Web Server Hardware and Software

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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

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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.

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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.

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Extranets

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

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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.

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Content-Delivery Sites

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

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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.

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Platform Neutrality of the Web

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Dynamic Content

• Dynamic content is nonstatic information
  constructed in response to a Web clients
  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.

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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.

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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.

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Two-Tier Client/Server Architecture
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Three-Tier and N-Tier Client/Server Architectures
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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

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Web Server Software

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

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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.

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Microsoft Internet Information Server (IIS)

• Comes bundled with Microsofts 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.

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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 packets round-trip times.

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Electronic Mail

• Originated in the 1970s 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

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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

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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.

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Data Analysis

• Web servers can capture visitor information,
  including data about who is visiting a Web site,
  how long the visitors 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.

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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.

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Link Checking

• Free link-checking and Web site validation
  programs, such as Elsop Linkscan, can be launched
  by entering the address of a Web sites 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.

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Link Checking
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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.

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Remote Server Administration Tool
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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.

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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
  servers performance.
• Throughput and response time can be used to
  measure a servers Web page delivery
  capability.

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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.

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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.

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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.

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Load-Balancing System Architecture
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Complex Load-Balancing
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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 providers 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.