xml vadim parizher cs 496-ebt fall 2003. learning objectives learn what xml is learn the various...

XML

Vadim Parizher

CS 496-EBT

Fall 2003

Learning Objectives

Learn what XML is Learn the various ways in which XML is used Learn the key companion technologies

Agenda

Overview Syntax and Structure The XML Alphabet Soup

OverviewWhat is XML?

A tag-based meta language Designed for structured data representation Represents data hierarchically (in a tree) Provides context to data (makes it meaningful)

Self-describing data

Separates presentation (HTML) from data (XML) An open W3C standard A subset of SGML

vs. HTML, which is an implementation of SGML

OverviewWhat is XML?

XML is a “use everywhere” data specification

DocumentsConfiguration

Database

Application X

Repository

XML XML

XML XML

OverviewDocuments vs. Data

XML is used to represent two main types of things: Documents

Lots of text with tags to identify and annotate portions of the document

Data Hierarchical data structures

OverviewXML and Structured Data

Pre-XML representation of data:

XML representation of the same data:

“PO-1234”,”CUST001”,”X9876”,”5”,”14.98”

<PURCHASE_ORDER><PO_NUM> PO-1234 </PO_NUM><CUST_ID> CUST001 </CUST_ID><ITEM_NUM> X9876 </ITEM_NUM><QUANTITY> 5 </QUANTITY><PRICE> 14.98 </PRICE>

</PURCHASE_ORDER>

OverviewBenefits of XML

Open W3C standard Representation of data across heterogeneous

environments Cross platform Allows for high degree of interoperability

Strict rules Syntax Structure Case sensitive

OverviewWho Uses XML?

Submissions by Microsoft IBM Hewlett-Packard Fujitsu Laboratories Sun Microsystems Netscape (AOL), and others…

Technologies using XML SOAP, ebXML, BizTalk, WebSphere, many others…

Agenda

Overview Syntax and Structure The XML Alphabet Soup

Syntax and StructureComponents of an XML Document

Elements Each element has a beginning and ending tag

<TAG_NAME>...</TAG_NAME> Elements can be empty (<TAG_NAME />)

Attributes Describes an element; e.g. data type, data range, etc. Can only appear on beginning tag

Processing instructions Encoding specification (Unicode by default) Namespace declaration Schema declaration

Syntax and StructureComponents of an XML Document

<?xml version=“1.0” ?><?xml-stylesheet type="text/xsl" href=“template.xsl"?><ROOT>

<ELEMENT1><SUBELEMENT1 /><SUBELEMENT2 /></ELEMENT1><ELEMENT2> </ELEMENT2><ELEMENT3 type=‘string’> </ELEMENT3><ELEMENT4 type=‘integer’ value=‘9.3’> </ELEMENT4>

</ROOT>

Prologue (processing instructions)

Elements

Elements with Attributes

Syntax and StructureRules For Well-Formed XML

There must be one, and only one, root element Sub-elements must be properly nested

A tag must end within the tag in which it was started

Attributes are optional Defined by an optional schema

Attribute values must be enclosed in “” or ‘’ Processing instructions are optional XML is case-sensitive

<tag> and <TAG> are not the same type of element

Syntax and StructureWell-Formed XML?

No, CHILD2 and CHILD3 do not nest propertly

<xml? Version=“1.0” ?><PARENT>

<CHILD1>This is element 1</CHILD1><CHILD2><CHILD3>Number 3</CHILD2></CHILD3>

</PARENT>

Syntax and StructureWell-Formed XML?

No, there are two root elements

<xml? Version=“1.0” ?><PARENT>

<CHILD1>This is element 1</CHILD1></PARENT><PARENT>

<CHILD1>This is another element 1</CHILD1></PARENT>

Syntax and StructureWell-Formed XML?

Yes

<xml? Version=“1.0” ?><PARENT>

<CHILD1>This is element 1</CHILD1><CHILD2/><CHILD3></CHILD3>

</PARENT>

Syntax and StructureAn XML Document

<?xml version='1.0'?><bookstore> <book genre=‘autobiography’ publicationdate=‘1981’ ISBN=‘1-861003-11-0’> <title>The Autobiography of Benjamin Franklin</title> <author> <first-name>Benjamin</first-name> <last-name>Franklin</last-name> </author> <price>8.99</price> </book> <book genre=‘novel’ publicationdate=‘1967’ ISBN=‘0-201-63361-2’> <title>The Confidence Man</title> <author> <first-name>Herman</first-name> <last-name>Melville</last-name> </author> <price>11.99</price> </book></bookstore>

Syntax and Structure Namespaces: Overview

Part of XML’s extensibility Allow authors to differentiate between tags of the

same name (using a prefix) Frees author to focus on the data and decide how to

best describe it Allows multiple XML documents from multiple authors

to be merged

Identified by a URI (Uniform Resource Identifier) When a URL is used, it does NOT have to represent

a live server

Syntax and Structure Namespaces: Declaration

xmlns: bk = “http://www.example.com/bookinfo/”

xmlns: bk = “urn:mybookstuff.org:bookinfo”

Namespace declaration examples:

Namespace declaration Prefix URI (URL)

xmlns: bk = “http://www.example.com/bookinfo/”

Syntax and Structure Namespaces: Examples

<BOOK xmlns:bk=“http://www.bookstuff.org/bookinfo”> <bk:TITLE>All About XML</bk:TITLE> <bk:AUTHOR>Joe Developer</bk:AUTHOR> <bk:PRICE currency=‘US Dollar’>19.99</bk:PRICE>

<bk:BOOK xmlns:bk=“http://www.bookstuff.org/bookinfo”xmlns:money=“urn:finance:money”> <bk:TITLE>All About XML</bk:TITLE> <bk:AUTHOR>Joe Developer</bk:AUTHOR> <bk:PRICE money:currency=‘US Dollar’> 19.99</bk:PRICE>

Syntax and Structure Namespaces: Default Namespace

An XML namespace declared without a prefix becomes the default namespace for all sub-elements

All elements without a prefix will belong to the default namespace:

<BOOK xmlns=“http://www.bookstuff.org/bookinfo”> <TITLE>All About XML</TITLE> <AUTHOR>Joe Developer</AUTHOR>

Syntax and Structure Namespaces: Scope

Unqualified elements belong to the inner-most default namespace. BOOK, TITLE, and AUTHOR belong to the default

book namespace PUBLISHER and NAME belong to the default

publisher namespace<BOOK xmlns=“www.bookstuff.org/bookinfo”> <TITLE>All About XML</TITLE> <AUTHOR>Joe Developer</AUTHOR> <PUBLISHER xmlns=“urn:publishers:publinfo”> <NAME>Microsoft Press</NAME> </PUBLISHER></BOOK>

Syntax and Structure Namespaces: Attributes

Unqualified attributes do NOT belong to any namespace Even if there is a default namespace

This differs from elements, which belong to the default namespace

Syntax and Structure Entities

Entities provide a mechanism for textual substitution, e.g.

You can define your own entities Parsed entities can contain text and markup Unparsed entities can contain any data

JPEG photos, GIF files, movies, etc.

Entity Substitution&lt; <

&amp; &

Agenda

Overview Syntax and Structure The XML Alphabet Soup

The XML ‘Alphabet Soup’

XML itself is fairly simple Most of the learning curve is knowing about

all of the related technologies

The XML ‘Alphabet Soup’

XML Extensible Markup Language

Defines XML documents

Infoset Information Set Abstract model of XML data; definition of terms

DTD Document Type Definition Non-XML schema

XSD XML Schema XML-based schema language

CSS Cascading Style Sheets Allows you to specify styles

XSL Extensible Stylesheet Language

Language for expressing stylesheets; consists of XSLT and XSL-FO

XSLT XSL Transformations Language for transforming XML documents

XSL-FO XSL Formatting Objects Language to describe precise layout of text on a page

The XML ‘Alphabet Soup’

XPath XML Path Language A language for addressing parts of an XML document, designed to be used by both XSLT and XPointer

XPointer XML Pointer Language Supports addressing into the internal structures of XML documents

XLink XML Linking Language Describes links between XML documents

XQuery XML Query Language (draft)

Flexible mechanism for querying XML data as if it were a database

DOM Document Object Model API to read, create and edit XML documents; creates in-memory object model

SAX Simple API for XML API to parse XML documents; event-driven

Data Island XML data embedded in a HTML page

Data Binding Automatic population of HTML elements from XML data

The XML ‘Alphabet Soup’ Schemas: Overview

DTD (Document Type Definitions) Not written in XML No support for data types or namespaces

XSD (XML Schema Definition) Written in XML Supports data types Current standard recommended by W3C

The XML ‘Alphabet Soup’ Schemas: Purpose

Define the “rules” (grammar) of the document Data types Value bounds

A XML document that conforms to a schema is said to be valid More restrictive than well-formed XML

Define which elements are present and in what order

Define the structural relationships of elements

The XML ‘Alphabet Soup’ Schemas: DTD Example

XML document:

DTD schema:<!DOCTYPE BOOK [<!ELEMENT BOOK (TITLE+, AUTHOR) ><!ELEMENT TITLE (#PCDATA) ><!ELEMENT AUTHOR (#PCDATA) >]>

<BOOK> <TITLE>All About XML</TITLE> <AUTHOR>Joe Developer</AUTHOR></BOOK>

The XML ‘Alphabet Soup’ Schemas: XSD Example

XML document:<CATALOG> <BOOK> <TITLE>All About XML</TITLE> <AUTHOR>Joe Developer</AUTHOR> </BOOK> …</CATALOG>

The XML ‘Alphabet Soup’ Schemas: XSD Example

<xsd:schema id="NewDataSet“ targetNamespace="http://tempuri.org/schema1.xsd" xmlns="http://tempuri.org/schema1.xsd" xmlns:xsd="http://www.w3.org/1999/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata"> <xsd:element name="book"> <xsd:complexType content="elementOnly"> <xsd:all> <xsd:element name="title" minOccurs="0" type="xsd:string"/> <xsd:element name="author" minOccurs="0" type="xsd:string"/> </xsd:all> </xsd:complexType> </xsd:element> <xsd:element name=“Catalog" msdata:IsDataSet="True"> <xsd:complexType> <xsd:choice maxOccurs="unbounded"> <xsd:element ref="book"/> </xsd:choice> </xsd:complexType> </xsd:element></xsd:schema>

The XML ‘Alphabet Soup’ Schemas: Why You Should Use XSD

Newest W3C Standard Broad support for data types Reusable “components”

Simple data types Complex data types

Extensible Inheritance support Namespace support Ability to map to relational database tables XSD support in Visual Studio.NET

The XML ‘Alphabet Soup’ Transformations: XSL

Language for expressing document styles Specifies the presentation of XML

More powerful than CSS

Consists of: XSLT XPath XSL Formatting Objects (XSL-FO)

The XML ‘Alphabet Soup’ Transformations: Overview

XSLT – a language used to transform XML data into a different form (commonly XML or HTML)

XML,HTML,

…

XML

XSLT

The XML ‘Alphabet Soup’ Transformations: XSLT

The language used for converting XML documents into other forms

Describes how the document is transformed Expressed as an XML document (.xsl) Template rules

Patterns match nodes in source document Templates instantiated to form part of result document

Uses XPath for querying, sorting, etc.

The XML ‘Alphabet Soup’ Transformations: Example

<sales> <summary> <heading>Scootney Publishing</heading> <subhead>Regional Sales Report</subhead> <description>Sales Report</description> </summary> <data> <region> <name>West Coast</name> <quarter number="1" books_sold="24000" /> <quarter number="2" books_sold="38600" /> <quarter number="3" books_sold="44030" /> <quarter number="4" books_sold="21000" /> </region> ... </data></sales>

The XML ‘Alphabet Soup’ Transformations: Example

<xsl:param name="low_sales" select="21000"/><BODY> <h1><xsl:value-of select="//summary/heading"/></h1> ... <table><tr><th>Region\Quarter</th> <xsl:for-each select="//data/region[1]/quarter"> <th>Q<xsl:value-of select="@number"/></th> </xsl:for-each> ... <xsl:for-each select="//data/region"> <tr><xsl:value-of select="name"/></th> <xsl:for-each select="quarter"> <td><xsl:choose> <xsl:when test="number(@books_sold &lt;= $low_sales)"> color:red;</xsl:when> <xsl:otherwise>color:green;</xsl:otherwise></xsl:choose> <xsl:value-of select="format-number(@books_sold,'###,###')"/></td> ... <td><xsl:value-of select="format-number(sum(quarter/@books_sold),'###,###')"/>

The XML ‘Alphabet Soup’ Transformations: Example

The XML ‘Alphabet Soup’XSL Formatting Objects (XSL-FO)

A set of formatting semantics Denotes typographic elements (for example:

page, paragraph, rule, etc.) Allows finer control obtained via formatting

elements Word, letter spacing Indentation Widow, orphan, hyphenation control Font style, etc.

The XML ‘Alphabet Soup’ XPath (XML Path Language)

General purpose query language for identifying nodes in an XML document

Declarative (vs. procedural) Contextual – the results depend on current node Supports standard comparison, Boolean and

mathematical operators (=, <, and, or, *, +, etc.)

The XML ‘Alphabet Soup’ XPath Operators

Operator Usage Description/ Child operator – selects only immediate children (when

at the beginning of the pattern, context is root)

// Recursive descent – selects elements at any depth (when at the beginning of the pattern, context is root)

. Indicates current context

* Wildcard

@ Prefix to attribute name (when alone, it is an attribute wildcard)

[ ] Applies filter pattern

The XML ‘Alphabet Soup’ XPath Query Examples

./author (finds all author elements within current context)

/bookstore (find the bookstore element at the root)

/* (find the root element)

//author (find all author elements anywhere in document)

/bookstore[@specialty = “textbooks”] (find all bookstores where the specialty

attribute = “textbooks”)

/book[@style = /bookstore/@specialty] (find all books where the style attribute = the specialty attribute of the bookstore element at the root)

The XML ‘Alphabet Soup’ XPointer

Builds upon XPath to: Identify sub-node data Identify a range of data Identify data in local document or remote documents

New standard

The XML ‘Alphabet Soup’ XLink

XML Linking Language Elements of XML documents Describes links between resources

Simple links (for example, HTML HREFs) Extended links

Remote resources Local resources Rules for how a link is followed, etc.

The XML ‘Alphabet Soup’ The XML DOM

XML Document Object Model (DOM) Provides a programming interface for manipulating

XML documents in memory Includes a set of objects and interfaces that represent

the content and structure of an XML document Enables a program to traverse an XML tree Allows elements, attributes, etc., to be added/deleted in

an XML tree Allows new XML documents to be created

programmatically

The XML ‘Alphabet Soup’ SAX (Simple API for XML)

API to allow developers to read/write XML data Event based

Uses a “push” model Sequential access only (data not cached) Requires less memory to process XML data than

the DOM SAX has less overhead (uses small input, work and

output buffers) than the DOM DOM constructs the data structure in memory (work

and output buffers = to size of data)

XML embedded in an HTML document Manipulated via client side script or data binding

<XML id=“XMLID”> <BOOK> <TITLE>All About XML</TITLE> <AUTHOR>Joe Developer</AUTHOR> </BOOK></XML>

<XML id=“XMLID” src=“mydocument.xml”>

The XML ‘Alphabet Soup’ Data Islands

The XML ‘Alphabet Soup’ Data Islands

Can be embedded in an HTML SCRIPT element XML is accessible via the DOM:

<SCRIPT language=“xml” id=“XMLID”><SCRIPT type=“text/xml” id=“XMLID”><SCRIPT language=“xml” id=“XMLID” src=“mydocument.xml”>

The XML ‘Alphabet Soup’ Data Islands

Access the XML via the HTML DOM:

Or access the XML directly via the ID:

function returnXMLData() { return document.all("XMLID").XMLDocument.nodeValue;}

function returnXMLData() { return XMLID.documentElement.text;}

The XML ‘Alphabet Soup’ Data Binding

Client-side data binding (in the browser) The XML Data Source Object (DSO) binds HTML

elements to an XML data set (or data island) When the XML data set changes, the bound elements

are updated dynamically DATASRC: the source of the data (e.g., the ID

of the data island) DATAFLD: the field (XML element) to display Can offload XSLT processing to the client IE only

The XML ‘Alphabet Soup’ Data Binding

<HTML><BODY> <XML ID="xmlParts"> <?xml version="1.0" ?> <parts> <part> <partnumber>A1000</partnumber> <description>Flat washer</description> <quantity>1000</quantity> </part> ... </XML> <table datasrc=#xmlParts border=1><tr> <td><div datafld="partnumber"></div></td> <td><div datafld="quantity"></div></td> </tr></table></BODY></HTML>

The XML ‘Alphabet Soup’ XLang (BizTalk)

An XML language for defining processes Processes usually on multiple platforms Support for:

Concurrency Long-running transactions

Exposed messaging and orchestration APIs Connect to COM components Connect to MSMQ queues Connect to SQL components

The XML ‘Alphabet Soup’ XML-Based Applications

Microsoft BizTalk Server Enables uniform exchange of data among disparate

systems (XLang) Backend interchange with partners/customers

Microsoft Commerce Server XML-based Product Catalog System Integrated with BizTalk Server for backend

communication

The XML ‘Alphabet Soup’ XML-Based Applications

Microsoft SQL Server Retrieve relational data as XML Query XML data Join XML data with existing database tables Update the database via XML Updategrams

Microsoft Exchange Server XML is native representation of many types of data Used to enhance performance of UI scenarios (for

example, Outlook Web Access (OWA))

XML in .NET Other XML Namespaces

System.Xml – Core XML namespace System.Xml.XPath – contains the XPathNavigator, XPath parser and evaluation engine

System.Xml.Xsl – support XSLT transformations

System.Xml.Serialization – Classes to serialize objects into XML documents or streams

System.Xml.Schema – Supports XSD schemas

Resources

http://msdn.microsoft.com/xml/ http://www.xml.com/ http://www.w3.org/xml/ Microsoft Press Books

(http://mspress.microsoft.com/) XML Step By Step XML In Action Developing XML Solutions

O’Reilly Press XML In A Nutshell

Resources

XML in .NEThttp://msdn.microsoft.com/msdnmag/issues/01/01/xml/xml.asp

Working with XML in the .NET Platformhttp://www.xmlmag.com/upload/free/features/xml/2001/05may01/dw0102/dw0102.asp