ITD3254 Chapter1 Student

8/12/2019 ITD3254 Chapter1 Student

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Late 1960s, Internet is called ARPANET

Consisted of two network nodes (hosts)

located at Univ. of Calif., Los Angeles andStanford Univ. connected by phone lines

Today, the Internet has grown into

interconnection of mobile phones, PDAs,

televisions, networks

Connections now consist of fiber optics

cables, satellites, phone lines, other media


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Foundations for WWW (triple W or Web)were laid in 1989 by Timothy Berners-Lee

and other researchers at CERN nuclearresearch facility near Geneva,Switzerland

Rather than using some crazy arrays ofterms, acronyms and commands, asimpler interface was created: the WWW


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An Internet service provideris a company or businessthat provides access to the Internet and relatedservices.

In the past, most ISPs were run by the phone

companies. Now, ISPs can be started by just about any individual

or group with sufficient money and expertise. In addition to Internet access via various

technologies such as dial-up and DSL, they may

provide a combination of services including Internettransit, domain name registration and hosting, webhosting, and collocation.


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IPis a network layer protocol in the Internetprotocol suite and is encapsulated in a datalink layer protocol (e.g., Ethernet).

As a lower layer protocol, IP provides theservice of communicable unique globaladdressing amongst computers.

An IP address(or Internet Protocol address) is

a unique address that certain electronicdevices use in order to identify andcommunicate with each other on a computernetwork utilizing the Internet Protocol standard(IP)in simpler terms, a computer address.


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IP addresses are managed and created bythe Internet Assigned Numbers Authority(IANA). The IANA generally allocates super-

blocks to Regional Internet Registries.

Figure 1b : An illustration of an IP address(version 4), in both dot-decimal notation

and binary.


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Method of organizing information thatgives readers control over the order thatinformation is presented

Gives quicker and simpler access todiverse pieces of information

Unlike reading a book, where a linear

progression is used (reading page bypage), hypertext allows a myriad ofways where readers can straight awaygo to where they desire


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Key to hypertext is hyperlinks (links)

Allows users to jump from one document to

another Individual web page may includes the

elements of multimedia

Texts, animation, graphics, audio, video and

other programs


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Web Server

This is where web pages are stored, which

made available to the network Web Browser

A client runs this to view a Web page


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Uniform Resource Locator (URL) iscomprised of the protocol, followed bythe domain name

Hypertext Transfer Protocol Domain name can be an IP addressor a

text version of this address

http://pucinfo.calumet.purdue.edu

http://205.216.71.230

protocol

IP

protocoldomain

name


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Domain Name System (DNS) is to translatehostnames to IP addresses. DNS distributesthe responsibility for assigning domainnames and mapping them to IP networks

by allowing an authoritative name server


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A search engine is an informationretrieval system designed to help find

information stored on a computersystem.

A Web search engine is a search enginedesigned to search for information onthe World Wide Web. Information mayconsist of web pages, images and othertypes of files.


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a. FTP File Transfer Protocol(FTP) is a network protocol used to transfer data from one

computer to another through a network, such as over the Internet. Whiletransferring data over the network, several data representations can be used. ASCII mode Binary mode: In "Binary mode", the sending machine sends each file byte for

byte and as such the recipient stores the bytestream as it receives it. (The FTPstandard calls this "IMAGE" or "I" mode)

e.g. ftp://ftp.centre2u.com/

b. Email

Electronic Mail (e-mail) is a store and forward method of composing, sending,receiving and storing messages over electronic communication systems

c. Newsgroups

Newsgroup is a web application for holding discussions and posting user-generated content. its also commonly referred to as Web forums, messageboards, discussion boards, (electronic) discussion groups, discussion forums,bulletin boards or forums.

d. Mailing Lists A mailing list is a collection of names and addresses used by an individual or

an organization to send material to multiple recipients.


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f. Chat Rooms

A chat room is a term used primarily by mass media to describe any form ofsynchronous conferencing, occasionally even asynchronous conferencing

The term can thus mean any technology ranging from real-time online chatover instant messaging and online forums to fully immersive graphical socialenvironments.

g. Web Portals

Web portal is site that provides a single function via a web page or site.Portals provide a way for enterprises to provide a consistent look and feel withaccess control and procedures for multiple applications, which otherwisewould have been different entities altogether.

Two broad categorization of portals are a. Horizontal portals (e.g. Yahoo) b.Vertical portals (focused on one functional area. e.g., salesforce.com)

h. telnet A terminal emulation program for TCP/IP networks such as the Internet. The

Telnet program runs on computer and connects PC to a server on thenetwork. User can enter commands through the Telnet program and they willbe executed directly on the server console. This enables user to control theserver and communicate with other servers on the network.


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Communication worldwide communication medium that lends itself to

the peculiar needs of international dialogue

Email, video conferencing, chat etc.

Education Formal and informal teaching and learning

Learning and Teaching Style

Enhances traditional teaching methods

Online education or web base environment (course,material etc.)

Entertainment Entertainment web sites include music, videos, sports,

games, and Online gambling.


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Business Electronic commerce (e-commerce) is the practice of

conducting business activities online, such as shopping Opportunity to change its relationships with the organizations

and individuals with which it does business--from tradingpartners to suppliers, from internal customers to end customers

Business-to-consumer (B2C), Business-to-business (B2B,Consumer-to-consumer (C2C).

Internet marketing, advertising. operation efficiencies and reduced costs.

Medical informational web-based tools for physicians, patients, and

their families for best practices in clinical care, research, andeducation.

Share online medical resources.


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A client is defined as a requester of services and aserver is defined as the provider of services.

Two tier architecturesconsist of three componentsdistributed in two layers: client (requester of services)

and server (provider of services). The three components are :

User System Interface (such as session, text input, dialog,and display management services)

Processing Management (such as process development,process enactment, process monitoring, and processresource services)

Database Management (such as data and file services)


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The three tier architecture (also referred to as the multi-tier architecture)

emerged to overcome the limitations of the two tier architecture. In the three tier architecture, a middle tier was added between the user

system interface client environment and the database management serverenvironment.

There are a variety of ways of implementing this middle tier, such astransaction processing monitors, message servers, or application servers. Themiddle tier can perform queuing, application execution, and databasestaging.


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Characteristics of a client :

Request sender is known as client

Initiates requests Waits for and receives replies.

Usually connects to a small number of serversat one time

Typically interacts directly with end-usersusing a graphical user interface


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Characteristics of a Server : Receiver of request which is sent by client is

known as server

Passive (slave)

Waits for requests from clients

Upon receipt of requests, processes themand then serves replies

Usually accepts connections from a largenumber of clients

Typically does not interact directly with end-users


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Greater ease of maintenance. For example, it is possible to replace,

repair, upgrade, or even relocate a server while its clients remainboth unaware and unaffected by that change. This independencefrom change is also referred to as encapsulation.

All the data is stored on the servers, which generally have far greatersecurity controls than most clients. Servers can better control accessand resources, to guarantee that only those clients with the

appropriate permissions may access and change data.

Since data storage is centralized, updates to those data are fareasier to administer than would be possible under a P2P paradigm.

Many mature client-server technologies are already available which

were designed to ensure security, 'friendliness' of the user interface,and ease of use.

It functions with multiple different clients of different capabilities.


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The term web server can mean one oftwo things: i) A computer program that is responsible for

accepting HTTP requests from clients, whichare known as web browsers, and servingthem HTTP responses along with optionaldata contents, which usually are web pages

such as HTML documents and linked objects(images, etc.).

ii) A computer that runs a computerprogram as described above.


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An application server is a software engine that deliversapplications to client computers or devices, typicallythrough the Internet and using the HyperText TransferProtocol(HTTP). Application servers are distinguished fromweb servers by the extensive use of server-side dynamic

content and frequent integration with databaseengines. Example :Wiki is an application server that allows users to

build dynamic content assembled from articles.Moreover, Wikipedia is an assembled Wiki that deliversan encyclopedia stored in a files ystem, with changes to

the encyclopedia stored in a database. The term is used to refer to servers of web-based

applications, such as integrated platforms for e-commerce, content management systems, and web-site builders. Alternatively, the term is used as a synonym

for web application framework.


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A database server is a computer programthat provides database services to othercomputer programs or computers, as

defined by the client-server model. Theterm may also refer to a computerdedicated to running such a program.Database management systems frequently

provide database server functionality, andsome DBMS's (e.g., MySQL) rely exclusivelyon the client-server model for databaseaccess.


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A database server allows users to store data in onecentral location.

It performs complex functions such as searching,sorting, and indexing on the server itself. This reduces

network traffic because fewer items need to betransferred between the client and the server.

Because data is stored centrally, there is enhancedsecurity.

A database server uses its own processing power to

find requested data, rather than sending thecomplete data to the client so that the clientsearches for the data, as is done in a file server.

A database server allows concurrent access to data.


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Astatic Webpage is a Web page that always comprises thesame information in response to all download requests fromall users. Contrast with Dynamic web page.

It displays the same information for all users, from all contexts,

providing the classical hypertext, where navigation isperformed through "static" documents.

Advantages Quick and easy to put together, even by someone who doesn't

have much experience.

Ideal for demonstrating how a site will look. Cache friendly, one copy can be shown to many people.

Disadvantages

Difficult to maintain when a site gets large. Difficult to keep consistent and up to date. Offers little visitor personalization (all would have to be client side).


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Web navigation can also provide an interactiveexperience that is termed "dynamic".

Content (text, images, form fields, etc.) on a webpage can change, in response to different contexts

or conditions. Dynamic HTMLor DHTML is a collection of

technologies used together to create interactive andanimated web sites by using a combination of astatic markup language (such as HTML), a client-side

scripting language (such as JavaScript), apresentation definition language (Cascading StyleSheets, CSS), and the Document Object Model.


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There are two ways to create this kind of interactivity:

a) Client-side : The Client-side dynamic content is generated on the client's

computer. The web server retrieves the page and sends it as is. Theweb browser then processes the code embedded in the page(typically written in JavaScript) and displays the page to the user.

1. ActionScript

2. JavaScript

The problems with client-side dynamic pages are:

- Some browsers do not support the language or they do not supportall aspects (like write command and innerHTML property) of thelanguage.

- The information cannot be stored anywhere but the user'scomputer, so it cannot really be used for statistics gathering.

- Search engines are not able to run client-side languages andcannot crawl links generated by them.

- Some users have scripting languages disabled in their browsers due

to possible security threats.


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THANK YOUANY QUESTION??

ITD3254 Chapter1 Student

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