Internet Infrastructure

Min DingSmeal College of Business AdministrationPennsylvania State University

The Future of Computers "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 SuiteWeb Technology – building blocks of e-

commerceWhat does it take to have your own web

server?

Internet Protocol SuiteCommunication 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 suiteApplication layer (e.g., HTTP)Transport layer (e.g., TCP)Network layer (IP)Physical layer (e.g., Ethernet)

Physical layers Internet is a network of many different

networks -- LAN (e.g., Ethernet, token ring) and WAN (e.g., dialup, frame relay, point-to-point 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 layerNetwork 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 LayerUnreliable Datagram Protocol (UDP)

Transmission Control Protocol (TCP)

Application layerApplication protocols, include

FTP HTTP Telnet…

Building blocks of e-commerce (WWW technology)

ProtocolsBrowsersServersApplication development structures

(e.g., Java, Active X, CGI)

World Wide WebYou 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 Netscape Navigator, Microsoft Internet Explorer Web browsers include built-in support for HTML

(hypertext markup language) and 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 ServersAOLserver (free)Apache, most popular web server (free)Microsoft IIS(internet information

server)/ASP(active server pages)

Server API (application programming interface)

CGI(the common gateway interface) Server-side scripting

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 Similar to server scripting

Uniform Resource Locators (URLs)

http://assets.wharton.upenn.edu/~min42

http:// protocol designatorassets.wharton.upenn.edu server name~min42 pathname to resource

Web content transportPull – information is retrieved by the

client browserPush – user signs up for a channel of

content and relevant information is automatically delivered to the desktop

Anybody can do it… Source: http://www.nysaes.cornell.edu/comm/staff/zakour

Three levels of web hostingPart of somebody else’s machine

assets.wharton.upenn.edu/~min42www.planetding.com (virtual hosting)

My machine in other people’s networke.g., Exodus

My machine, my network

Choosing a computerUnix

Run Linux on PCWindows NT

Connect to the internet 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?