XML - A Single Entity

XML

A Single Entity


xml

a single entity

Objectives
:



understand the data model



describe the XML Document



describe the XML Schema



describe the XML Stylsheet (XSL)

the data model


WineStore


Wine


wineID

winery

style

vintage

country

region

cost

price

inventory

description


xml Document



XML
-

a markup language capable of
describing many different kinds of data



primary purpose
-

to facilitate the
sharing of data across different systems



defined in a formal way



allows programs to modify and validate
documents without prior knowledge of
their form

picked out from Wikipedia

xml schema




an XML Document



provides a template for an XML

Document



governs the structure and content



ensures validity of an XML Document



confidence in data transfer

xml Stylesheet



eXtensible Stylesheet Language (XSL)



allows for the structured format of the
XML Document to be presented visually



allows for a single XML document to
have a variety of display designs

xml Document

•

Prolog (XML Declaration)

•

Elements

•

Attributes

•

Rules to follow

•

Well
-
formed XML documents

<?xml version="1.0" encoding="UTF
-
8"?>

<wineStore>


<wine>


<wineID>1</wineID>


<winery>Ravenswood</winery>


<style>Zinfandel</style>


<vintage>2003</vintage>


<country>United States</country>


<region>Sonoma County, California</region>


<cost currency='USdollars'>12.50</cost>


<price currency='USdollars'>20.75</price>


<inventory>35</inventory>


<description>This 2003 Zinfandel has huge,
jammy, inky, slightly porty aromas infused with black
pepper, vanilla and hints of tar, smoke and coffee
blend. A very broad, intense wine with huge fruit, lots
of those luscious Dry Creek bing cherry and sweet
plum characters.</description>


</wine>

</wineStore>


prolog

root element

parent element

child element

sibling

elements

xml Document
-

prolog

<?xml version="1.0" encoding="UTF
-
8"?>



basic XML Document:



prolog = XML declaration



xml



=


this is an XML document



version="1.0"



=


XML 1.0 is the

W3C recommend version



encoding="UTF
-
8"



=


the character
encoding used in the document (UTF 8
corresponds to 8
-
bit ASCII characters)

back

xml Document

-

root element

<wineStore> …. </wineStore>



the XML document's major theme



must have exactly one and only one
root element



all other elements are contained
within the one root element



follows the XML declaration

back

xml Document

-

parent element

<wine> …. </wine>



any element that contains other

elements, child elements



<wineStore> is also a parent element
with <wine> as its child element



an element can be a parent element to
some elements as well as a child element
to another element

back

xml Document

-

child element

<style> …. </style>



any element that is contained within
another element, the parent element



<style> is a child element of <wine>



<winery>, <vintage>, <country>,
<price>, etc. are all also child elements
of <wine>

back

xml Document

-

sibling elements



any elements that share a common
parent element



<wineID>, <winery>, <vintage>,
<style>, <country>, <region>, <cost>,
<price>, <inventory>, and <description>
are all sibling elements

xml Document

-

elements

<elementName> data </elementName>


<elementName attribute=“value” />


(empty tag or empty element)


(example:
<img src="Belize.gif" />
)

xml Document

-

attributes

•

aid in modifying the content of a given element

•

provide additional or required information

•

contained within the element's opening tag

<cost currency='USdollars'>7.50</cost>

xml Document
-

Rules



first line = XML Declaration



root element contains all other elements



every element must have an opening tag and a closing tag



attribute values should have quotation marks around them
and no spaces



empty tags or empty elements must have a space and a slash
(/) at the end of the tag



Comments in the XML language begin with
"
<!
--
"

and end
with
"
--
>
"


well
-
formed XML
-

abides by rules of syntax

NetBeans

select ‘New Project’

right click on the
newly created
project

select a new
XML document

you can also select file/folder and
choose XML => XML document

if we had already written
an XML schema

but, we will first just write an
XML Document

the start of an XML document

-

note the .xml extension

xml schema

•

Prolog

•

Element Declarations

•

Simple Type

•

Complex Type

•

Attribute Declarations

•

Datatype Declarations

•
Valid XML documents

xml schema


A schema defines:


•

the structure of the document

•

the elements

•

the attributes

•

the child elements

•

the order of elements

•

the names and contents of all elements

•

the data type for each element

xml schema
-

prolog

the XML declaration
:

<?xml version=“1.0” encoding=“UTF
-
8”?>

the Schema declaration
:

(from chapter)

<xsd:schema

xmlns:xsd=http://www.w3.org/2001/XMLSchema

elementFormDefault="unqualified“>

(from NetBeans)


<xsd:schema

xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:ns="http://xml.netbeans.org/examples/targetNS"
targetNamespace="http://xml.netbeans.org/examples/targetNS"
xmlns=http://xml.netbeans.org/examples/targetNS
elementFormDefault="qualified">

xml schema

-

element declarations

define the elements in the schema


include:

•

the element name

•

the element data type (optional)


basic element declaration format:


<xsd:element name="name" type="type">

xml schema

-

element declarations

Two types:

•

Simple Type

•

do NOT have Child Elements

•

do NOT have Attributes

•

Complex Type

•

can have Child Elements

•

can have Attributes

xml schema

-

Complex type

-

child elements

<xsd:element name="wineStore">


<xsd:complexType>


<xsd:sequence>


<xsd:element name="wine" type="wineDescription" />


</xsd:sequence>


</xsd:complexType>

</xsd:element>

xml schema

-

Complex type

-

attributes

<xsd:element name="cost" type="xsd:decimal">


<xsd:complexType>


<xsd:attribute name="currency" type="xsd:string" />


</xsd:complexType>

</xsd:element>

minOccurs = "1" maxOccurs="unbounded"

Occurrence Indicators
:


-

minOccurs

= the minimum number of
times an element can occur

(here it is 1 time)


-

maxOccurs

= the maximum number of
times an element can occur (here it is an
unlimited number of times, 'unbounded')

<
wineStore



xmlns:xsi='http://www.w3.org/2001/XM
LSchema
-
instance'


xsi:schemaLocation='http://xml.netbeans.
org/examples/targetNS file:/


C:/Documents and Settings/Viji
Kannan/Desktop/TheWineStore/wineStor
eSchema.xsd'>


these attributes are added to the root
element in the XML document


xml schema
-

Reference

xml stylesheet (xsl)

•

a means to transform and format the contents
of an XML document for display

•

separates the data and the presentation logic

•

multiple views of the same data can be
created using different stylesheets

node tree

–

a hierarchical representation
of the entire XML document
–

each node
represents a piece of the XML document,
such as an element, attribute or some text
content

•

contains predefined “templates” that
contain instructions on what to do with the
nodes

•

uses the match attribute to relate XML
element nodes to the templates, and
transform them into the resulting
document.

xml stylesheet (xsl)

XSL
-

prolog

<?xml version="1.0" encoding="UTF
-
8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/T
ransform">

<xsl:output method="html"/>

•

the XML declaration

•

the stylesheet declaration

•

the namespace declaration

•

the output document format

XSL
-

templates

•

the
<xsl:template>

element is used to
create templates that describe how to
display elements and their content

•

each template within an XSL describes a
single node
–

to identify which node a
given template is describing, use the
'match' attribute

•

<xsl:template> defines the start of a
template and contains rules to apply when
a specified node is matched