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Mastering XML: A Comprehensive Guide to Writing, Validating, and Displaying Data

Learn all about XML - the extensible, object-oriented data language for structuring and formatting information. Discover how to write, validate, read, display, and format XML documents with ease. Dive into examples, parsers, schemas, and more to gain a strong understanding of XML basics and advanced techniques.

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Mastering XML: A Comprehensive Guide to Writing, Validating, and Displaying Data

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  1. Chapter 13XML Yingcai Xiao

  2. What is XML?What is it for?ExamplesHow to write?How to validate?How to read?How to display?How to format? How to translate?

  3. XML • Extensible Markup Language. • De facto data language. http://www.w3.org/TR/REC-XML. • HTML expresses appearance; XML describes data and its structure. • Text based (platform-independent). • Object-oriented data representation. • Has no predefined tags. • Provides rules to format data. • Many XML parsers already available. • Strong XML support in the FCL. .

  4. XML Example (Guitars.xml) <?xml version="1.0"?> <Guitars> <Guitar> <Make>Gibson</Make> <Model>SG</Model> <Year>1977</Year> <Color>Tobacco Sunburst</Color> <Neck>Rosewood</Neck> </Guitar> <Guitar> <Make>Fender</Make> <Model>Stratocaster</Model> <Year></Year> <Color>Black</Color> <Neck>Maple</Neck> </Guitar> </Guitars>

  5. XML Example (Guitars.xml) • Document element (root): Guitars. • Guitar elements are children of Guitars. • Make contain data. • Empty element: <Year></Year> • Nested elements. • The content of an XML document can be viewed as a tree. • Attributes <Guitar Year="1977">

  6. XML Description • XML Elements: text-based object-oriented data (object) • Error checking? • Text-based object-oriented type (class) definition? • Early days: document type definitions (DTDs). • Today: XML Schema Definitions (XSDs). http://www.w3.org/TR/xmlschema-1 http://www.w3.org/TR/xmlschema-2. • Schema: a collection of meta data. • Meta data: data that describes data. • XSD is an XML-based language for describing XML documents and the types that they contain.

  7. Example: Guitars.xsd <?xml version="1.0"?> <xsd:schema id="Guitars" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <xsd:element name="Guitars"> <xsd:complexType> <xsd:choice maxOccurs="unbounded"> <xsd:element name="Guitar"> <xsd:complexType> <xsd:sequence> <xsd:element name="Make" type="xsd:string" /> <xsd:element name="Model" type="xsd:string" /> <xsd:element name="Year" type="xsd:Year“ minOccurs="0" /> <xsd:element name="Color" type="xsd:string“ minOccurs="0" /> <xsd:element name="Neck" type="xsd:string“ minOccurs="0" /> </xsd:sequence> </xsd:complexType> </xsd:element> </xsd:choice> </xsd:complexType> </xsd:element> </xsd:schema>

  8. Example: Guitars.xsd Examples\c13\Validate\ Typo => xsd:Year should be xsd:string run.bat Validate Guitars.xml Guitars.xsd run-bad-xml.bat Validate Guitars-Missing-Make.xml Guitars.xsd

  9. XML Parsers • Most XML parsers implement one of two popular APIs: DOM or SAX. • DOM: Document Object Model http://www.w3.org/TR/DOM-Level-2-Core. • SAX: Simple API for XML, unofficial, http://www.saxproject.org. • FCL XmlDocument, managed DOM implementation • Examples of using XmlDocument: Validate ReadXml XmlView Transform Quotes ExpressAnalyzer

  10. ReadXml.cs (also see XmlView) using System; using System.Xml; class MyApp { static void Main () { XmlDocument doc = new XmlDocument (); doc.Load ("Guitars.xml"); XmlNodeList nodes = doc.GetElementsByTagName ("Guitar"); foreach (XmlNode node in nodes) { Console.WriteLine(“Maker {0}; Model {1}", node["Make"].InnerText, node["Model"].InnerText); } } }

  11. XPath • XML Path Language • For addressing parts of an XML document. • “/Guitars/Guitar” is an XPath expression. • http://www.w3.org/TR/xpath.

  12. XSL • XSL is a language for expressing style sheets. • Adopted from CSS, a file that describes how to display an XML document of a given type. • Styling requires a source XML documents, containing the information that the style sheet will display and the style sheet itself which describes how to display a document of a given type. It supports: Formatting Objects. • It also adds a transformation language for XML documents: XSLT. Examples\c13\Quotes\Quotes.xsl http://winserv1.cs.uakron.edu/Examples/C13/Quotes/quotes.aspx

  13. XSL Transformations (XSLT) • Extensible Stylesheet Language Transformations. • Converting XML documents into HTML documents. • Converting HTML documents into other XML documents. Examples\c13\Transform\Transform.cs http://winserv1.cs.uakron.edu/Examples/C13/Transform/Quotes.html

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