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XML

  • eXtensible Markup Language, markup language
  • designed to store and transport data
  • provide an easy to use and store self data describing data
  • is designed to be self descriptive
  • tags are not predefined, to must define your own tags
  • platform and language independent

XML syntax rules

  • All XML elements must have a closing tag.
  • XML tags are case sensitive.
  • All XML elements must be properly nested.
  • All XML documents must have a root element.
  • Attribute values must always be quoted.

XML Attributes

  • XML elements can have attributes, just like HTML.
  • Attributes are designed to contain data related to a specific element.
  • they must be quoted
    • <person gender="female">

XML Namespaces

  • XML Namespace is used to avoid element name conflict in XML document.

Namespace declaration

  • An XML namespace is declared using the reserved XML attribute.
  • This attribute name must be started with "xmlns".
<element xmlns:name = "URL">

XML CSS

  • CSS (Cascading Style Sheets) can be used to add style and display information to an XML document. It can format the whole XML document.

  • link style sheet

<?xml-stylesheet type="text/css" href="cssemployee.css"?>

employee {
  background-color: pink;
}
firstname,
lastname,
email {
  font-size: 25px;
  display: block;
  color: blue;
  margin-left: 50px;
}

XML DTD (document type definition)

What is DTD

DTD stands for Document Type Definition. It defines the legal building blocks of an XML document. It is used to define document structure with a list of legal elements and attributes.

Purpose of DTD

Its main purpose is to define the structure of an XML document. It contains a list of legal elements and define the structure with the help of them.

CDATA

  • CDATA: (Unparsed Character data)
  • CDATA contains the text which is not parsed further in an XML document. Tags inside the CDATA text are not treated as markup and entities will not be expanded.
<?xml version="1.0"?>
<!DOCTYPE employee SYSTEM "employee.dtd">
<employee>
<![CDATA[
  <firstname>geu</firstname>
  <lastname>dehradun</lastname>
  <email>info@geu.ac.in</email>
]]>
</employee>

PCDATA

  • PCDATA: (Parsed Character Data)
  • XML parsers are used to parse all the text in an XML document.
  • PCDATA stands for Parsed Character data.
  • PCDATA is the text that will be parsed by a parser.
  • Tags inside the PCDATA will be treated as markup and entities will be expanded.
  • In other words you can say that a parsed character data means the XML parser examine the data and ensure that it doesn't content entity if it contains that will be replaced.
<?xml version="1.0"?>
<!DOCTYPE employee SYSTEM "employee.dtd">
<employee>
  <firstname>geu</firstname>
  <lastname>dehradun</lastname>
  <email>info@geu.ac.in</email>
</employee>

will give when parsed,

geu dehradun info@geu.ac.in