Introduction to e-Commerce
Web Server Hardware and
Software
Objectives
In this chapter, you will learn about:
Š Web server basics
Š Software for Web servers
Š E-mail management and spam control issues
Š Internet and Web site utility programs
Š Web server hardware
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Web Server Basics
Š Main job of a Web server computer is to
respond to requests from Web client
computers
Š Three main elements of a Web server
„
Hardware
„
Operating system software
„
Web server software
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Types of Web Sites
Š Development sites
„
Used to evaluate different Web designs
Š Intranets
„
Corporate networks that house internal memos,
corporate policy handbooks
Š Extranets
„
Intranets that allow authorized parties outside the
company to access information stored in the
system
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Types of Web Sites (continued)
Š Transaction-processing sites
„
Commerce sites that must be available 24 hours
a day, seven days a week
Š Content-delivery sites
„
Deliver content such as news, histories,
summaries, and other digital information
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Web Clients and Web Servers
Š Client/server architectures
„
Client computers typically request services
„
Server processes clients’ requests
Š Web software
„
Lets different types of computers, running
different operating systems, communicate
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Platform Neutrality of the Web
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Dynamic Content
Š Nonstatic information constructed in response to a
Web client’s request
Š Dynamic page
„
Web page whose content is shaped by a program in
response to user requests
Š Static page
„
An unchanging page retrieved from disk
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Dynamic Content (continued)
Š Server-side scripting
„
Programs running on a Web server create Web
pages before sending them back to the requesting
Web clients
Š Dynamic page-generation technologies
„
Active Server Pages (ASP)
„
JavaServer Pages (JSP)
„
PHP: Hypertext Preprocessor (PHP)
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Various Meanings of “Server”
Š Server
„
Computer used to provide files or make programs
available to other computers
Š Server software
„
Used by a server computer to make files and
programs available to other computers
Š Database server
„
Server computer on which database management
software runs
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Two-Tier Client/Server
Architecture
Š Has only one client and one server
Š Request message
„
Message that a Web client sends to request a file
or files from a Web server
Š Typical request message
„
Request line
„
Optional request headers
„
Optional entity body
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Message Flows in a Two-Tier
Client/Server Network
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Two-Tier Client/Server
Architecture (continued)
Š Request line
„
Contains a command, the name of the target
resource, and the protocol name and version
number
Š Request headers
„
Can contain information about types of files that
the client will accept in response to a request
Š Entity body
„
Used to pass bulk information to the server
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Three-Tier and N-Tier
Client/Server Architectures
Š Three-tier architecture
„
Extends two-tier architecture to allow additional
processing
Š N-tier architectures
„
Higher-order architectures
„
Third tier includes software applications that
supply information to the Web server
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Message Flows in a Three-Tier
Client/Server Network
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Software for Web Servers
Š Operating system tasks
„
Running programs and allocating computer
resources
Š Linux
„
Open-source operating system that is easy to
install, fast, and efficient
Š Open-source software
„
Developed by a community of programmers who
make it available for download at no cost
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Web Server Software
Š Most popular Web server programs
„
Apache HTTP Server
„
Microsoft Internet Information Server (IIS)
„
Sun Java System Web Server (JSWS)
Š Netcraft
„
A networking consulting company in Bath,
England
„
Accumulates popularity rankings
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Apache HTTP Server
Š Ongoing group software development effort
Š Dominated the Web since 1996 because it is
free and performs efficiently
Š Apache
„
Developed by Rob McCool at the University of
Illinois in1994 at the NCSA
„
Currently available on the Web at no cost as
open-source
software
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Microsoft Internet Information
Server
Š Comes bundled with current versions of Microsoft
Windows Server operating systems
Š Used on many corporate intranets
Š Supports the use of
„
ASP
„
ActiveX Data Objects
„
SQL database queries
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Sun Java System Web Server
(Sun ONE, iPlanet, Netscape)
Š Descendant of the original NCSA Web
server program
Š Formerly sold under the names
„
Sun ONE
„
Netscape Enterprise Server
„
iPlanet Enterprise Server
Š Charges between $1400 and $5000 for the
licensing fee
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Electronic Mail (E-Mail)
Š Useful feature
„
Attachments
Š Drawbacks
„
Time spent by business people responding to email
„
Computer virus
z
Program that attaches itself to another program
z
Can cause damage when the host program is activated
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Unsolicited Commercial E-Mail
(UCE, Spam)
Š Electronic junk mail that can include
„
Solicitations, advertisements, or e-mail chain
letters
Š Can consume large amounts of Internet
capacity
Š Companies now offer software to limit the
amount of spam
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Growth of Spam as a Proportion
of all Business E-mail
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Solutions to the Spam Problem
Š Reduce the likelihood that a spammer can
automatically generate e-mail addresses
Š Control exposure of an e-mail address
Š Use multiple e-mail addresses
Š Content filtering strategy
„
Require software that identifies content elements
that indicate if a message is (or is not) spam
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Solutions to the Spam Problem
(continued)
Š Content-filtering techniques
„
Black list spam filter
z
„
White list spam filter
z
„
Looks for known spammer From addresses in
incoming messages
Examines From addresses and compares them to a list
of known good sender addresses
Challenge-response
z
Compares all incoming messages to a white list
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Indexing and Searching Utility
Programs
Š Search engines or search tools
„
Search either a specific site or the entire Web for
requested documents
Š Indexing program
„
Can provide full-text indexing that generates an
index for all documents stored on a server
„
Can often index documents stored in many
different file formats
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Data Analysis Software
Š Web servers can capture
„
Data about who is visiting a Web site
„
How long the visitor’s Web browser viewed site
„
Date and time of each visit
„
Which pages a visitor viewed
Š Data captured by Web servers are stored in a
log file
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WebTrends Log File Analysis
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Link-Checking Utilities
Š Link checker
„
Examines each Web page and reports on URLs
that are
z
Broken, seem broken, or are in some way incorrect
Š Orphan file
„
File on a Web site not linked to any page
Š Dead link
„
When clicked, it displays an error message
rather than a Web page
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Watchfire Link Report
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Remote Server Administration
Š Web site administrator can control a Web
site from any Internet-connected computer
Š NetMechanic
„
Offers a variety of link-checking, HTML
troubleshooting, site-monitoring, and other
programs
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Web Server Hardware
Š Web server computers
„
More memory, larger hard disk drives, and faster
processors than typical PCs
Š Blade servers
„
Placing small server computers on a single
computer board, then installing boards into a rackmounted frame
Š Virtual server (virtual host)
„
Maintains more than one server on one machine
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Thin Clients
Š Internet in a Box: Inexpensive Thin Servers
and Software:
„
„
„
„
„
„
Cobalt Qube 2
Encanto Super e.go 210
eSoft TEAM Internet
FreeGate OneGate 150
Linux Hot-To site
WindDance Breeze NS
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Web Server Performance
Evaluation
Š Benchmarking
„
Testing used to compare the performance of
hardware and software
Š Throughput
„
Number of HTTP requests that a hardware and
software combination can process in a unit of
time
Š Response time
„
Time required by a server to process one request
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Web Server Performance
Evaluation
Š Web Server Performance Evaluation:
„
PC Magazine Web server tests
z
„
A report comparing several Web servers and the operating systems
running them
Ziff-Davis benchmark programs
Š Web Server Benchmarking Tools
„
„
„
„
„
„
„
„
NetBench
ServerBench
Exodus (formerly Service Metrics)
SPEC SFS97
SPECweb99
WCAT
WebBench
WebStone
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Web Page, Browser Compatibility,
and Web Site Analysis Software
Š NetMechanic Tests
„
Home page for all the following tests.
Š Browser Compatibility Check
„
See if your web pages are compatible with popular browsers.
Š GIFBot
„
Reduce the size of your graphics and speed up your site.
Š HTML Check
„
Spot bad tags and HTML errors.
Š Link Check
„
Check your site for dead links.
Š Load Time Check
„
Test your pages for load times.
Š Spell Check
„
Check your pages for spelling errors.
Š Exodus (formerly Service Metrics)
„
Real-time, Web site performance assessments and reports.
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Web Server Hardware
Architectures
Š Server farms
„
Large collections of servers
Š Centralized architecture
„
Uses a few very large and fast computers
Š Distributed/decentralized architecture
„
Uses a large number of less powerful computers
„
Divides the workload among them
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Load-Balancing Systems
Š Load-balancing switch
„
Piece of network hardware that monitors the
workloads of servers attached to it
„
Assigns incoming Web traffic to a server that has
the most available capacity at that instant in time
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A Load-Balancing System in a
Decentralized Architecture
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Software for application construction
Š Packages to help develop websites:
„
„
„
„
Point and click
HTML, CGI understanding
Upload the design site
Version control
Š Microsoft FrontPage, MicroMedia
DreamWeaver
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Summary
Š Web uses a client/server architecture
Š For simple HTTP requests a two-tier
architecture works well
Š Operating systems commonly used on Web
server computers
„
Microsoft server operating systems
„
UNIX-based operating systems
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Summary (continued)
Š Utility programs running on Web server
computers
„
Finger, Ping, Tracert, e-mail server software,
Telnet, and FTP
Š Unsolicited commercial e-mail (spam)
„
„
Has grown dramatically in recent years
Content filters are becoming available to deal with
the problem
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Summary (continued)
Š Web server hardware
„
Server computer must have enough memory and
disk space
Š Factors that affect Web server performance
„
„
„
Operating system
Connection speed
User capacity
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