deck_17215195 Flashcards
The three main elements of a Web server
– Hardware
– Operating system software
– Web server software
Types of Web Site
– simple development sites
– Intranets
– information-only sites
– business-to-business portals
– Storefronts
– Content-delivery site
- transaction processing sites
Development Sites (stand alone)
simplest Web site
least costly to implement
developed with low-cost Web site building tools, e.g. Microsoft FrontPage or Macromedia Dreamweaver
Testers can access the site through their PCs on the existing LAN.
Intranet
Corporate intranets
– house internal memos,
– corporate policy handbooks,
– expense account worksheets,
– budgets,
– newsletters,
– a variety of other corporate documents.
Intranets are shielded from the Internet and they do not require additional security software
Extranet
allow certain authorized parties outside the company to access certain parts of the information stored in the system.
e.g. VPN, Secured Site (HTTPS)
Transaction-Processing Sites
b2b/b2c
available 24/7.
High-reliability servers
– Require spare server computers to handle high traffic volumes
– security software
Content-Delivery Sites
- Content-delivery sites deliver contents
– e.g. news, histories, summaries, and other digital information. - Able to be presented rapidly on the visitor’s screen
- Must be updated frequently
- Able to locate articles quickly with a fast and precise search engine.
Web Clients and Servers
- Visitor on the Web is the 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.
LAN
Local area network
high speed connections between computers within same building
WAN
Wide area network
connecting several LANs
Limited to a corporation or a organisation
MAN
Metropolitan Area Network
span several buildings within same city or town
GAN
GAN
Global Area Network
composed of different interconnected computer networks (WAN) globally
Broadband Global Area Network
Provide high speed internet connection & phone from any part of the world
Dynamic Content
non- static information constructed in response to a Web client’s reques
Future of Dynamic Web Page Generation
Apache Cocoon project: content stored with XML tags that describe meaning of each content item
Cocoon: instead of a webpage, produce a response tailored to the request by applying a style sheet to the data
Meanings of Server
any computer used to provide files to other computers connected to it through a network
Server software
– Database server
2 tier client/server architecture
Web client (html document) ->TCP/IP Internet -> Web Server
HTTP (message request)
Web client (html document) <-TCP/IP Internet <- Web Server
HTTP (message response)
Operating Systems for Web Servers
A computer must have an operating system to run programs and keep track of multiple users logged on to the system.
It must also ensure that they do not interfere with one another
Web Server Software
Apache, HTTP Server, Microsoft Internet Information Server (IIS) and iPlanet Enterprise
Serve
Web Site and Internet Utility Programs
Finger, Tracert, Ping
Finger
program that runs on UNIX operating systems. It allows users to obtain information about other network users. Many organizations have disabled Finger commands for privacy and security reasons
Tracert
sends data packets to every computer on the path (Internet) between
computers and clocks the packet’s round-trip times
Ping (Packet Internet Groper)
tests the connectivity between two computers connected to
the Internet
Electronic Mail (e-mail)
convey messages within seconds
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
Telnet
allows users to log on to a computer that is connected to the Internet
FTP, File Transfer Protocol
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
o Displays remote and local computers’ directories
o Has built-in error controls to copy files accurately
Indexing and Searching
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.
Data Analysis
Web servers can capture:
– visitor information,
– data about who is visiting a Web site
– how long the visitor’s browse the site
– the date and time of each visit
– and which pages were displayed
Analog Web server log file analyzer
WebTrends Web server log file analyzer.
Remote Server Administration
administrator can control a Web site from any Internet-connected computer.
Remote service maintenance
Remote backup
Web Server Hardware
process and respond to Web client requests sent
using HTT
Web server computers have more memory, larger and faster hard disk drives, and
faster processors than typical desktop or notebook PCs.
virtual server, or virtual host
virtual server, or virtual host, is a feature that maintains more than one server on one machine.
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.
Web Server Hardware Architectures
large collections of servers that these sites have are called server farms architecture, which uses a few very large and very fast computers
decentralized architecture, which uses a large number of servers. Most large decentralized sites use load-balancing systems.
Load-Balancing Systems
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
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
Internet-> router->load-balancing switch->web servers
Web Hosting Choices
hardware, platform, software can be upgraded when traffic increases (scalability)
service provider hosting service vs inhouse affects staffing burden
