Prof. A. Taleb-Bendiab Room 605

Prof. A. Taleb-BendiabRoom 605

[email protected]://www.cms.livjm.ac.uk/taleb/lectures/cmscb3005

A. Taleb-Bendiab, Module: Contemporary Issues in IT, Code: CMSCB3005, Lecture: 2, Page: A. Taleb-Bendiab, Module: Contemporary Issues in IT, Code: CMSCB3005, Lecture: 2, Page: 11

Distributed Application Services Distributed Application Services and E-business and E-business

Part IIPart II

Liverpool John Moores UniversitySchool of Computing and Mathematical Sciences

A. Taleb-Bendiab, Module: Multimedia Systems Development, Code: CMSSEM011, Lecture: 2, Page: A. Taleb-Bendiab, Module: Multimedia Systems Development, Code: CMSSEM011, Lecture: 2, Page: 22

So far …So far … E-business

Definitions, E-business Models E-business Patterns Systems requirements

E-business drivers for Multi-tier Applications Architecture

Emerging web development technologies Thin versus Thick Clients, and Thin server vs Thick server

In this session …. A brief introduction to Java

Brief introduction to Java Overview of XML

Web applications using Java and XML An example web application services

Tutorial session


What is Java?What is Java?

Java language and environment Born on May 23rd 1995. Grew out of a product called Oak

Oak was designed for embedded software and consumer devices.

See http://www.javasoft.com

Java is an environment is Ideal environment for writing object-oriented, distributed

and platform independent applications, real-time, etc.

Java has a lot in common with C and C++ Versions and editions

1.0 1.1 Java 2 PlatformJava 2 PlatformEnterprise editionStandard editionStandard edition

Micro edition


The Java timelineThe Java timeline

19951995 19961996 19971997 19981998 19991999

JDK 1.1 ships

JDK 1.1 ships

May - Sun launches Java (alpha version) on the Internet

May - Sun launches Java (alpha version) on the Internet

January - Java Development Kit (JDK) 1.0

ships

January - Java Development Kit (JDK) 1.0

ships

Sun announces

Java 2 Platform (JDK

1.2)

Sun announces


1.2)

Sun announce

s Jini technolog

y

Sun announce

s Jini technolog

y

Sun announces


1.3)

Sun announces


1.3)

20002000

Sun announces


1.4)

Sun announces


1.4)

2001 ++2001 ++

Many moreMany more


How does it work?How does it work?

A Java program is compiled into bytecodes These bytecodes are interpreted by a JVM The JVM converts these instructions into

appropriate machine code The program executes on the machine Each platform therefore needs its own JVMEach platform therefore needs its own JVM

Enabling WORA -- “Write Once, Run Anywhere”“Write Once, Run Anywhere” Java Virtual Machine

“An imaginary machine that is implemented by emulating it in software on a real machine.”

It specifies: Instruction set, register set, class file format, stack, garbage collection, memory area

A JVM exists for various operating systems including; Windows 95/98/NT/2000, Solaris, Macintosh, OS/2, Linux, OS/400,

OS/390, HPUX, AIX, IRIX, EPOC, Windows CE, PlamOS, etc.


Java Runtime EnvironmentJava Runtime Environment

JavaJavasourcesource(java)(java)

JavaJavasourcesource(java)(java)

Java Java compilercompiler

Java Java compilercompiler

JavaJavabyte byte codecode

(class)(class)

JavaJavabyte byte codecode

(class)(class)

Java byte codes move locally or

through network

Class loaderClass loaderByte code Byte code

verifierverifier

Class loaderClass loaderByte code Byte code

verifierverifier

Java Java class class

librarieslibraries

Java Java class class

librarieslibraries

Java Java interpreterinterpreter

Java Java interpreterinterpreter

Just-in-time Just-in-time compilercompiler

Just-in-time Just-in-time compilercompiler

Runtime systemRuntime systemRuntime systemRuntime system

Operating systemOperating systemOperating systemOperating system

HardwareHardwareHardwareHardware


Running Java ProgramsRunning Java Programs

A Java application is a stand-alone program that can use all of the features of the Java language environment

A Java applet is a restricted Java application that is designed to be run inside a Java-enabled web browser

Security restrictions Applets have a different lifecycle to applications

A Java servlet is the equivalent of an applet, which is executed at server-side

It is a Java application that is designed to be run inside a Http servers


/** Comments here – Example of authenticator class */package test;

import java.util.*;import java.security.*; import com.server.http.*;

public class TestAuthenticator extends AbstractAuthenticator { public void init(CauchoApplication app, RegistryNode params)

{ } public Principal authenticateCookie(String cookieValue)

{ return null; } public Principal authenticate(String user, String password) {

if (password != null && password.equals("quidditch")) return new BasicPrincipal(user);

else return null; } public boolean updateCookie(Principal user, String cookieValue)

{return true; } public boolean isUserInRole(Principal user, String role)

{return user != null && "user".equals(role); } }

Examples: Java ProgrammeExamples: Java Programme


Java Java 2 2 Enterprise EditionEnterprise Edition Enterprise JavaBeansTM Architecture

Defines an API to enable developers to create, deploy and manage cross-platform, component-based enterprise applications.

JavaServer PagesTM Enables rapid development of server-side web-based

applications, such as; dynamic web content management. JavaTM Servlet Java Naming and Directory InterfaceTM (JNDI) JavaTM Message Service (JMS)

Provides a standard Java API for enterprise messaging services such as reliable queuing, publish and subscribe communication and various aspects of push/pull technologies.

JavaTM Transaction API (JTA) JavaMail


Example Application #1Example Application #1

Location AD Service Manager

System

Location & Advertisement ServicesLocation & Advertisement Services


… … But …But …

RequestRequest

Data sourceData source

Web LayerWeb LayerResponseResponse


Web Page ExampleWeb Page Example


HTML CodeHTML Code<html ><head><meta name="GENERATOR" content="Microsoft FrontPage 4.0"><meta name="Microsoft Theme" content="global 101, default"><meta name="Microsoft Border" content="tlrb, default"><title>Home Page</title> </head><body background="../../_themes/global/glotextb.gif" bgcolor="#FFFFCC"

text="#510000" link="#999900" vlink="#CC9966" alink="#990066"><table border="0" cellpadding="0" cellspacing="0" width="100%"><tr><td><font face="Arial, Helvetica"><p align="center"><br><font size="4" face="Arial">Student Learning Space</font></p><p align="center"><a href="../Default.htm">Home</a> <a

href="../cmssem011/Module%20specification.doc">Module<a href="http://www.cms.livjm.ac.uk/markallen/multi-media.htm">Tutorials</a> <a

href="../cmssem011/indicative_references.htm"> Reading List</a></p><p align="left"><font size="4">Contemporary issues in IT: Distributed

Applications and E-Commerce <em>CMSCB3005</em><font size="4" face="Arial"> </font></font></p>

</html>


Associated XML CodeAssociated XML Code

<?xml version="1.0"?> ><?xml-stylesheet type="text/xsl" href="..\xsl\ENR-change-table.xsl"?><!DOCTYPE Components SYSTEM "Project6.dtd"><head><meta name="Microsoft Theme" content="global 101, default"><title> Student Learning Space </title> </head><body> <main> <page type=“html” href="../Default.htm"> <headings>

<heading 1 href="../cmssem011/Module%20specification.doc">

<heading 2 href="http://www.cms.livjm.ac.uk/markallen/multi-media.htm">

<heading 3 href="../cmssem011/indicative_references.htm"></headings>

</main></body></xml>


What is XML? What is XML? XML is

an eXtensible Markup Language for describing both structured and unstructured information, which could be used on the web.

XML documents containing structured information including;

Content: words, pictures (vector graphics), e-commerce transactions, mathematical equations, object meta-data, server APIs, and other XML documents.

XML is a meta-language for defining other markup languages not like HTML or SGML

Unlike Html or SGML it provides; extensible tag semantics a facility to define tags and the structural relationships

between them. All of the semantics of an XML document will either be

defined by the applications that process them or by stylesheets.


How Is XML Defined?How Is XML Defined?

XML is defined by a number of related specifications: Extensible Markup Language (XML) 1.0

Defining the syntax of XML. XML Pointer Language (XPointer) and

XML Linking Language (XLink) Defining a standard way to represent links between resources.

In addition to simple links, like HTML's <A> tag, XML has mechanisms for links between multiple resources and links between read-only resources.

XPointer describes how to address a resource, XLink describes how to associate two or more resources.

Extensible Style Language (XSL) Defines the standard stylesheet language for XML.

XQL -- Defines a standard query language for XML. XUL -- Defines a standard user-interface language for XML.


XML Markup #1XML Markup #1

Six kinds of markup used in XML documents: 1. Elements -- Delimited by angle brackets, most

elements identify the nature of the content they surround.

It begins with a start-tag, <element>, and ends with an end-tag, </element>.

Attributes -- Attributes are name-value pairs that occur inside start-tags after the element name.

<div class="preface">is a div element with the attribute class having the value preface.

2. entity references -- introduce markup into a document, some characters have been reserved to identify the start of markup.

entities are used to represent these special characters. Entities are also used to refer to often repeated or varying text and to include the content of external files.

Entity references begin with the ampersand and end with a semicolon.

XML Markup #2XML Markup #2 For example, the lt entity inserts a literal < into a document. So the

string <element> can be represented in an XML document as <element>.

A special form of entity reference, called a character reference, can be used to insert arbitrary Unicode characters into your document. This is a mechanism for inserting characters that cannot be typed directly on your keyboard.

3. Comments -- begin with . Comments can contain any data except the literal string.

4. processing instructions (PIs) -- are an escape hatch to provide information to an application.

Processing instructions have the form: <?name pidata?>. The name, called the PI target, identifies the PI to the application.

5. CDATA Sections – to instruct the parser to ignore most markup characters.

to prevent xml parser from evaluating a CDATA. <![CDATA[ *p = &q; b = (i <= 3); ]]>


XML Markup #3XML Markup #3 Between the start of the section, <![CDATA[ and the end of

the section, ]]>, all character data is passed directly to the application, without interpretation.

The only string that cannot occur in a CDATA section is ]]>.

6. Document Type Declarations XML allows you to create your own tag names. DTD enables document to communicate their meta-

information to the parser including; allowed sequence and nesting of tags, attribute values and their types defaults, the names of external files that may be referenced formats of some external (non-XML) data that may be

referenced, the entities that may be encountered.


ValidationValidation Two categories of XML documents:

Well-formed Documents it obeys the syntax and the grammar of XML documents. A document that includes sequences of markup

characters that cannot be parsed or are invalid cannot be well-formed.

not well-formed document -- is not XML document.

well-formed and valid: well-formed document is valid only if it contains a proper

document type declaration and if the document obeys the constraints of that declaration.


Well-formed?

XMLDocument

DTD

DTDRequired?

Valid?Yes Yes

No

NoNo

XMLSyntax

Error Message

StructuralNon-conformance

Error Message

Stop Processing / Edit XML and/or DTD / Re-initiate Parsing

Well-formedXML

Well-formed& Valid

XML

PARSER

Fur

ther

pro

cess

ing

ofX

ML

Doc

umen

t

XML Document Parsing


• XML Document/DTD/Parser

• Document Object Model (DOM)

• Script/Programming (manipulation of objects)

• XSL (render ready transformation)

• Browser/Display Application(rendering)

XML Processing and Rendering

XMLDocument

DTD

PARSERDOM

XML API

ApplicationScript/Program

XSL

XSL-basedProcessing

layer

HTMLOutput

RTF(MS Word)

SAX

PDFOutput

Other Markup

LanguagesWML

Scalable Vector

Graphics(SVG)

RDF, XMI Etc.


Mobilisation tool

Fire Fighter

Search Engine

Login System

C&C Operator

System Admin.

Admin tools

Reporting tools

Communication

RDBMS

Combining Java and XMLCombining Java and XML


Presentation Tier( XML Web Browser )

Servlets

Login Query Machanism

XML Generation

Callback Machanism

Control GUI

Applet

Delivery Machanism

Http & XML

RMI

Table

Table

DBMSJDBC

Table

Romote Mothod

Middle Tier(Servlet-supported Web Server ) Database Tier

XML File

System

XML File

System

XML File

System

Target System ArchitectureTarget System Architecture


Implementation #1Implementation #1

Prof. A. Taleb-Bendiab Room 605

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