Web Server Hardware and Software

1. Chapter 8
Web Server Hardware
and Software

2. Learning Objectives
In this chapter, you will learn about:
•Web server basics
•Software for Web servers
•Internet utility programs
•Web server hardware
•Web site hosting alternatives

3. Web Server Basics
•The main job of a Web server computer is to respond
to requests from Web client computers.
•The three main elements of a Web server are the:
–Hardware
–Operating system software
–Web server software

4. Types of Web Sites
•An important first step in planning a Web server is to
determine what the company wants to accomplish
with the server.
•The company must estimate how many visitors will be
connecting to the Web site and what types of files will
be delivered through the site.
•Companies create Web sites in a wide variety of forms
including simple development sites, intranets,
information-only sites for customers, business-to-
business portals, storefronts, or content-delivery
sites.

5. Development Sites
•The simplest Web site and the least costly to
implement is a development site.
•A development site can reside on an existing PC and
can be developed with low-cost Web site building
tools, such as Microsoft FrontPage or Macromedia
Dreamweaver.
•Testers can access the site through their PCs on the
existing LAN.

6. Intranets
•Corporate intranets house internal memos, corporate
policy handbooks, expense account worksheets,
budgets, newsletters, and a variety of other corporate
documents.
•Intranets are shielded from the Internet; they do not
require additional security software to protect them
against threats from outside the company.

7. Extranets
•Extranets are intranets that allow certain authorized
parties outside the company to access certain parts of
the information stored in the system.

8. Transaction-Processing Sites
•Transaction-processing sites, such as business-to-
business and business-to-consumer electronic
commerce sites must be available 24 hours a day,
seven days a week; that is, they must be high-
reliability servers.
•Transaction-processing sites must also have spare
server computers to handle high traffic volumes.
•Transaction-processing sites must also run security
software.

9. Content-Delivery Sites
•Content-delivery sites deliver content such as news,
histories, summaries, and other digital information.
•Content must be presented rapidly on the visitor’s
screen.
•Visitors must be able to locate articles quickly with a
fast and precise search engine.

10. Web Clients and Servers
•Internet connections that are part of the Web
become Web client computers on a
worldwide client/server network.
•Client/server architectures are used in LANs,
WANs, and the Web.
•Web software is platform neutral, letting
computers communicate with each other
easily.

11. Platform Neutrality of the Web

12. Dynamic Content
•Dynamic content is nonstatic information constructed
in response to a Web client’s request.
•Server-side technologies are programs running on the
Web server to create the Web pages before sending
them back to the client.
•ASP, JSP, and PHP are server-side scripting
mechanisms that build dynamic sites and Web
applications.

13. The Future of Dynamic Web Page
Generation
•The Apache Cocoon Project is an initiative where
content is stored with XML tags that describe the
meaning of each content item.
•Instead of creating a Web page, Cocoon can produce
a response tailored to the request by applying a style
sheet to the data.
•Other similar efforts are underway from Microsoft
(.NET) and Oracle.

14. Various Meanings of “Server”
•Server – any computer used to provide files to other
computers connected to it through a network.
•Sometimes included in that meaning, however, are:
–Server software
–Database server
–It is important to ask qualifying questions
when determining what one might mean by
“server”.

15. Two-Tier Client/Server Architecture

16. Three-Tier and N-Tier Client/Server
Architectures

17. Operating Systems for Web Servers
•A computer must have an operating system to run
programs as well as keep track of multiple users logged on
to the system to ensure that they do not interfere with one
another.
•The most common operating systems for Web servers from
Microsoft are: Windows NT Server, Windows 2000
Advanced Server, and Microsoft .NET.
•Unix-based products are also popular: Linus, Solaris, and
FreeBSD

18. Web Server Software
•The most popular Web server programs in use
today:
–Apache
–HTTP Server
–Microsoft Internet Information Server (IIS)
–iPlanet Enterprise Server

19. Apache HTTP Server
•Free and performs efficiently.
•Runs on many operating systems and the
hardware that supports them.
•Has a built-in search engine and HTML authoring
tools and supports FTP.
•Can be managed from either a server console or
a Web server.

20. Microsoft Internet Information Server (IIS)
•Comes bundled with Microsoft’s Windows
2000 Server operating systems.
•Includes an integrated search engine.
•Permits administration from a remote server.
•Combines HTML pages, ActiveX components,
and scripts to produce dynamic pages.

21. Sun ONE (iPlanet, Netscape) Web
Server
•Formerly sold under the names Netscape
Enterprise Server and iPlanet Enterprise
Server.
•Runs on many operating systems, including
HP-UX, Solaris, and Windows.
•Its management tools allow administrators to
manage users and monitor server activity
interactively.

22. Web Site and Internet Utility Programs
•Finger is a program that runs on UNIX operating systems
and allows users to obtain information about other network
users.
–Many organizations have disabled Finger
commands for privacy and security reasons.
•Ping (Packet Internet Groper) tests the connectivity
between two computers connected to the Internet.
•Tracert (TRACE RouTe) sends data packets to every
computer on the path (Internet) between computers and
clocks the packet’s round-trip times.

23. Electronic Mail
•Originated in the 1970’s on the ARPANET.
•Used in business to convey messages within
seconds, there are many benefits to using email.
•There are also drawbacks:
–Spam or junk mail:
•Wastes time and disk space
•Often contains offensive content that poses risks for
employers
–Viruses:
•Can be carried by email and infect entire systems
–Time
•Business people can spend up to two hours a day
responding to messages

24. Telnet and FTP Utilities
•Telnet allows users to log on to a computer that
is connected to the Internet.
•FTP, File Transfer Protocol, is the part of the TCP/
IP rules that defines the formats used to transfer
files between TCP/IP computers.
–Can transfer files one at a time, or several at once
–Displays remote and local computers’ directories
–Has built-in error controls to copy files accurately

25. Indexing and Searching
•Search engine and indexing programs are important
elements of many Web servers.
•Search engines, or search tools, search either a
specific site or the entire Web for requested
documents.
•An indexing program can provide full-text indexing
that generates an index for all documents stored on a
server.

26. Data Analysis
•Web servers can capture visitor information,
including data about who is visiting a Web
site, how long the visitor’s Web browser
viewed the site, the date and time of each
visit, and which pages were displayed.
•Two of the most popular Web log file analysis
programs are the Analog Web server log file
analyzer and the WebTrends Web server log
file analyzer.

27. Link Checking
•A link checker examines each page on the site and
reports on any URLs that are broken, that seem to be
broken, or that are in some way incorrect.
•An orphan file is a file on a Web site that is not linked
to any page.
•Other important site management features include
script checking and HTML validation.
•A dead link, when clicked, displays an error message
rather than a Web page.

28. Link Checking
•Free link-checking and Web site validation programs,
such as Elsop Linkscan, can be launched by entering
the address of a Web site’s home page and checking
a few boxes.
•Commercial site checkers, such as Big Brother
software from Watchfire, produce more
comprehensive results and more detailed site
analyses than do the free products.

29. Link Checking

30. Remote Server Administration
•With remote server administration, a Web site
administrator can control a Web site from any
Internet-connected computer.
•Although all Web sites provide administrative
controls, it is convenient for an administrator to be
able to fix the server from wherever he or she
happens to be.

31. Remote Server Administration Tool

32. Web Server Hardware
•The fundamental job of a Web server is to process
and respond to Web client requests sent using HTTP.
•Web server computers have more memory, larger and
faster hard disk drives, and faster processors than
typical desktop or notebook PCs.
•A virtual server, or virtual host, is a feature that
maintains more than one server on one machine.

33. Web Server Performance Evaluation
•Benchmarking is a form of testing used to compare
the performance of hardware and software.
•Hardware and operating systems are key areas for
benchmarking.
•The speed of its connection can affect a Web server’s
performance.
•Throughput and response time can be used to
measure a server’s Web page delivery capability.

34. Web Server Hardware Architectures
•Large electronic commerce Web sites must deliver
millions of individual Web pages every day.
•They must also process thousands of customer and
vendor transactions each day.
•The large collection of servers that these sites have
are called server farms.

35. Web Server Hardware Architectures
•One approach to Web server architecture is called a
centralized architecture, which uses a few very large
and very fast computers.
•Another approach is a decentralized architecture,
which uses a large number of servers.
•Most large decentralized sites use load-balancing
systems.

36. Load-Balancing Systems
•A load-balancing switch is a piece of network
hardware that monitors the workloads of the servers
attached to it and assigns incoming Web traffic to the
server that has the most available capacity.
•In a simple load-balancing system, the traffic that
enters the site from the Internet, encounters the load-
balancing switch, which then directs the traffic to the
Web server best able to handle the traffic.

37. Load-Balancing System Architecture

38. Complex Load-Balancing

39. Web Hosting Choices
•When making Web server hosting decisions, a
company should ask whether the hardware, or
platform and software combination, can be upgraded
when the traffic on its site increases.
•Using a service provider’s shared or dedicated
hosting services instead of building an in-house
server or using a co-location service means that the
staffing burden shifts from the company to the Web
host.