Transcript Internet Infrastructure

Internet Infrastructure
Min Ding
Smeal College of Business Administration
Pennsylvania State University
The Future of Computers
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"I think there is a world market for maybe five
computers." --Thomas Watson, chairman of IBM, 1943
"Computers in the future may weigh no more than 1.5
tons." --Popular Mechanics, 1949
"But what ... is it good for?" --Engineer at the Advanced
Computing Systems Division of IBM, 1968, commenting
on the microchip.
"There is no reason anyone would want a computer in
their home." --Ken Olson, president, chairman and
founder of Digital Equipment Corp., 1977
"640K ought to be enough for anybody." -- Bill Gates,
1981
Today’s Topics
 Internet
Communication -- Internet
Protocol Suite
 Web Technology – building blocks of ecommerce
 What does it take to have your own web
server?
Internet Protocol Suite
 Communication
among computers is
achieved by following a set of
agreements (or protocols);
 Each protocol suite has multiple layers;
 TCP/IP is the most widely implemented
protocol suite in use.
Layers of TCP/IP suite
 Application
layer (e.g., HTTP)
 Transport layer (e.g., TCP)
 Network layer (IP)
 Physical layer (e.g., Ethernet)
Physical layers
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Internet is a network of many different
networks -- LAN (e.g., Ethernet, token ring)
and WAN (e.g., dialup, frame relay, point-topoint circuits);
 Internet routers are used to connect these
networks;
 Routing protocols determine how information
(packet) are forwarded;
 Routers are often used as first line of defense
against network attack.
Network layer
 Network
layer takes care of IP address
and domain name service (DNS)
 IP provides both packet (data) addressing
and best-effort forwarding services (kind
of like mailroom);
 IP layer assigns a uniform address
structure (32 bit address) to each
computer connected to the network.
 IP address, e.g., 255.255.255.255
Network layer (continued)
 Domain
Name Systems (DNS) offers
easily readable names for IP addresses
 IP
address and DNS name do not
always correspond to each other.
Transport Layer
 Unreliable
Datagram Protocol (UDP)
 Transmission
Control Protocol (TCP)
Application layer
Application protocols, include
 FTP
 HTTP
 Telnet
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Building blocks of e-commerce
(WWW technology)
 Protocols
 Browsers
 Servers
 Application
development structures
(e.g., Java, Active X, CGI)
World Wide Web
You mean web is not the same as internet?
 Web
is only a part of internet mainly
based on one type of application
protocol, namely, HTTP.
 HTTP: hypertext transfer protocol
WWW browsers
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Netscape Navigator, Microsoft Internet Explorer
Web browsers include built-in support for HTML
(hypertext markup language) and
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MIME (multimedia internet mail extensions), e.g., image/gif,
video/mpeg
Plug-ins (added application to help browser display new data
type);
Scripting (permit executable scripts to be embedded in web
pages, e.g., JavaScript or VBScript);
Applets (written in Java, downloaded on demand from server)
ActiveX controls (used by Internet Explorer), similar to Java
applets, but has free control of the computer.
Takeaway:
Potential customers using less advanced
browsers may not be able to access all your features..
Web Servers
 AOLserver
(free)
 Apache, most popular web server (free)
 Microsoft IIS(internet information
server)/ASP(active server pages)
Server
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API (application programming interface)
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Server-side scripting
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CGI(the common gateway interface)
Server-side includes (simple)
Server-side scripting (Java, JavaScript, VBScript),
Microsoft’s ASP is an execution environment for
server scripts and control.
Database-driven templates
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Similar to server scripting
Uniform Resource Locators (URLs)
http://assets.wharton.upenn.edu/~min42
http://
assets.wharton.upenn.edu
~min42
protocol designator
server name
pathname to resource
Web content transport
– information is retrieved by the
client browser
 Push – user signs up for a channel of
content and relevant information is
automatically delivered to the desktop
 Pull
Anybody can do it…
Source: http://www.nysaes.cornell.edu/comm/staff/zakour
Three levels of web hosting
 Part
of somebody else’s machine
assets.wharton.upenn.edu/~min42
www.planetding.com (virtual hosting)
 My
machine in other people’s network
e.g., Exodus
 My
machine, my network
Choosing a computer
 Unix
 Run
Linux on PC
 Windows
NT
Connect to the internet
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ISDN (integrated services digital network),
128k point to point connection from the phone
company
 Cable modems (AtHome, can’t be used as
server in this area), around 1 Mbps
 ADSL(asymmetrical digital subscriber line), up
to 6 Mbps
 T1: 1.5 Mbps dedicated connection to
somebody’s backbone network
($2000/month);
 T3: 45 Mbps ($50,000/month)
Take Home Message
(translation: things to remember for final exam)
 The
concept of protocol suite, and
TCP/IP.
 Understand the roles of browser and
servers.
 What do you need to do to set up your
own web server?