Xml iet 2015

XML
•XML stands for eXtensible Markup Language.
•Markup language for documents containing
structured information.
•XML is designed to transport and store data.
•XML is very easy to learn.
•XML tags are not predefined. You can define
your own tags.
•XML is designed to be self-descriptive.
•XML is a W3C Recommendation.

XML……..
•Based on Standard Generalized Markup Language
(SGML).
•Version 1.0 introduced by World Wide Web Consortium
(W3C) in 1998.
•Bridge for data exchange on the Web.
•Standard Generalized Markup Languages are:

Also XML….
• Excellent for handling data with a complex
structure or a typical data
• Data described using mark-up language
• Text data description
• Human- and computer-friendly format
• Handles data in a tree structure having one-
and only one-root element
• Excellent for long-term data storage and data
reusability

1. Excellent for Handling Data with a Complex
Structure or Atypical Data
• Data managed using RDB tables has a regular
data structure. One could say that nothing
surpasses RDB for handling data of this type of
structure.

• However, not all of the various data that exists
in the world today is of a structure that can be
managed using tables. Most such data has
either an extremely complex structure
(system logs, e-mail data, etc.), or is atypical
data (product manuals, specification sheets,
etc.) that has no specific structure. What can
be done to handle these data types without
extensive manipulation? XML is a data format
well-suited to handling these circumstances.

2. Text Data Description
• XML allows for the description of data in a
text format. Since XML uses text data, XML
data created on a Windows platform can also
be used in a UNIX system. Data can be
delivered back and forth without having to
take OS and systems differences into account.

3. Excellent for Long-Term Data Storage and
Data Reusability
• Data created through a specific application becomes
useless or even impossible to access if the application is
eventually unusable or cannot maintain backward
compatibility.
• However, XML documents are text data, and do not rely
on any particular application. The data can be stored for
long periods of time with little fear of ever becoming
unusable. Using "XSLT (XSL Transformation)" (note), an
XML document can be transformed into a document of a
different structure or format (HTML, CSV, etc.),
increasing the reusability of XML documents-a "one-
source, multi-use" solution.

4. Human- and Computer-Friendly Format
• CSV is a typical example of a data format
expressed using text. Data in CSV format is
easily understood by programs designed to
process CSV data, but only appears as a
continuous string of characters to the human
eye. Data expressed in XML, however, is
"marked up" so it is not only an easy format
for computer processing, but can be read and
understood by humans.

5. Data Described using Mark-up Language
• With XML, each individual piece of information
is "marked up" (a marker shows the meaning of
the associated data) with a tag that attaches
meaning to the information. The unit of data to
which a meaning has been attached is called an
"element." An "element" consists of a "start
tag", "content," and an "end tag."
• When required, an "attribute" can be described
in the start tag of an element, allowing more
detailed information to be assigned to the data.

6. Handles data in a tree structure having one-
and only one-root element
• With XML, a hierarchical element structure
can be created by nesting elements. Under
the XML specification, one-and only one-XML
root element (the outmost element in an XML
document) must exist, giving XML a single
"tree structure" always having a single root
element at the top. A collection of compiled
data starting with a root element is called an
"XML Document."

Difference b/w XML & HTML
HTML XML
Extensible set of tags. No predefined tags.
Content Oriented. Presentation oriented.
Allow multiple output
forms.
Single presentation.
Design to display the
data with focus on how
data looks.
Design to transport and
store the data with
focus on what data is.
HTML for humans
(describe web pages).
XML for computers
(describe the data).

XML – related technologies
•DTD (Document Type Definition) and XML Schemas are
used to define legal XML tags and their attributes for
particular purposes
•CSS (Cascading Style Sheets) describe how to display HTML
or XML in a browser
•XSLT (eXtensible Stylesheet Language Transformations) and
XPath are used to translate from one form of XML to
another
•DOM (Document Object Model), SAX (Simple API for XML,
and JAXP (Java API for XML Processing) are all APIs for XML
parsing.

1) Extensible--XML is extensible. It lets to define own tags, the order
in which they occur, and how they should be processed or
displayed. Another way to think about extensibility is to consider
that XML allows all of us to extend our notion of what a document
is: it can be a file that lives on a file server, or it can be a transient
piece of data that flows between two computer systems (as in the
case of Web Services).
2) Markup-- The most recognizable feature of XML is its tags, or
elements (to be more accurate). In fact, the elements create in XML
will be very similar to the elements already been creating in HTML
documents. However, XML allows to define own set of tags.
3) Language-- XML is a language similar to HTML. It is more flexible
as it allows to create own custom tags. However, XML is not just a
language. XML is a meta-language: a language that allows us to
create or define other languages. For example, with XML we can
create other languages, such as RSS, MathML (a mathematical
markup language), and even tools like XSLT.

Need of an XML
• We need XML because HTML is specifically designed to describe
documents for display in a Web browser. It becomes cumbersome
if you want to display documents in a mobile device or do
anything that’s even slightly complicated, such as translating the
content from German to English. HTML’s sole purpose is to allow
anyone to quickly create Web documents that can be shared with
other people. XML, on the other hand, isn’t just suited to the Web
– it can be used in a variety of different contexts, some of which
may not have anything to do with humans interacting with
content (for example, Web Services use XML to send requests and
responses back and forth).
• HTML rarely (if ever) provides information about how the
document is structured or what it means. In layman’s terms,
HTML is a presentation language, whereas XML is a data-
description language.

XML……….
•XML defines its own tags –
Opening the tag (<); Closing the tag (</)
e.g. <TAGNAME> student </TAGNAME>
• XML tags are case sensitive.
• These tags include attributes that provide additional
information about the content of tag. These attribute
resides within the tags:
e.g. <TAGNAME attributename =“value”> student
</TAGNAME>

XML Structure
• The basic structure is like:
<root>
<child>
<subchild>.....</subchild>
</child>
</root>

Programme
This is an example if we have one book in book-
store:
<bookstore>
<book category="COOKING">
<title lang="en">Everyday Italian</title>
<author>Giada De Laurentiis</author>
<year>2005</year>
<price>30.00</price>
</book>

If more than one book………

XML Syntax rules
• XML tags are case-sensitive.
• Once the tag opened must be closed.
• XML document must have root element. e.g.
<root> <child>
<subchild>.....</subchild>
</child>
</root>
• XML attribute value must be in quotation.
• Comments in XML : 
• XML stores a new line as LF (Line Feed).

XML Syntax rules/ Entity References….
• There are 5 predefined entity references in XML:
< < less than
> > greater than
& & ampersand
' ' apostrophe
" " quotation mark

XML Elements
•An element can contain:
other elements, text, attributes, or a mix of all of
the above...
• <bookstore> <book category="CHILDREN">
<title>Harry Potter</title>
<author>J K. Rowling</author>
<year>2005</year <price>29.99</price>
</book>
• Here, <bookstore> ,<book> has element contents and
<book> also has attribute while <title>,<author> , <year>
contain the text contents.

XML Element - Naming rules
XML elements must follow these 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 (or XML, or Xml,
etc)
• Names cannot contain spaces
• Any name can be used, no words are reserved
• Name cannot have hyphen(-), colon(: ), termination(.) –
they are reserved and have specific meaning.

XML Attribute
• Attribute provide extra information about the element.
• XML attribute must be quoted.
• <person sex="female"> (Here, sex is an attribute)
<firstname>Anna</firstname>
<lastname>Smith</lastname>
</person>
• <person> <sex>female</sex> (Sex is an element)
<firstname>Anna</firstname>
<lastname>Smith</lastname>
</person>
• Attributes are handy in HTML not in XML.

Attribute Vs Element
• Attributes cannot contain multiple values (elements can)
• Attributes cannot contain tree structures (elements can)
• Attributes are not easily expandable (for future changes)
• Attributes are difficult to read and maintain.

O:xml
• What is o:XML-- Well, it's a dynamically typed,
general-purpose object-oriented
programming language. It's got threads,
exception handling, regular expressions,
namespaces, and all the other things you
would expect from a modern language. And
it's expressed entirely in XML. Maybe o:XML is
a bit like Python crossed with XML

Viewing XML Files
<?xml version="1.0" encoding=“mg1"?>
- <note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
</note>
Name of file: abc.xml

Contd…..
•The XML document will be displayed with color-
coded root and child elements.
•A plus (+) or minus sign (-) to the left of the
elements can be clicked to expand or collapse
the element structure.
•To view the raw XML source (without the + and
- signs), select "View Page Source" or "View
Source" from the browser menu.

For Example---
<?xml version="1.0" encoding=“a12" ?>

+ < CATLOG>
Here + means it can be expanded. E.g.
<?xml version="1.0" encoding="ISO-8859-1" ?>

- <CATALOG>
- <CD>
<TITLE>Empire Burlesque</TITLE>
<ARTIST>Bob Dylan</ARTIST>
<COUNTRY>USA</COUNTRY>
<COMPANY>Columbia</COMPANY>
<PRICE>10.90</PRICE>
<YEAR>1985</YEAR>
</CD>

For example---- with multiple values

Linking With CSS (Cascading Style
Sheets)<?xml version="1.0" encoding=“a12"?>
<?xml-stylesheet type="text/css" href="cd_catalog.css"?>
<CATALOG>
<CD>
<TITLE>Empire Burlesque</TITLE>
<ARTIST>Bob Dylan</ARTIST>
<COUNTRY>USA</COUNTRY>
<COMPANY>Columbia</COMPANY>
<PRICE>10.90</PRICE>
<YEAR>1985</YEAR>
</CD>
<CD>
<TITLE>Hide your heart</TITLE>
<ARTIST>Bonnie Tyler</ARTIST>
<COUNTRY>UK</COUNTRY>
<COMPANY>CBS Records</COMPANY>
<PRICE>9.90</PRICE>
<YEAR>1988</YEAR>
</CD>
</CATALOG>

CSS File –used for formating
CATALOG
{ background-color: #ffffff;
width: 100%; }
CD { display: block; margin-bottom: 30pt;
margin-left: 0; }
TITLE { color: #FF0000; font-size: 20pt; }
ARTIST { color: #0000FF; font-size: 20pt; }
COUNTRY,PRICE,YEAR,COMPANY
{ display: block; color: #000000; margin-left:
20pt; }

With CSS program appear like this….

Editor for creating XML programme
• Notepad
•WWW Consortium’s browser and editor
( A complete development environment for XML and many
child languages)
http://www.w3.org/User/BinDist.html
• http://www.softsquad.com (XMetaL)
•
http://www.extensiblity.com/products/xml_authority.htm

Parsers to run XML programme
• Two types of parsers are there: Nonvalidating;
Validating
• Non validating are the simplest; used to check for well-
formedness with in XML document.
• Nonvalidting parsers donot ensure that all of your XML
tags are proper.
• IE version 5 has built-in parser that checks for well-
formedness without validaing the actual XML code.
• Validating parsers with checking the well-formedness
also verifies the conforms to a specific to external or
internal DTD.

• Parsing is splitting up information into its component
parts.
• In computing, a parser is a program (or a piece of code
or API that you can reference inside your own programs)
which analyses files to identify the component parts. All
applications that read input have a parser of some kind,
otherwise they'd never be able to figure out what the
information means.
• XML applications contain a parser which reads XML and
identifies the function of each the pieces of the
document, and it then makes that information available
in memory to the rest of the program

• While reading an XML file, a parser checks the syntax (pointy
brackets, matching quotes, etc) for well-formedness, and
reports any violations (reportable errors). The XML
Specification lists what these are.
Well-formed XML:- 1. All tags must be balanced.
2. All attribute values must be in quotes.
3. Any EMPTY elements must either end with /> or they
must look like non-EMPTY elements by having a real end-tag.
e.g. <br> would become either <br/> or <br></br> (with
nothing in between).
4. Elements must nest inside each other properly .
5. DTDless well-formed documents may use attributes on
any element, but the attributes are all assumed to be of type
CDATA.

• Validation is another stage beyond parsing. As
the component parts of the program are
identified, a validating parser can compare
them with the pattern laid down by the DTD
or Schema, to check that they conform. In the
process, default values and data-types (if
specified) can be added to the in-memory
result of the validation that the validating
parser gives to the application.
http://xml.silmaril.ie

XML DATA
XML data considered as PCDATA and CDATA.
Parsed Character Data
(Unparsed) Character data

PCDATA --XML
• PCDATA is termed used to show the text
data which will be parsed by XML parser.
• <name> -----example
<first>Bill</first>
<last>Gates</last>
</name>
• when XML element is parsed, its data also
parsed.

XML ---CDATA (Unparsed)
• “<“ and “&” symbols perform illegal function in XML.
• Parser treats “<“ -- as starting of a new element.
• Parser treats “&” as start of new character entity.
• If we write anything in CDATA section—it is ignored
by parser.
• A CDATA section starts with "<![CDATA[" and ends
with "]]>“.
• Nested CDATA is not permissible.
• The "]]>" that marks the end of the CDATA section
and cannot contain spaces or line breaks.

Script using CDATA
<script>
<![CDATA[
function match(a,b)
{
if (a < b && a < 0) then
{
return 1;
}
else
{
return 0;
}
}
]]>
</script>

PCDATA and CDATA
• CDATA and PCDATA are concepts while CDATA
and #PCDATA are keywords. CDATA keyword
is an attribute type and may also be used in
element sections, but it is not considered
wise. #PCDATA keyword can just be used in
element section. As far as I understand both
CDATA and #PCDATA keywords denote just
plain text.

• In PCDATA text, the tags inside the text will be treated as markup
and entities will be expanded, where as in CDATA, text will NOT
be parsed by the XML parser.
• PCDATA stands for Parsed Character Data. That means the
characters are to be parsed by the XML, XHTML, or HTML parser.
(< will be changed to <, <p> will be taken to mean a paragraph
tag, etc). Compare that with CDATA, where the characters are not
to be parsed by the XML, XHTML, or HTML parser.
• The term CDATA, meaning character data, is used for distinct, but
related purposes in the markup languages SGML and XML. The
term indicates that a certain portion of the document is general
character data, rather than non-character data or character data
with a more specific, limited structure.

• A CDATA section cannot contain the string "]]>" and therefore it
is not possible for a CDATA section to contain nested CDATA
sections. The preferred approach to using CDATA sections for
encoding text that contains the triad "]]>" is to use multiple
CDATA sections by splitting each occurrence of the triad just
before the ">". For example, to encode "]]>" one would write:
<![CDATA[]]]]><![CDATA[>]]>
• This means that to encode "]]>" in the middle of a CDATA
section, replace all occurrences of "]]>" with the following:
• ]]]]><![CDATA[>
• This effectively stops and restarts the CDATA section.

DTD (Document Type Definition)

DTD
•The purpose of a DTD (Document Type
Definition) is to define the legal building blocks of
an XML document.
•It defines the document structure with a list of
legal elements and attributes.
•A DTD can be declared inline inside an XML
document, or as an external reference.

Building Block of XML Document..DTD
• Elements
• Attributes
• Entities
• PCDATA
• CDATA

How to declare an element in DTD
• In a DTD, elements are declared with an ELEMENT
declaration.
• Syntax is:
<!ELEMENT element-name (element-content)>
• Elements with parsed character data is defined as:
<!ELEMENT element-name (#PCDATA)>
• Elements with empty element declared as:
<!ELEMENT element-name EMPTY>
• Elements with children declared as:
<!ELEMENT element-name (child1,child2,...)>

How to declare an attribute in DTD
•Attributes are declared with an ATTLIST declaration.
• Syntax is: <!ATTLIST element-name attribute-name
attribute-type default-value>
• attribute-type can be any one of the following:
Type Description
CDATA The value is character data
ID The value is a unique id
ENTITY The value is an entity
ENTITIES The value is a list of entities
NMTOKEN The value is a valid xml name
xml: The value is a predefined xml value

• Default-value can be any one of the following:
1.With Default - attribute value:
DTD:
<!ELEMENT square EMPTY>
<!ATTLIST square width CDATA "0"> -----default value
2.With #required value: syntax is------
<!ATTLIST element-name attribute-name attribute-type
#REQUIRED>-------used when we want attribute to be present
3. With #Fixed syntax is-----
<!ATTLIST element-name attribute-name attribute-type #FIXED
"value"> -------Value is fixed-----cannot change---
Value Explanation
Value The default value of the attribute
#REQUIRED The attribute is required
#IMPLIED The attribute is not required
#FIXED value The attribute value is fixed

Enumerated attribute value
•Use enumerated attribute values when you want the
attribute value to be one of a fixed set of legal values.
•Syntax is:-
<!ATTLIST element-name attribute-name (en1|en2|..)
default-value>
• for example:-
DTD:
<!ATTLIST payment type (check|cash) "cash">
XML example:
<payment type="check" />
or
<payment type="cash" />

Internal DTD Declaration
•If the DTD is declared inside the XML file, it
should be wrapped in a DOCTYPE definition with
the following syntax:
<!DOCTYPE root-element [element-declarations]>

XML program using internal DTD
<?xml version="1.0"?>
<!DOCTYPE note [
<!ELEMENT note (to,from,heading,body)>
<!ELEMENT to (#PCDATA)>
<!ELEMENT from (#PCDATA)>
<!ELEMENT heading (#PCDATA)>
<!ELEMENT body (#PCDATA)>
]>
<note>
<to>abc</to>
<from>xyz</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend</body>
</note>

DTD…..
The DTD above is interpreted like this:
!DOCTYPE note defines that the root element of this document is
note
!ELEMENT note defines that the note element contains four
elements: "to,from,heading,body"
!ELEMENT to defines the to element to be of type "#PCDATA"
!ELEMENT from defines the from element to be of type "#PCDATA"
!ELEMENT heading defines the heading element to be of type
"#PCDATA"
!ELEMENT body defines the body element to be of type
"#PCDATA"

External DTD Declaration
If the DTD is declared in an external file, it should
be wrapped in a DOCTYPE definition with the
following syntax:
<!DOCTYPE root-element SYSTEM "filename">

XML programme with external DTD

Hence…….DTD
•With a DTD, each of XML files can carry a
description of its own format.
•With a DTD, independent groups of people can
agree to use a standard DTD for interchanging
data.
•An application can use a standard DTD to verify
that the data receive from the outside world is
valid.
•We can also use a DTD to verify our own data.

DTD---Entities
• Entities are variables used to define shortcuts to standard text
or special characters.
• Entity references are references to entities.
• Entities can be declared internal or external.
• An entity has three parts: an ampersand (&), an entity name,
and a semicolon (;).
• Declaration of an internal entity:
<!ENTITY entity-name "entity-value">
e.g.-
In DTD: <!ENTITY writer "Donald Duck.">
<!ENTITY copyright "Copyright Warnier Brother">
In XML :
<author>&writer;&copyright;</author>

• Declaration of an external entity:
Syntax is: <!ENTITY entity-name SYSTEM "URI/URL">
• For example:
In DTD: <!ENTITY writer SYSTEM
"http://www.abc.com/entities.dtd">
<!ENTITY copyright SYSTEM
"http://www.abc.com/entities.dtd">
In XML: <author>&writer;&copyright;</author>

DTD (Document Type Definition)
<!DOCTYPE NEWSPAPER [
<!ELEMENT NEWSPAPER (ARTICLE+)>
<!ELEMENT ARTICLE (HEADLINE,BYLINE,LEAD,BODY,NOTES)>
<!ELEMENT HEADLINE (#PCDATA)>
<!ELEMENT BYLINE (#PCDATA)>
<!ELEMENT LEAD (#PCDATA)>
<!ELEMENT BODY (#PCDATA)>
<!ELEMENT NOTES (#PCDATA)>
<!ATTLIST ARTICLE AUTHOR CDATA #REQUIRED>
<!ATTLIST ARTICLE EDITOR CDATA #IMPLIED>
<!ATTLIST ARTICLE DATE CDATA #IMPLIED>
<!ATTLIST ARTICLE EDITION CDATA #IMPLIED>
]>

For the Internal declaration DTD:-
•The simplest way to define a DTD is through internal declarations.
•In this case, all declarations are simply placed between the
open/close square brackets.
e.g. <!DOCTYPE person [

<!ELEMENT person (name, age)>
<!ELEMENT name (#PCDATA)
<!ELEMENT age (#PCDATA)> ]>
<person>
<name>Billy Bob</name>
<age>33</age>
</person>
• External DTD declaration is useful because it allows you to reuse
the déclarations in multiple document instances.

ENTITY
• Entities are the most atomic unit of information in XML.
•Entities are used to construct logical XML documents (as well as DTDs)
from physical resources.
• An XML document that contains a DOCTYPE declaration is known as the
document entity.
•There are several other types of entities, each of which is declared using
an ENTITY declaration.
•A given entity is either general or parameter, internal or external, and
parsed or unparsed.
• General versus parameter entities:
General Entity may only be referenced in an XML document (not the DTD).
Parameter Entity may only be referenced in a DTD (not the XML document).

•Internal versus external entities:
•Parsed versus unparsed entities:
•All of these are declared using an ENTITY declaration.
Internal Entity value defined inline.
External Entity value contained in an external resource.
Parsed Entity value parsed by a processor as XML/DTD
content.
Unparsed Entity value not parsed by XML processor.

• Figure illustrates how the syntax varies for each type of Entity:-

ENITITY…..
•As we can see from Figure, unparsed entities are always general
and external whereas parameter/internal entities are always
parsed.
• In reality, there are only five distinct entity types (besides the
document entity), which are:
• Although the syntax for external entities only shows using a
system identifier, public identifiers may also be used as shown in
Figure .
Syntax Description
<!ENTITY % name "value"> Internal parameter
<!ENTITY % name SYSTEM "systemId"> External parameter
<!ENTITY name "value"> Internal general
<!ENTITY name SYSTEM "systemId"> External parsed general
<!ENTITY name SYSTEM "systemId" NDATA nname> Unparsed

How Entities can be referenced?
Syntax Description
&name; General
%name; Parameter
Name is used as the value of an attribute of type
ENTITY or ENTITIES
Unparsed

Conditional Statements: INCLUDE and IGNORE
•The Syntax is:
<![INCLUDE[
...
]]>
<![IGNORE[
...
]]>
• They may be used to control what declarations are processed as
part of the DTD at a given point in time.
• Declarations within INCLUDE blocks are included in the DTD
where as declarations within IGNORE blocks are ignored.

NOTATION
• <!NOTATION name PUBLIC "publicId">
• <!NOTATION name PUBLIC "publicId" "systemId">
• <!NOTATION name SYSTEM "systemId">
• Notation declarations associate a name with a type identifier,
which can be either a public or a system identifier.
• The actual type identifiers are application specific, although it’s
common to see MIME types used within public identifiers.
• Unparsed entities are associated with notation names to
associate type with the referenced binary resource.

XML Namespaces
• Goal of XML namespace was to create a mechanism in which a
single document can use elements and attributes.
• It works by adding a prefix to the names of elements and
attributes so that each attribute is associated with its originating
document.
• XML Namespaces provide a method to avoid element name
conflicts.
• A namespace act as a scope for all elements associated with it.
• A namespace name is a URI.
• The namespace and local name of an element together form a
unique name known as qualified name.
• The syntax of namespace is:
xmlns: prefix = ‘URI’ …………using prefix

• Also we can write it as…
<root
xmlns:h="http://www.w3.org/TR/html4/"
xmlns:f="http://www.w3schools.com/furniture">
<h:table>
<h:tr>
<h:td>Apples</h:td>
<h:td>Bananas</h:td>
</h:tr>
</h:table>
<f:table>
<f:name>African Coffee Table</f:name>
<f:width>80</f:width>
<f:length>120</f:length>
</f:table>
</root>
When a namespace is defined for an element, all child elements with the
same prefix are associated with the same namespace.

• An XML Schema describes the structure of an XML document.
• XML Schema provides a set of built-in data types. Some of these
types are primitives, described in the specification, whereas others
are derived types described in a schema.
• In all examples, the xs namespace prefix is mapped to the
namespace name of the XML schema language.
• Similarly, the tns namespace prefix is mapped to the same
namespace name as the target Namespace attribute of the schema
element even if that element is not shown.

Data type grouping
Numeric types
Date and time types
Type Description
Decimal An arbitrary-precision decimal number
integer An arbitrary-length integer
long A 64-bit signed integer
int A 32-bit signed integer
Short A 16-bit signed integer
Byte An 8-bit signed integer
float A single-precision floating point number
Type Description
dateTime An instant in time
duration A duration in time
time An instant in time

Name and string types
Type Description
string A general string type
Qname An XML Name
token A string with normalized whitespace and with
preceding and trailing whitespace removed
normalizedString A string with normalized whitespace
XML 1.0 types
Type Description
ID An XML 1.0 ID
IDREF An XML 1.0 IDREF
ENTITY An XML 1.0 ENTITY
NOTATION An XML 1.0 NOTATION

Datatypes
•Datatypes in the XML Schema specification are defined
in terms of a value space, the set of values the type can
hold, and a lexical space.
•We can say that, how those values are represented as
characters in XML.
•Some datatypes have multiple lexical representations
whereas others only have one.
Some datatypes are:----

anyURI
The anyURI datatype represents a URI reference
according to RFC 2396 and RFC 2732. (See References at
the end of the chapter.)
Value space:
Any absolute or relative URI reference including those
with a fragment identifier.
Lexical space:
The set of strings matching the URI reference production
of RFC 2396, as amended by RFC 2732.
Applicable facets:
enumeration, length, maxLength, minLength, pattern,
and whiteSpace

base64Binary
The base64Binary datatype represents base64-encoded binary
data.
Value space:
Any finite sequence of binary octets.
Lexical space:
Any finite sequence of binary octets encoded according to
the Base64 Content-Transfer-Encoding per RFC 2045.
Applicable facets:
enumeration, length, maxLength, minLength, pattern and
whiteSpace.
Note:- A prime number sequence for the numbers 1, 2, 3, 5, 7, 9,
11, 13, 17, and 19 encoded in base64.

byte
The byte datatype represents the range of integer values
that can be stored in an 8-bit signed field.
Base type: short.
Value space: +127 to –128.
Lexical space: A finite sequence of decimal digits with an
optional leading sign character (+ or –). The default sign is
positive. Leading zeros may appear.
Canonical representation: Leading zeros are prohibited,
as is the preceding + sign.
Applicable facets: enumeration, fractionDigits,
maxExclusive, maxInclusive, minExclusive, minInclusive,
pattern, totalDigits, and whiteSpace.

boolean
The boolean datatype represents two-value
logic.
Value space: true, false.
Lexical space: true, false, 1, 0 (where 1 and 0
correspond to true and false respectively).
Canonical representation: true, false.
Applicable facets: pattern and whiteSpace.

date
The date datatype represents a Gregorian calendar date.
Value space:
Any date.
Lexical space:
CCYY-MM-DD where CC, YY, MM, and DD correspond to the
century, year, month, and day respectively. Additional digits may
appear to the left of CC to indicate years greater than 9999.
Applicable facets:
enumeration, maxExclusive, maxInclusive,
minExclusive, minInclusive, pattern, and whitespace.

decimal
The decimal datatype represents arbitrary precision decimal
numbers.
Value space: The infinite set of all decimal numbers.
Lexical space: A finite sequence of decimal digits with a period as
the decimal point indicator and an optional leading sign character (+
or –). The default sign is positive. Leading and trailing zeros may
appear. If the digits following the decimal point are all zero, those
digits and the decimal point may be omitted.
Applicable facets: enumeration, fractionDigits, maxExclusive,
maxInclusive, minExclusive, minInclusive, pattern, totalDigits, and
whiteSpace.
Derived type: integer.

ENTITIES
The ENTITIES datatype represents the XML 1.0 ENTITIES type, a list
of ENTITY names separated by whitespace. This type should only be
used for attribute values.
A given ENTITY value in the list must match the name of an
unparsed entity declared elsewhere in the XML document.
Base type: ENTITY
Derived by: list
Value space: The set of finite, nonzero-length sequences of ENTITY
values that have been used in an XML document.
Lexical space: The set of whitespace-separated lists of ENTITY values
that have been used in an XML document.
Applicable facets: enumeration, length, maxLength, minLength,
and whiteSpace.

Figure shows the -- type hierarchy for the built-in types
derived from decimal

Figure shows the -- type hierarchy for the built-in types
derived from strings

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 Schemas are the Successors of DTDs
Here are some reasons:
•XML Schemas are extensible to future additions
•XML Schemas are richer and more powerful than
DTDs
•XML Schemas are written in XML
•XML Schemas support data types
•XML Schemas support namespaces

XML Schemas Support Data Types
•It is easier to describe allowable document
content.
•It is easier to validate the correctness of data.
•It is easier to work with data from a database.
•It is easier to define data facets (restrictions on
data).
•It is easier to define data patterns (data formats).
•It is easier to convert data between different data
types.

Facets
•Facets are used to restrict the set of values a
data type.
•The new value range must be equal to or
narrower than the value range of the base type.
• It is not possible to expand the value space of
a type using facets.
•There are 12 facet elements.
• Attribute is of type xs:string, the value must
typically be a valid value of the type to which
the facet is applied.

FACETS
e.g. minExclusive facet is being used to constrain the
decimal datatype then the value must be numerical.
The facets are listed in alphabetical order:
Enumeration, fractionDigits, length, maxExclusive,
maxInclusive, maxLength, minLength, pattern, totaldigits,
whitespace

enumeration
•<xs:enumeration value='string' fixed='boolean' id='ID' />
•Defines a fixed value that the type must match. Multiple
enumeration facets can be used to specify multiple legal values.
Thus, multiple enumeration facets have a cumulative effect,
allowing multiple possible values.
•Values: Any value that matches the type of the base type.
•Applies to: anyURI, base64Binary, byte, date, dateTime, decimal,
•double, duration, ENTITIES, ENTITY, float, gDay, gMonth,
•gMonthDay, gYear, gYearMonth, hexBinary, ID, IDREF, IDREFS,
•int, integer, language, long, Name, NCName, negativeInteger,
•NMTOKEN, NMTOKENS, nonNegativeInteger, nonPositiveInteger,
•normalizedString, NOTATION, positiveInteger, QName, short,
string, time, token,.

Xml iet 2015

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Editor's Notes