advance internet technique s

2008 Pearson Education, Inc. All rights reserved.

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Advance Internet Techniques

Advance Internet Techniques

Present by:Ms.Azza Zeinelabdin Karrar


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11Introduction to Computers and

the Internet


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OBJECTIVES

In this Lecture you will learn: Basic computing concepts. The different types of programming

languages. The evolution of the Internet and the World

Wide Web. What Web 2.0 is and why it’s having such

an impact among Internet-based and traditional businesses.

What Rich Internet Applications (RIAs) are and the key software technologies used to build RIAs.


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1.1 Introduction

1.2 What Is a Computer?

1.3 Computer Organization

1.4 Machine Languages, Assembly Languages and High-Level Languages

1.5 History of the Internet and World Wide Web

1.6 World Wide Web Consortium (W3C)

1.7 Web 2.0

1.8 Personal, Distributed and Client/Server Computing

1.9 Hardware Trends

1.10 Key Software Trend: Object Technology

1.11 JavaScript: Object-Based Scripting for the Web

1.12 Browser Portability

1.13 C, C++ and Java

1.14 BASIC, Visual Basic, Visual C++, C# and .NET

1.15 Software Technologies


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1.1 Introduction

Software

– Instructions to command the computer to perform actions and

make decisions.

– JavaScript and PHP are popular software development languages

for web-based applications.

Computer development

– Computer use increasing in most fields

– Computer costs and size decreasing


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1.1 Introduction (Cont.) Applications

– Prepares for higher learning in C++, Java, C#, Visual Basic.NET as well

as object-oriented programming

– Allows development of applications with graphical user interfaces (GUIs)

- Multimedia capabilities

- Integration with the Internet and World Wide Web

– Apply database technologies

– Applications that are not limited to the desktop

– Portability

- Multiple platforms (i.e., different types of computers running

different operating systems).


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1.2 What is a Computer?

Computer

– Device capable of

- Performing computations

- Making logical decisions

– Works billions of times faster than human beings

– Fastest supercomputers today

- Perform hundreds of billions of additions per second


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Programs

– Sets of instructions that process data

– Guide computer through orderly sets of actions specified by

computer programmers

Computer system

– Comprised of various hardware devices

- Keyboard

- Screen

- Disks

- Memory

- DVD drives

- Processing Units

1.2 What is a Computer? (Cont.)


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Every computer divided into six units1. Input unit

- “Receiving” section of computer- Obtains data from input devices

Usually a keyboard, mouse, disk, scanner, uploads (photos and videos) and networks (Internet)

- Places data at disposal of other units

2. Output unit- “Shipping” section of computer- Puts processed info on various output devices

Screens, paper printouts, speakers- Makes info available outside the computer (e.g., Internet)

1.3 Computer Organization


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3. Memory unit

- Rapid access, low capacity “warehouse”

- Retains information entered through input unit

- Retains info that has already been processed until can be sent

to output unit

- Often called memory, primary memory, or random access

memory (RAM)

4. Arithmetic and Logic Unit

- “Manufacturing” section of computer

- Performs calculations (addition, subtraction, multiplication and

division)

- Contains decision mechanisms and can make comparisons

1.3 Computer Organization (Cont.)


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5. Central Processing Unit (CPU)

- “Administrative” section of computer

- Coordinates and supervises other sections

- Multiple CPUs (multiprocessors)

6. Secondary storage unit

- Long-term, high-capacity “warehouse”

- Stores programs or data not currently being used by

other units on secondary storage devices (like CDs and

DVDs)

- Takes longer to access than primary memory

1.3 Computer Organization (Cont.)


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1.4 Machine Languages, Assembly Languages and High-Level Languages

Three general types of programming languages

– Machine languages

– Assembly languages

– High-level languages


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Machine languages

– “Natural language” of a computer

– Defined by hardware design of computer

– Generally consists of strings of numbers

– Are machine dependent

– Cumbersome for humans

- Example: Adding overtime pay to base pay and storing the

result in gross pay

+1300042774

+1400593419

+1200274027

– Slow and tedious for most programmers

1.4 Machine Languages … (Cont.)


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Assembly languages

– Programmers began using English-like abbreviations

to substitute for machine languages

– Represents elementary operations of computer

– Translator programs called assemblers convert

assembly-language to machine-language

– Example:

LOAD BASEPAY

ADD OVERPAY

STORE GROSSPAY

1.4 … Assembly Languages…(Cont.)


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High-level languages

– Developed as computer usage increased, assembly

language proved inadequate and time-consuming

– Single statements can be written to accomplish

substantial tasks

– Translator programs called compilers

– Allow programmers to write instructions almost like

every-day English

– Example:

grossPay = basePay + overTimePay

1.4 Machine Languages, Assembly Languages and High-Level Languages (Cont.)


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High-level languages (II)

– Much more desirable from programmer’s

standpoint

– Specific languages include

- C, C++, Visual Basic.NET, C# and Java

- Among most powerful and widely used languages

today

– Interpreter programs developed to execute high-

level programs without compiling

- Popular in program development environments



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High-level languages (III)

– Once program developed, compiled version made

– several key programming languages

- JavaScript, ActionScript, PHP and Ruby on Rails—each

of these scripting languages is processed by

interpreters

– Study markup languages

- XHTML and XML, which can be processed by

interpreted scripting languages

- Achieve their goal of portability across a variety of

platforms



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Performance Tip 1.1

Interpreters have an advantage over compilers in scripting. An interpreted program can begin executing as soon as it is downloaded to the client’s machine, without the need to be compiled before it can execute. On the downside, scripts generally run much slower than compiled code.


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Portability Tip 1.1

Interpreted languages are more portable than compiled languages. Interpreters can be implemented for each platform on which the interpreted languages need to execute.


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Software Engineering Observation 1.1

Interpreted languages are more dynamic than compiled languages. For example, server-side applications can generate code in response to user interactions, and that code can then be interpreted in a browser.


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ARPANET

– Implemented in late 1960’s by ARPA (Advanced

Research Projects Agency of DOD)

– Networked computer systems of a dozen universities

and institutions with 56KB communications lines

– Grandparent of today’s Internet

– Intended to allow computers to be shared

– Became clear that key benefit was allowing fast

communication between researchers – electronic-mail

(email)


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ARPA’s goals

– Allow multiple users to send and receive info at same

time

– Network operated packet switching technique

- Digital data sent in small packages called packets

- Packets contained data, address info, error-control info

and sequencing info

- Greatly reduced transmission costs of dedicated

communications lines

– Network designed to be operated without centralized

control

- If portion of network fails, remaining portions still able to

route packets


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Transmission Control Protocol (TCP)

– Name of protocols for communicating over ARPAnet

– Ensured that messages were properly routed and that

they arrived intact

Organizations implemented own networks

– Used both for intra-organization and communication


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Huge variety of networking hardware and software

appeared

– ARPA achieved inter-communication between all platforms

with development of the IP

- Internetworking Protocol

- Current architecture of Internet

– Combined set of protocols called TCP/IP

The Internet

– Limited to universities and research institutions

– Military became big user

– Next, government decided to access Internet for commercial

purposes


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Internet traffic grew (I)

– Businesses spent heavily to improve Internet

- Better service their clients

– Fierce competition among communications carriers

and hardware and software suppliers

– Resulted in massive bandwidth increase and

plummeting costs


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Internet traffic grew(II)– Tim Berners-Lee invents HyperText Markup

Language (HTML)- Also writes communication protocols to form the

backbone new information system = World Wide Web

- Hypertext Transfer Protocol (HTTP):

– a communications protocol used to send information over the web

– Web use exploded with availability in 1993 of the Mosaic browser

– Marc Andreessen founds Netscape- Company many credit with initiating the explosive

Internet of late 1990s.


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1.6 World Wide Web Consortium (W3C)

W3C Founded in 1994 by Tim Berners-Lee Homepage at www.w3.org Goals

– Internet universally accessible– Standardization

- W3C Recommendations: Technologies standardized by W3Cinclude the Extensible HyperText Markup Language

(XHTML), Cascading Style Sheets (CSS), HyperText Markup Language (HTML—now considered a “legacy” technology) and the Extensible Markup Language (XML).

not an actual software product, but a document that specifies a technology’s role, syntax rules and so forth.


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1.7 Web 2.0

2003 noticeable shift in how people and businesses were using the web and developing web-based applications

The term Web 2.0 was coined by Dale Dougherty of O’Reilly – Web 2.0 definition = companies use the web as a platform to

create collaborative, community-based sites (e.g., social networking sites, blogs, wikis, etc.).

Web 1.0 (1990s and early 2000s) focused on a small number of companies and advertisers producing content for users to access

– “brochure web”) Web 2.0 involves the

– Web 1.0 is as a lecture, – Web 2.0 is a conversation

Websites like MySpace , Facebook , Flickr , YouTube, eBay and Wikipedia , users create the content, companies provide the platforms.


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1.7 Web 2.0 (Cont.)

Architecture of participation

– Open source software

– Collective

– Rich Internet Applications (RIAs)

– Software as a Service (SaaS)

Web services incorporate functionality from existing

applications and websites into own web applications

– Amazon Web Services

– Maps web services with eBay web services


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1.7 Web 2.0 (Cont.)

Future computers learn to understand the meaning

of the data on the web = Semantic Web

Deitel Web 2.0 Resource Center at

www.deitel.com/web2.0/ for more information.


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1.8 Personal, Distributed and Client/Server Computing

1977 Apple Computer popularized personal computing

– Computers became economical for personal or business use

Machines could be linked together in computer networks

– Local area networks (LANs) – Distributed computing

Workstations Servers offer data storage and other

capabilities that may be used by client computers distributed throughout the network,

– Client/server computing Popular operating systems

– UNIX, Linux, Mac OS X and Microsoft’s Windows


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1.9 Hardware Trends

Improving technologies (I)

– Internet community thrives on improvements of

- Hardware, Software and Communications

– Cost of products and services

- Consistently dropping over the decades

– Computer capacity and speed

- Doubles every two years (on average) = Moore’s Law


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1.9 Hardware Trends

Improving technologies (II)

– Microprocessor chip

- Laid groundwork in late 1970s and 1980s for productivity

improvements of the 1990s

– Hardware moving toward mobile, wireless technology.

- Hand-held devices more powerful than early

supercomputers

- Portability

- Wireless data-transfer speeds


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1.10 The Key Software Trend: Object Technology

Objects

– Reusable software components that model items in

the real world (classes)

– Makes software developers more productive

– Object-oriented programs often easier to understand,

correct and modify than older types of programs


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1.11 JavaScript: Object-BasedScripting for the Web

JavaScript– Attractive package for advancing level of

programming language education

– Object-based language

– Supports proper software engineering techniques

– Free as part of today’s most popular Web browsers

– Powerful scripting language- Portable

- Programs execute interpretively on client machines

Universal client scripting language, simplifying web application development


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Portability Tip 1.2

Although it is easier to write portable programs in JavaScript than in many other programming languages, differences among interpreters and browsers make portability difficult to achieve. Simply writing programs in JavaScript does not guarantee portability. Programmers occasionally need to research platform variations and write their code accordingly.


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1.12 Browser Portability

Browser portability

– Great challenge

- Great diversity of client browsers in use

- Many different platforms also in use

Difficult to

– Know capabilities and features of all browsers and

platforms in use

– Find correct mix between absolute portability,

complexity and usability of features


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Portability Tip 1.4

The web is populated with many different browsers, which makes it difficult for authors and web application developers to create universal solutions. The W3C is working toward the goal of a universal client-side platform.


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1.13 C, C++ and Java

C– developed by Dennis Ritchie at Bell Laboratories – development language of the UNIX operating system– virtually all new major operating systems are written in C and/or

C++ C++

– developed by Bjarne Stroustrup in early 1980s – “spruce up” the C language and provides capabilities for object-

oriented programming Java

– developed by Sun Microsystems in 1991 – Sun saw the immediate potential of using Java to add dynamic

content (e.g., interactivity, animations and the like) to web pages

– Sun formally announced Java at an industry conference in May 1995

– Java is now used to - develop large-scale enterprise applications- enhance the functionality of web servers - provide applications for consumer devices


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1.14 BASIC, Visual Basic, Visual C++, C# and .NET

BASIC – Developed in the mid-1960s at Dartmouth College – Primary purpose was to familiarize novices with

programming techniques Microsoft’s Visual Basic language

– Based on Basic– Has become one of the most popular programming

languages in the world Microsoft’s .NET platform

– Provides the capabilities developers need to create computer applications that can execute on computers distributed across the Internet

- Visual Basic (based on the original BASIC)- Visual C++ (based on C++)- Visual C# (based on C++ and Java)


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1.15 Software Technologies

Agile Software Development – Set of methodologies that try to get software

implemented quickly – Agile Alliance (www.agilealliance.org) – Agile Manifesto (www.agilemanifesto.org)

Refactoring – Reworking code to make it clearer and easier to

maintain while preserving its Design patterns

– Proven architectures for constructing flexible and maintainable object-oriented software

– Open source code


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1.15 Software Technologies (Cont.)

Linux – Open source operating system

Apache – Most popular open source web server

MySQL , PostgreSQL– Open source database management system

PHP – Most popular open source server-side “scripting” language for developing

Internet-based applications LAMP

– Linux, Apache, MySQL and PHP (or Perl or Python) Game programming

– Software techniques used in game programming Adobe Flash CS3

Software as a Service (SaaS)– Software runs on servers elsewhere on the Internet

- Salesforce.com, Google, Microsoft and 37Signals all offer SaaS


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22Developing Web Applications

Overview


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OBJECTIVES Describe the Web development process Describe a typical server-side application

• Using TCP / IP and HTTP protocols

• Including GET, POST and Form Header methods

Describe the contemporary server-side technologies

• CGI

• Server-side Java Scripts (SSJS)

• Servlet

• JSP

• ASP

• PHP


Client-Server Architecture

Front end Back end

Order is processed

here


Two-tier systems

Drawbacks of two-tier systems:

• Servers must be multi-lingual, as different clients may speak different languages

• Clients have to decide which queue is the shortest, to get their order quickly

• People may have to wait in long queues at the server

• If the queues are too long, then a client may decide to leave


Bill

A customer enters the restaurant

A waiter accepts the order and then serves food

The customer asks for the bill, pays the money and leaves the restaurant

Exit

A day in a typical restaurant


A day in a typical restaurant – (1)

Advantages of this system:

• The customer does not have to stand in a queue. He

can comfortably sit at a table and wait for his order to

be taken.

• The client has to interact only with a waiter. Thus, the

waiter alone needs to understand more than two

languages.

• There is a separate counter for paying bills. So

clients need not wait for the others to clear their bills

first.


The Web based solution

A customer browses the restaurant site on the Web, located at a particular URL

He places the order (request) based on the available menu, which is received by the Web server

The request is processed here, by the JSP or servlet engine

The database is checked for any required information – like stock of items

The results are sent back to the client

Process


The Web based solution – (1)

The process of placing an order and being served by the

waiter can be explained as follows:

– Placing an order, which is accepted by the waiter, is

comparable to an HTTP request

– Being served by the waiter is similar to receiving an HTTP

response

– The entire mode of communication, that is sending and

receiving HTTP requests and responses is based on the TCP/

IP suite


The Web development process – Some definitions

Web Page: • simple text file consisting of text and HTML tags

Web Browser: • connects to a Web Server, sends a request for a page and

receives and displays the result

• interprets HTML tags to display the page exactly the way the designer wanted it to be


The Web development process – Some definitions – (cont.)

Web Server:

– software which can respond to a Web browser’s

request for a page and then send that page to the

browser

Database:

– an RDBMS that stores data – connected to the Web

Server


A brief note on TCP/IP and HTTP protocols

TCP/IP is a protocol suite that drives the Internet

Handles network communications between nodes

It is composed of layers:

• Internet Protocol

• Transmission Control Protocol

• Sockets


A brief note on TCP/IP and HTTP protocols – (cont.)

HTTP defines:

• the way messages are formatted and transmitted

• what the Web servers and browsers do in response

to various commands


Connecting the client and server through HTTP

HyperText Link HyperText Link

Web Client running a Browser


How does a Web server work?

When a browser sends a request to the Web

server, the following occur:

• The browser divides the URL into three parts:

• The protocol (HTTP)

• The server name (www.Microsoft.com)

• The file name (index.asp)

• The browser communicates with this server to

translate the server name into an IP address


How does a Web server work?

Translate

2. Server name – Microsoft.com

3. File name – index.asp

1. Protocol – HTTP

www.Mi… IP address

Connection

Browser sends a GET request

Server returns the HTML page


How does a Web server work? –(Cont.)

http://servername/HelloWorld.html

File system contains HelloWorld.html


Web Application architecture

ClientClient


Web Application architecture –(Cont.)Forms

Collecting Data

Sending a Request to the Web

Executing the Server Script

Returning Results to the browser


The Prevalent Server-side Technologies

Common Gateway Interface (CGI)

• Perl is the most popular programming language for

CGI programming

• CGI acts as a gateway between a request and the

response

• Disadvantage is that it does not scale well – a new

process is created each time the server receives a

new request


The Prevalent Server-side Technologies – (Cont.)

Proprietary Web Server APIs (ISAPI, NSAPI)

• Allow developers to write server applications as

shared libraries

• These libraries can service multiple requests

without creating a new process for each of these


Server-side Java Scripts (SSJS)

• Uses JavaScript as the scripting language

• Has built-in features for

• database and e-mail support

• session management

• inter-operability with server-side Java classes



Personal Home Page (PHP)

• Provides strong support for pattern matching and

database access

• Is an open source product and is available on a large

number of platforms

Servlet

• Small Java-based applications for adding dynamic

functionalities to Web servers

• Servlet requests are handled by threads



Active Server Pages (ASP)

• Supports multiple scripting languages, including PerlScript,

JScript and VBScript

• The only limitation that it has is that it can run only on IIS on

Windows NT JavaServer Pages (JSP)

• Supports two different styles for adding dynamic content –

through scripts and tags

• Separates presentation from implementation logic



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Thank you

See you next week

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