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- 2. UNIT I INTRODUCTION TO XML XML document structure – Well formed and valid documents – Namespaces – DTD – XML Schema – X-Files.
- 3. XML and XSLT With XSLT One can transform an XML document into HTML.
- 4. Displaying XML with XSLT • XSLT means eXtensible Stylesheet Language Transformations • XSLT is the recommended style sheet language for XML. • XSLT is far more sophisticated than CSS. • With XSLT, one can – Add/remove elements and attributes to or from the output file. – Rearrange and sort elements, – Perform tests and make decisions about which elements to hide and display, and a lot more.
- 5. XSLT Example • XSLT uses XPath to find information in an XML document. <?xml version="1.0" encoding="UTF-8"?> <breakfast_menu> <food> <name>Belgian Waffles</name> <price>$5.95</price> <description>Two of our famous Belgian Waffles with plenty of real maple syrup</description> <calories>650</calories> </food> <food> <name>Strawberry Belgian Waffles</name> <price>$7.95</price> <description>Light Belgian waffles covered with strawberries and whipped cream</description> <calories>900</calories> </food>
- 7. XSLT Example • XSLT uses XPath to find information in an XML document. <?xml version="1.0" encoding="UTF-8"?> <html xsl:version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <body style="font-family:Arial;font-size:12pt; background-color:#EEEEEE"> <xsl:for-each select="breakfast_menu/food"> <div style="background-color:teal;color:white;padding:4px"> <span style="font-weight:bold"><xsl:value-of select="name"/> - </span> <xsl:value-of select="price"/> </div>
- 8. XSLT Example • XSLT uses XPath to find information in an XML document. <div style="margin-left:20px;margin-bottom:1em;font-size:10pt"> <p> <xsl:value-of select="description"/> <span style="font-style:italic"> (<xsl:value-of select="calories"/> calories per serving) </span> </p> </div> </xsl:for-each> </body> </html>
- 9. Displaying XML with XSLT • This is displayed in a browser:
- 11. Xpath (XML Path language) A language with a standard syntax for finding information in an XML document
- 12. Introduction • What is XPath? – XPath is a syntax for defining parts of an XML document – XPath uses path expressions to navigate in XML documents – XPath contains a library of standard functions – XPath is a major element in XSLT – XPath is also used in XQuery, XPointer and XLink – XPath is a W3C recommendation • XPath was created – To reduce the amount of time to find the elements and attributes desired by an author
- 13. XPath Path Expressions • XPath uses path expressions – To select nodes or node-sets in an XML document. • XPath expressions can be used in – JavaScript, – Java, – XML Schema, – PHP, – Python, – C and C++, and lots of other languages.
- 14. XPath Standard Functions • XPath includes over 100 built-in functions. • There are functions for – String values, – Numeric values, – Date and time comparison, – Node and QName manipulation, – Sequence manipulation, – Boolean values, and more.
- 15. XPath is Used in XSLT • XPath was designed to be used by – XSLT, – XPointer and – Other XML parsing software. • Without XPath knowledge – You will not be able to create XSLT documents.
- 16. XPath Terminology - Nodes • XML documents are treated as trees of nodes. • Topmost element of the tree is called the root element. • In XPath, there are seven kinds of nodes: – Element, attribute, text, namespace, processing-instruction, comment, and document nodes.
- 17. <?xml version="1.0" encoding="UTF-8"?> <bookstore> <book> <title lang="en">Harry Potter</title> <author>J K. Rowling</author> <year>2005</year> <price>29.99</price> </book> </bookstore> Example of nodes in this XML document: <bookstore> (root element node) <author>J K. Rowling</author> (element node) lang="en" (attribute node) Atomic values are nodes with no children or parent. Example of atomic values: J K. Rowling "en" Items are atomic values or nodes.
- 18. Relationship of Nodes • Parent - Each element and attribute has one parent. • Children - Element nodes may have zero, one or more children. • Siblings - Nodes that have the same parent. • Ancestors - A node's parent, parent's parent, etc. • Descendants - A node's children, children's children, etc. • In this example; – book element is the parent of the title, author, year, and price – title, author, year, and price elements are all children of book element – title, author, year, and price elements are all siblings – ancestors of title element are book element and bookstore element: <bookstore> <book> <title>Harry Potter</title> <author>J K. Rowling</author> <year>2005</year> <price>29.99</price> </book> </bookstore> Descendants of bookstore element are the book, title, author, year, and price elements:
- 19. XPath Syntax • XPath uses path expressions to select nodes in an XML document • Node is selected by following a path or steps. Expression Description nodename Selects all nodes with the name "nodename" / Selects from the root node // Selects nodes in the document from the current node that match the selection no matter where they are . Selects the current node .. Selects the parent of the current node @ Selects attributes
- 20. Example for Xpath <?xml version="1.0" encoding="UTF-8"?> <bookstore> <book> <title lang="en">Harry Potter</title> <price>29.99</price> </book> <book> <title lang="en">Learning XML</title> <price>39.95</price> </book> </bookstore> Path Expression Result bookstore Selects all nodes with the name "bookstore" /bookstore Selects the root element bookstore Note: If the path starts with a slash ( / ) it always represents an absolute path to an element! bookstore/book Selects all book elements that are children of bookstore //book Selects all book elements no matter where they are in the document bookstore//book Selects all book elements that are descendant of the bookstore element, no matter where they are under the bookstore element //@lang Selects all attributes that are named lang
- 21. Predicates • Used to find a specific node or a node that contains a specific value. • Predicates are always embedded in square brackets. Path Expression Result /bookstore/book[1] Selects the first book element that is the child of the bookstore element. Note: In IE 5,6,7,8,9 first node is[0], but according to W3C, it is [1]. To solve this problem in IE, set the SelectionLanguage to XPath: In JavaScript: xml.setProperty("SelectionLanguage","XPath"); /bookstore/book[last()] Selects the last book element that is the child of the bookstore element
- 22. Predicates Path Expression Result /bookstore/book[last()-1] Selects the last but one book element that is the child of the bookstore element /bookstore/book[position()<3] Selects the first two book elements that are children of the bookstore element //title[@lang] Selects all the title elements that have an attribute named lang //title[@lang='en'] Selects all the title elements that have a "lang" attribute with a value of "en" /bookstore/book[price>35.00] Selects all the book elements of the bookstore element that have a price element with a value greater than 35.00 /bookstore/book[price>35.00]/title Selects all the title elements of the book elements of the bookstore element that have a price element with a value greater than 35.00
- 23. Selecting Unknown Nodes • XPath wildcards can be used to select unknown XML nodes. • Example: Wildcard Description * Matches any element node @* Matches any attribute node node() Matches any node of any kind Path Expression Result /bookstore/* Selects all the child element nodes of the bookstore element //* Selects all elements in the document //title[@*] Selects all title elements which have at least one attribute of any kind
- 24. Selecting Several Paths • By using the | operator in an XPath expression you can select several paths. • Some path expressions and the result of the expressions: Path Expression Result //book/title | //book/price Selects all the title AND price elements of all book elements //title | //price Selects all the title AND price elements in the document /bookstore/book/title | //price Selects all the title elements of the book element of the bookstore element AND all the price elements in the document
- 26. Example for Xpath <?xml version="1.0" encoding="UTF-8"?> <bookstore> <book> <title lang="en">Harry Potter</title> <price>29.99</price> </book> <book> <title lang="en">Learning XML</title> <price>39.95</price> </book> </bookstore> Path Expression Result //book/title | //book/price Selects all the title AND price elements of all book elements //title | //price Selects all the title AND price elements in the document /bookstore/book/title | //price Selects all the title elements of the book element of the bookstore element AND all the price elements in the document
- 27. XPath Syntax • XPath uses path expressions – To select nodes in an XML document • Node is selected by following a path or steps. Expression Description nodename Selects all nodes with the name "nodename" / Selects from the root node // Selects nodes in the document from the current node that match the selection no matter where they are . Selects the current node .. Selects the parent of the current node @ Selects attributes
- 28. XPath Syntax • XPath uses path expressions – To select nodes in an XML document • Node is selected by following a path or steps. Expression Description nodename Selects all nodes with the name "nodename" / Selects from the root node // Selects nodes in the document from the current node that match the selection no matter where they are . Selects the current node .. Selects the parent of the current node @ Selects attributes