Web Based Applications

sounderslipInternet and Web Development

Oct 22, 2013 (4 years and 18 days ago)

105 views

Web Based Applications

Basic Building Blocks


HTTP/HTTPS


XML


E
X
tensible
M
arkup
L
anguage


Designed to carry data


User
-
defined tags

<?xml version="1.0"
encoding="ISO
-
8859
-
1"?>
<note id="501"

>

<to>ABC</to>
<from>XYZ</from>
<heading>Reminder</heading>

<body>Call 123</body>

</note>

XML Namespace

<root>

<h:table xmlns:h="http://www.w3.org/TR/html4/">

<h:tr>


<h:td>Apples</h:td> <h:td>Bananas</h:td>

</h:tr>

</h:table>


<f:table xmlns:f="http://www.w3schools.com/furniture">


<f:name>African Coffee Table</f:name>


<f:width>80</f:width> <f:length>120</f:length>

</f:table>

</root>

XML Schema

<?xml version="1.0"?>

<note xmlns=“http://www.w3schools.com”

xmlns:xsi=“http://www.w3.org/2001/XMLSchema
-
instance”

xsi:schemaLocation="http://www.w3schools.com note.xsd">

<to>Tove</to>

<from>Jani</from>

<heading>Reminder</heading>

<body>Don't forget me this weekend!</body>

</note>


XML Schema

<?xml version="1.0"?>

<xs:schema xmlns:xs=“http://www.w3.org/2001/XMLSchema”

targetNamespace=“http://www.w3schools.com”

xmlns=“http://www.w3schools.com”

elementFormDefault="qualified">

<xs:element name="note">


<xs:complexType>



<xs:sequence>




<xs:element name="to" type="xs:string"/> …..



</xs:sequence>


</xs:complexType>

</xs:element>

</xs:schema>

Web Services


Defined as “a software
system designed to
support interoperable
Machine to Machine
interaction over a
network “


Components are


SOAP


WSDL


UDDI

SOAP


Simple Object Access Protocol


A protocol for exchanging XML
-
based
messages over computer networks


Works on top of HTTP/HTTPS


Advantage


Work over http proxies


Disadvantage


Slower

SOAP Message

A SOAP message contains:


Envelope element


Header element (optional)


Body element


Fault element (optional)


SOAP Message Example

<?xml version="1.0"?>

<soap:Envelope xmlns:soap=http://www.w3.org/2001/12/soap
-
envelope

soap:encodingStyle="http://www.w3.org/2001/12/soap
-
encoding">


<soap:header> ... ... </soap:header>

<soap:Body>


... ...


<soap:fault>


... ...


</soap:fault>

</soap:Body>

</soap:Envelope>


Request

<?xml version="1.0"?>

<soap:Envelope

xmlns:soap=“http://www.w3.org/2001/12/soap
-
envelope”

soap:encodingStyle="http://www.w3.org/2001/12/soap
-
encoding">

<soap:Body>


<m:GetPrice xmlns:m="http://www.w3schools.com/prices">


<m:Item>Apples</m:Item>


</m:GetPrice>

</soap:Body>

</soap:Envelope>

Response

<?xml version="1.0"?>

<soap:Envelope

xmlns:soap=“http://www.w3.org/2001/12/soap
-
envelope”

soap:encodingStyle="http://www.w3.org/2001/12/soap
-
encoding">


<soap:Body>


<m:GetPriceResponse xmlns:m="http://www.w3schools.com/prices">


<m:Price>1.90</m:Price>


</m:GetPriceResponse>

</soap:Body>

</soap:Envelope>

WSDL


Web Service Description Language


Provides a model for describing Web
Services


Defines services as collections of network
endpoints, or ports


Client program parses the WSDL
description of the services offered by the
server

Document Structure

<definitions>


<types>…………definition of types........……</types>


<message>.……definition of a message......</message>


<portType>.……definition of a port...............</portType>


<binding>………definition of a binding……..</binding>


</definitions>

WSDL Example

<message name="getTermRequest">


<part name="term" type="xs:string"/>

</message>

<message name="getTermResponse">


<part name="value" type="xs:string"/>

</message>

<portType name="glossaryTerms">


<operation name="getTerm">


<input message="getTermRequest"/>


<output message="getTermResponse"/>


</operation>

</portType>


Example contd.

<binding type="glossaryTerms" name="b1">

<soap:binding style="document“

transport="http://schemas.xmlsoap.org/soap/http" />


<operation>



<soap:operation




soapAction="http://example.com/getTerm"/>



<input>

……<soap:body use="literal"/> …….</input>



<output>…..<soap:body use="literal"/>………</output>
</operation>

</binding>


UDDI


Universal Description, Discovery and Integration


A platform
-
independent, XML
-
based registry for
businesses worldwide to list themselves on the Internet


Open industry initiative, sponsored by OASIS


Consists of the following components


White Pages


Information about WS providers


Yellow Pages


Available Web services


Green Pages


Technical interfaces for to access and manage WS

Models of Web Services


RPC


Message Oriented


Service Oriented


Resource Oriented


Policy Based



BPEL4WS



Used for defining a new Web service by
composing a set of existing services


Primitive activities


Invoke, Receive, Reply, Wait, Assign, Throw,
Terminate.


Structure activities


Sequence, Switch, While, Pick, Flow


Partners

Example

Semantic Web


Goal is to express the web content in such a
format, which can be read and used by software


Uses the following standards


XML


XML Schema


RDF


RDF Schema


OWL


SPARQL


Semantic Web Contd.


RDF


a general method of modeling information,
through a variety of syntax formats


Expresses knowledge about resources in the
form of subject
-
predicate
-
object expressions


Resource is named by Uniform Resource
Identifier (URI).

Semantic Web contd.


XML Schema


expresses a schema: a set of rules to which an
XML document must conform in order to be
considered 'valid' according to that schema


RDF Schema


Knowledge representation language


Describes predominantly in terms class,
subclass, domain and range

Semantic Web contd.


OWL


Web Ontology Language


adds more vocabulary for describing properties
and classes than RDF Schema


SPARQL


protocol and query language for semantic web
data sources