Internet, Intranets, and Extranets By T.R. Vaidyanathan
Principles and Learning Objectives
The Internet is like many other technologies—it
provides a wide range of services, some of which are effective and practical for use today, others that are still evolving, and still others that will fade away from lack of use
Briefly describe how the Internet works, including
alternatives for connecting to it and the role of Internet service providers
2
Principles and Learning Objectives (continued)
• Originally developed as a document-management
system, the World Wide Web is a menu-based system that is easy to use for personal and business applications
– Describe the World Wide Web and the way it works
– Explain the use of Web browsers, search engines, and
other Web tools – Identify and briefly describe the applications associated with the Internet and the Web
3
Principles and Learning Objectives (continued)
• Because the Internet and the World Wide Web are becoming more
universally used and accepted for business use, management, service and speed, privacy, and security issues must continually be addressed and resolved – Identify who is using the Web to conduct business and discuss some of the pros and cons of Web shopping – Outline a process for creating Web content – Describe Java and discuss its potential impact on the software world Define the terms intranet and extranet and discuss how organizations are using them Identify several issues associated with the use of networks
4
Why Learn About the Internet?
Internet is an important part of most people’s lives Individuals can investigate career opportunities Businesses sell and advertise online Employees can communicate with co-workers and bosses
5
Use and Functioning of the Internet
Internet: a collection of interconnected networks, all
freely exchanging information ARPANET
Ancestor of the Internet. ARPANET (Advanced Research Projects Agency
Network), created by the Defense Advanced Research Projects Agency (DARPA) of the United States Department of Defense, was the world's first operational packet switching network, and the predecessor of the contemporary global Internet. Project started by the U.S. Department of Defense (DoD) in 1969
6
Use and Functioning of the Internet (continued)
• Internet Protocol (IP): communication standard
that enables traffic to be routed from one network to another as needed • Research to make Internet faster and easier to use
– “Digital objects”: allow all types of computer systems to
use and share programs and data – Internet2 (I2), Next Generation Internet (NGI), Abilene: provide Internet speeds of up to 2 Gbps or more
7
Use and Functioning of the Internet (continued)
A Brief History of the Internet
8
How the Internet Works
• Internet transmits data from one computer (called a
host) to another • If the receiving computer is on a network to which the first computer is directly connected, it can send the message directly • If the receiving computer is not on a network to which the sending computer is connected, the sending computer relays the message to another computer that can forward it
9
How the Internet Works (continued)
Data is passed in chunks called packets
Transmission Control Protocol (TCP): widely used
transport layer protocol that is used in combination with IP by most Internet applications Uniform Resource Locator (URL): assigned address on the Internet for each computer
10
Use and Functioning of the Internet (continued)
TCP/IP is a two-layer program. The higher layer,
Transmission Control Protocol, manages the assembling of a message or file into smaller packets that are transmitted over the Internet and received by a TCP layer that reassembles the packets into the original message. The lower layer, Internet Protocol, handles the address part of each packet so that it gets to the right destination. Each gateway computer on the network checks this address to see where to forward the message. Even though some packets from the same message are routed differently than others, they'll be reassembled at the destination.
11
How the Internet Works (continued)
Accessing the Internet Connect via LAN server Connect via Serial Line Internet Protocol (SLIP)/Pointto-Point Protocol (PPP) Connect via an online service Other ways to connect cell phones, PDAs, and home appliances: e.g., wireless application protocol (WAP) for cell phones
12
How the Internet Works (continued)
Routing Messages over the Internet
13
How the Internet Works (continued)
U.S. Top-Level Domain Affiliations
14
How the Internet Works (continued)
Internet Growth: Number of Internet Domain Names
15
How the Internet Works (continued)
Several Ways to Access the Internet
16
Internet Service Providers
Modem,
short for modulator-demodulator is an electronic device that converts a computer’s digital signals into specific frequencies to travel over telephone or cable television lines. At the destination, the receiving modem demodulates the frequencies back into digital data. Computers use modems to communicate with one another over a network. Internet service provider (ISP): any company that provides individuals or organizations with access to the Internet Most charge a monthly fee Many ISPs and online services offer broadband Internet access through digital subscriber lines (DSLs), cable, or satellite transmission
17
What is DSL(Digital Subscribe Line)
When you connect to the Internet, you might connect through a regular modem, through a local-area network connection in your office, through a cable modem
or through a digital subscriber line (DSL) connection. DSL is a very highspeed connection that uses the same wires as a regular telephone line. Here are some advantages of DSL: You can leave your Internet connection open and still use the phone line for voice calls. The speed is much higher than a regular modem DSL doesn't necessarily require new wiring; it can use the phone line you already have. The company that offers DSL will usually provide the modem as part of the installation.
18
Internet Service Providers (continued)
A Representative List of Internet Service Providers
20
Internet Service Providers (continued)
Approximate Times to Perform Basic Tasks with Various Internet Connections
21
The World Wide Web
WWW- also called the Web or W3. The World Wide Web (or the proper World-Wide Web;
abbreviated as WWW or W3,] and commonly known as the Web) is a system of interlinked hypertext documents accessed via the Internet. With a web browser, one can view web pages that may contain text, images, videos, and other multimedia and navigate between them via hyperlinks. Menu-based system that uses the client/server model Organizes Internet resources throughout the world into a series of menu pages, or screens, that appear on your computer Hypermedia: tools that connect the data on Web pages, allowing users to access topics in whatever order they wish. Hypertext and hypermedia refer to Web pages and other kinds of on-screen content that employ hyperlinks
22
The World Wide Web (continued)
Hypertext Markup Language (HTML): standard page description language for Web pages
HTML tags: let the browser know how to format text on a Web page and whether images, sound, and other elements should be inserted Extensible Markup Language (XML): markup language for Web documents containing structured information, including words, pictures, and other elements
23
The World Wide Web (continued)
Sample Hypertext Markup Language
24
Web Browsers
Web browser: software that creates a unique, hypermedia-based
menu on a computer screen, providing a graphical interface to the Web Menu consists of graphics, titles, and text with hypertext links Popular Web browsers: Microsoft Internet Explorer, Netscape Navigator, Mozilla Firefox, Apple Computer’s Safari Applet: small program embedded in Web pages. An applet is a small program that can be sent along with a Web page to a user. Java applets can perform interactive animations, immediate calculations, or other simple tasks without having to send a user request back to the server. Web browser plug-in: external program that is executed by a Web browser when it is needed
25
Search Engines and Web Research
Search engine: Web search tool Examples: Yahoo.com, Google.com Most search engines are free Searches can use words, such as AND and OR to refine
the search Meta-search engine: submits keywords to several individual search engines and returns results from all these search engines
26
Search Engines and Web Research (continued)
Popular Search Engines
27
Web Programming Languages
Java Object-oriented programming language from Sun Microsystems based on C++ Allows small programs (applets) to be embedded within an HTML document
28
Web Programming Languages (continued)
Downloading an Applet from a Web Server
29
Web Programming Languages (continued)
Other programming languages used to develop Web
Suggestions for creating a Web page
Computer must be linked to a Web server 2. Web browser program needed to view the HTML pages you create 3. Options for designing the Web page
1.
a)
b) c) d)
Write your copy with a word processor, and use an HTML converter to convert the page into HTML format Use an HTML editor to write text and add HTML tags Edit an existing HTML template to meet your needs Use an ordinary text editor and type the start and end tags for each item
31
Developing Web Content (continued)
Suggestions for creating a Web page (continued):
See HTML page in browser; correct any mistakes 2. Add links to your home page 3. Store pictures as files before adding them
1.
a)
b)
c) d) e)
Draw them using a graphics software package Copy pictures from other Web pages (with permission) Buy a disk of clip art Scan photos Use a digital camera
32
Developing Web Content (continued)
Suggestions for creating a Web page (continued): 1. Add sound by using a microphone connected to your computer to create a file, and then adding a link to the file on a Web page 2. Upload the HTML file to your Web site 3. Review the Web page to make sure that all links are correctly established to other Web sites 4. Advertise your Web page to others and encourage them to take a look and send feedback by e-mail
33
Web Services
Web services: standards and tools that streamline and
simplify communication among Web sites for business and personal purposes XML is used within a Web page to describe and transfer data between Web service applications
34
Web Services (continued)
Other components used in Web service applications: SOAP (Simple Object Access Protocol) WSDL (Web Services Description Language) UDDI (Universal Discovery Description and Integration)
35
Internet and Web Applications
The types of Internet and Web applications available are vast and ever expanding
36
Business Uses of the Web
In 1991, Commercial Internet Exchange (CIX) Association was established to allow businesses to connect to the Internet
Firms use the Internet for many types of applications
37
E-Mail, Instant Messaging, and Push Technology
E-mail
No longer limited to simple text messages
Can embed sound and images Can attach files
Instant messaging: online, real-time communication
between two or more people who are connected to the Internet Push technology: automatic transmission of information over the Internet rather than make users search for it with their browsers
38
E-Mail, Instant Messaging, and Push Technology (continued)
Table 7.7: Some Common Abbreviations Used in Personal E-Mail
39
Internet Cell Phones and Handheld Computers
Cell phones connected to the Internet allow people to
search for information, buy products, and chat with business associates and friends Short Message Service (SMS) or texting Brief text messages can be sent between two or more cell phone users Handheld computers and other devices are connected to the Internet using phone lines or wireless connections
40
Career Information and Job Searching
Use search engines to look for specific companies or
industries Internet sites specialize in helping you find job information and apply for jobs online
Examples: www.monster.com, www.hotjobs.com, and
www.careerbuilder.com
41
Telnet and FTP
What is Telnet? Telnet: terminal emulation protocol that enables users to log on to other computers on the Internet to gain access to public files. Telnet is a user command and an underlying TCP/IP protocol for accessing remote computers. Through Telnet, an administrator or another user can access someone else's computer remotely. On the Web, HTTP and FTP protocols allow you to request specific files from remote computers, but not to actually be logged on as a user of that computer. With Telnet, you log on as a regular user with whatever privileges you may have been granted to the specific application and data on that computer. File Transfer Protocol (FTP): protocol that describes a file transfer process between a host and a remote computer and allows users to copy files from one computer to another
42
Web Log (Blog), Video Log (Vlog), and Podcasting
Web log or blog: Web site that people create and use
to write about their observations, experiences, and feelings on a wide range of topics Video log or vlog: video content placed on the Internet using the same overall approach as a blog Podcast: audio broadcast over the Internet People and corporations use podcasts to listen to audio material, increase revenues, or advertise products and services
43
Usenet and Newsgroups
Usenet: system closely allied with the Internet that
uses e-mail to provide a centralized news service
Protocol that describes how groups of messages can be
stored on and sent between computers
Newsgroups: online discussion groups that focus on
specific topics
44
Usenet and Newsgroups (continued)
Selected Usenet Newsgroups
45
Chat Rooms
Chat room: enables two or more people to engage in
interactive “conversations” over the Internet Internet Relay Chat (IRC) requires participants to type their conversation rather than speak Voice chat allows participants to speak their conversation Must have a microphone, sound card, speakers, a fast modem or broadband, and voice-chat software compatible with the other participants’
46
Internet Phone and Videoconferencing Services
Internet phone service
Relatively inexpensive, especially for international
calls Voice-over-IP (VoIP) technology Network managers can route phone calls and fax transmissions over the same network they use for data Internet videoconferencing Supports both voice and visual communications Webcasts or Webinars
47
Content Streaming
Method for transferring multimedia files, radio broadcasts, and other content over the Internet
Data stream of voice and pictures plays more or less continuously without a break, or with very few breaks Enables users to browse large files in real time
Works best when the transmission of a file can keep up with the playback of the file
48
Shopping on the Web
You can shop for almost anything over the Internet
Convenient, easy, and cost effective Many Web sites also offer free shipping and pickup for
returned items Bot: a software tool that searches the Web for information, products, or prices
Finds the best prices or features from multiple Web sites
49
Web Auctions
Web auction: Internet site that matches buyers and
sellers Businesses grow or reach customers for a low cost per transaction One of the most popular auction sites: eBay Potential problems with auction Web sites Auction sites cannot always determine whether the people and companies listing products and services are legitimate Some Web sites have illegal or questionable items offered
50
Music, Radio, Video, and TV on the Internet
Audio and video programs: play on the Internet or
download files for later use Music players and music formats such as MP3: download music from the Internet and listen to it anywhere
Musicians can gain exposure without a lucrative music
contract
Radio broadcasts Audio books
51
Music, Radio, Video, and TV on the Internet (continued)
Video and TV are increasingly becoming available on
the Internet New, innovative devices let you record TV programs and view them at any time and place Many content providers offer their programs over the Internet
52
Office on the Web
Internet office: Web site that contains files, phone
numbers, e-mail addresses, an appointment calendar, and more Allows your desktop computer, phone books, appointment schedulers, and other important information to be with you wherever you are Many services and software products give you remote access to your files and programs over the Internet
53
Internet Sites in Three Dimensions
Some Web sites offer three-dimensional views of
places and products Examples
3-D Internet auto showroom: allows people to get
different views of a car 3-D real estate site: people can tour the property, go into different rooms, etc.
54
Other Internet Services and Applications
Libraries: provide vast amounts of information
Movies: ordered and delivered over the Internet Critical information during times of disaster or
terrorism Translation: words, sentences, or complete documents from one language into another
55
Other Internet Services and Applications (continued)
Distance learning: online courses
Internet cameras: conduct job interviews; hold group
meetings with people around the world; monitor young children at daycare centers, etc. Connect with friends or others with similar interests
56
Intranets and Extranets
Intranet: internal corporate network built using Internet and World Wide Web standards and products
Used by employees to gain access to corporate information Reduces the need for paper
An "intranet" is the generic term for a collection of private computer networks within an organization. An "extranet" is a computer network that allows controlled access from the outside for specific business or educational purposes. Intranets and extranets are communication tools designed to enable easy information sharing within workgroups. A buzzword that refers to an intranet that is partially accessible to authorized outsiders. Whereas an intranet resides behind a firewall and is accessible only to people who are members of the same company or organization, an extranet provides various levels of accessibility to outsiders. You can access an extranet only if you have a valid username and password, and your identity determines which parts of the extranet you can view. Extranets are becoming a very popular means for business partners to exchange information.
57
Intranets and Extranets (continued)
Extranet: network based on Web technologies that link selected
resources of a company’s intranet with its customers, suppliers, or other business partners. An extranet is a computer network that allows controlled access from the outside, for specific business or educational purposes. An extranet can be viewed as an extension of a company's intranet that is extended to users outside the company, usually partners, vendors, and suppliers. It has also been described as a "state of mind" in which the Internet is perceived as a way to do business with a selected set of other companies (business-to-business, B2B), in isolation from all other Internet users. In contrast, business-to-consumer (B2C) models involve known servers of one or more companies, communicating with previously unknown consumer users Virtual private network (VPN): secure connection between two points across the Internet Tunneling: process by which VPNs transfer information by encapsulating traffic in IP packets over the Internet
58
Intranets and Extranets (continued)
An extranet requires security and privacy. These can include firewall
server management, the issuance and use of digital certificates or similar means of user authentication, encryption of messages, and the use of virtual private networks (VPNs) that tunnel through the public network. Companies can use an extranet to: Exchange large volumes of data using Electronic Data Interchange (EDI) Share product catalogs exclusively with wholesalers or those "in the trade" Collaborate with other companies on joint development efforts Jointly develop and use training programs with other companies Provide or access services provided by one company to a group of other companies, such as an online banking application managed by one company on behalf of affiliated banks Share news of common interest exclusively with partner companies
59
Intranets and Extranets (continued)
Summary of Internet, Intranet, and Extranet Users
60
Net Issues
Management issues
Preventing attacks
Service and speed issues
Keeping up with Internet traffic and traffic on
company intranets Privacy Fraud Security Unauthorized Internet sites
61
Summary
Internet: collection of interconnected networks, all freely exchanging information
Internet Protocol (IP): communication standard that enables traffic to be routed from one network to another as needed Packets: Internet data passed in chunks
Transmission Control Protocol (TCP): widely used transport layer protocol that is used in
combination with IP by most Internet applications
62
Summary (continued)
Uniform Resource Locator (URL):- the global address of documents
and other resources on the World Wide Web. The first part of the address is called a protocol identifier and it indicates what protocol to use, and the second part is called a resource name and it specifies the IP address or the domain name where the resource is located. The protocol identifier and the resource name are separated by a colon and two forward slashes. For example, the two URLs below point to two different files at the domain pcwaterpulp.com. The first specifies an executable file that should be fetched using the FTP protocol; the second specifies a Web page that should be fetched using the HTTP protocol: ftp://www.pcwaterpulp.com/stuff.exe http://www.pcwaterpulp.com/index.html
63
Summary (continued)
World Wide Web: menu-based system that organizes Internet
resources into a series of menu pages, or screens, that appear on your computer Hypertext Markup Language (HTML): standard page description language for Web pages Search engine: Web search tool Internet and Web applications: e-mail, instant messaging, Internet cell phones, Web logs, newsgroups, Web shopping, etc.
64
Summary (continued)
Intranet: internal corporate network built using Internet and World Wide Web standards
Extranet: network based on Web technologies that links selected resources of a company’s intranet with its customers, suppliers, or other business partners
Network issues: management, service, speed, privacy, fraud, security, and unauthorized Internet sites
65
Summary (continued)
What is Internet? The Internet is a massive networks of networks, a networking infrastructure. It connects millions of computers together globally, forming a network in which any computer can communicate with any other computer as long as they are both connected to the Internet. Information that travels over the Internet does so via a variety of languages known as protocols. What is The Web (World Wide Web)? The World Wide Web, or simply Web, is a way of accessing information over the medium of the Internet. It is an information-sharing model that is built on top of the Internet. The Web uses the HTTP protocol, only one of the languages spoken over the Internet, to transmit data. Web services, which use HTTP to allow applications to communicate in order to exchange business logic, use the Web to share information. To sum up, the Internet functions as the tr4ansport mechanism, and the Web(WWW) is an application that runs on the Internet, as does-email, VoIP.