Types of Websites
- Web site planning is first step
– Determine site goals - Estimate visitors, types of files
- Assess existing information technology staff
- Five Web site categories
– Development sites: evaluate Web designs
– Intranets: house internal information
– Extranets: allow outside party access
– Transaction-processing sites: commerce site
– Content-delivery sites: deliver news, histories,
summaries, digital content
Web Client and Web Servers
- Client/server architectures
– Client requests services from server - Client computer
– Uses Web browser software (Web client software) - Server computer
– More memory and larger, faster disk drives - Platform neutral Web software
– Various computers communicate easily, effectively
– Critical ingredient for rapid spread, widespread Web acceptance
Dynamic Content
•Server performance affected by:
– Web page mix and type delivered to client
• Dynamic page
– Client Web page content shaped by program
• Static page
– Unchanging page retrieved from disk
– Sometimes stored in Web server’s active memory
• Static versus dynamic page delivery
– Static page requires less computing power
– Servers delivering mostly static pages perform better
• Dynamic content
– Nonstatic information constructed in response
to Web client’s request
– Example: order inquiry with unique customer
number
• Web sites using collection of HTML pages
– Changed by editing HTML (cumbersome)
• Specific query-customized pages not allowed
• Create customized pages on the fly using:
– Server-side scripting
– Dynamic page-generation technology
• Server-side scripting
– Used by first Web sites providing dynamic pages
– Also called:
• Server-side includes
• Server-side technologies
– Web server programs create Web pages before sending pages back to client
– Server-side technologies are slow
– Large online business Web sites alternative
• Dynamic page-generation technologies
– Examples
• Microsoft Active Server Pages (ASP)
• Sun Microsystems JavaServer Pages (JSP)
• Open-source Apache Software Foundation
Hypertext Preprocessor (PHP)
• Adobe Cold Fusion
– Dynamic Web page creation
• Server-side scripts mix with HTML tagged text
– Java servlets
• Server-side programs created using Java programming language (Sun)
– Popular tools to generate dynamic Web
pages and make them interactive
• AJAX (asynchronous JavaScript and XML): creates interactive Web sites looking like applications
• Ruby on Rails: creates dynamic Web pages with interface looking like application
• Python scripting language
• The future of dynamic Web page generation
– Criticisms of previous approaches
• Do not solve problem of dynamic page generation
• Shift dynamic page creation from HTML coders to ASP (JSP, PHP) programmers
– Apache Cocoon project initiative
• Query XML formatted data and generate output in multiple formats
• HTML output: useful for dynamic Web page creation
• May apply style sheet to data: tailored response
• Portable Document Format (PDF) file, Wireless Markup Language (WML) file
– Latest Cocoon version
• Divides work into four areas of concern
• Limits area interactions to five specific contracts
• Breaks direct connection between logic and style
• Future dynamic Web page design easier
– Other initiatives
• Microsoft: Microsoft.NET Framework
• Oracle: including explicit PHP support (other scripting languages) in its database products
Web Client/Server Communication
- •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 - Browser displays information if it is an HTML page
- Graphics can be slow to appear
Operating System for Web Servers
• Operating system tasks
– Running programs, allocating computer resources, providing input and output services
– More responsibilities (large systems)
• Tracking multiple users, ensuring no interference
• Microsoft Windows Server products
– Considered simple to learn and use
– Raise security concerns
• Linux-, UNIX-based products
– Popular
– Considered secure as Web servers
• Linux (open-source operating system)
– Fast, efficient, installs easily
– Open-source software
• Developed by community of programmers
• Software available for download (free)
• Others use it, improve it, submit improved versions
• More information
– Open Source Initiative Web site
• Companies selling Web server computers
– Include Linux in default configurations
• Companies may buy Linux through commercial distributors
– Include useful additional software (installation utilities)
– Provide support contracts
– Examples: Mandriva, Red Hat, SCO Group, SuSE
• Sun Microsystems
– Sells Web server hardware
– Solaris: UNIX-based operating system
Web Server Software
• Commonly used Web server programs
– Apache HTTP Server, Microsoft Internet Information Server (IIS), Sun Java System Web Server (JSWS)
• Netcraft networking consulting company Web
survey
– Measures Web server software’s relative popularity
• Stabilizing in recent years
• Web server performance differences
– Workload, operating system, Web pages served
• Critical: choose right server for each business need
• Apache HTTP Server
– 1994: Rob McCool developed Apache
– Original core system with lots of patches
• Known as “a patchy” server
– Ongoing group software development effort
– Dominated Web since 1996
• Free, performs efficiently
– In IBM WebSphere application server package
– Zeus based on Apache open-source code
– Most widely installed Web server software package
– Runs on many operating systems, hardware
• Microsoft Internet Information Server
– Bundled with Microsoft Windows Server operating systems
• Runs on Windows server operating system (by design)
– Used on many corporate intranets
• Adopted Microsoft products as standard products
– ASP, ActiveX Data Objects, SQL database queries
– Microsoft FrontPage Web site development tool, reporting tools
– HTML pages, ActiveX components, scripts can be combined to produce dynamic Web pages
• Sun Java System Web Server (Sun ONE, iPlanet, Netscape)
– Original NCSA Web server program descendent
– Former names: Sun ONE, Netscape Enterprise Server, iPlanet Enterprise Server
– AOL-Sun Microsystems partnership called iPlanet
• Agreement expired March 2002
• iPlanet became part of Sun
– Not free: reasonable licensing fee
– Runs on many operating systems
–Web server use •One percent of all Web servers •Busiest and best-known Internet sites: BMW, Dilbert, E*TRADE, Excite, Lycos, Schwab •More than 30 percent of all public Web sites •More than half of top 100 enterprise Web sites –Supports dynamic application development –Provides connectivity to database products
Electronic Mail
- Electronic commerce important technologies
– Web: interactions between Web servers and clients
– E-mail - Gather information, execute transactions, perform other electronic commerce-related tasks
- 1970s origin: ARPANET
- Most popular form of business communication
- Far surpassing: telephone, conventional mail, fax (in volume)
Spam
• Magnitude of spam problem
– 24-hour period in 2008
• 220 billion spam e-mail messages sent
– Researchers believe:
• More than 98 percent of all e-mail messages will be spam before effective technical solutions implemented
• Spam leveling off (approaching 100 percent)
– Absolute spam e-mail numbers could continue to grow rapidly
• AOL active has taken active role limiting spam through legal channels
– 2005: temporary decline
– Now: resumed increase
• Antispam efforts
– Limit spam annoyance and cost
– E-mail server computer software
• Limit amount of spam getting through to employees
– Individual users
• Install client-based spam-filtering programs, set filters
• More effective, less costly to eliminate spam before downloaded
Solution to the Spam Problems
• Some solutions require:
– Passing of new laws
– Technical changes in Internet mail-handling systems
• Other approaches
– Implemented with existing laws and current technologies
• Requires cooperation from large numbers of organizations and businesses
• Individual e-mail users
– Few tactics available to reduce spam
• Individual user antispam tactics
– Focus
• Limit spammer’s access to (use of) e-mail address
– Use complex e-mail address
– Control e-mail address exposure; software robots
• Discussion boards, chat rooms, other online sources
– Use multiple e-mail addresses
• Switch to another if spammers uses one
Legal Solutions to the Spam Problems
• January 2004: U.S. CAN-SPAM law went into effect
• Spammers slowed down activities immediately
• Seeing no threat of broad federal prosecution:
– Spam rates increased
– Spam estimate: over 80 percent of all e-mail messages
• CAN-SPAM
– Regulates all e-mail messages
– Regulates messages advertising or promoting commercial product or service
– Includes messages promoting Web site content
– Prohibits misleading e-mail message address header information, facilitating agreed-upon transaction or updating customer in existing business relationship
– Successful prosecution: fines ($11,000) and imprisonment
Web Server Hardware
• Hosting electronic commerce operations
– Use wide variety of computer brands, types, sizes
– Some small companies run Web sites on desktop PCs
– Most Web sites operated on computers
• Designed for site hosting
Server Computers
• Use more capable hardware elements
– Usually more expensive than workstation PCs
• Price range of Web server computer
– Between $3000 and $200,000
• Companies selling Web server hardware
– Provide Web site configuration tools
• Visitors design their own Web server
• Housing Web server computers
– Freestanding cases
– Installed in equipment racks
• Blade servers: servers-on-a-card
– Small: 300 installed in single 6-foot rack
• Fundamental Web server job
– Process and respond to Web client requests
• Sent using HTTP
• 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
Web Server Hardware Architecture
• 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
• Distributed architecture (decentralized architecture)
– Uses a large number of less powerful computers
• Spreads risk over large number of servers
• Servers are less expensive
• Requires additional hubs or switches to connect servers to each and the Internet
• Requires cost of load balancing
• Load-balancing systems ($5000 – $50,000)
– Network hardware monitoring; server workloads
• Assigns incoming Web traffic to 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
– More complex load-balancing systems
• Incoming Web traffic enters from two or more routers
• Directed to groups of dedicated Web server
ecommerce and website development 