xml
DESCRIPTION
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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.
XML Documents Form a Tree Structure
• All elements can have sub elements (child elements):
<root> <child> <subchild>.....</subchild> </child></root>
XML Documents Form a Tree Structure
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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