h:table> </xdc:bookreview> </h:body> </h:html>


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XML Namespaces

The prefixes are linked to the full names using the attributes on the top element.whose names begin xmlns:.

The prefixes are just shorthand placeholders for the full names Those full names are URLs, i.e. Web addresses


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Extensibility in XML

Anyone can invent new tags and attach a meaning to those tags

But if every user creates its own XML definition for describing his data, it is not possible to achieve interoperability

For example, one may prefer to use the tag name “POR”, while another prefers using the tag name “PurchaseOrderReq”

In other words, a tagged document is not very useful without some kind of agreement on the tags among inter-operating applications


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Many Efforts for Standardized Tags… HL7 for healthcare RosettaNet for supply chain integration in

Information Technology and Electronic Components domain

ebXML for eBusiness Common Business Library (CBL) for

electronic catalogs, purchase orders, etc. …


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XML Parsers

A parser takes an XML document and makes its structure and content available to an application through an API

There are two main Application Programming Interfaces (APIs) for writing parsers: Document Object Model (DOM) and Simple API for XML (SAX)

Today, many parsers are both DOM and SAX compliant


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XML DOM ParserApplication Code

Initialize Parser

In memory DOM: PerformProcessing

XMLParser

XMLDocument

Begin parsing

Parsing complete

A parser validates and makes the data contained in an XML document availableto the application


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XSLT Processor

XMLDocument

XSL StyleSheet 2

Output from Style

Sheet 1

Output fromStyle

Sheet 2

XSL StyleSheet 1

Parser

XSLT Processor

• Converts an XML document to another form

• An XSL style sheet is a set of transformation instructions for converting a source XML document to a target document


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table.xsl

bar.xsl

art.xsl


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Why XML?

EDI XML

BGM+220+1234ABCD+9' DTM+137:20030601:102'

LIN+1' PIA+5+9344:EN+1078341ITEM:VP' QTY+21:16:EA' PRI+AAA:95'

LIN+2' …

<PurchaseOrderRequest> <PONumber>1234ABCD </PONumber> <PurchaseOrderDate>20030601</PurchaseOrderDate> <FirstLineItem> <ItemEAN_Identification no=9344 /> <QuantityOrdered> 16 </QuantityOrdered> <UnitPrice> 95 <UnitPrice></FirstLineItem> <SecondLineItem>…


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XML vs EDI

XML is an open human-readable, text format

EDI documents are typically in a compressed, machine-only readable form

XML is designed to require one customised mapping per industry grouping, so most companies will be able to work to one format and use XML

EDI traditionally requires customised mapping of each new trading partners document format

XML requires a reliable PC with an Internet connection

EDI typically requires dedicated servers that cost from USD10,000 and up


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XML vs EDI

XML documents are typically sent via the Internet - i.e. a relatively low-cost public network

EDI documents are typically sent via private and relatively expensive value-added networks (VANs)

XML in Internet-based has low ongoing flat-rate costs using existing Internet connections and relatively low-cost Web Servers

EDI can involve high on-going transaction based costs keeping up the connection to the EDI network and keeping the servers up and running


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XML vs EDI

XML appears to have no upper limit in terms of numbers of users

EDI is estimated to be limited to 300,000 companies worldwide and about 20% of their suppliers because of operational costs and complexity

XML is being developed in a world of shared software development populated by many low-cost tools and open source projects.

EDI was traditionally built from the ground up in semi-isolation without being able to share resources with other programs

Documents

A. Dogac Grenoble Ecole de Managenent MEDFORIST Workshop1 Grenoble Ecole de Management MEDFORIST Workshop XML in Brief Asuman Dogac Middle East Technical