Embed Size (px)
Citation preview
Computer Networks
• 2 or more computers connected together
• Typically a:– Client: requests and receives data– Server: receives requests and serves data
Hardware Connection
• Phone line/Modem: slow
• Cable Modem: varies
• DSL: Up to 8 megabit
• T3 to T1
• Ethernet: Up to 10 gigabit
Hardware Connection
The Internet
• Internet: network of computers using the TCP/IP protocol suite– TCP: Transmission control protocol– IP: Internet Protocol
• Includes IP Addresses
Hardware Connection
TCP/IP
IP Addresses
• Each computer has an IP address:– 128.54.105.1– Each number can be 0 to 255– 4, 8-bit bytes for 32 bits total
Hardware Connection
TCP/IP
Static IPDynamic IP
Internet Protocols
• http: Hypertext transfer protocol
• smtp: Small mail transfer protocol
• ftp: File transfer protocol
Hardware Connection
TCP/IP
Static IPDynamic IPhttp
World-Wide-Web
• Built on top of the Internet
• Uses http: hypertext transfer protocol to transfer html: hypertext markup language pages (web pages)
• The links make it a “Web of Pages”
Hardware Connection
TCP/IP
Static IPDynamic IPhttp
Uniform Resource Locators
• URL: http://www.niiss.org/jim/home.html
• http: hypertext transfer protocol
• www.niiss.org: domain name– Converted to an IP Address
• /jim/home.html: path to a file– http://www.niiss.org/jim:
• Has a default file that redirects to home.html
Requesting a Page
1. Client sends an http request with a URL to a server
2. Server find the file based on the URL and returns it
3. Can also request: mpeg, jpeg, gif, etc.
HTML Page
Request with URL
How Web Servers Work
Browser
Client Server
Web Server
HTML File
Image File
HTML File
Image File
Internet
URL
Dynamic Web Pages (server)
Browser
Client Server
Web Server
HTML File
Image File
HTML File
Image File
Database
Web Script
Internet
Web Services
Program
Client Server
Web Server
XML File
Image File
Database
Web Script
Internet
