01+ +XML+Programming+in++.NET

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Open XML Developer Workshop

XML Programming in .NET


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Introduction to XML in .NETReading and Writing XML

Working with XML Namespaces

Validating XML

Querying XML

Overview


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Widely used W3C standards for XML

W3C

XML 1.0

Namespaces

SchemaXPath

XSLT


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Lesson: Reading and Writing XML

XML StreamsWorking with the DOM


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Working with XML Streams

XmlReader

Here

Code

Your

Read()

ReadStartElement()ReadElementContentAsInt()

WriteStartElement()

WriteValue()WriteComment()

StreamFile

String

XmlWriter StreamFile

String


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The stream based approach

Reading XML withan XmlReader

XmlReaderSettingssettings = newXmlReaderSettings();settings.IgnoreComments = true;using(XmlReaderreader = XmlReader.Create(sample.xml , settings)){ while(reader.Read()){ if(reader.IsStartElement() && reader.LocalName == orderItem ){ reader.ReadToDescendant(quantity , xmlNamespace);intquantity = reader.ReadElementContentAsInt();

reader.ReadToNextSibling(unitPrice , xmlNamespace);decimalunitPrice = reader.ReadElementContentAsDecimal();Console.WriteLine(Total: + quantity * unitPrice);}}}

1034.99


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The stream based approach

Writing XML with an XmlWriter

See Demos\01-XML Programming\Demo 1Stream based XML

XmlWriterSettingssettings = newXmlWriterSettings();settings.CloseOutput = true;settings.Indent = true;using(XmlWriterwriter = XmlWriter.Create(Console.Out, settings)){ writer.WriteStartDocument(true); // standalonewriter.WriteStartElement(order , xmlNamespace);writer.WriteStartElement(orderItem , xmlNamespace);writer.WriteElementString(quantity , xmlNamespace,XmlConvert.ToString(10));writer.WriteElementString(unitPrice , xmlNamespace,Convert.ToString(34.99));writer.WriteEndElement();writer.WriteEndElement();

}1034.99


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Working with the DOM

DOM is the W3C programming interface for XMLDOM models an XML

source as a in memory

tree of nodes

You can use the DOM toNavigate and search

Modify content

Seattle

DocumentNode

ElementNode

ElementNode

AttributeNode

TextCharacterData

lcid=en-US

Seattle


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Working with the DOMLoading from and saving to an XML source

The XmlDocument class is the core structureFor data store Use this method

String LoadXml()

Stream Load() and Save()

File

XmlReader / XmlWriter

XmlDocumentdocument = newXmlDocument();using(FileStream fs =newFileStream(sample.xml , FileMode.Open, FileAccess.Read)){document.Load(fs);}// save using a streaming writer with indentationusing(XmlTextWriterwriter = newXmlTextWriter(Console.Out)){ writer.Formatting = Formatting.Indented;document.Save(writer);}


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Working with the DOMNavigating through XML

The XmlNode class serves as the base class for variousDOM elements

XmlElement and XmlAttribute are samples

?xmlversion=1.0?>XML.NET19.99

XmlNodebook = doc.FirstChild;XmlNodepriceNode = book.ChildNodes[1];XmlNodeisbnNode = book.GetAttributeNode(isbn );stringprice = priceNode.FirstChild.Value;stringisbn = isbnNode.Value;


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Working with the DOMManipulating XML

The XmlDocument class serves as a factory for new XMLelements

19.99

// first create the nodesXmlDocumentdoc = newXmlDocument();XmlElementbookNode = doc.CreateElement(book );XmlNodepriceNode = doc.CreateElement(price );// set the node valuepriceNode.Value = 19.99 ;// set an attributebookNode.SetAttribute(title , XML is Cool );// add the nodes togetherbookNode.AppendChild(priceNode); doc.AppendChild(bookNode);


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Working with the DOMManipulating XML

The XmlDocument allows creation of all DOM elements

To remove nodes, use the parent XmlNode

Importing XML from another XmlDocument

See Demos\01-XML Programming\Demo 2DOM based XML

XmlCommentcomment = doc.CreateComment(Some comment );XmlProcessingInstructionpi = doc.CreateProcessingInstruction(xml-stylesheet , type='text/xsl' href='style.xsl' );

bookNode.RemoveChild(priceNode); bookNode.RemoveAttribute(title );

XmlDocumentother;XmlNodenode = doc.ImportNode(other.DocumentElement, true);


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Lesson: Working with XML namespaces

Basics of XML NamespacesThe XmlNamespaceManager class


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Basics of XML namespaces

Many documents use the same element namesorderfor instance

To differentiate the elements you apply namespaces

http://mycompany.com/myOrderSchemabecomes

http://mycompany.com/myOrderSchema#order

Prefixes are used for abbreviation

xmlns:myO=http://mycompany.com/myOrderSchema


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The XmlNamespaceManager class

The XmlNamespaceManager stores namespaces andprefixes

The prefixes in the source document do not have to be

equal to the one specified in the namespace manager

Create and use a namespace manager with all querieswhich use XML namespaces

XmlDocumentdocument;XmlNamespaceManagermgr = newXmlNamespaceManager();mgr.AddNamespace(myPf , http://xmlnamespaceInDocument );document.SelectSingleNode(//myPf:someElement , mgr);


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Lesson: Validating XML

Overview of Validation Technologies

The Schema Object Model

Validating with the XmlReader

Validating an XmlDocument

The XmlSchemaValidator


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Overview of Validation Technologies

Various XML validation technologies exist today:

Document Type Definitions (DTDs)

Xml-Data Reduced schema (XDRs)

XML-Schema Definition Language (XSDs)

Regular Language for XML Next Generation (Relax-NG)

XML-Schema is the standard validation technology today

Supported through the Schema Object Model


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The Schema Object Model

Represented by the XmlSchema class

There are two collection classes for XmlSchema objects

The XmlSchemaCollection, which is now obsolete

The XmlSchemaSet class is the new/improved approach

The XmlSchemaSet

Improved standards compliance and performance

Forms one big logical schema from all contained itemsSupport for duplicate target namespaces


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Validating with the XmlReader

Validation performed implicitly when configuring the

XmlReader.Create factory method

/ Create the XML SchemaXmlSchemaschema = null;using(XmlReaderreader = XmlReader.Create(sample.xsd )){schema = XmlSchema.Read(reader, null);}

// Create the settings for the XmlReaderXmlReaderSettingssettings = newXmlReaderSettings();settings.ValidationType = ValidationType.Schema;// add it to the XmlSchemaSet of the settings classsettings.Schemas.Add(schema); // Now read with the reader which also performs validationusing(XmlReaderreader = XmlReader.Create(sample.xml , settings)){ while(reader.Read()) ;}


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Validating an XmlDocument

The XmlDocument acts as a container for XML schemas

See Demos\01-XML Programming\Demo 3Validating Documents

// Create the XMLSchema objectXmlSchemaschema = null;using(XmlReaderreader = XmlReader.Create(sample.xsd )){ schema = XmlSchema.Read(reader, null);}// Load a document and attach the schemaXmlDocumentdocument = newXmlDocument();document.Load(sample.xml );document.Schemas.Add(schema); // Validate it using the attached schemasdocument.Validate(OnValidateSchema);


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Open XML schemas: best practice

The Ecma spec contains 89 separate schemas

There are circular references between those schemas

XmlSchemaSet can handle circular references

BUT only when theyre all in one Add() method call

The solution: use the provided all.xsdfile, which imports

all of the Open XML schemas into a single schema

HOL Solution\Solution\Schemas\all.xsd


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Lesson: Querying XML

The Query Process

Querying the DOM



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The Query Process

MoveToRoot( )

MoveToNext( )

MoveToPrevious( )

MoveToFirstChild( )

MoveToParent( ) .ReturnType

XPathDocument

CreateNavigator

XPathNavigator

Evaluate( )

Select( )

Compile( )

Boolean

String

Double

NodeSet

XPathNodeIterator

MoveNext( )

For EachXPathExpression

5. Check the ReturnType1. Load XPathDocument

2. Create XPathNavigator 4. Compile XPathExpression

3. Create the Query


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Querying the DOM

The XmlDocument has support for X-Path in various

places

Create a new XPathNavigator using the CreateNavigator()method

Use the XmlDocument SelectNodes(xpath)orSelectSingleNode(xpath)

Use an XPathDocument for optimized queries

XmlNodenode = document.SelectSingleNode(/order/orderItems );XPathNavigatornavigator = node.CreateNavigator();foreach(XPathNavigatoritemNavigator innavigator.Select(orderItem )){}


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Automatic prefix mapping

All document contain their own prefix mappings, the

System.Xml 2.0 library allows you to use these in your

queries

Pass in an IXmlNamespaceResolver when using the

XPathNavigatorThe XML namespace needs to be in scope (i.e., you must

have read past it in the XPathNavigator):

XPathNavigatornavigator = document.CreateNavigator();navigator.MoveToChild(XPathNodeType.Element);foreach(XPathNavigatoritemNavigator innavigator.Select(o:orderItem , navigator)){}


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Best practice: use IXmlNamespaceResolver

Sample syntax (from demo lab):

See Demos\01-XML Programming\Demo 4Querying Documents

XPathNavigatornavigator = document.CreateNavigator();XmlNamespaceManagernamespaceManager = newXmlNamespaceManager(navigator.NameTable);namespaceManager.AddNamespace(w ,http://schemas.openxmlformats.org/wordprocessingml/2006/main );XPathExpressionsearchPhrase =XPathExpression.Compile(@ //w:p[w:r/w:t[contains(text(), +toolStripTextBox1.Text + @ )]] , namespaceManager);


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Introduction to XML in .NETReading and Writing XML


Validating XML

Querying XML

Go through LAB 01XML Programming in .NET

Optional: demo labs 1-4

Review


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