Xml Lecture Notes

1 XML Mrs.C.Santhiya Assistant Professor TCE,Madurai

2 XML is not… • A replacement for HTML (but HTML can be generated from XML) • A presentation format (but XML can be converted into one) • A programming language (but it can be used with almost any language) • A network transfer protocol (but XML may be transferred over a network) • A database (but XML may be stored into a database)

3 XML by Example <article> <author>Gerhard Weikum</author> <title>The Web in 10 Years</title> </article> • Easy to understand for human users • Very expressive (semantics along with the data) • Well structured, easy to read and write from programs This looks nice, but…

4 XML by Example <t108> <x87>Gerhard Weikum</x87> <g10>The Web in 10 Years</g10> </t108> • Hard to understand for human users • Not expressive (no semantics along with the data) • Well structured, easy to read and write from programs … this is XML, too:

5 XML by Example <data> ch37fhgks73j5mv9d63h5mgfkds8d984lgnsmcns983 </data> • Impossible to understand for human users • Not expressive (no semantics along with the data) • Unstructured, read and write only with special programs … and what about this XML document: The actual benefit of using XML highly depends on the design of the application.

6 Possible Advantages of Using XML • Truly Portable Data • Easily readable by human users • Very expressive (semantics near data) • Very flexible and customizable (no finite tag set) • Easy to use from programs (libs available) • Easy to convert into other representations (XML transformation languages) • Many additional standards and tools • Widely used and supported

7 A Simple XML Document <article> <author>Gerhard Weikum</author> <title>The Web in Ten Years</title> <text> <abstract>In order to evolve...</abstract> <section number=“1” title=“Introduction”> The <index>Web</index> provides the universal... </section> </text> </article> Freely definable tags

8 Element Content of the Element (Subelements and/or Text) A Simple XML Document <article> <author>Gerhard Weikum</author> <title>The Web in Ten Years</title> <text> <abstract>In order to evolve...</abstract> <section number=“1” title=“Introduction”> The <index>Web</index> provides the universal... </section> </text> </article> End Tag Start Tag

9 A Simple XML Document <article> <author>Gerhard Weikum</author> <title>The Web in Ten Years</title> <text> <abstract>In order to evolve...</abstract> <section number=“1” title=“Introduction”> The <index>Web</index> provides the universal... </section> </text> </article> Attributes with name and value

10 Elements in XML Documents • (Freely definable) tags: article, title, author – with start tag: <article> etc. – and end tag: </article> etc. • Elements: <article> ... </article> • Elements have a name (article) and a content (...) • Elements may be nested. • Elements may be empty: <this_is_empty/> • Element content is typically parsed character data (PCDATA), i.e., strings with special characters, and/or nested elements (mixed content if both). • Each XML document has exactly one root element and forms a tree. • Elements with a common parent are ordered.

11 Elements vs. Attributes Elements may have attributes (in the start tag) that have a name and a value, e.g. <section number=“1“>. What is the difference between elements and attributes? • Only one attribute with a given name per element (but an arbitrary number of subelements) • Attributes have no structure, simply strings (while elements can have subelements) As a rule of thumb: • Content into elements • Metadata into attributes Example: <person born=“1912-06-23“ died=“1954-06-07“> Alan Turing</person> proved that…

12 XML Documents as Ordered Trees article author title text sectionabstract The index Web provides … title=“…“ number=“1“ In order … Gerhard Weikum The Web in 10 years

13 More on XML Syntax • <root> <child> <subchild>.....</subchild> </child></root> • <?xml version="1.0" encoding="UTF-8"?> • XML Tags are Case Sensitive • XML Elements Must be Properly Nested • XML Attribute Values Must be Quoted •  • Some special characters must be escaped using entities: < → < & → & (will be converted back when reading the XML doc) • Some other characters may be escaped, too: > → > “ → " ‘ → '

14 Well-Formed XML Documents A well-formed document must adher to, among others, the following rules: • Every start tag has a matching end tag. • Elements may nest, but must not overlap. • There must be exactly one root element. • Attribute values must be quoted. • An element may not have two attributes with the same name. • Comments and processing instructions may not appear inside tags. • No unescaped < or & signs may occur inside character data.

15 Well-Formed XML Documents A well-formed document must adher to, among others, the following rules: • Every start tag has a matching end tag. • Elements may nest, but must not overlap. • There must be exactly one root element. • Attribute values must be quoted. • An element may not have to attributes with the same name. • Comments and processing instructions may not appear inside tags. • No unescaped < or & signs may occur inside character data. Only well-formed documents can be processed by XML parsers.

16 Namespace Syntax <dbs:book xmlns:dbs=“http://www-dbs/dbs“> Unique URI to identify the namespace Signal that namespace definition happens Prefix as abbrevation of URI

17 Namespace Example <dbs:book xmlns:dbs=“http://www-dbs/dbs“> <dbs:description> ... </dbs:description> <dbs:text> <dbs:formula> <mathml:math xmlns:mathml=“http://www.w3.org/1998/Math/MathML“> ... </mathml:math> </dbs:formula> </dbs:text> </dbs:book>

18 Default Namespace • Default namespace may be set for an element and its content (but not its attributes): <book xmlns=“http://www-dbs/dbs“> <description>...</description> <book> • Can be overridden in the elements by specifying the namespace there (using prefix or default namespace)

19 3.1 Document Type Definitions Sometimes XML is too flexible: • Most Programs can only process a subset of all possible XML applications • For exchanging data, the format (i.e., elements, attributes and their semantics) must be fixed ⇒ Document Type Definitions (DTD) for establishing the vocabulary for one XML application (in some sense comparable to schemas in databases) A document is valid with respect to a DTD if it conforms to the rules specified in that DTD. Most XML parsers can be configured to validate. <!DOCTYPE element DTD identifier [ declaration1 declaration2 ........ ]>

20 DTD Example: Elements <!ELEMENT article (title,author+,text)> <!ELEMENT title (#PCDATA)> <!ELEMENT author (#PCDATA)> <!ELEMENT text (abstract,section*,literature?)> <!ELEMENT abstract (#PCDATA)> <!ELEMENT section (#PCDATA|index)+> <!ELEMENT literature (#PCDATA)> <!ELEMENT index (#PCDATA)> Content of the title element is parsed character data Content of the article element is a title element, followed by one or more author elements, followed by a text element Content of the text element may contain zero or more section elements in this position

21 Element Declarations in DTDs One element declaration for each element type: <!ELEMENT element_name content_specification> where content_specification can be • (#PCDATA) parsed character data • (child) one child element • (c1,…,cn) a sequence of child elements c1…cn • (c1|…|cn) one of the elements c1…cn For each component c, possible counts can be specified: – c exactly one such element – c+ one or more – c* zero or more – c? zero or one Plus arbitrary combinations using parenthesis: <!ELEMENT f ((a|b)*,c+,(d|e))*>

22 More on Element Declarations • Elements with mixed content: <!ELEMENT text (#PCDATA|index|cite|glossary)*> • Elements with empty content: <!ELEMENT image EMPTY> • Elements with arbitrary content (this is nothing for production-level DTDs): <!ELEMENT thesis ANY>

23 Attribute Declarations in DTDs Attributes are declared per element: <!ATTLIST section number CDATA #REQUIRED title CDATA #REQUIRED> declares two required attributes for element section. element name attribute name attribute type attribute default

24 Attribute Declarations in DTDs Attributes are declared per element: <!ATTLIST section number CDATA #REQUIRED title CDATA #REQUIRED> declares two required attributes for element section. Possible attribute defaults: • #REQUIRED is required in each element instance • #IMPLIED is optional • #FIXED default always has this default value • default has this default value if the attribute is omitted from the element instance

25 Attribute Types in DTDs • CDATA string data • (A1|…|An) enumeration of all possible values of the attribute (each is XML name) • ID unique XML name to identify the element • IDREF refers to ID attribute of some other element („intra-document link“) • IDREFS list of IDREF, separated by white space • plus some more

26 Attribute Examples <ATTLIST publication type (journal|inproceedings) #REQUIRED pubid ID #REQUIRED> <ATTLIST cite cid IDREF #REQUIRED> <ATTLIST citation ref IDREF #IMPLIED cid ID #REQUIRED> <publications> <publication type=“journal“ pubid=“Weikum01“> <author>Gerhard Weikum</author> <text>In the Web of 2010, XML <cite cid=„12“/>...</text> <citation cid=„12“ ref=„XML98“/> <citation cid=„15“>...</citation> </publication> <publication type=“inproceedings“ pubid=“XML98“> <text>XML, the extended Markup Language, ...</text> </publication> </publications>

27 Attribute Examples <ATTLIST publication type (journal|inproceedings) #REQUIRED pubid ID #REQUIRED> <ATTLIST cite cid IDREF #REQUIRED> <ATTLIST citation ref IDREF #IMPLIED cid ID #REQUIRED> <publications> <publication type=“journal“ pubid=“Weikum01“> <author>Gerhard Weikum</author> <text>In the Web of 2010, XML <cite cid=„12“/>...</text> <citation cid=„12“ ref=„XML98“/> <citation cid=„15“>...</citation> </publication> <publication type=“inproceedings“ pubid=“XML98“> <text>XML, the extended Markup Language, ...</text> </publication> </publications>

28 Linking DTD and XML Docs • Document Type Declaration in the XML document: <!DOCTYPE article SYSTEM “http://www-dbs/article.dtd“> keywords Root element URI for the DTD

29 Linking DTD and XML Docs • Internal DTD: <?xml version=“1.0“?> <!DOCTYPE article [ <!ELEMENT article (title,author+,text)> ... <!ELEMENT index (#PCDATA)> ]> <article> ... </article> • Both ways can be mixed, internal DTD overwrites external entity information: <!DOCTYPE article SYSTEM „article.dtd“ [ <!ENTITY % pub_content (title+,author*,text) ]>

Internal & External DTD • <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE note SYSTEM "Note.dtd"> • Note.dtd <!DOCTYPE note [ <!ELEMENT note (to,from,heading,body)> <!ELEMENT to (#PCDATA)> <!ELEMENT from (#PCDATA)> <!ELEMENT heading (#PCDATA)> <!ELEMENT body (#PCDATA)> ]> 30

• <?xml version="1.0"?> <!DOCTYPE note [ <!ELEMENT note (to,from,heading,body)> <!ELEMENT to (#PCDATA)> <!ELEMENT from (#PCDATA)> <!ELEMENT heading (#PCDATA)> <!ELEMENT body (#PCDATA)> ]> <note> <to>Tove</to> <from>Jani</from> <heading>Reminder</heading> <body>Don't forget me this weekend</body> </note> 31

XSD-Schema • Syntax <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name="x" type="y"/> <xs:attribute name="x" type="y"/> Example Simple Type <xs:element name="phone_number" type="xs:int”/> 32

Complex Type <?xml version="1.0" encoding="UTF-8"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name=“Address"> <xs:complexType> <xs:sequence> <xs:element name="name" type="xs:string" /> <xs:element name="company" type="xs:string" /> <xs:element name="phone" type="xs:int" /> </xs:sequence> </xs:complexType> </xs:element> </xs:schema> 33

Global Type <xs:element name="AddressType"> <xs:complexType> <xs:sequence> <xs:element name="name" type="xs:string" /> <xs:element name="company" type="xs:string" /> </xs:sequence> </xs:complexType> </xs:element> 34

Loading XML DOC <script type=“text/javascript” language=“javascript”> Fn fnname() { var xmldoc; xmldoc=new ActiveXobject(“Microsoft.XMLDOM”) xmldoc.load(“src”) noderootelement=xmldoc.element; nodeelement=nodeelementname.firstchild; nodeelement=nodeelement.nextsibiling ………………………………………………..} Example address.xml <?xml version="1.0"?> <contact-info> <name>Tanmay Patil</name> <company>TutorialsPoint</company> <phone>(011) 123-4567</phone> </contact-info> 35

<!DOCTYPE html> <html> <body> <h1>TutorialsPoint DOM example </h1> <div> <b>Name:</b> <span id="name"></span><br> <b>Company:</b> <span id="company"></span><br> <b>Phone:</b> <span id="phone"></span> </div> <script> if (window.XMLHttpRequest) { // code for IE7+, Firefox, Chrome, Opera, Safari xmlhttp = new XMLHttpRequest(); } else {// code for IE6, IE5 xmlhttp = new ActiveXObject("Microsoft.XMLHTTP"); } xmlhttp.open("GET","/xml/address.xml",false); xmlhttp.send(); xmlDoc=xmlhttp.responseXML; document.getElementById("name").innerHTML= xmlDoc.getElementsByTagName("name")[0].childNodes[0].nodeValue; document.getElementById("company").innerHTML= xmlDoc.getElementsByTagName("company")[0].childNodes[0].nodeValue; document.getElementById("phone").innerHTML= xmlDoc.getElementsByTagName("phone")[0].childNodes[0].nodeValue; </script> </body> </html> 36

XML - Namespaces <?xml version="1.0" encoding="UTF-8"?> <cont: contactxmlns:cont="www.tutorialspoint.com/profile"> <cont:name>Tanmay Patil</cont:name> <cont:company>TutorialsPoint</cont:company> <cont:phone>(011) 123-4567</cont:phone> </cont:contact> 37

Xml with CSS CATALOG.xml <?xml version="1.0" encoding="UTF-8" standalone="yes"?> <?xml-stylesheet type="text/css" href=“CATALOG.css"?> <CATALOG> <CD> <TITLE>Empire Burlesque</TITLE> <ARTIST>Bob Dylan</ARTIST> <COUNTRY>USA</COUNTRY> <COMPANY>Columbia</COMPANY> <PRICE>10.90</PRICE> <YEAR>1985</YEAR> </CD> <CD> <TITLE>Hide your heart</TITLE> <ARTIST>Bonnie Tyler</ARTIST> <COUNTRY>UK</COUNTRY> <COMPANY>CBS Records</COMPANY> <PRICE>9.90</PRICE> <YEAR>1988</YEAR> </CD> </CATALOG> 38

CATALOG.css CATALOG { background-color: #ffffff; width: 100%; } CD { display: block; margin-bottom: 30pt; margin-left: 0; } TITLE { display: block; color: #ff0000; font-size: 20pt; } ARTIST { display: block; color: #0000ff; font-size: 20pt; } COUNTRY, PRICE, YEAR, COMPANY { display: block; color: #000000; margin-left: 20pt; } 39

Xml file <?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> </ breakfast_menu> 40

Xml with xslt • <?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> <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> 41

Xpath /bookstore/book[1] /bookstore/book[last()] /bookstore/book[last()-1] /bookstore/book[position()<3] //title[@lang] //title[@lang='en‘] /bookstore/book[price>35.00] /bookstore/book[price>35.00]/title 42

Xml Link XLink Syntax <?xml version="1.0" encoding="UTF-8"?> <homepages xmlns:xlink="http://www.w3.org/1999/xlink"> <homepage xlink:type="simple" xlink:href="http://www.w3sch ools.com">Visit W3Schools</homepage> <homepage xlink:type="simple" xlink:href="http://www.w3.org ">Visit W3C</homepage> </homepages> Specifications •xlink:actuate •xlink:href •xlink:show •xlink:type 43

example • <?xml version="1.0" encoding="UTF-8"?> <bookstore xmlns:xlink="http://www.w3.org/1999/xlink"> <book title="Harry Potter"> <description xlink:type="simple" xlink:href="/images/HPotter.gif" xlink:show="new"> As his fifth year at Hogwarts School of Witchcraft and Wizardry approaches, 15-year-old Harry Potter is....... </description> </book> • </bookstore> 44

Xml with ids • <?xml version="1.0" encoding="UTF-8"?> <dogbreeds> <dog breed="Rottweiler" id="Rottweiler"> <picture url="http://dog.com/rottweiler.gif" /> <history>The Rottweiler's ancestors were probably Roman drover dogs.....</history> <temperament>Confident, bold, alert and imposing, the Rottweiler is a popular choice for its ability to protect....</temperament> </dog> • </dogbreeds> 45

Xml with xpointer • <?xml version="1.0" encoding="UTF-8"?> <mydogs xmlns:xlink="http://www.w3.org/1999/xlink"> <mydog> <description> Anton is my favorite dog. He has won a lot of..... </description> <fact xlink:type="simple" xlink:href="http://dog.com/dogbreeds.xml#Rottweiler"> Fact about Rottweiler </fact> </mydog> • </mydogs> 46

Xml into the server • <% 'Load XML set xml = Server.CreateObject("Microsoft.XMLDOM") xml.async = false xml.load(Server.MapPath("simple.xml")) 'Load XSL set xsl = Server.CreateObject("Microsoft.XMLDOM") xsl.async = false xsl.load(Server.MapPath("simple.xsl")) 'Transform file Response.Write(xml.transformNode(xsl)) %> 47

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