Transcript Chapter Slides

XML
BIS4430 – unit 10
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>
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
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>
Namespaces
• Namespaces resolve ambiguous
element tag names, in order to
associate correct elements in an XML
document.
Namespaces
OrderInfo.xml
BillingInfo.xml
<Order_Info>
<Billing_Info>
<Name>John Dow</Name>
<Name>Angela Dow</Name>
<Address>19 Footlong
Court</Address>
<Payment>Visa</Payment>
<City>Tallwood</City>
<Order>Cigars</Order>
<Date>31-12-02</Date>
</Order_Info>
<Number>12344</Number>
</Billing_Info>
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>
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
XML Processing
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.
Content Access
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.
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>
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>
Database Integration
• XML Database Mapping
– More description on next slide
• Using Native XML Databases
– Store XML data in XML document
– Data is serialised
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
XML Web Services
• Advantages of Web Services
– Component independence
– Component based
– XML based interfaces