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Chapter 8: Web Server Hardware and Software


Dynamic page: Web page whose content is shaped by a program in response to user requests ... Content filtering strategy. Requires software that identifies ... – PowerPoint PPT presentation

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Title: Chapter 8: Web Server Hardware and Software

Chapter 8Web Server Hardware and Software
  • 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

Web Server Basics
  • The main job of a Web server is to respond to
    requests from Web client computers
  • There are 3 components of a Web server
  • Hardware
  • Operating system software
  • Web server software

Types of Web Sites
  • Development sites Used to evaluate different Web
  • Intranets Corporate networks that house internal
    memos, corporate policy handbooks, and a variety
    of other corporate documents
  • Extranets Intranets that allow authorized
    parties outside the company to access information
    stored in the system
  • Transaction-processing sites Commerce sites that
    must be available 24 hours a day, seven days a
  • Content-delivery sites Deliver content such as
    news, histories, summaries, and other digital

Web Clients and Web Servers
  • Client/server architectures
  • Client computers request services
  • A server processes the clients requests
  • Web software is platform neutral, meaning that it
    lets different types of servers communicate with
    a variety of clients

Dynamic Content
  • Dynamic content is nonstatic information
    constructed in response to a Web clients request
  • Dynamic page Web page whose content is shaped by
    a program in response to user requests
  • Static page An unchanging page retrieved from

Dynamic Content
  • Server-side scripting (or includes)
  • Programs running on a Web server create Web pages
    before sending them back to the requesting Web
  • Dynamic page-generation technologies Server side
    scripts are combined with html tags to create
    dynamic content
  • Active Server Pages (ASP)
  • JavaServer Pages (JSP)
  • PHP Hypertext Preprocessor (PHP)

Various Meanings of Server
  • Server
  • Computer used to provide files or make programs
    available to other computers
  • Server software Used by a server to make files
    and programs available to other computers
  • Database server Server on which database
    management software runs

Two-Tier Client/Server Architecture
  • Two-tier client/server architecture has one
    client and one server

Two-Tier Client/Server Architecture
  • Request message Message that a Web client sends
    to request a file or files from a Web server
  • Typical request message contains
  • Request line
  • Contains a command, the name of the target
    resource, and the protocol name and version
  • Request headers
  • Can contain information about types of files that
    the client will accept in response to a request
  • Entity body
  • Used to pass bulk information to the server

Three-Tier and N-Tier Client/Server Architectures
  • Three-tier architecture
  • Extends two-tier architecture to allow additional
    processing (e.g., collection of data from a
    database) before reponses to requests are made
  • N-tier architectures
  • Higher-order architectures
  • Third tier includes software applications that
    interactively supply and update information to
    and from the web server

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Software for Web Servers
  • Operating system tasks include running programs
    and allocating computer resources
  • Open-source software Developed by a community of
    programmers who make it available for download at
    no cost
  • Linux Open-source operating system that is easy
    to install, fast, and efficient

Web Server Software
  • The most popular Web server programs are
  • Apache HTTP Server
  • Microsoft Internet Information Server (IIS)
  • Sun Java System Web Server (JSWS)
  • Netcraft
  • A networking consulting company in Bath, England
  • Accumulates popularity rankings

Apache HTTP Server
  • Apache is the results of an ongoing group
    software development effort, first developed by
    Rob McCool at the University of Illinois in 1994
    at the NCSA
  • Apache has dominated the Web since 1996 because
    it is free (open source) and performs efficiently

Microsoft Internet Information Server
  • Comes bundled with current versions of Microsoft
    Windows Server operating systems
  • Used on many corporate intranets
  • Supports the use of
  • ASP
  • ActiveX Data Objects
  • SQL database queries

Sun Java System Web Server (Sun ONE, iPlanet,
  • Descendant of the original NCSA Web server
  • Formerly sold under the names
  • Sun ONE
  • Netscape Enterprise Server
  • iPlanet Enterprise Server
  • Charges between 1400 and 5000 for the licensing

Electronic Mail (E-Mail)
  • We all know the benefits of email
  • Email drawbacks include
  • Time spent by business people responding to
  • Computer viruses
  • Programs that attach to other programs
  • Can cause damage when the host program is
  • Spam

  • Spam is unsolicited or commercial e-mail
  • During one 24-hour period in 2005 researchers
    estimated that 106 billion spam e-mail messages
    were sent

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Solutions to the Spam Problem
  • Reduce the likelihood that a spammer can
    automatically generate e-mail addresses
  • Control exposure of an e-mail address
  • Use multiple e-mail addresses
  • Content filtering strategy
  • Requires software that identifies content
    elements that indicate if a message is (or is
    not) spam

Solutions to the Spam Problem
  • Content-filtering techniques
  • Black list spam filter
  • Looks for known spammer From addresses in
    incoming messages
  • White list spam filter
  • Examines From addresses and compares them to a
    list of known good sender addresses
  • Challenge-response technique
  • Compares all incoming messages to a white list

Web Site and Internet Utility Programs
  • Finger
  • Runs on UNIX operating systems
  • Allows users to obtain information about other
    network users
  • Command yields a list of users who are logged on
    to a network
  • Ping (Packet Internet Groper)
  • Tests connectivity between two computers
    connected to the Internet

Tracert and Other Route-Tracing Programs
  • Tracert (TRACE RouTe)
  • Sends data packets to every computer on the path
    between one computer and another
  • Clocks packets roundtrip times
  • Calculates and displays the number of hops
    between computers
  • Calculates the time it takes to traverse an
    entire one-way path between machines

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Telnet and FTP Utilities
  • Telnet
  • Program that allows users to log on to a computer
    connected to the Internet
  • Telnet protocol
  • Set of rules used by Telnet programs
  • File Transfer Protocol (FTP)
  • Defines formats used to transfer files between
    TCP/IP-connected computers

Indexing and Searching Utility Programs
  • Search engines or search tools
  • Search either a specific site or the entire Web
    for requested documents
  • 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

Data Analysis Software
  • Web servers can capture
  • Data about who is visiting a Web site
  • How long the visitors Web browser viewed the
  • Date and time of each visit
  • Which pages a visitor viewed
  • Data captured by Web servers are stored in a log

Link-Checking Utilities
  • Link checker examines each Web page and reports
    on URLs that
  • Are broken
  • Seem broken
  • Are incorrect in some way
  • Orphan file
  • File on a Web site not linked to any page
  • Dead link
  • When clicked, it displays an error message rather
    than a Web page

Remote Server Administration
  • Web site administrator can control a Web site
    from any Internet-connected computer
  • NetMechanic
  • Offers a variety of link-checking, HTML
    troubleshooting, site-monitoring, and other

Web Server Hardware
  • Web server computers
  • More memory, larger hard disk drives, and faster
    processors than typical PCs
  • Blade servers
  • Placing small server computers on a single
    computer board, then installing boards into a
    rack-mounted frame
  • Virtual server (virtual host)
  • Maintains more than one server on one machine

Web Server Performance Evaluation
  • Benchmarking
  • Testing used to compare the performance of
    hardware and software
  • Throughput
  • Number of HTTP requests that a hardware and
    software combination can process in a unit of
  • Response time
  • Time required by a server to process one request

Web Server Hardware Architectures
  • Server farms
  • Large collections of servers
  • Centralized architecture
  • Uses a few very large and fast computers
  • Distributed/decentralized architecture
  • Uses a large number of less powerful computers
  • Divides the workload among them

Load-Balancing Systems
  • 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

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  • The Web uses a client/server architecture
  • For simple HTTP requests a two-tier architecture
    works well
  • Operating systems commonly used on Web server
    computers include
  • Microsoft server operating systems
  • UNIX-based operating systems

  • Utility programs running on Web server computers
  • Finger, Ping, Tracert, e-mail server software,
    Telnet, and FTP
  • Unsolicited commercial e-mail (spam) has grown
    dramatically in recent years
  • Content filters are becoming available to deal
    with the problem

  • Web server hardware
  • Server computer must have enough memory and disk
  • Factors that affect Web server performance
  • Operating system
  • Connection speed
  • User capacity
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