Lecture Outline 14 Networked Computing Uses telecommunications technology

Speed of transmission Measures in bits per second (bps) Thousands of bits per second - Kbps Millions - Mbps Billions - Gbps Broadband telecommunication : rate of exchange of data > 1.5 Mbps *MC

Transmission Media Physical pathways between network members Computers send bits to each other (+ / -) Different media chosen to make up pathways Cables: twisted pair, coaxial, fibre optic Read WiFi p. 166 *MC

Networking Fundamentals – Transmission Media (continued) *MC Twisted Pair (TP) Two or more pairs of insulated copper wires twisted together and may be shielded (STP) or unshielded (UTP). It is the lowest capacity of the cable options Coaxial (COAX) Contains a solid inner copper conductor surrounded by insulation and outer braided copper or foil shield. It is higher capacity than twisted pair Fiber-Optic Made of light-conducting glass or plastic core, surrounded by more glass, called cladding, and a tough outer sheath. It is high capacity and used in high speed backbones 4 4

Networking Fundamentals – Media (Microwave) *X Satellite Microwave A line-of-site technology that uses relay stations to transfer signals between antennae located on earth and a satellite orbiting the earth. It can be used to access very remote locations and, like a terrestrial microwave, attenuation, EMI and eavesdropping are also problems 5 5

Networking Fundamentals – Media (Microwave) *X A high frequency radio signal that is sent through the air using either terrestrial (earth-based) or satellite systems Terrestrial Microwave A line-of-site technology (unobstructed) used to cross inaccessible terrain or to connect buildings where cable installation would be expensive. Attenuation is low over short distance but higher over longer distances, and high winds, heavy rain, EMI and eavesdropping are also problems 6 6

Networked Computing Most common arrangement in business computing See telecommunications overview p 158. Make brief notes Types of networks (p. 160) *MC

Local Area Network Computer network in a small area Private cabling (twisted pair or coaxial) Some may be wireless Usually has a file server (“captain”) *MC

Why Connect? **L Share data (which resides on server) Share software Share peripherals (printer) Computers (workstations) can communicate with each other and send files files services, print services, message services, application services

  Common Network Components *L - what will we need in order to set up a computer network (LAN)? - server: main computer in a network - workstations: other computers in the network - Network Interface Cards (NICs) - private cabling - Network Operating System e.g. (networking parts of Windows ) 8

Wireless LANs *MC same as the traditional LAN but they have a wireless interface. With the introduction of small portable devices such as smartphones, the WLAN technology is becoming very popular.

Wireless LAN – benefits *MC WLANs provide high speed data communication in small areas such as a building or an office A wireless LAN allows users to move around in a confined area while they are still connected to the network

Wide Area Network *L Spans large geographical area Goes across cities and countries Uses a variety of hardware and transmission media Global, enterprise or value-added

The Internet p. 171+ A network of networks Worldwide Read and make own notes p. 173-176

World Wide Web p. 194 *L Web servers dish out web pages which are read and displayed by web browsers Web page – consists of text, graphics, and hyperlinks that lead to another page; this is hypertext Hypertext Markup Language (HTML) is the language to define web pages p. 195 Browsers read HTML and render a page

World Wide Web *L Web Browser Hypertext A Web page stored on a Web server Contains information and links to other related information (hyperlinks) HTML (Hypertext Markup Language) A standard method used to specify the format of Web pages Uses codes/tags which stipulate how the content should appear to the user Web Browser A software program used to locate and display Web pages Includes text, graphics, and multimedia content Web Browser 16 16

A Website *L Collection of interlinked web pages created by the same author(s) for common purpose Respond to requests over the Internet from browsers according to the hypertext transfer protocol (http) URL (Uniform Resource Locator) Each site has a URL address http://www.uwinnipeg,ca

Web addresses *MC Website: http://www.xxx.yy Page on that site:http://www.xxx.yy/zz Domain name: xxx.yy Prefix: xxx e.g. uwinnipeg Suffix: yy e.g. .com – business .org – nonprofit organization .ca - Canada

., Internet E-MAIL address: *MC john@uwinnipeg.ca   ., Internet E-MAIL address: *MC john@uwinnipeg.ca e-mail address has @ symbol user name @ domain name   Domain names (general areas):   .com commercial organization .edu educational organization .gov government organization .ca Canada .us U.S. .hk Hong Kong

IP Addresses 190+ *X Each domain name is associated with an IP address uwinnipeg.ca is associated with an IP address 32-bit numeric address written as 4 numbers separated by periods Domain name is translated to IP Address by a special server on the Internet eg. 1.160.10.240 World Wide Web

World Wide Web *MC HTTP (Hypertext Transfer Protocol) A protocol used to process user requests for displaying Web pages from a Web server Web Servers A special computer that is specifically designed to store and “serve up” Web pages This machine contains special hardware and software to perform its many specialized functions 21 21

             Additional details regarding the Web: *L Types of web sites: 1. Static: collection of static documents created in HTML and tied together with links 2. Static with forms: 90% is pure document delivery, but also has fill-in forms to collect information from the user   

3. Dynamic Data Access: via a Web page,    3. Dynamic Data Access: via a Web page, users can search a catalogue or perform queries on the contents of a database 4. Web-based software applications: facilitate business processes beyond providing information; have a business information system on a Web-site, e.g., inventory tracking, sales force automation      

Overview of a Web Session: **L 1. User, with browser software, requests a document from a remote Web server on the Internet - enters desired address as Uniform Resource Locator (URL) e.g., http://www.irwin.com - URL specifies where something is, not what it is 2. Actual address is determined from a domain name server (computer) on the Internet *

  3. Once the machine has been located, a request can be sent to the server (discussion between the Web browser and the Web server is handled by HTTP (hypertext transfer protocol - defines how a client must ask for data (pages) from the server and how the server responds when it returns what was asked for) {HTTP does not specify how the data is transferred, that is up to TCP/IP, at a lower level} )

  4. Server attempts to process request (is it valid?) - it may send back HTML 'data' (a page) - server machines often run the Unix or Windows operating systems - they send data from disk onto the network; it uses Web Server software, such as Apache

5. The browser, on the client, reads what 5. The browser, on the client, reads what has been sent to it, identifies it as an HTML document, and places the page in the browser window - information moves from the network or modem to the client system - once in the client computer, information goes along a bus to the hard disk or into main memory (browser might temporarily put info onto disk) - it is then processed by the browser software only)   9

Search Engine p. 183-85 *MC Locates on the Web, topics requested Returns list of links to web pages Examples; Google, Yahoo, Alta Vista

Intranets and Extranets p. 192+ Intranet uses internet technology but is limited to one organization Extranet is a company Intranet that is also connected to several specific external organizations (e.g. retailer and its supplier) *MC

E-Mail *MC Common and useful form of Internet communication Web-based systems (Hotmail) Dedicated e-mail software (Outlook) On which computer is your e-mail stored?

Illustration of Internet Travel https://www.wimp.com/how-the-internet-works/

FINALLY The End of ACS 1803 Good Luck on Exams and in Future!!!