XML

Disclaimer: This presentation is prepared by trainees of baabtra as a part of mentoring program. This is not official document of baabtra –Mentoring PartnerBaabtra-Mentoring Partner is the mentoring division of baabte System Technologies Pvt . Ltd

XML

Sharan [email protected]/

psharanp89twitter.com/sharan_kvkin.linkedin.com/in/sharankvk8129935578

contents

• What is xml• XML Example• XML schema• XML Syntax Rules• XML Parsing• Glade XML Structure

What is xml

• XML stands for EXtensible Markup Language• XML is a markup language much like HTML• XML was designed to carry data, not to display

data• XML tags are not predefined. You must define

your own tags• XML is designed to be self-descriptive

XML Example

<?xml version="1.0"?> <note> <to>Tove</to> <from>Jani</from> <heading>Reminder</heading> <body>Don't forget me this

weekend!</body></note>

XML is Not a Replacement for HTML

• XML is a complement to HTML.• It is important to understand that XML is not a

replacement for HTML. In most web applications, XML is used to transport data, while HTML is used to format and display the data.

XML schema• The purpose of an XML Schema is to define the legal building

blocks of an XML document, just like a DTD.• An XML Schema:

– defines elements that can appear in a document– defines attributes that can appear in a document– defines which elements are child elements– defines the order of child elements– defines the number of child elements– defines whether an element is empty or can include text– defines data types for elements and attributes– defines default and fixed values for elements and attributes

XML Documents Form a Tree Structure

• XML documents must contain a root element. This element is "the parent" of all other elements.

• The elements in an XML document form a document tree. The tree starts at the root and branches to the lowest level of the tree.


• All elements can have sub elements (child elements):

<root> <child> <subchild>.....</subchild> </child></root>

XML Syntax Rules

• All XML Elements Must Have a Closing Tag• XML Tags are Case Sensitive• XML Elements Must be Properly Nested• XML Documents Must Have a Root Element• XML Attribute Values Must be Quoted• White-space is Preserved in XML

XML Parsing

It is a software library (or a package) that provides methods (or interfaces) for client applications to work with XML documents

It checks the well-formattednessIt may validate the documentsIt does a lot of other detailed things so that a

client is shielded from that complexities

• We will consider two parsing methods

SAX = Simple API for XMLDOM = Document Object Model

SAX

• XML is read sequentially

• When a parsing event happens, the parser invokes the corresponding method of the corresponding handler

DOM

• Parser creates a tree object out of the document

• User accesses data by traversing the tree– The tree and its traversal conform to a W3C

standard• The API allows for constructing, accessing and

manipulating the structure and content of XML documents

XML Parsing

Parse an XML Document

• The following code fragment parses an XML document into an XML DOM object

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","books.xml",false);xmlhttp.send();xmlDoc=xmlhttp.responseXML;

Parse an XML String

• The following code fragment parses an XML string into an XML DOM object:

• txt="<bookstore><book>";txt=txt+"<title>Everyday Italian</title>";txt=txt+"<author>Giada De Laurentiis</author>";txt=txt+"<year>2005</year>";txt=txt+"</book></bookstore>";

if (window.DOMParser) { parser=new DOMParser(); xmlDoc=parser.parseFromString(txt,"text/xml"); }else // Internet Explorer { xmlDoc=new ActiveXObject("Microsoft.XMLDOM"); xmlDoc.async=false; xmlDoc.loadXML(txt); }

GladeXML

Object HierarchyThis object represents an `instantiation' of an XML interface description.

When one of these objects is created, the XML file is read, and the interface is created. The GladeXML object then provides an interface for accessing the widgets in the interface by the names assigned to them inside the XML description.

GObject +----GladeXML

GladeXML

typedef struct { GObject parent; char *filename; }

GladeXML;

GladeXMLClass

typedef struct {

GObjectClass parent_class; /* Virtual function: gets the appropriate gtype for the typename.*/ GType (* lookup_type) (GladeXML*self, const char *gtypename); } GladeXMLClass;

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