XML

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XML (Extensible Markup Language) is a set of rules for encoding documents electronically. It is defined in XML 1.0 specification produced by W3C and several other related specifications.
XML

XML is used to design and transport data.
It is a simple text based format
Benefits of XML

Simple to learn
Easy to read
Used widely over Internet
Strong unicode support
Text based therefore freely and widely edited
Many editors
Platform independent
Can be used for representing structured information for variety of pruposes
Some of the purposes for which it could be used is:

documents
data
configuration
books
transactions
invoices
applications
user interface templates
games

XML tags are not predefined.
You must define your own tags
XML tags are case sensitive
XML Elements be properly nested
XML documents must have root element
White space is preserved in XML
XML Naming Rules

Names can contain letters, numbers, and other characters
Names cannot start with a number or punctuation character
Names cannot start with the letters xml (XML or Xml etc)
Names cannot contain spaces

XML documents must be well formed
Displaying CSS with XML Files

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

<?xml version="1.0" encoding="ISO-8859-1"?>
<open>
<to>Example</to>
<skj>Area</skj>
<head>Rest</head>
<body>Welcom to SKJ Platform</body>
</open>
XML Syntax Rules

Document must begin with the XML declaration

eg: <?xml version="1.0"?>

Document must have one unique root element
The start tags in an XML document must have matching end tags
All elements in XML :

Are case sensitive
Must be closed
Must be properly nested

All attribute values must be quoted
Entities must be used for special characters in an XML document

XML Based Languages

XHTML the latest version of HTML
WSDL for describing available web services
WAP and WML as markup languages for handheld devices
RSS languages for news feeds
RDF and OWL for describing resources and ontology
SMIL for describing multimedia for the web
SOAP for exchanging structured information in the implementation of Web Services in computer networks

Features in XML which are different from HTML

All elements must be closed or marked as empty.
In XML, attribute values must always be quoted. For eg. <Employee type="Manager" />
In XML, there are no built-in names (although names starting with xml have special meanings)
In XML, there are only five built-in character entities:

< (<)
> (>)
& (&)
" (")
' (')
You can define your own entities in a Document Type Definition, or you can use any Unicode character

XML also allows hexadecimal references

Technical Things (Should be read only by programmers)

A software module called an XML processor is used to read XML documents and provide access to their content and structure
Each XML document has both a logical and a physical structure.
Physically, the document is composed of units called entities
An entity may refer to other entities to cause their inclusion in the document.
A document begins in a "root" or document entity
All XML processors must accept the UTF-8 and UTF-16 encodings of Unicode
Comments

Start with <!--
End with -->

Standalone Document Declaration

In a standalone document declaration, the value "yes" indicates that there are no external markup declarations which affect the information passed from the XML processor to the application.
The value "no" indicates that there are or may be such external markup declarations.
eg. <?xml version="1.0" standalone='yes'?>

A special attribute named xml:lang may be inserted in documents to specify the language used in the contents and attribute values of any element in an XML document
Language information may also be provided by external transport protocols (e.g. HTTP or MIME). When available, this information may be used by XML applications, but the more local information provided by xml:lang should be considered to override it
XML attribute types are of three kinds:

a string type
a set of tokenized types
enumerated types

XML Namespace

An XML namespace is a collection of names, identified by a URI reference [RFC2396], which are used in XML documents as element types and attribute names.
URI references which identify namespaces are considered identical when they are exactly the same character-for-character
Eg.

<job xmlns:skj='http://skjword.org/schema'>
  

  <skj:price units='Rs'>81.28</skj:price>
</job>

XML Schema (XSD)

XML Schema is generally referred as XSD document written in XML Language
XSD can be used to express a set of rules to which an XML document must conform in order to be considered 'valid' according to that schema.
XML Schema is an XML-based alternative to DTD
Unlike DTD the XML Schema is itself written in XML
XML Schema (XSD) defines

Elements that can appear in a document
Attributes that can appear in a document
Which elements are child elements
The order of child elements
The number of child elements
Whether an element is empty or can include text
Data types for elements and attributes
Default and fixed values for elements and attributes

The XML representation of schema components uses a vocabulary identified by the namespace named http://www.w3.org/2001/XMLSchema
For brevity, the text and examples used in W3C's XSD specification and in examples used by some people use the prefix xs: to stand for this namespace; in practice, any prefix can be used
Many attributes used are identified by another namespace named http://www.w3.org/2001/XMLSchema-instance
For brevity, the text and examples used in W3C's XSD specification and in examples used by some people use the prefix xsi: to stand for this namespace; in practice, any prefix can be used
The xsi:schemaLocation and xsi:noNamespaceSchemaLocation attributes can be used in a document to provide hints as to the physical location of schema documents which may be used for assessment
MIME Type - application/xml or text/xml
Elements in XML Schema

schema

Description

It is the root element in XML Schema

Attributes

xmlns

This indicates that the data types and elements used in this schema come from the name space given as value of this attribute. It specifies the default namespace declaration

schemaLocation

This attribute has two values
First value is the namespace to use
Second value is the location of the XML Schema for that namespace to use

targetNamespace

elementFormDefault

Child Elements

schema element can contain two types of child elements
Simple type of child elements
Complex type of child elements

Simple Elements

Description

It is an XML element that only contains values in one of the 19 primitive data types
They cannot contain attributes
It cannot contain any other elements inside it

Attributes

name

Defines name of the element

type

Defines primitive type of the element

default

Defines the default value of the element.
Default value is to be used when no other value is specified

fixed

Defines the fixed value of the element
No other value can be defined by the document writer if this attribute is used

Complex Elements

Description

They are elements that can contain attributes and other elements inside them
Tag : <complexType>

Attributes
Child Elements

complexContent

It signals that we intend to restrict or extend the content model of a complex type

any

It enables us to extend the XML document with elements not specified by the schema
When present in a complex element definition it tells that any other element can be added to this complex element even if the XSD does not define it

anyAttribute

It enables us to extend the XML document with attributes not specified by the schema
When present in a complex element definition it tells that any other attribute can be added to this complex element even if the XSD does not define it

Indicators

Order Indicators (they are used to define the order of the elements)

All

The <all> indicator specifies that the child elements can appear in any order, and that each child element must occur only once
When using the <all> indicator you can set the <minOccurs> indicator to 0 or 1
<maxOccurs> indicator can only be set to 1

Choice

specifies that either one child element or another can occur

Sequence

specifies that the child elements must appear in a specific order

Occurrence Indicators (the are used to define how often an element can occur)

maxOccurs

specifies the maximum number of times an element can occur
Default value is 1

minOccurs

specifies the minimum number of times an element can occur
Default value is 1
To allow an element to appear an unlimited number of times, use the maxOccurs="unbounded"

Group Indicators (they are used to define related sets of elements)

Element Groups

syntax : <group name="groupname">

Attribute Groups

syntax : <attributeGroup name="groupname">

Global Elements

Elements that are immediate children of the "schema" element

Local Elements

Elements nested within elements other than schema element

Element Substitution

To understand please refer to this example
Eg.

<element name="country" type="xs:string"/>
<element name="desh" substitutionGroup="name"/>
In the example above, the "country" element is the head element and the "desh" element is substitutable for "country".

block attribute

The element can use the block attribute (block="substitution") in its definition to stop element substitution

All elements in the substitutionGroup (head element and the substitutable elements) must be declared as global elements, otherwise element substitution will not work

Element Reference

ref attribute

Any element can be reference by using the 'ref' attribute
This can help in dividing the document

Attributes in XML Schema

Description

All attributes in XML Schema are defined as a simple type in a way similar to simple elements
Syntax : <attribute name="aaa" type="bbb"/>

Attributes of the element 'attribute'

name

Defines name of the element

type

Defines primitive type of the element

default

Defines the default value of the element.
Default value is to be used when no other value is specified

fixed

Defines the fixed value of the element
No other value can be defined by the document writer if this attribute is used

use

Defines whether this attribute is compulsorily required or is optional
All attributes are optional by default
Values : optional/required
Using this attribute with 'required' as value means that filing this attribute is compulsory

XSD provides a set of 19 primitive data types :

boolean

It is used to specify a true or false value
Legal values for boolean are following :

true
false
1 (which indicates true)
0 (which indicates false)

string

It can contain the following things

characters
line feeds
carriage returns
tab characters

The following is a list of data types that derive from string primitive data type

ENTITIES
ENTITY
ID

A string that represents the ID attribute in XML (only used with schema attributes)

IDREF

A string that represents the IDREF attribute in XML (only used with schema attributes)

IDREFS
language

A string that contains a valid language id

Name

A string that contains a valid XML name

NCName
NMTOKEN

A string that represents the NMTOKEN attribute in XML (only used with schema attributes)

NMTOKENS
normalizedString

A string that does not contain line feeds, carriage returns, or tabs

token

A string that does not contain line feeds, carriage returns, tabs, leading or trailing spaces, or multiple spaces

The following restrictions can be imposed on string

enumeration

length

maxLength

minLength

pattern (NMTOKENS, IDREFS, and ENTITIES cannot use this constraint)

whiteSpace

decimal

It is used to specify a numeric value
The following date types have been derived from the decimal primitive data type

byte

A signed 8-bit integer

int

A signed 32-bit integer

integer

An integer value

long

A signed 64-bit integer

negativeInteger

An integer containing only negative values (..,-2,-1)

nonNegativeInteger

An integer containing only non-negative values (0,1,2,..)

nonPositiveInteger

An integer containing only non-positive values (..,-2,-1,0)

positiveInteger

An integer containing only positive values (1,2,..)

short

A signed 16-bit integer

unsignedLong

An unsigned 64-bit integer

unsignedInt

An unsigned 32-bit integer

unsignedShort

An unsigned 16-bit integer

unsignedByte

An unsigned 8-bit integer

The restrictions that can be placed on this data type and the ones derived from it are

enumeration

fractionDigits

maxExclusive

maxInclusive

minExclusive

minInclusive

pattern

totalDigits

whiteSpace

double
float
anyURI

It is used to specify a URI

QName
hexBinary

It is used for expressing hexadecimal-encoded binary data.

base64Binary

It is used for expressing Base64-encoded binary data.

duration

Defines a time interval
It uses this format for writing time interval - "PnYnMnDTnHnMnS" where

P indicates the period (required)
nY indicates the number of years
nM indicates the number of months
nD indicates the number of days
T indicates the start of a time section (required if you are going to specify hours, minutes, or seconds)
nH indicates the number of hours
nM indicates the number of minutes
nS indicates the number of seconds

This is how it may look in document : <time-passed>P5Y2M10DT15H</time-passed>
To use a negative duration just place minus sign before the value in the document
Restrictions that can be placed on it

enumeration
maxExclusive
maxInclusive
minExclusive
minInclusive
pattern
whiteSpace

date

It specifies dates
The following format is used by it for writing dates

"YYYY-MM-DD"
YYYY indicates the year

MM indicates the month

DD indicates the day

All the three are required for a valid date

To specify a time zone, you can either enter a date in UTC time by adding a "Z" behind the date
To specify an offset from the UTC time add a positive or negative time behind the date

Restrictions that can be placed on it

enumeration
maxExclusive
maxInclusive
minExclusive
minInclusive
pattern
whiteSpace

time

It specifies the time
The following format is used by it for writing time

"hh:mm:ss"

hh indicates the hour

mm indicates the minute

ss indicates the second

To specify a time zone, you can either enter a date in UTC time by adding a "Z" behind the date

To specify an offset from the UTC time add a positive or negative time behind the date

Restrictions that can be placed on it

enumeration
maxExclusive
maxInclusive
minExclusive
minInclusive
pattern
whiteSpace

dateTime

It can be used to specify both date and time in one element
The following format is used by it for writing date and time

"YYYY-MM-DDThh:mm:ss"
YYYY indicates the year
MM indicates the month
DD indicates the day
T indicates the start of the required time section
hh indicates the hour
mm indicates the minute
ss indicates the second

To specify a time zone, you can either enter a date in UTC time by adding a "Z" behind the date

To specify an offset from the UTC time add a positive or negative time behind the date

Restrictions that can be placed on it

enumeration
maxExclusive
maxInclusive
minExclusive
minInclusive
pattern
whiteSpace

gYear

Part of a date - the year (YYYY)

Restrictions that can be placed on it

enumeration
maxExclusive
maxInclusive
minExclusive
minInclusive
pattern
whiteSpace

gYearMonth

Part of a date - the year and month (YYYY-MM)

Restrictions that can be placed on it

enumeration
maxExclusive
maxInclusive
minExclusive
minInclusive
pattern
whiteSpace

gMonth

Part of a date - the month (MM)

Restrictions that can be placed on it

enumeration
maxExclusive
maxInclusive
minExclusive
minInclusive
pattern
whiteSpace

gMonthDay

Part of a date - the month and day (MM-DD)

Restrictions that can be placed on it

enumeration
maxExclusive
maxInclusive
minExclusive
minInclusive
pattern
whiteSpace

gDay

Part of a date - the day (DD)

Restrictions that can be placed on it

enumeration
maxExclusive
maxInclusive
minExclusive
minInclusive
pattern
whiteSpace

NOTATION

It allows new data types to be constructed from these primitives by three mechanisms:

restriction (reducing the set of permitted values)
list (allowing a sequence of values)
union (allowing a choice of values from several types).

Twenty-five derived types are defined within the specification itself, and further derived types can be defined by users in their own schema.
Facets

Restrictions on XML elements are called facets
Types of restrictions allowed

enumeration

List of acceptable values

fractionDigits

Maximum number of decimal places allowed
Must be equal to or greater than 0

length

Exact number of characters or list items allowed
Must be equal to or greater than 0

maxExclusive

Upper bounds for numeric values (the value must be less than this value)

maxInclusive

upper bounds for numeric values (the value must be less than or equal to this value)

maxLength

Maximum number of characters or list items allowed
Must be equal to or greater than 0

minExclusive

Lower bounds for numeric values (the value must be greater than this value)

minInclusive

Lower bounds for numeric values (the value must be greater than or equal to this value)

minLength

Minimum number of characters or list items allowed
Must be equal to or greater than 0

pattern

It imposes the restriction as to the exact sequence of characters that are acceptable
It allows for imposing relatively sophisticated restrictions

totalDigits

Specifies the exact number of digits allowed
Must be greater than 0

whiteSpace

Specifies how white space is handled
White space includes

line feeds
tabs
spaces
carriage returns

Possible restrictions of white spaces

preserve

It tells that white spaces should not be removed

replace

It tells that all white spaces should be replaced by spaces

collapse

It tells that all white space characters should be replaced with spaces, leading and trailing spaces should be removed and multiple spaces should be reduced to a single space

Benefits of XSD

Gives ability to create markup languages very fast
Defines vocabulary
Documentation generation
Code generation
Ability to use existing XML editor to edit Schema files
Ability to use existing XML parser to parse Schema files
Ability to manipulate Schema with the XML DOM
Ability to transform Schema with XSLT
It is extensible which allows one to

Reuse Schema in other Schemas
Create own data types derived from the standard types
Reference multiple schemas in the same document

(Work for SKJ Team) Find more about

Elements
Attributes

XSLT Essentials

XSLT is the most important part of XSL
XSLT transforms an XML document into another XML document
XSLT is used to transform an XML document into another XML document, or another type of document that is recognized by a browser, like HTML and XHTML. Normally XSLT does this by transforming each XML element into an (X)HTML element.
Support on almost all browsers
The root element that declares the document to be an XSL style sheet is <xsl:stylesheet> or <xsl:transform>
The correct way to declare an XSL style sheet according to the W3C XSLT Recommendation is:

<xsl:transform version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

Steps to Create XSLT

Start with RAW XML Document
Create an XSL Style Sheet
Link the XSL Stylesheet to XML Document

The <xsl:template> element is used to build templates.

The match attribute is used to associate a template with an XML element. The match attribute can also be used to define a template for the entire XML document. The value of the match attribute is an XPath expression (i.e. match="/" defines the whole document)