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Chapter 8:
Web Server Hardware and Software
Electronic Commerce, Seventh Annual Edition 2
Web Server Basics
• The main job of a Web server computer is to respond to requests from Web client computers
• Three main elements of a Web server:
– Hardware
– Operating system software
– Web server software
Electronic Commerce, Seventh Annual Edition 3
Server Connection
• WWW requests from the Client computer Browser are detected and handled on port 80 of the server.
• FTP requests on port 21 of the Server.• Mail on port 25• Telnet on port 23
Electronic Commerce, Seventh Annual Edition 4
Types of Web Sites
• Development sites– Used to evaluate different Web designs
• 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
Electronic Commerce, Seventh Annual Edition 5
Types of Web Sites (continued)
• Transaction-enabled sites– E-Commerce enabled sites (database, shopping
cart, payment processing capability).
– Examples: Web Catalog (e-store), Transaction Fee Model, Subscription Model, Auction Sites
• Content sites– Deliver content such as news, histories,
summaries, and other digital information.
– Examples: CNN.Com, IBM.com, Portals
Electronic Commerce, Seventh Annual Edition 6
Electronic Commerce, Seventh Annual Edition 7
Static Content
• Static HTML Web pages – Static information
• File Extension: .html or htm
Electronic Commerce, Seventh Annual Edition 8
Dynamic Content
• Dynamic content (DHTML) is nonstatic information constructed on a “Dynamic Webpage” in response to a Web client’s request. (Server-side Scripting)
Programs that create dynamic content use these File Extensions:
.asp – (Microsoft) - Active Server Pages .jsp – (Sun Microsystems) - Java Server Pages .php – (Apache Open Source) - Hypertext Preprocessor .cfm – (Macromedia) - ColdFusion
Electronic Commerce, Seventh Annual Edition 9
Electronic Commerce, Seventh Annual Edition 10
Electronic Commerce, Seventh Annual Edition 11
Web Server Operating System
• Operating system tasks include running programs and allocating computer resources.
• Unix• Windows • Open-source software
– Developed by a community of programmers who make it available for download at no cost (Example- Linux)
Electronic Commerce, Seventh Annual Edition 12
Web Server Software
The most popular Web Server programs are: – Apache HTTP Server (Open Source)
(JSP, PHP, CFM)
– Microsoft (Internet Information Server (IIS) or Microsoft Server 2008)
(ASP, .Net)
– Sun Java System Web Server (JSWS) (JSP)
Electronic Commerce, Seventh Annual Edition 13
Application Servers
– Database Server – Manages Product Catalog, Customer database, etc.).
– Mail Server – Manages Internet e-mail
– Proxy Server – Controls access to main computer
– Ad Server – Maintains database of banner ads
– List Server – Creates and manages special e-mail lists.
Electronic Commerce, Seventh Annual Edition 14
Spam – Phishing - Virus
• Spam – Any Unsolicited e-mail.
• Phishing – Amateur & Professional hackers attempting to obtain Personal Information or access to Content.
• Virus – Malicious Content
Electronic Commerce, Seventh Annual Edition 15
Spam – Unsolicited E-Mail
Spam by the Numbers (2006)
Source: http://spam-filter-review.toptenreviews.com/spam-statistics.html
Electronic Commerce, Seventh Annual Edition 17
Dealing With the Spam Problem
• Industry – Can reduce the likelihood that a spammer can automatically generate e-mail addresses
• User – Can control exposure of an e-mail address
• User – Can use multiple e-mail addresses
• User/Server – Can employ content filtering software
Electronic Commerce, Seventh Annual Edition 18
Some Filtering Strategies
1. Black List spam filter
--Checks incoming messages against a known bad e-mail address list.
2. White List spam filter
--Checks incoming messages against a known good e-mail address list.
3. Challenge-Response technique--Forces a reply to all incoming messages not on a white
list.
4. Advanced Content Analysis
--Utilizes contextual filtering
Electronic Commerce, Seventh Annual Edition 19
Server Firewalls
• Network Layer Firewall - Filter network traffic based on many packet attributes like IP Address, Domain name and destination port.
• Application Layer Firewall- inspect all packets for improper application content.
• Proxy Server – Can serve as a firewall by blocking unwanted content.
Electronic Commerce, Seventh Annual Edition 20
Server Data Analysis Software
• Web Server Log File can capture:
– IP Address of Visitor
– Type of Request & Pages Viewed or Files Downloaded
– Date and time of each activity (timestamp)
– Status Code (successful, “404” error etc.)
– Type of browser viewed on
– Referrer URL (not always available)
Electronic Commerce, Seventh Annual Edition 21
Server Log File
Electronic Commerce, Seventh Annual Edition 22
Web Server Hardware Terms
• 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
Electronic Commerce, Seventh Annual Edition 23
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 time
• Response time – Time required by a server to process one request
Electronic Commerce, Seventh Annual Edition 24
Factors that can Influence Web Server Performance
There is always going to be a limit to the number of pages that a server can serve in a given time frame.
• Volume - Amount of Web Traffic (Hits)• Duty Cycle - No. of CPU-Intensive Operations• Capacity - Bandwidth Available
Electronic Commerce, Seventh Annual Edition 25
More Web Server Hardware Terms
• 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
Electronic Commerce, Seventh Annual Edition 26
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 time
Electronic Commerce, Seventh Annual Edition 27
Electronic Commerce, Seventh Annual Edition 28