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1 XML Introduction 1. XML Stands for EXtensible Mark-up Language (XML). 2. SGML Electronic Publishing challenges HTML Web Presentation challenges XML Data Representation challenges W3C- World Wide Web Consortium (W3C) 6. CSS- Cascading Style Sheets (CSS) 7. XML is the Universal format for Structuring Documents and Data on the Web. 8. Actually Extensible Mark-up Language is not a mark-up language, but a set of rules for creating a new mark-up language. 9. XML is a Subset of Standard Generalized Mark-up Language (SGML). 10. SGML specifies the Rules for Creating Mark-up Languages. 11. The XML 1.0 was made a World Wide Web Consortium (W3C) recommendation on February 10, XML is Replacement of HTML? 1. One thing we must keep in our mind that XML is not a replacement for HTML. We can treat it as complementary language for HTML 2. XML is used to represent the data contained in the tags. HTML is used to represent web pages 3. XML is used to carry information. More clear answer of this question is explained beautifully 4. In order to write XML file we must have text editor. 5. Our recommendation is to use Notepad++ for Editing and Writing XML files. 6. Save this Document with.xml extension Difference between XML and HTML : HTML XML HTML focuses on How data looks? XML focuses on What data is? HTML is used to Display Information. HTML Tags are Predefined HTML is used to Design Web pages. HTML is Case Insensitive XML is used to Describe Information. XML Tags can be user Defined. XML is designed to Carry data or to Create new Scripting Language. XML is case Sensitive.

2 HTML HTML does not preserve white space HTML is not Strict. HTML is presentation language XML XML preserves White Space XML is String as Strict. XML neither a programming language nor a presentation language HTML XML Definition Markup language for displaying web pages in a web browser. Designed to display data with focus on how the data looks Markup language defines a set of rules for encoding documents that can be read by both humans and machines. Designed with focus on storing and transporting data. Date when invented Extended from SGML SGML Type Static Dynamic Usage Processing/Rules Display a web page No strict rules. Browser will still generate data to the best of its ability Transport data between the application and the database. To develop other mark up languages. Strict rules must be followed or processor will terminate processing the file Language type Presentation Neither presentation, nor programming Tags Predefined Custom tags can be created by the author White Space Cannot preserve white space Preserves white space Limitations Data does not know itself very well. Data cannot change in response to environment. Data cannot be easily maintained. Cannot store or call on variables. Lacks the capability to define new structures by defining relationships between classes. Tags are not useful for exchanging the document between applications. Cannot be used as a subtype of a sql_variant instance. Does not support casting or converting to either text or ntext. Does not support the following column and table constraints. XML provides its own encoding. Collations apply to string types only. Cannot be compared or sorted. Cannot be used in Distributed Partitioned Views. Not well supported by browsers.

3 How to Parse XML Document? 1. An XML processor is more commonly called a parser. 2. XML Parser parses XML and provides needed information to the application. 3. XML Parser reads document characters by character and determines which characters are part of the document s markup and which are part of the document s data. 4. XML Parser does all processing of XML document before an application can make use of it. 5. In market there are many Parser available from different Vendors. Some Well Known XML Parsers : 1. Microsoft Internet Explorer Parser Microsoft s XML parser is known as MSXML. MSXML first shipped with Internet Explorer 4. The latest version of the parser is available for download from Microsoft s MSDN site. Comes built-in with the Internet Explorer browser. 2.Apache Xerces The Apache Software Foundation s Xerces subproject of the Apache XML Project has resulted in XML parsers in Java and C++, plus a Perl wrapper for the C++ parser. These tools are free, and the distribution of the code is controlled by the GNU Public License (GPL). 3. James Clark s Expat Completely Written in C. 4.Xml4j It is free for both private and commercial use Can be Downloaded From Here. Created and Owned By IBM. Completely written in Java. Available for free. Different XML Editors : XML Notepad XML Cooktop XML Pro XML Spy Liquid XML Studio

4 Features of XML Editor : 1. Easy XML Syntax Highlighting. 2. Drag and Drop Tags. 3. More Readable XML Document. 4. Increases Performance Time of Writing XML Document. 5. Can Create Well Formed XML Document. XML Declaration : <?xmlversion="1.0"encoding="utf-8"standalone="no"?> 1. XML Declaration is Optional. 2. XML Declaration must be First Line in XML Document if we write Declaration. 3. XML Declaration tells that Document Written is in XML. 4. XML Declaration tells XML Version used to Write Document. 5. XML Declaration tells Encoding Style Used to Encode XML Document. 6. If XML Document is standalone i.e if it does not depends on other external document then we need to specify standalone= yes. 7. W3C recommends to include XML Declaration. Document Type Definition (DTD) <!DOCTYPE document system "Person.dtd"> 1. Document Type definition is used to Define XML Document. 2. DTD is used when you Validate your XML document. 3. DTD can be Internal or External. 4. DTD rule tells which Element is allowed to nest inside Other Element. Comment 1. Comments are Optional part of XML Document. 2. Comments in XML are similar to HTML. <! and > 3. Content Written inside Comment is ignored by Parser. (Comment part is not parsed by Parser) 4. Comments can appear anywhere inside XML Document. Styling and Processing Instruction <?xml-stylesheettype="text/css"href="styles.css"?> 1. Processing Instructions begin with <? and ends with?> 2. Processing Instructions are instructions for the XML processor. 3. Processing instructions are processor dependant so not all processors understand all processing instructions.

5 White Space 1. White Space can be created using Carriage Return, Line Feed and Tab. 2. White Space cannot affect Parsing of Document. 3. User is Free to Use White Space anywhere inside document. 4. XML recommendation specifies that XML documents use the UNIX convention for line endings. 5. It means that you should use a linefeed character only (ASCII code 10) to indicate the end of a line. Note:- XML Declaration- <?xml version="1.0" encoding="utf-8" standalone="no"?> Document Type Definition (DTD)- <!doctype document system "Person.dtd"> Comment- <!-- Here is a comment --> Processing Instructions-<?xml-stylesheet type="text/css" href="styles.css"?> Root Node-<Student> Sub Nodes-<Boy> and <Girl> Sub-Sub Nodes-<name> and <marks> XML Tree Structure: Ex: <Student> <Boy name="pritesh" marks="90"></boy> <Boy name="pooja" marks="89"></boy> </Student>

6 Root Element : 1. Each XML Document must have One and Only One Root Element. 2. Other XML elements must be Nested inside Root Element. 3. Opening Tag of Root Element is the Opening Tag of Document. 4. Closing Tag of Root Element is the Closing Tag of Document. Some Facts: 1. XML is Organized as Tree Structure. 2. XML can have User Defined Tags. 3. XML consists of any number of nodes. Elements & Content Root element opening tag- <Person> Child elements and content- <Student> <Boy> <name>pritesh</name> <marks>90</marks> </Boy> <Girl> <name>pooja</name> <marks>89</marks> </Girl> </Student> Root element closing tag- </Person> XML Syntax Rules : Different XML Parsing Rules 1. We have already discussed in our previous chapter about difference between XML and HTML. 2. HTML tags are not case sensitive. XML is Case Sensitive. 3. XML have some syntax rules that are somewhat simple and logical. XML Rules are : 1. XML Document must have Exactly One Root Element. 2. XML Tags Must be Closed 3. XML Tags are Case Sensitive. 4. XML Tags Must be Properly Nested. 5. XML Attribute Values Must be Quoted. XML Syntax Rules are : XML Document Must have One and Only One Root Element XML Document Consists of Elements Arranged Like Tree.

7 XML Document Must have One and Only One Root Element. In HTML many elements don t have closing tags. XML Element must have Closing Tag. It is illegal to have non-closing tag in XML. All XML Tags are Case Sensitive. Opening Tag must have Closing tag with Same Case and Spelling. Opening Tag Must have Same Spelling to that of Closing Tag. Opening Tag and Closing Tags must have same Case. HTML does not care improperly nested element. It does not show any error. XML does Strict Checking of Elements. It will give parsing error if Parser finds any Improper nesting of Elements. What is XML Attribute? 1. XML Attributes are just like HTML Attributes. 2. XML Attributes provides additional information about XML Element. 3. Attributes Consists of name/value pairs associated with an element. 4. Attributes are attached to the start-tag, but not to the end-tag Well Formed XML Document Rule No Rule No 1 : Rule No 2 : Rule No 3 : Rule No 4 : Rule No 5 : Explanation XML Document must have Single Root Element XML Elements must have a Closing Tag XML Tags are Case Sensitive XML Elements must be properly nested XML Attribute Value must be quoted XML DTD Introduction: 1. DTD stands for Document Type Definition (DTD) 2. DTD is used to define structure of a document encoded in XML 3. DTD is used to define legal building blocks of an XML document. 4. DTD provids us list of all legal elements and attributes defined in the XML file 5. DTD is declared inside the XML document or it can be defined as an external dtd file.

8 Main XML DTD Building Blocks : Building Block Elements Attributes Entities PCDATA CDATA Explanation Main nodes and main building block Extra information about element. Special characters in XML parsed character data character data XML Elements : Ex: <Book pages="100"> <name>learn XML</name> <author>pritesh</author> <type>scripting</type> </Book> Element Root Element Child Elements Name of the Element Book name,author,type XML Entities : Entity References Character < < > > & & " &apos;

9 PCDATA / CDATA : PCDATA PCDATA means parsed character data. Generally used for Elements PCDATA is text that will be parsed by a parser Tags inside the text will be treated as markup and entities will be expanded CDATA CDATA means character data. Generally used for Attributes CDATA is text that will not be parsed by a parser Tags inside the text will NOT be treated as markup and entities will not be expanded DTD Elements : DTD elements are declared with an ELEMENT declaration. <!ELEMENT element-name keyword> <!ELEMENT element-name (element-content)> Different ways of using DTD Element : We can use DTD element like below syntax OR DTD Element Empty Elements Elements with Parsed Character Data Elements with any Contents Usage Using EMPTY keyword Using #PCDATA Using ANY Keyword Elements with childres Using list wrapped inside () Element with Only One Occurrence Element with Minimum One Occurrence Element with Zero or More Occurrences Element with Zero or One Occurrences Element with either or Using element name only Using + Operator Using * Operator Using? Operator Using Operator Empty Elements : EMPTY Keyword is used to specify Empty elements. Please look at following syntax <!ELEMENT element-name EMPTY>

10 Example : DTD Example XML Example <!ELEMENT br EMPTY> <!ELEMENT hr EMPTY> <br /> <hr /> Internal DTD Declaration : DTD Element!DOCTYPE bookdocument!element Book!ELEMENT name!element author!element type Explanation defines that the root element of this document is Book Tells that the Book element contains four elements : "name,author,type,pages" Tells that name element is of type "#PCDATA" Tells that author element is of type "#PCDATA" Tells that type element is of type "#PCDATA"!ELEMENT pages Tells that pages element is of type "#PCDATA" External DTD Declaration : If we wrote a DTD file then we must wrap it in DOCTYPE definition with the following syntax <!DOCTYPE root-element SYSTEM "filename">