Electronic Commerce
Ninth Edition
Chapter 8
Web Server Hardware and Software
Electronic Commerce, Ninth Edition 22
Learning Objectives
In this chapter, you will learn about:
• Web server basics
• Sof...
Web Server Basics
• Chapter topics
– Basic technologies to build online business Web sites
• Server software and hardware
...
Web Server Basics (cont’d.)
• Web browser software
– Uses Web browser software (Web client software)
– Make computers work...
Electronic Commerce, Ninth Edition 5
FIGURE 8-1 Platform neutrality of the Web
Electronic Commerce, Ninth Edition 6
Web Server Basics (cont’d.)
• Web server
– Main job: respond to Web client requests
–...
Electronic Commerce, Ninth Edition 7
Dynamic Content Generation
• Dynamic page
– Web page content shaped by program
• Stat...
Electronic Commerce, Ninth Edition 8
Dynamic Content Generation (cont’d.)
• Approaches for creating dynamic content
– Clie...
Electronic Commerce, Ninth Edition 9
Dynamic Content Generation (cont’d.)
• Dynamic page generation technologies
– Server-...
Dynamic Content Generation (cont’d.)
• Dynamic page generation tools
– AJAX (asynchronous JavaScript and XML)
• Creates in...
Electronic Commerce, Ninth Edition 11
Various Meanings of “Server”
• Server
– Computer providing files, making programs av...
Electronic Commerce, Ninth Edition 12
Various Meanings of “Server” (cont’d.)
• Web server
– Computer connected to the Inte...
Web Client/Server Architectures
• Web browser requests files from Web server
– Transportation medium: the Internet
– Reque...
Web Client/Server Architectures
(cont’d.)
• Repeating process
– Client requests, server responds, client displays result
–...
Electronic Commerce, Ninth Edition 15
FIGURE 8-2 Message flows in a two-tier client/server network
Electronic Commerce, Ninth Edition 16
Web Client/Server Architectures
(cont’d.)
• Request message
– Web client message sen...
Web Client/Server Architectures
(cont’d.)
• Server receiving request message executes
command included in message
– Retrie...
Electronic Commerce, Ninth Edition 18
Web Client/Server Architectures
(cont’d.)
• Three-tier architecture
– Extends two-ti...
Electronic Commerce, Ninth Edition 19
FIGURE 8-3 Message flows in a three-tier client/server network
Electronic Commerce, Ninth Edition 20
Web Client/Server Architectures
(cont’d.)
• n-tier architectures
– More than three t...
Electronic Commerce, Ninth Edition 21
Software for Web Servers
• Web server software may:
– Run on one or several computer...
Operating Systems for Web Servers
• Operating system tasks
– Running programs, allocating computer resources,
providing in...
Operating Systems for Web Servers
(cont’d.)
• Microsoft server products
– Considered simple to learn and use
– Raise secur...
Electronic Commerce, Ninth Edition 24
Operating Systems for Web Servers
(cont’d.)
• Linux (cont’d.)
– Commercial Linux exa...
Electronic Commerce, Ninth Edition 25
Web Server Software
• Commonly used Web server programs
– Apache HTTP Server, Micros...
Electronic Commerce, Ninth Edition 26
FIGURE 8-4 Percent of Web active sites that use major
Web server software products
Web Server Software (cont’d.)
• Apache HTTP Server
– 1994: Rob McCool developed Apache
– Extension had original core syste...
Web Server Software (cont’d.)
• Microsoft Internet Information Server
– Bundled with Microsoft Windows Server OS
– Used on...
Electronic Commerce, Ninth Edition 29
Web Server Software (cont’d.)
• Sun Java System Web Server
– Original NCSA Web serve...
Electronic Commerce, Ninth Edition 30
Web Server Software (cont’d.)
• Sun Java System Web Server (cont’d.)
– Runs on about...
Finding Web Server Software
Information
• Netcraft Web site
– “What’s that site running?” link
• Leads to search function ...
Electronic Commerce, Ninth Edition 32
Electronic Mail (E-Mail)
• Electronic commerce important technologies
– Web
• Provid...
Electronic Commerce, Ninth Edition 33
E-Mail Benefits
• Reason people originally attracted to the Internet
• Conveys messa...
E-Mail Drawbacks
• Time spent answering e-mail
– Managers: five minutes per e-mail
– Average person: two hours a day
– Cre...
Electronic Commerce, Ninth Edition 35
Spam
• Magnitude of spam problem
– Recent 24-hour period showed 220 billion spam e-
...
Electronic Commerce, Ninth Edition 36
FIGURE 8-5 Growth of spam as a proportion of all business e-mail
Electronic Commerce, Ninth Edition 37
Spam (cont’d.)
• Antispam efforts and software products
– E-mail server software
• L...
Electronic Commerce, Ninth Edition 38
Solutions to the Spam Problem
• Methods to limit spam and its effects
– Passing new ...
Electronic Commerce, Ninth Edition 39
Solutions to the Spam Problem
(cont’d.)
• Individual user antispam tactics
– Limit s...
Solutions to the Spam Problem
(cont’d.)
• Basic content filtering
– Content-filtering techniques differ in terms of:
• Con...
Solutions to the Spam Problem
(cont’d.)
• Basic content filtering (cont’d.)
– Black list spam filter
• Looks for known spa...
Electronic Commerce, Ninth Edition 42
Solutions to the Spam Problem
(cont’d.)
• Challenge-response content filtering
– Com...
Electronic Commerce, Ninth Edition 43
Solutions to the Spam Problem
(cont’d.)
• Drawbacks
– Potential abuse
– Doubles amou...
Electronic Commerce, Ninth Edition 44
Solutions to the Spam Problem
(cont’d.)
• Advanced content filtering
– More effectiv...
Solutions to the Spam Problem
(cont’d.)
• Advanced content filtering (cont’d.)
– Bayesian revision statistical technique
•...
Electronic Commerce, Ninth Edition 46
Solutions to the Spam Problem
(cont’d.)
• Advanced content filtering (cont’d.)
– Naï...
Electronic Commerce, Ninth Edition 47
FIGURE 8-7 Training screen in the POPFile naïve Bayesian filter
Electronic Commerce, Ninth Edition 48
FIGURE 8-8 POPFile summary statistics page
Electronic Commerce, Ninth Edition 49
Solutions to the Spam Problem
(cont’d.)
• Advanced content filtering (cont’d.)
– POP...
Electronic Commerce, Ninth Edition 50
Solutions to the Spam Problem
(cont’d.)
• Legal solutions
– January 2004: U.S. CAN-S...
Electronic Commerce, Ninth Edition 51
Solutions to the Spam Problem
(cont’d.)
• Legal solutions (cont’d.)
– CAN-SPAM
• Pro...
FIGURE 8-9 U.S. Federal Trade Commission Spam information site home page
Electronic Commerce, Ninth Edition 52
Electronic Commerce, Ninth Edition 53
Solutions to the Spam Problem
(cont’d.)
• Legal solutions (cont’d.)
– Reasons spam c...
Electronic Commerce, Ninth Edition 54
Solutions to the Spam Problem
(cont’d.)
• Legal solutions (cont’d.)
– Spam eliminati...
Electronic Commerce, Ninth Edition 55
Solutions to the Spam Problem
(cont’d.)
• Technical solutions
– Internet design not ...
Solutions to the Spam Problem
(cont’d.)
• Technical solutions (cont’d.)
– Slowing down acknowledgment messages (cont’d.)
•...
Electronic Commerce, Ninth Edition 57
Solutions to the Spam Problem
(cont’d.)
• Technical solutions (cont’d.)
– Teergrubin...
Electronic Commerce, Ninth Edition 58
Web Site Utility Programs
• TCP/IP supports utility programs (tools)
– Run on Web se...
Electronic Commerce, Ninth Edition 59
Finger and Ping Utilities
• Finger program
– Runs on UNIX operating systems
– Provid...
Tracert and Other Route-Tracing
Programs
• Tracert (TRACE RouTe)
– Sends data packets to every computer on path
• Between ...
Electronic Commerce, Ninth Edition 61
Tracert and Other Route-Tracing
Programs (cont’d.)
• Tracert (cont’d.)
– Sends serie...
Electronic Commerce, Ninth Edition 62
FIGURE 8-10 Tracing a path between two computers on the Internet
Electronic Commerce, Ninth Edition 63
Telnet and FTP Utilities
• Telnet program
– Provides remote login capability
– Usefu...
Electronic Commerce, Ninth Edition 64
Telnet and FTP Utilities (cont’d.)
• File Transfer Protocol (FTP)
– Part of TCP/IP r...
Electronic Commerce, Ninth Edition 65
Telnet and FTP Utilities (cont’d.)
• FTP remote computer access methods
– FTP client...
Electronic Commerce, Ninth Edition 66
Indexing and Searching Utility
Programs
• Search engines (search tools)
– Search for...
Electronic Commerce, Ninth Edition 67
Data Analysis Software
• Web servers capture visitor information
– Placed into Web l...
Electronic Commerce, Ninth Edition 68
Link-Checking Utilities
• Dead link
– Displays error message rather than Web page wh...
Electronic Commerce, Ninth Edition 69
Link-Checking Utilities (cont’d.)
• Link-checking programs
– Adobe Dreamweaver, Elso...
Electronic Commerce, Ninth Edition 70
Remote Server Administration
• Remote server administration
– Web site administrator...
Electronic Commerce, Ninth Edition 71
Web Server Hardware
• Hosting electronic commerce operations
– Wide variety of compu...
Electronic Commerce, Ninth Edition 72
Server Computers
• Comparing desktop PCs to server computers
– Servers use faster an...
Electronic Commerce, Ninth Edition 73
Server Computers (cont’d.)
• Blade servers: servers-on-a-card
– Small: 300 installed...
Electronic Commerce, Ninth Edition 74
Web Server Performance Evaluation
• Benchmarking: testing to compare hardware and
so...
Electronic Commerce, Ninth Edition 75
Web Server Performance Evaluation
(cont’d.)
• Throughput: HTTP requests hardware and...
Web Server Hardware Architectures
• Electronic commerce Web sites use tiered
architecture
– Divides work of serving Web pa...
Electronic Commerce, Ninth Edition 77
Web Server Hardware Architectures
(cont’d.)
• Distributed architecture (decentralize...
Web Server Hardware Architectures
(cont’d.)
• Load-balancing systems
– Load-balancing switch
• Network hardware monitoring...
Electronic Commerce, Ninth Edition 79
FIGURE 8-12 A load-balancing system in a decentralized architecture
Web Server Hardware Architectures
(cont’d.)
• Load-balancing systems (cont’d.)
– More complex load-balancing systems
• Inc...
Electronic Commerce, Ninth Edition 81
FIGURE 8-13 Complex load balancing
Summary
• Client/server Web architecture
– HTTP-based tiered architectures
• Several operating systems used on Web servers...
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Chapter 8

  1. 1. Electronic Commerce Ninth Edition Chapter 8 Web Server Hardware and Software
  2. 2. Electronic Commerce, Ninth Edition 22 Learning Objectives In this chapter, you will learn about: • Web server basics • Software for Web servers • E-mail management and spam control issues • Internet and Web site utility programs • Web server hardware
  3. 3. Web Server Basics • Chapter topics – Basic technologies to build online business Web sites • Server software and hardware • Utility function software • Client/server architectures – Used in LANs, WANs, and the Web – Client requests server services • Servers – Have more memory and larger, faster disk drives Electronic Commerce, Ninth Edition 3
  4. 4. Web Server Basics (cont’d.) • Web browser software – Uses Web browser software (Web client software) – Make computers work as Web clients – Web browser also called Web client software – Platform neutral • Critical in rapid spread and widespread Web acceptance Electronic Commerce, Ninth Edition 4
  5. 5. Electronic Commerce, Ninth Edition 5 FIGURE 8-1 Platform neutrality of the Web
  6. 6. Electronic Commerce, Ninth Edition 6 Web Server Basics (cont’d.) • Web server – Main job: respond to Web client requests – Main elements: • Hardware, operating system software, Web server software • Web site goals followed by site development estimations – Number of visitors – Number of pages viewed during an average visit – How large pages will be – Maximum number of simultaneous visitors
  7. 7. Electronic Commerce, Ninth Edition 7 Dynamic Content Generation • Dynamic page – Web page content shaped by program • Static page – Unchanging page retrieved from Web server file(s) • Web sites using collection of HTML pages – Changed by editing HTML (cumbersome) • Specific query-customized pages not allowed • Dynamic content – Nonstatic information constructed in response to Web client’s request – Gives user an interactive experience
  8. 8. Electronic Commerce, Ninth Edition 8 Dynamic Content Generation (cont’d.) • Approaches for creating dynamic content – Client-side scripting • Software operates on the Web client (browser) • Software changes Web page display in response to a user’s actions • Software examples: JavaScript or Adobe Flash – Server-side scripting • Program runs on a Web server • Program creates Web page in response to request for specific information from a Web client
  9. 9. Electronic Commerce, Ninth Edition 9 Dynamic Content Generation (cont’d.) • Dynamic page generation technologies – Server-side scripts mixed with HTML-tagged text – Examples: • Microsoft Active Server Pages (ASP): ASP.NET • Sun Microsystems JavaServer Pages (JSP): Java servlets • Open-source Apache Software Foundation Hypertext Preprocessor (PHP) • Adobe Cold Fusion – Server-side languages generally use: • Common Gateway Interface (CGI)
  10. 10. Dynamic Content Generation (cont’d.) • Dynamic page generation tools – AJAX (asynchronous JavaScript and XML) • Creates interactive Web sites looking like applications • Example: Google Maps – Ruby on Rails • Creates dynamic Web pages with interface looking like application – Python • Scripting language Electronic Commerce, Ninth Edition 10
  11. 11. Electronic Commerce, Ninth Edition 11 Various Meanings of “Server” • Server – Computer providing files, making programs available to other computers connected to it through a network – Software used to make files and programs available • May be part of the operating system (OS) • Server OS software may be referred to as server software (confusing) – May connect through a router to the Internet • Run Web server software
  12. 12. Electronic Commerce, Ninth Edition 12 Various Meanings of “Server” (cont’d.) • Web server – Computer connected to the Internet – Runs Web server software • Makes server’s files available to other computers • E-mail server: handles incoming, outgoing e-mail • Database server – Runs database management software • “Server” describes several types of computer hardware, software – Note context for a better understanding
  13. 13. Web Client/Server Architectures • Web browser requests files from Web server – Transportation medium: the Internet – Request formatted by browser using HTTP – Request sent to server computer – Server receives request • Retrieves file containing requested Web page • Formats using HTTP • Sends back to client over the Internet – Client Web browser software • Displays page on client machine Electronic Commerce, Ninth Edition 13
  14. 14. Web Client/Server Architectures (cont’d.) • Repeating process – Client requests, server responds, client displays result – Possible result: • Dozens or even hundreds of separate server responses – Graphics and other objects • May be slow to appear in client’s Web browser window • Two-tier client/server architecture – One client and one server computer • Create and read messages Electronic Commerce, Ninth Edition 14
  15. 15. Electronic Commerce, Ninth Edition 15 FIGURE 8-2 Message flows in a two-tier client/server network
  16. 16. Electronic Commerce, Ninth Edition 16 Web Client/Server Architectures (cont’d.) • Request message – Web client message sent to request file(s) from a Web server – Three major parts • Request line: contains command, target resource name, protocol name, version number • Optional request headers: file type information client accepts • Optional entity body: passes bulk information to server
  17. 17. Web Client/Server Architectures (cont’d.) • Server receiving request message executes command included in message – Retrieves Web page file from disk – Creates response message: sent back to client • Identical in structure to request message (slightly different function) • Response header line: server HTTP version, response status, status information explanation • Response header field: information describing server’s attributes • Entity body: returns HTML page requested Electronic Commerce, Ninth Edition 17
  18. 18. Electronic Commerce, Ninth Edition 18 Web Client/Server Architectures (cont’d.) • Three-tier architecture – Extends two-tier architecture • Allows additional processing before server responds to client’s request – Often includes databases and related software applications • Supplies information to the Web server – Web server uses software applications’ output when responding to client requests
  19. 19. Electronic Commerce, Ninth Edition 19 FIGURE 8-3 Message flows in a three-tier client/server network
  20. 20. Electronic Commerce, Ninth Edition 20 Web Client/Server Architectures (cont’d.) • n-tier architectures – More than three tiers – Example: catalog-style Web site search, update, display functions • Track customer purchases stored in shopping carts, look up sales tax rates, keep track of customer preferences, query inventory databases, keep company catalog current
  21. 21. Electronic Commerce, Ninth Edition 21 Software for Web Servers • Web server software may: – Run on one or several computer operating systems • Section topics – Learn about operating system software used on most Web servers – Learn about Web server software itself – Learn about other programs • Running on Web servers or other computers as part of electronic commerce operations
  22. 22. Operating Systems for Web Servers • Operating system tasks – Running programs, allocating computer resources, providing input and output services – Larger system responsibilities • Tracking multiple users, ensuring no interference • Web server operating systems software – Microsoft Windows Server products – Linux – UNIX-based operating systems • FreeBSD or Sun’s Solaris Electronic Commerce, Ninth Edition 22
  23. 23. Operating Systems for Web Servers (cont’d.) • Microsoft server products – Considered simple to learn and use – Raise security concerns • Linux – Open-source – Fast, efficient, easy to install – Can be downloaded free from the Web – Most companies buy it through a commercial distributor • Includes additional utilities, support Electronic Commerce, Ninth Edition 23
  24. 24. Electronic Commerce, Ninth Edition 24 Operating Systems for Web Servers (cont’d.) • Linux (cont’d.) – Commercial Linux examples: Mandriva, Red Hat, SCO Group, SuSE Linux Enterprise • UNIX-based operating system – Solaris
  25. 25. Electronic Commerce, Ninth Edition 25 Web Server Software • Commonly used Web server programs – Apache HTTP Server, Microsoft Internet Information Server (IIS), Sun Java System Web Server (JSWS) • Netcraft December 2009 Web survey indicates: – Web server software market share stabilized in recent years • Web server performance differences – Workload, operating system, Web pages served
  26. 26. Electronic Commerce, Ninth Edition 26 FIGURE 8-4 Percent of Web active sites that use major Web server software products
  27. 27. Web Server Software (cont’d.) • Apache HTTP Server – 1994: Rob McCool developed Apache – Extension had original core system with patches • Known as “a patchy” server (“Apache”) – Reasons Apache dominated Web since 1996 • Free and performs efficiently – Runs on many operating systems and supporting hardware • FreeBSD-UNIX, HP-UX, Linux, Microsoft Windows, SCO-UNIX, and Solaris Electronic Commerce, Ninth Edition 27
  28. 28. Web Server Software (cont’d.) • Microsoft Internet Information Server – Bundled with Microsoft Windows Server OS – Used on many corporate intranets – Used by small and large sites – Run only on Windows server operating systems (by design) – Supports ASP, ActiveX Data Objects, SQL database queries – Produces dynamic Web pages by: • Including HTML pages, ActiveX components, scripts Electronic Commerce, Ninth Edition 28
  29. 29. Electronic Commerce, Ninth Edition 29 Web Server Software (cont’d.) • Sun Java System Web Server – Original NCSA Web server program descendent – Former names: Sun ONE, Netscape Enterprise Server, iPlanet Enterprise Server – 2009: key elements became open source – Runs on many operating systems: • HP-UX, Solaris, Windows
  30. 30. Electronic Commerce, Ninth Edition 30 Web Server Software (cont’d.) • Sun Java System Web Server (cont’d.) – Runs on about 1 percent of all Web servers – Runs on some of the busiest servers • BMW, Dilbert, E*TRADE, Excite, Lycos, Schwab – Supports dynamic application development for server- side applications – Provides connectivity to a number of database products
  31. 31. Finding Web Server Software Information • Netcraft Web site – “What’s that site running?” link • Leads to search function page • Provides operating system, Web server software specific site now running • Provides past site information Electronic Commerce, Ninth Edition 31
  32. 32. Electronic Commerce, Ninth Edition 32 Electronic Mail (E-Mail) • Electronic commerce important technologies – Web • Provides interactions between Web servers and clients – E-mail: • Used to gather information, execute transactions, perform other electronic commerce related tasks • Originated from ARPANET • Most popular form of business communication
  33. 33. Electronic Commerce, Ninth Edition 33 E-Mail Benefits • Reason people originally attracted to the Internet • Conveys messages in seconds – Contains simple ASCII text or character formatting • Useful feature – Attachments: most important message part • E-mail uses – Confirm receipt of customer orders, confirm shipment of items ordered, send information about a purchase to buyer, announce specials and sales, keep in touch with customers
  34. 34. E-Mail Drawbacks • Time spent answering e-mail – Managers: five minutes per e-mail – Average person: two hours a day – Creating resentment • Computer virus (virus) – Program attaching itself to another program • Causes damage when host program activated – Attachment can contain viruses – Cost for e-mail convenience • Virus protection software, dealing with security threats Electronic Commerce, Ninth Edition 34
  35. 35. Electronic Commerce, Ninth Edition 35 Spam • Magnitude of spam problem – Recent 24-hour period showed 220 billion spam e- mail messages sent – Researchers believe spam growth has leveled off • Appears to be declining slightly – Until effective technical solutions implemented • 90 percent of all e-mail messages will continue to be spam
  36. 36. Electronic Commerce, Ninth Edition 36 FIGURE 8-5 Growth of spam as a proportion of all business e-mail
  37. 37. Electronic Commerce, Ninth Edition 37 Spam (cont’d.) • Antispam efforts and software products – E-mail server software • Limit amount of spam getting to employees – Client-based spam-filtering programs – Set filters available within client e-mail client software – Most effective • Eliminate spam before downloaded to user
  38. 38. Electronic Commerce, Ninth Edition 38 Solutions to the Spam Problem • Methods to limit spam and its effects – Passing new laws – Technical changes in Internet mail-handling systems – Use existing laws and current technologies • Requires cooperation from large numbers of organizations and businesses – Use tactics available for individual e-mail users
  39. 39. Electronic Commerce, Ninth Edition 39 Solutions to the Spam Problem (cont’d.) • Individual user antispam tactics – Limit spammers access to e-mail address – Use complex e-mail address • xq7yy23@mycompany.com – Control e-mail address exposure • Spammer software robots search for e-mail addresses • Discussion boards, chat rooms, other online sources – Use multiple e-mail addresses • Switch to another if spammers use one – Use filtering techniques • Based on contents
  40. 40. Solutions to the Spam Problem (cont’d.) • Basic content filtering – Content-filtering techniques differ in terms of: • Content elements examined • Spam indications • How strictly message classification rules applied – Basic content filters examine e-mail headers – Filtering task software location • Client-level filtering: individual users’ computers • Server-level filtering: mail server computers Electronic Commerce, Ninth Edition 40
  41. 41. Solutions to the Spam Problem (cont’d.) • Basic content filtering (cont’d.) – Black list spam filter • Looks for known spammers in incoming messages’ From addresses – White list spam filter • Looks for good sender From addresses in incoming messages • High false positives rate – Used in client-level or server-level filters • Can also use approaches together with other content- filtering approaches Electronic Commerce, Ninth Edition 41
  42. 42. Electronic Commerce, Ninth Edition 42 Solutions to the Spam Problem (cont’d.) • Challenge-response content filtering – Compares all incoming messages to a white list • If sender not on white list, automated e-mail response sent (challenge) • Challenge asks sender to reply to e-mail (response) • Reply must contain response to a challenge presented in the e-mail – Designed so human can respond easily – More information • Carnegie Mellon University CAPTCHA Project site
  43. 43. Electronic Commerce, Ninth Edition 43 Solutions to the Spam Problem (cont’d.) • Drawbacks – Potential abuse – Doubles amount of useless e-mail messages sent FIGURE 8-6 Example of a challenge that uses distorted letters and numbers
  44. 44. Electronic Commerce, Ninth Edition 44 Solutions to the Spam Problem (cont’d.) • Advanced content filtering – More effective than basic content filters – Looks for spam indicators in entire e-mail message • Indicator identified: message’s spam “score” raised – Indicator types • Words, word pairs, certain HTML codes, information about where word occurs – Problems • Spammers stop including defined indicators
  45. 45. Solutions to the Spam Problem (cont’d.) • Advanced content filtering (cont’d.) – Bayesian revision statistical technique • Additional knowledge used to revise earlier probability estimates – Naïve Bayesian filter • Software begins by not classifying messages • User reviews messages • Message type indicated to software: spam (not spam) • Software gradually learns message element Electronic Commerce, Ninth Edition 45
  46. 46. Electronic Commerce, Ninth Edition 46 Solutions to the Spam Problem (cont’d.) • Advanced content filtering (cont’d.) – Naïve Bayesian filter success rates • Few dozen messages classified: 80 percent effective • Eventually: effective rate rises above 95 percent – 2002: POPFile released • First functional Bayesian filter product for individuals • Open-source software development project • Installs on individual client computers • Works with many different e-mail clients: Post Office Protocol (POP) connection required
  47. 47. Electronic Commerce, Ninth Edition 47 FIGURE 8-7 Training screen in the POPFile naïve Bayesian filter
  48. 48. Electronic Commerce, Ninth Edition 48 FIGURE 8-8 POPFile summary statistics page
  49. 49. Electronic Commerce, Ninth Edition 49 Solutions to the Spam Problem (cont’d.) • Advanced content filtering (cont’d.) – POPFile success • Initially caught 30 percent of spam messages • After two weeks: caught more than 90 percent • Eventually: caught more than 99 percent • False positives: small rate – POPFile magnet feature • Implement white and black list filtering – Naïve Bayesian filters’ effectiveness • Very effective client-level filters • Major drawback: users must update filters regularly
  50. 50. Electronic Commerce, Ninth Edition 50 Solutions to the Spam Problem (cont’d.) • Legal solutions – January 2004: U.S. CAN-SPAM law went into effect • Spam decreased first three months – After no threat of broad federal prosecution: • Spam rates increased – CAN-SPAM regulates: • All e-mail messages • Messages advertising or promoting commercial product or service • Messages promoting Web site content
  51. 51. Electronic Commerce, Ninth Edition 51 Solutions to the Spam Problem (cont’d.) • Legal solutions (cont’d.) – CAN-SPAM • Prohibits misleading e-mail message address header information, e-mail address transfer • Possible $11,000 fine and imprisonment – More CAN-SPAM information • U.S. Federal Trade Commission CAN-SPAM Law information pages
  52. 52. FIGURE 8-9 U.S. Federal Trade Commission Spam information site home page Electronic Commerce, Ninth Edition 52
  53. 53. Electronic Commerce, Ninth Edition 53 Solutions to the Spam Problem (cont’d.) • Legal solutions (cont’d.) – Reasons spam continuing • Spammers simply continue violating laws: no fear of prosecution • Mail servers located in other countries: jurisdiction unclear • Fines or collection of damages difficult to obtain • Spammers evade cease-and-desist orders: move operations from one server to another (in minutes) • Spammers hijack servers to forward mail • FTC refused to create do-not-spam list
  54. 54. Electronic Commerce, Ninth Edition 54 Solutions to the Spam Problem (cont’d.) • Legal solutions (cont’d.) – Spam elimination requires cost-effective prosecution – Cost effective when: • Spammers identified easily – Best way to make spammers easier to find • Make technical changes in the e-mail transport mechanism
  55. 55. Electronic Commerce, Ninth Edition 55 Solutions to the Spam Problem (cont’d.) • Technical solutions – Internet design not intended for today's needs • E-mail: incidental afterthought • No mechanisms ensuring e-mail sender identity – Internet’s polite set of rules • Send and wait for acknowledgement (fast) – Slowing down acknowledgment messages • Originating computer will slow (must continue to scan for acknowledgment) • Will not send more messages until acknowledgment received
  56. 56. Solutions to the Spam Problem (cont’d.) • Technical solutions (cont’d.) – Slowing down acknowledgment messages (cont’d.) • Requires defending company to develop way to identify computers sending spam – IBM software: access to large database tracking such computers – Other vendors: software identifying multiple e-mail messages from single source in rapid succession – Once identified: software delays sending message acknowledgment Electronic Commerce, Ninth Edition 56
  57. 57. Electronic Commerce, Ninth Edition 57 Solutions to the Spam Problem (cont’d.) • Technical solutions (cont’d.) – Teergrubing: launching a return attack • Sending e-mail messages back to computer originating suspected spam – Teergrubing objective • Ensure computer sending spam is trapped • Drag down ability to send spam • Concern: counterattack might violate laws – Ultimate spam problem • New e-mail protocols providing absolute verification of e-mail message source
  58. 58. Electronic Commerce, Ninth Edition 58 Web Site Utility Programs • TCP/IP supports utility programs (tools) – Run on Web server or client computers • Earliest Internet utility program – E-mail • Most important utility • Key element in electronic commerce strategies
  59. 59. Electronic Commerce, Ninth Edition 59 Finger and Ping Utilities • Finger program – Runs on UNIX operating systems – Provides information about other network users – Many organizations disable Finger command • Privacy and security – Built into some e-mail programs • Ping: Packet Internet Groper – Tests connectivity between two Internet-connected computers – Provides performance data about connection – Available as freeware and shareware
  60. 60. Tracert and Other Route-Tracing Programs • Tracert (TRACE RouTe) – Sends data packets to every computer on path • Between one computer and another computer – Clocks packets’ round-trip times – Provides indication of time message needs to travel from one computer to another and back – Ensures remote computer online – Pinpoints data traffic congestion – Calculates and displays: • Number of hops between computers • Time to traverse entire one-way path Electronic Commerce, Ninth Edition 60
  61. 61. Electronic Commerce, Ninth Edition 61 Tracert and Other Route-Tracing Programs (cont’d.) • Tracert (cont’d.) – Sends series of packets to particular destination – Router along Internet path between originating and destination computers: • Reports IP address and time packet arrived – Graphical user interface route-tracing programs: • Provides map plot of packets’ route – Determines Internet locations with greatest delay – Example • Visualware VisualRoute route-tracing program
  62. 62. Electronic Commerce, Ninth Edition 62 FIGURE 8-10 Tracing a path between two computers on the Internet
  63. 63. Electronic Commerce, Ninth Edition 63 Telnet and FTP Utilities • Telnet program – Provides remote login capability – Useful if no Web interface – Availability • Free Internet downloads, Microsoft Telnet.exe – Provides remote troubleshooting – Telnet protocol: set of rules used by Telnet program – Web browser Telnet client • “telnet://” followed by remote host domain name – Telnet use decreasing
  64. 64. Electronic Commerce, Ninth Edition 64 Telnet and FTP Utilities (cont’d.) • File Transfer Protocol (FTP) – Part of TCP/IP rules defining formats • Transfer files between TCP/IP-connected computers – Useful services • Displaying remote, local computers’ directories • Changing current client’s or server’s active directory • Creating and removing local and remote directories – Uses TCP and its built-in error controls: • To copy files accurately
  65. 65. Electronic Commerce, Ninth Edition 65 Telnet and FTP Utilities (cont’d.) • FTP remote computer access methods – FTP client program – Browser protocol name (ftp://) before remote computer domain name • Full-privilege FTP – FTP connection to computer (user has an account) • Anonymous FTP – Guest account • Username: “anonymous” • Password: e-mail address
  66. 66. Electronic Commerce, Ninth Edition 66 Indexing and Searching Utility Programs • Search engines (search tools) – Search for requested documents on specific site or entire Web • Indexing program – Provides full-text indexing • Browser search methods – Compare index terms to requester’s search term – Use complex relevance ranking rules • Advanced search engine software (Google) • Web server software contains indexing software
  67. 67. Electronic Commerce, Ninth Edition 67 Data Analysis Software • Web servers capture visitor information – Placed into Web log file (grows quickly) • Third-party Web log file analysis programs summarize information – Query log file – Return gross summary information or accumulating details • Popular Web log file analysis programs – Adobe Omniture, Urchin from Google, WebTrends
  68. 68. Electronic Commerce, Ninth Edition 68 Link-Checking Utilities • Dead link – Displays error message rather than Web page when clicked • Link checker – Examines each site page • Reports broken, incorrect URLs – Identifies orphan files • Web site file not linked to a page – Script checking and HTML validation
  69. 69. Electronic Commerce, Ninth Edition 69 Link-Checking Utilities (cont’d.) • Link-checking programs – Adobe Dreamweaver, Elsop LinkScan • Reverse link checker – Checks company’s link exchange program sites – Ensures link exchange partners fulfilling obligation • Include link back to company’s Web site – Example: LinxCop
  70. 70. Electronic Commerce, Ninth Edition 70 Remote Server Administration • Remote server administration – Web site administrator controls Web site • From any Internet-connected computer – Provides convenience – Examples • Website Garage • NetMechanic
  71. 71. Electronic Commerce, Ninth Edition 71 Web Server Hardware • Hosting electronic commerce operations – Wide variety of computer brands, types, sizes used – Small companies • Run Web sites on desktop PCs – Most Web sites • Operate on computers designed for site hosting
  72. 72. Electronic Commerce, Ninth Edition 72 Server Computers • Comparing desktop PCs to server computers – Servers use faster and higher-capacity hardware • Costs – Low-end: $800-$1,500 – More common: $2,000-$200,000 • Companies selling Web server hardware provide Web site configuration tools • Housing Web server computers – Freestanding cases – Installed in equipment racks
  73. 73. Electronic Commerce, Ninth Edition 73 Server Computers (cont’d.) • Blade servers: servers-on-a-card – Small: 300 installed in single 6-foot rack • Fundamental Web server job – Process and respond to HTTP Web client requests • Virtual server (virtual host) – Maintains more than one server on one machine – Different groups have separate domain names • All domain names refer to same physical Web server
  74. 74. Electronic Commerce, Ninth Edition 74 Web Server Performance Evaluation • Benchmarking: testing to compare hardware and software performance • Elements affecting overall server performance – Hardware, operating system software, server software, connection speed, user capacity, type of Web pages delivered – Connection speed (T3 faster than T1) – Number of users server can handle • Important and hard to measure
  75. 75. Electronic Commerce, Ninth Edition 75 Web Server Performance Evaluation (cont’d.) • Throughput: HTTP requests hardware and software process in a unit of time • Response time: time server requires to process one request • Choosing Web server hardware configurations – Run tests on various combinations, consider scalability, compare standard benchmarks • Run benchmarks regularly • Objective – Provide site visitors with best service possible
  76. 76. Web Server Hardware Architectures • Electronic commerce Web sites use tiered architecture – Divides work of serving Web pages – May use more than one computer within each tier • Server farms: large collections of servers – Lined up row after row • Centralized architecture – Uses a few large and fast computers • Requires expensive computers • More sensitive to technical problems • Requires adequate backup plans Electronic Commerce, Ninth Edition 76
  77. 77. Electronic Commerce, Ninth Edition 77 Web Server Hardware Architectures (cont’d.) • Distributed architecture (decentralized architecture) – Uses large number of less-powerful computers • Spreads risk over large number of servers • Uses less-expensive servers • Requires additional hubs or switches to connect servers to each and the Internet • Requires cost of load balancing
  78. 78. Web Server Hardware Architectures (cont’d.) • Load-balancing systems – Load-balancing switch • Network hardware monitoring server workloads • Assigns incoming Web traffic to the server with most available capacity – Simple load-balancing system • Traffic enters through site’s router • Encounters load-balancing switch • Directs traffic to best Web server Electronic Commerce, Ninth Edition 78
  79. 79. Electronic Commerce, Ninth Edition 79 FIGURE 8-12 A load-balancing system in a decentralized architecture
  80. 80. Web Server Hardware Architectures (cont’d.) • Load-balancing systems (cont’d.) – More complex load-balancing systems • Incoming Web traffic enters from two or more routers • Directed to groups of dedicated Web servers Electronic Commerce, Ninth Edition 80
  81. 81. Electronic Commerce, Ninth Edition 81 FIGURE 8-13 Complex load balancing
  82. 82. Summary • Client/server Web architecture – HTTP-based tiered architectures • Several operating systems used on Web servers • Web server utility programs can be helpful • E-mail has benefits and drawbacks – Spam problem has grown dramatically • Web server hardware – Important consideration in online business site design • Understand Web server performance – Factors, evaluation tools, solutions Electronic Commerce, Ninth Edition 82

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