2002 Prentice Hall Chapter 10 Inside the Internet and the Web.
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Transcript of 2002 Prentice Hall Chapter 10 Inside the Internet and the Web.
2002 Prentice Hall
Chapter 10
Inside the Internet and the Web
2002 Prentice Hall 2
The Internet: A Network of Networks
Internet Applications: Communication and Connection
Inside the World Wide Web
The Evolving Internet
Topics
“It’s a bit like climbing a mountain. You don’t know how far you’ve come until you stop and look back.”
Vint Cerf
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The Internet is an interconnected network of thousands of networks linking academic, research, government, and commercial institutions.
The Internet: A Network of Networks
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The Internet provides scientists, engineers, educators, students, business people, and others with a variety of services such as:
Electronic mail (send/receive mail messages) Remote login (Telnet - access to other computers)
Internet Services
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Internet Services
Transferring files (FTP - accessing archives of data)
Newsgroups (Usenet - on-line public discussions)
World Wide Web (a collection of multimedia documents)
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Counting Connections
Today, the Internet connects computers to about every country in the world. However, the Internet is:
growing too fast to measure its growth too decentralized to quantify a network with no hard boundaries
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The language at the heart of the Internet is TCP/IP…
Transmission Control Protocol/Internet Protocol Allows cross-network communication
Internet Protocols
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Internet Protocols
TCP breaks messages into packets Each packet has all the information needed to travel
from network to network Host systems called Routers determine how to route
transmissions
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Internet Protocols
IP is the address for the packets Each Internet host computer has a unique IP Address Each address is comprised of four sets of numbers
separated by periods, such as 123.23.168.22
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Internet Addresses
The host is named using DNS (domain name system), which translates IP addresses into a string of names.
“Each person on the “Internet” has a unique e-mail “address” created by having a squirrel run across a computer
keyboard.”
Dave Barry
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Internet Addresses
Top level domains include: .edu - educational sites
.com - commercial sites
.gov - government sites
.mil - military sites
.net - network administration sites
.org - nonprofit organizations
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Internet Addresses
An Internet address includes: [email protected]
username is the person’s “mailbox”
hostname is the name of the host computer and is followed by one or more domains separated by periods:
– host.subdomain.domain
– host.domain
– host.subdomain.subdomain.domain
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Internet Addresses
Examples:
User President whose mail is stored on the host whitehouse in the government domain
User hazel_filbert at the server for Lane County, Oregon, k-12 school district
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Direct (dedicated) Connection Computer has its own IP address and
is attached to a LAN
No need to dial up
Files are stored on your computer
Response time is quick
Internet Access Options
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Internet Access Options
Dialup Connections limited connection using a modem Full access dial up uses SLIP or PPP via modem
Broadband Connections
DSL service is newer, faster, and cheaper than ISDN
Can share phone line with voice traffic
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Internet Access Options
Cable Modem Connection allow Internet connections using shared TV cables can exceed DSL speeds Carry increased privacy and security risks
Satellite Connections provides connections using DirecTV satellite dishes
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Internet Access Options
Internet Service Providers (ISPs) local ISPs provide connections through
local telephone lines national ISPs offer connections on a
nationwide scale
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The Internet use the client/server model for most Internet applications.
In the client/server model a client program asks for information, and a server program fields the request and provides the requested information from databases and documents.
Internet Applications:Communication and Connection
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An email server acts like a local post office for a particular Internet host—a business, an organization, or an ISP.
File servers are common within LANs, but they’re also used to share programs, media files, and other computer data across the Internet.
Internet Applications:Communication and Connection
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File transfer protocol (FTP) allows users to download files from remote servers to their computers and to upload files.
File compression saves storage space on disk and saves transmission time when files are transferred through networks.
Internet Applications:Communication and Connection
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An application server stores applications- PC office applications, databases, or other applications - and makes them available to client programs that request them.
An application server might be housed at an application service provider (ASP) - a company that manages and delivers application services on a contract basis.
A Web server stores Web pages and sends pages to client Web browsers.
Internet Applications:Communication and Connection
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WWW is a distributed browsing and searching system developed at CERN
System was designed to give Internet documents unique addresses
HTML language was created for encoding and displaying documents
Browser software was built for viewing documents from remote locations
Inside the Web
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Inside the Web
Web pages are made up of text and images
A Web site is a collection of web pages
A Home page is the main entry to a Web site
A Web browser like Netscape Communicator or Internet Explorer allows you to explore the Web by clicking links
Web site Jargon:
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Inside the Web
Hyperlinks (links) are words or pictures that act as buttons, allowing you to go to another Web page
Links are typically underlined or displayed in a different color
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Inside the Web
More Web site Jargon
Links allow you to locate information without knowing its exact location (it may move from time to time)
Back and Forward buttons let you retrace your steps
Bookmarks and Favorites can be set up to mark your favorite Web locations
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Web Addresses
Pronounced Earl…like the name
A typical URL looks like this:
http://www.prenhall.com.beekman
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Web Addresses
Protocol for Web pages
Dissecting Web Page address:
http:// www.vote-smart.org/
Path to the host
Resource Page
help/database.html
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Publishing on the Web
An HTML document includes codes that determines the format, layout, and structure of a Web document
HTML (Hypertext Markup Language)
HTML is not WYSIWYG
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Publishing on the Web
This text coded as HTML …
Appears like this on the screen …
<H1>Welcome to Computer Confluence</H1><b>Publishing on the Web</b>
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Publishing on the Web
Alternatives to HTML…
Programs that convert document format features into HTML codes
Microsoft Word, FileMaker
Web authoring programs HomePage, GoLive, FrontPage
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From Hypertext to Multimedia
Tables
Frames
Forms
Downloadable audio and video
Streaming audio and video
Real-time live audio or video
3-D environments
Typical Web pages can contain:
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From Hypertext to Multimedia
Plug-Ins are software extensions that add new features. Examples include…
QuickTime
Shockwave/Flash
RealPlayer
Acrobat
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Beyond HTML
Dynamic HTML:adds more programming power to HTML by allowing code to automatically modify itself under certain circumstances
JavaScript: a simple language for enhancing HTML Web pages
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Beyond HTML
WML Wireless Markup Language helps create Web documents
containing stock quotes, phone numbers, and other small nuggets of information
XML Will replace HTML plus provide additional features and
extensions
VRML Virtual Reality Modeling Language creates 3-D virtual worlds
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Beyond HTML
Java A full-featured, cross platform, object-oriented programming
language
Java applets Small Java programs that can be automatically downloaded
onto your client computer and can run on any platform