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Looking Back

Tightly coupled systems and communication

Proprietary, closed protocols and methods

Data sharing between 3rd party solutions unwieldy

Non-extensible solutions

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XML!

XML technologies introduced:XML 1.0 - Document Basics

XML Schemata

XSLT: Style sheets and Transformations

.NET & XML:The System.Xml Namespace

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XML 1.0 - Document Basics

What is XML?

XML Tags and Tag Sets

Components of an XML Document

Document Instance

XML Document by Example

The XML Parser

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What is XML?2/2

Designed for describing and interchanging dataData is logically structured

Human readable, writeable and understandable text file!

Easy to Parse; Easy to Read; and Easy to Write!

Metadata:Data that describes data; data with semantics

Looks like HTMLbut it isnt!

Uses tags to delimit data and create structureDoes not specify how to display the data

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XML Tag-SetsBegin with and end with

Can have an empty element: < someTag />

Exceptions are:XML document declaration:

Comments: The document type declaration

< DOCTYPE [ ... ]>

Definition of document elements in an Internal DTD:

, , etc

Promote logical structuring of documents and dataUser definable

Create hierarchically nested structure

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Components of an XML Document 1/3

XML Processing Instruction

Document Type Declaration

Document Instance

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XML Processing Instruction

version information

encoding type: UTF-8 , UTF-16, ISO-10646-UCS-2, etc

standalone declaration; indicates if there are external file references

Namespace declaration(s), Processing Instructions (for applications), etc

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Document Type Declaration. Two types: An Internal declaration

An External reference

Document InstanceThis is the XML document instance

Read as: the XML -ized data

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Document Instance: The Markup

Document Root ElementRequired if a document type declaration exists

Must have the same name as the declaration

ElementsCan contain other elements

Can have attributes assigned to them

May or may not have a value

AttributesProperties that are assigned to elements

Provide additional element information

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XML By Example: A Document < DOCTYPE CustomerOrder

SYSTEM http://www.myco.com/dtd/order.dtd >

Olaf

Smith

91 Park So, New York, NY 10018

Hauptstrasse 55, D-81671 Munich

10 100 200

< -- More s ... -->

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XMLData + DTD

Not Valid!DTD< -- XML Data-->

Some 100 101

< -- XML Data-->

Some Thing

Valid

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Whats a DTD?

Document Type Definition (DTD)Defines the syntax, grammar & semantics

Defines the document structure

What Elements, Attributes, Entities, etc are permitted?

How are the document elements related & structured?

Referenced by or defined in XML documents, but its not XML!

Enables validation of XML documents using an XML Parser

Can be referenced to by more than one XML documentDTDs may reference other DTDs

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DTD By Examplehttp://www.myco.com/dtd/order.dtd

< DOCTYPE CustomerOrder [

< ELEMENT CustomerOrder (Customer, Orders*) >

< ELEMENT Customer (Person, Address+) >< ELEMENT Person (FName, LName) >< ELEMENT FName (#PCDATA) >< ELEMENT LName (#PCDATA) >< ELEMENT Address (#PCDATA) >< ATTLIST Address

AddrType ( billing | shipping | home ) shipping >

< ELEMENT Orders (OrderNo, ProductNo+) >< ELEMENT OrderNo (#PCDATA) >< ELEMENT ProductNo (#PCDATA) >

]>

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XML Parser in Action!

Browser orApplication

XMLParser

XMLSchema

OrDTD

XMLSource

Document

ValidatedXML

Document

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The XML Parser: What is it?

Used to Process an XML DocumentReads, parses & interprets the DTD and XML document

Performs substitutions, validation or additional processing

Knows the XML language rules and can determine:Is the document Well-Formed?

Is it Valid?

Creates a Document Object Model (DOM) of the instanceProvides programmatic access to the DOM or instance

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What is the DOM?

DOM stands for Document Object Model

Programming interface for HTML & XML documents

An in-memory representation of a document

Defines the document structure through an object modelTree-view of a document

Nodes, elements and attributes, text elements, etc

W3C defined the DOM Level 1 and Level 2 Corehttp://www.w3.org/TR/1998/REC-DOM-Level-1-19981001/

http://www.w3.org/TR/2000/REC-DOM-Level-2-Core-20001113/

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Generating The DOM

Parser

XMLDocument

Dom Tree

Root ElementChild Element

TextChild Element

Text

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Where Do You Find XML Parsers?

Transparently built into XML enabled productsInternet Explorer, SQL Server 2000, etc

All over the Internet!

Microsoft XML Parserhttp://msdn.microsoft.com/xml/general/xmlparser.asp

IBM/Apache Xerceshttp://xml.apache.org

http://alphaworks.ibm.com
http://msdn.microsoft.com/xml/general/xmlparser.asphttp://xml.apache.org/http://alphaworks.ibm.com/http://alphaworks.ibm.com/http://xml.apache.org/http://msdn.microsoft.com/xml/general/xmlparser.asp

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XML Schema

Whats a Schema? Schema vs. DTDs

Datatypes & Structure

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XML Documents + XML Schema

Not Valid!-- Some XML Schema -->

< -- XML Data-->

Some 100 101

< -- XML Data-->

Some Thing

Valid

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Whats a Schema?

Websters Collegiate Dictionary defines it as: A diagrammatic presentation; a structured framework

The XML world defines it as: A structured framework for your XML Documents!

A definition language - with its own syntax & grammar

A means to structure data and enhance it with semantics!

Best of all: Its an alternative to the DTD!

Composed of two parts:Structure : http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/

Datatypes : http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/

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Schema vs. DTDs

Both are XML document definition languagesSchemata are written using XML

Unlike DTDs, XML Schema are Extensible like XML!

More verbose than DTDs but easier to read & write

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Datatypes & Structure

Defining datatypesThe simple or primitive datatypes

Based on (or derived) from the Schema datatypes

Complex types

Facets

Declaring data types

by example

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XML Schema Datatypes

Two kinds of datatypes: Built-in and User-defined

Built-inPrimitive Datatypes

string , double , recurringDuration , etc

Derived Datatypes:CDATA, integer , date , byte , etc

Derived from the primitive types

Example: integer is derived from double

User-definedDerived from built-in or other user-defined datatypes

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The Simple Type:

The Simplest Type Declaration:

Based on a primitive or the derived built-in datatypes

Cannot contain sub-elements or attributesCan declare constraining properties (facets)

minLength, maxLength, Length, etc

May be used as base type of a complexType

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The Complex Type:

Used to define a new complex typeMay be based on simple or existing complexTypes

May declare elements or element references:

May declare attributes or reference attribute groups

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Defining a complexType By Example

< -- AddrType attribute not shown -->

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More Complex Types

DerivationsimpleContent complexContent

Extension & Restriction (well see some of this)

Substitution Groups

Abstract Elements and Types

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The Many Facets of a Datatype!

http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/

A way to constrain datatypesConstrain the value space of a datatype

Specify optional properties

Examples of Constraining Facets:precision, minLength,enumeration , ...

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Declaring ElementsElements are declared using the tag

Based on either a simple or complex type

May contain simple or other complex types

May reference an existing element

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Declaring AttributesDeclared using tag

Value pairs

Can only be assigned to types

May be grouped into an attribute group more later!

Based on a , by reference or explicitly

< -- OR -->

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Declaring Attribute Groups 1/2

Way to group related attributes together

Promotes logical organization

Encourages reuse defined once, referenced many times

Facilitates maintenance

Improves Schema readability

Must be unique within an XML Schema

Referenced from complexType definitions

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Declaring Attribute Groups 2/2

< -- Define the unique group: -->

< -- Then you can reference it from a complexType: -->

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Schema Namespaces

Equivalent to XML namespaceshttp://www.w3.org/TR/1999/REC-xml-names-19990114/

Used to qualify schema elements

must itself be qualified with the schema namespace

Namespace may have a namespace prefix for the schemaPrefix qualifies elements belonging to the targetNamespace

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targetNamespace Attribute

targetNamespace attributeDeclares the namespace of the current schema

This must be a universally unique Universal Resource Identifier (URI)

Helps the parser differentiate type definitions

Used during schema validationDifferentiates differing schema vocabularies in the schema

targetNamespace:namespace_prefix = some_URI...

Should match the schema namespace declarationExample:

targetNamespace:CO ="http://www.myCo.com/CO"

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XML By Example

< -- Declare the root element of our schema -->

< -- Further Definitions & declarations not shown -->

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Follow the Yellow Brick XPath

Specification found at:http://www.w3.org/TR/1999/REC-xpath-19991116

Language used to address parts of an XML document

Permits selection of nodes in an XML documentUses a path notations like with URLs

Absolute paths: /CustomerOrder/Orders

Relative paths: Orders

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Roadmap To Selection

Location Syntaxaxis :: node_test [ predicate ]

Location PathsAxis : Defines from where to start navigating

parent , child , ancestor , attribute , / (the document), etc

Node test : Selects one or more nodesBy tag name, node selector or wildcard ( *)

node( ) , text( ) , comment( ) , etc

Predicates : Optional function or expression enclosed in [... ] position( ) , count( ) , etc

Example: /Address:: * [@AddrType=billing]

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Taking XPath Shortcuts

Abbreviated Syntax existsThe following are equivalent

OrderNo[position=1]/ProductNo[position=3]OrderNo[1]/ProductNo[3]

.. instead of parent::node()

. instead self::node()

// instead of /descendant-or-self::node()/

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Operators

To select an attribute value use @CustomerOrder/Customer/Address[@AddrType]

To select the value of an element use $CustomerOrder/Orders/ProductNo[1][$ProductNo]

Can compare objects arithmetically< (for ),

Conditional processing< xsl:if test = >

< xsl:choose >, ,

Sorting

Etc

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Brief look at XML in .NET

.NET Support for XMLXML Namespaces in .NET

Some XML Classes in .NET

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.NET Supports XML!XML 1.0

http://www.w3.org/TR/1998/REC-xml-19980210

XML Namespaceshttp://www.w3.org/TR/1999/REC-xml-names-19990114/

XML Schemashttp://www.w3.org/TR/2001/REC-xmlschema-1-20010502/

http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/XPath expressions

http://www.w3.org/TR/1999/REC-xpath-19991116

XSL/T transformationshttp://www.w3.org/TR/1999/REC-xslt-19991116

DOM Level 1 and Level 2 Corehttp://www.w3.org/TR/1998/REC-DOM-Level-1-19981001/


SOAP 1.1http://msdn.microsoft.com/xml/general/soapspec.asp

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XML Namespaces in .NET

System.Xml

.Serialization

.Schema

.XPath

.Xsl

l

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System.Xml Namespace

Overall namespace for classes that provide XML supportClasses for creating, editing, navigating XML documents

Reading, writing and manipulating documents via the DOM

Use the XmlDocument class for XML documentsUse the XmlDataDocument class relational or XML data

Classes that correspond to every type of XML element: XmlElement, XmlAttribute, XmlComment, etc

Used by the XmlDocument and XmlDataDocument classes

l d

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XmlReader Abstract base class for reading XML

Fast, forward-only, non-cached XML stream reader

Base class for XmlTextReader

Properties of InterestValue : Gets the value of the node

NodeType : Returns the type of node

HasValue : Returns true if the node has a value

LocalName : Gets the name of the node without its prefix

ReadState : Returns the ReadState of the streamClosed, EndOfFile, Error, Initial or Interactive

X lW i

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XmlWriter

Abstract base classes for writing XMLFast, forward-only, non-cached XML stream writer

Base classes for XmlTextWriter

Properties of InterestWriteState : Returns the WriteState of the stream

Attribute, Content, Element, etc

XmlLang : Returns the current xml:lang scope

XmlSpace : Returns the current xml:space

X lT R d & X lT W i

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XmlTextReader & XmlTextWriter

Derived from the XmlReader & XmlWriter abstract classesImplement all the functionality defined by their base classes

Designed to work with a text based stream

As opposed to an in-memory DOMInherit the properties of the XmlReader and XmlWriter

XmlTextReader methods support reading XML elementsRead, MoveToElement, ReadString, etc

XmlTextWriter methods support writing XML elementsWriteDocType, WriteComment, WriteName, etc

X lD

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XmlDocumentDerived from the XmlNode class

Represents an entire (in memory) XML document

Supports DOM Level 1 and Level 2 Core functionality

Reading & writing built on top of XmlReader & XmlWriter

Load a document and generate the DOMUsing: URI, file, XmlReader , XmlTextReader or Stream

P i & M h d f I

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Properties & Methods of InterestProperties of Interest:

ChildNodes : Returns all the children of the current nodeDocumentType : Gets the DOCTYPE declaration node

DocumentElement : Returns the root XmlElement

XmlResolver : Used to resolve DTD & schema references

FirstChild : Returns the first child of the current nodeParentNode : Returns the parent of the current nodeValue : Returns the (string) value of the current node

Methods of Interest

CreateComment : Creates a comment node CreateElement : Creates an element node Load : Loads XML data using a URL, file, Stream , etc

Save : Saves the XML document to a file, Stream , orwriter

X lD & h NET DOM

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XmlDocument & the .NET DOMSystem.Xml

.Serialization.Schema.XPathXsl

EntityHandlingFormattingNameTableReadStateTreePositionValidationWriteStateXmlAttributeXmlAttributeCollectionXmlCDataSectionXmlCharacterData

XmlCharTypeXmlCommentXmlConvert

XmlDataDocumentXmlDeclarationXmlDocumentXmlDocumentFragmentXmlDocumentTypeXmlElementXmlEntityXmlEntityReferenceXmlNamedNodeMap

XmlNodeXmlNodeReaderXmlNodeType

XmlNotationXmlReaderXmlSpaceXmlTextXmlTextReaderXmlTextWriterXmlUrlResolverXmlWhitespaceXmlWriter...

X lD t B E l

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XmlDocument By Exampleusing System.Xml;

//Create an XmlDocument, Load it, Write it to the Console//One way:XmlDocument xDoc = new XmlDocument();xDoc.Load( C: \\myData.xml");xDoc.Save( Console.Out);

//Second way (Use a XmlTextReader to read in load the XML):XmlTextReader reader = new XmlTextReader(C: \\myData.xml");xDoc.Load( reader );xDoc.Save( Console.Out);

//Third way (Use a XmlTextWriter to output the XML document):XmlTextWriter writer = new XmlTextWriter( Console.Out );writer.Formatting = Formatting.Indented;xDoc.WriteContentTo( writer );writer.Flush();Console.WriteLine();writer.Close();

S t X l X l N

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System.Xml.Xsl Namespace

Provides support for XSL TransformationsSome of the classes:

XsltTransform : Transforms using a stylesheet

XsltException : Used to handle transformation exceptionsXsltContext: The XSLT processors execution context

X ltT f

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XsltTransform

Four simple steps to perform a transformationInstantiate a XsltTransform object

Load a stylesheet

Load the dataTransform!

T f ti B E l

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Transformation By Example

Using System.Xml.Xsl;

// 1. Create a XslTransform objectXslTransform xslt = new XslTransform();

// 2. Load an XSL stylesheetxslt.Load("http://somewhere/favorite.xsl");

// 3 & 4. Load the XML data file & transformxslt.Transform(http://somewhere/mydata.xml,

C: \\somewhere_else\\ TransformedXmlOutput.xml);

S

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Summary

XML is powerful, flexible, open & extensibleXML is easy to learn easy to read & easy to use

XML, XML Schema and XSLT combine to let you

Have data with semanticsDictate and enforce you data structure

Separate data and data representation

Easily transform your data

.NET is XML -ized .NET lives on XML!Not only exposes XML functionality, built using it

Section 4: Q&A

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Section 4: Q&A

Document Object Model (DOM)

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Document Object Model (DOM)1/2

Use an XML parser to generate and manipulate the DOMLoad an XML file using a parser

Use the parsers programming interface to: Navigate through the Document Object Model

Manipulate the DOM: Add, Delete, Move, Modify DOM elements

Using a DOM the parser can insure well formed documents

Some parsers can validate the DOM Validating Parser

By loading and comparing to either a DTD or a Schema

Document Object Model (DOM)

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Document Object Model (DOM)2/2

System.Xml contains DOM related classesXmlDocumentXmlDataDocumentXmlNavigator

XmlDataNavigatoretc

.NET supports DOM Level 1 and most of the Level 2 Corehttp://www.w3.org/TR/1998/REC-DOM-Level-1-19981001/


XML Namespaces 1/2

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XML Namespaces 1/2

Another W3C specificationhttp://www.w3.org/TR/REC-xml-names/

Create collection of tags that share the same semantics

Used to qualify tags that would otherwise collideMultiple documents can use the same tag differently

For example:Document A may use to designate a persons name

Document B may use to designate a file name

XML Namespaces 2/2
http://www.w3.org/TR/REC-xml-names/http://www.w3.org/TR/REC-xml-names/http://www.w3.org/TR/REC-xml-names/http://www.w3.org/TR/REC-xml-names/http://www.w3.org/TR/REC-xml-names/http://www.w3.org/TR/REC-xml-names/

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XML Namespaces 2/2

A URI is used to uniquely identify a namespacexmlns=urn:schemas -microsoft- com:customerdata

May assign a namespace prefix to the namespacexmlns:ms=urn:schemas -microsoft- com:data

Use the prefix to differentiate elements & attributes John Smith

Documents have a default namespace

Default prefix is xmlns