Internet Infrastructure Min Ding Smeal College of Business Administration Pennsylvania 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 Suite  Web Technology – building blocks of e- commerce  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  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 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.,

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 …

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.  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 Servers  AOLserver (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) designator assets.wharton.upenn.eduserver name ~min42pathname to resource

Web content transport  Pull – 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

Anybody can do it… Source:

Three levels of web hosting  Part of somebody else’s machine assets.wharton.upenn.edu/~min42 (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  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?