1. XML BIS4430 – unit 10

2. XML Origins • Extensible Markup Language (XML) 1998 • Inspired by Standard Generalized Markup Language (SGML) and HTML. • SGML defines how any given markup language can be formally specified • HTML combines markup from several categories: Text Structuring Tags <H1>, • Formatting Tags <B>, Linking <A>, <IMG>, and Data Input Tags <FORM>,<INPUT>

3. The key benefits of XML are: · Readable by both humans and computers · Facilitates the optimal structuring of data · Free and/or inexpensive · Widely available · Easy to learn · Supported by all major software vendors

4. XML vs HTML <P>Book</P><P>Title: XML by Example</P><P>Author: Sean McGrath</P><P>Publisher: Prentice Hall, Inc.</P> <P>Date Published: 1999</P><P>Description: Building E-commerce Applications </P> <book><title>XML by Example</title><author>Sean McGrath</author><publisher>Prentice Hall, Inc.</publisher><publish_date>1999</publish_date><description>Building E-commerce Applications with XML</description></book>

5. Namespaces • Namespaces resolve ambiguous element tag names, in order to associate correct elements in an XML document.

6. Namespaces OrderInfo.xml <Order_Info> <Name>John Dow</Name> <Address>19 Footlong Court</Address> <City>Tallwood</City> <Order>Cigars</Order> <Date>31-12-02</Date> </Order_Info> BillingInfo.xml <Billing_Info> <Name>Angela Dow</Name> <Payment>Visa</Payment> <Number>12344</Number> </Billing_Info>

7. Namespaces: Explicit <order: Order_Info xmlns:order =”http://www.mdx.ac.uk/~ariel/order” xmlns:bill=“http://www.mdx.ac.uk/~ariel/bill” > <order:Name >John Dow</order:Name> < order:Address>19 Footlong Court</ order:Address> < order:City>Tallwood</ order:City> < order:Order>Cigars</ order:Order> < order:Date>31-12-02</ order:Date> <bill:Billing_Info > < bill:Name >Angela Dow</bill:Name> < bill:Payment>Visa</ bill:Payment> < bill:Number>12344</ bill:Number> </ bill:Billing_Info> </ order:Order_Info>

8. XML Parsers • XML processor is used to read XML documents and provide access to their content and structure • It is assumed that an XML processor is doing its work on behalf of another module, called the application

9. XML Processing

10. Parsers • Nonvalidating – they simply verify if the document adheres to rules of the XML syntax i.e. whether the XML document is well formed • Validating – these parsers read in XML documents, check if they are well formed and verify their compliance with a specified XML schema or other validation set, i.e. they verify if the XML document is valid.

11. Content Access

12. Converting XML with XSLT • XSL technologies allow to transform XML documents into various formats, such as PDF( Adobe Acrobat Reader), WML for wireless devices, and into HTML.

13. Retrieve the element content • <xsl:value-of select="element name goes here"/> • <xsl:if test= "boolean-expression-goes here">....</xsl:if> <xsl:for-each select="element name goes here"> <!--processing instructions go here--> </xsl:for-each>

14. Example xsl:for-each select="student_list/student"> <b>Name: </b><xsl:value-of select="name"/><p/><b>ID: </b><xsl:value-of select="student_ID"/><p/><b>Studying : </b><xsl:value-of select="major"/> </xsl:for-each>

15. Database Integration • XML Database Mapping • More description on next slide • Using Native XML Databases • Store XML data in XML document • Data is serialised

16. XML Database Mapping • Associate elements in an XML document with the relational database fields. • Query the database with SQL • Convert results into an XML document • Popular solution: Java & JDBC

17. XML Web Services • Advantages of Web Services • Component independence • Component based • XML based interfaces