Communication And Emerging Technologies
Communication And Emerging Technologies COM 43500
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This 7 page Class Notes was uploaded by Elda Bahringer on Saturday September 19, 2015. The Class Notes belongs to COM 43500 at Purdue University taught by William Collins in Fall. Since its upload, it has received 30 views. For similar materials see /class/207920/com-43500-purdue-university in Communication Studies at Purdue University.
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Date Created: 09/19/15
Terminology Internet global collection of networks both big and small The Internet is a gigantic collection of millions of computers all linked together on a computer network The network allows all of the computers to communicate with one another A home computer may be linked to the Internet using a phoneline modem E or cable modem that talks to an Internet service provider ISP A computer in a business or university will usually have a network interface card NIC that directly connects it to a m area network LAN inside the business The business can then connect its LAN to an ISP using a high speed phone line like a T1 line ATl line can handle approximately 15 million bits per second while a normal phone line using a modem can typically handle 30000 to 50000 bits per second ISPs then connect to larger ISPs and the largest ISPs maintain fiberoptic quotbackbonesquot for an entire nation or region Backbones around the world are connected through fiberoptic lines undersea cables or satellite links see An Atlas of Cyberspaces for some interesting backbone maps In this way every computer on the Internet is connected to every other computer on the Internet World Wide Web an internetbased hypermedia initiative for global information sharing Protocol sets of rulesstandards to facilitate system interaction Convergence Metadata URL httpwwwlibpurdueedulibrariesZindexhtml anatomy protocolserverfolderfile HTML 3 quotmarkupquot language Standardsbased Evolving stands for Hyper Text Markup Language A quotmarkup languagequot is a computer language that describes how a page should be formatted If all you want to do is display a long string of black and white text with no formatting then you don39t need HTML But if you want to change fonts add colors create headlines and embed graphics in your page HTML is the language you use to do it H39I39I39P method for moving information Golden MeanRule of Thirds Web Image Format Design Principles Content relevant infosubstance should cater the need of the audience Usability Website should be userfriendly and the navigation and interface design should be simple Appearance the text and images should depict a uniform style and overall consistency The style should be appropriate professional and appealing Visual Appeal First impression quality of content and consistency Design v Download speed download time and connectivity user experience and accessiny Marketing and Branding Issues audience analysis organization profile quality of website and communication needs Purpose of good design Navigation and content should be predictable and information should be found easily Visual design should not be an adherence Visual identity of pages should represent a cohesive theme Navigation Header logo menu content footer Balance Symmetrical Linear balanced on one or more than one axis Radia around a center point Asymmetrica Unity Proximity Repetition Emphasis placement continuity isolation contrast Proportion perspective light and shade pattern background color and image Left column navigation bigger third 23 on left Right column navigation bigger third 23 on right Three column navigation three equal 13s Typography Common Fonts Arial Comic sans impact times new roman trebuchet verdana etc Anatomy serif sanserif script and display font Vertical kerningtracking and Horizontal leading spacing Color Temperature Warm color Cool color Value Tint Pure Shade Saturation when white and black are added Primary Secondary and Tertiary color Monochromatic Achromatic color Analogous color adjacent Complementary split complementary triadic color etc Xanadu first hypertext project founded in 1960 by Ted Nelson Domain Because most people have trouble remembering the strings of numbers that make up IP addresses and because IP addresses sometimes need to change all servers on the Internet also have humanreadable names called domain names For example wwwhowstuffworkscom is a permanent humanreadable name It is easier for most of us to remember wwwhowstuffworkscom than it is to remember 2091166966 Memex a device in which an individual compresses and stores all of their books records and communications which is then mechanized so that it may be consulted with exceeding speed and flexibility A document can be given a simple numerical code that allows the user to access it after dialing the number combination Documents are also able to be edited in realtime This process makes annotation fast and simple The memex is an enlarged intimate supplement to one39s memory1 The memex has 39 quot Ithe 39 39 r of 39 I 39 39 hypertext and intellect augmenting computer systems Vannevar Bush Mundaneum gather together the entire world39s knowledge and classify it according to a system they developed called the Universal Decimal Classification Paul Otlet Absolute and Relative Links absolute link if the URL and file name can be found from anywhere on the Web not just from a single Web site An absolute ink specifies a fullyqualified URL the protocol must be present in addition to a domain name and often a file name must be included as well A relative link specifies the name of the file to be linked to only as it is related to the current document For example if all the files in your Web site are contained within the same directory or folder and you want to establish a link from page1html to page2htm the code on page1htm will be lta hrefquotpage2htmlquotgtGo to page 2ltagt Semantic Web see below Web 102030 10 v 20 double click v google mp3com v Napster brittanica online v Wikipedia publishing v participating directories v tagging personal websites v blogging page views v cost per click semantic web semantics the study of meaning how do we make the machines smarter Not people working but computer doing all the work 20 Characteristics Hegel Web as platform operating system web is not selfcontained but builtupon Emerging everything is always in beta Networkcentric it is global and device independent Creation not just publishing users not39ust experts in a collaborative way Users nonexpert driven Distributed Collaborative Cumulative Physical tagslogical tags physical ltbgt ltfontgt ltcentergt etc logical lth1gt ltpgt ltugt etc CSSStyle sheet cascading style sheet file allows you to separate your web sites XHTML content from it s style internal method This way you are simply placing the CSS code within the ltheadgtltheadgt tags of each XHTML file you want to style with the CSS With this method each XHTML file contains the CSS code needed to style the page Meaning that any changes you want to make to one page will have to be made to all This method can be good if you need to style only one page or if you want different pages to have varying styles external CSS file can be created with any text or HTML editor such as quotNotepadquot or quotDreamweaverquot A CSS file contains no XHTML only CSS You simply save it with the css file extension You can link to the file externally by placing one of the following links in the head section of every XHTML file you want to style with the CSS file By using an external style sheet all of your XHTML files link to one CSS file in order to style the pages This means that if you need to alter the design of all your pages you only need to edit one css file to make global changes to your entire website Here are a few reasons this is better Easier Maintenance Reduced File Size Reduced Bandwidth and Improved Flexibility Blog Content management system Often built from a combination of components a set of programs of scripts providing core functionality a database for storing site content templates for managing page design and layout Offer a wide range of functionality easy content editing management of features user roles and permissions Can be general or specific in nature Examples blogging systems wikis social networking sites media sharing sites and learning management systems Static Websites sites are collections of individual pages to be served pages are individually created by 39 39 r little I 39 between 39 quot design and content in the development process Dynamic Websites sites are quotapplicationsquot to be run pages are quotassembledgenerated on demand by a program heavy separation of functionality design and content nline styles are defined right in the XHTML file alongside the element you want to style nline styles will NOT allow the user to change styles of elements or text formatted this way All the various methods will cascade into a new quotpseudoquot stylesheet in the following order 1 nline Style inside XHTML element 2 Internal Style Sheet inside the ltheadgt tag 3 External Style Sheet As far as which way is better it depends on what you want to do If you have only one file to style then placing it within the ltheadgtltheadgt tags internal will work fine Though if you are planning on styling multiple files then the external file method is the way to go Synchronousasynchronous same time facetoface microphone overhead projector different time email cave painting postit note msg on chalkboards etc Collocateddistributed CoI to occur in 39 39 with 39 39 U 39 I I 39 U 39 Because it is pervasive web 20 facilitates distributed creation it doesn39t matter where the individuals or communities reside they can access the platform Tags quotmetaquot logical physical Structure elementstag attributes values open and close components Organization hierarchies and nesting Search Engine Optimization ARPANET Internet was brought online in 1969 under a contract let by the renamed Advanced Research Projects Agency ARPA Dis People to know Focus on their major ideas and contributions Vannevar Bush memex Paul Olet mundaneum Tim Nelson project xanadu Tim Berners Lee World Wide Web Important DocumentsMedia to Review Videos Wright The Web that Wasn39t Kevin Kelly Predicting the Next 5000 Days Articles A History of the Internet JCR Licklider of MIT Leonard Kleinrock of MIT and Lawrence Roberts of MIT founders of the internet The Internet then known as ARPANET was brought online in 1969 under a contract let by the renamed Advanced Research Projects Agency ARPA which initially connected four major computers at universities in the southwestern US UCLA Stanford Research Institute UCSB and the University of Utah The Internet was designed in part to provide a communications network that would work even if some of the sites were destroyed by nuclear attack If the most direct route was not available routers would direct traffic around the network via alternate routes EmaiI was adapted for ARPANET by Ray Tomlinson of BBN in 1972 The telnet protocol enabling logging on to a remote computer was published as a Request for Comments RFC in 1972 RFC39s are a means of sharing developmental work throughout community The p protocol enabling file transfers between Internet sites was published as an RFC in 1973 and from then on RFC39s were available electronically to anyone who had use of the ftp protocol The Internet matured in the 7039s as a result of the TCPZIP architecture first proposed by Bob ahn at BBN and further developed by Kahn and Vint Cerf It was adopted by the Defense Department in 1980 replacing the earlier Network Control Protocol NCP and universally adopted by 1983 In 1986 the National Science Foundation funded NSFNet as a cross country 56 Kbps backbone for the Internet They maintained their sponsorship for nearly a decade setting rules for its noncommercial government and research uses In 1991 the first really friendly interface to the Internet was developed at the University of Minnesota In 1989 another significant event took place in making the nets easier to use Tim Berners Lee and others at the European Laboratory for Particle Physics more popularly known as CERN proposed a new protocol for information distribution This protocol which became the World Wide Web in 1991 was based on hypertext a system of embedding links in text to link to other text which you have been using every time you selected a text link while reading these pages Although started before gopher it was slower to develop Delphi was the first national commercial online service to offer Internet access to its subscribers It opened up an email connection in July 1992 and full Internet service in November 1992 All pretenses of limitations on commercial use disappeared in May 1995 when the National Science Foundation ended its sponsorship of the Internet backbone and all traffic relied on commercial networks How the Internet Infrastructure Works For example you may use a modem and dial a local number to connect to an Internet Service Provider ISP At work you may be part ofa local area network M but you most likely still connect to the Internet using an ISP that your company has contracted with When you connect to your ISP you become part of their network The ISP may then connect to a larger network and become part of their network The Internet is simply a network of networks Most large communications companies have their own dedicated backbones connecting various regions In each region the company has a Point of Presence POP The POP is a place for local users to access the company39s network often through a local phone number or dedicated line The amazing thing here is that there is no overall controlling network Instead there are several highlevel networks connecting to each other through Network Access Point or NAPs Here39s an example Imagine that Company A is a large ISP In each major city Company A has a POP The POP in each city is a rack full of modems that the ISP39s customers dial into Company A leases fiber optic lines from the phone company to connect the POPs together see for example this UUNET Data Center Connectivity Map Imagine that Company B is a corporate ISP Company B builds large buildings in major cities and corporations locate their Internet server machines in these buildings Company B is such a large company that it runs its own fiber optic lines between its buildings so that they are all interconnected In this arrangement all of Company A39s customers can talk to each other and all of Company B39s customers can talk to each other but there is no way for Company A39s customers and Company B39s customers to intercommunicate Therefore Company A and Company B both agree to connect to NAPs in various cities and traffic between the two companies flows between the networks at the NAPs In the real Internet dozens of large Internet providers interconnect at NAPs in various cities and trillions of bytes of data ow between the individual networks at these points The Internet is a collection of huge corporate networks that agree to all intercommunicate with each other at the NAPS In this way every computer on the Internet connects to every other The routers determine where to send information from one computer to another Routers are specialized computers that send your messages and those of every other Internet user speeding to their destinations along thousands of pathways A router has two separate but related jobs I It ensures that information doesn39t go where it39s not needed This is crucial for keeping large volumes of data from clogging the connections of quotinnocent bystandersquot I It makes sure that information does make it to the intended destination Backbones are typically fiber optic trunk lines The trunk line has multiple fiber optic cables combined together to increase the capacity Fiber optic cables are designated OC for optical carrier such as OC3 OC12 or 0048 Every machine on the Internet has a unique identifying number called an IP Address The IP stands for Internet Protocol The four numbers in an IP address are called octets because they each have eight positions when viewed in binary form If you add all the positions together you get 32 which is why IP addresses are considered 32bit numbers The octets serve a purpose other than simply separating the numbers They are used to create classes of IP addresses that can be assigned to a particular business government or other entity based on size and need The octets are split into two sections Net and Host The Net section always contains the first octet It is used to identify the network that a computer belongs to Host sometimes referred to as Node identifies the actual computer on the network The Host section always contains the last octet Domain Name System DNS which maps text names to IP addresses automatically When you use the Web or send an email message you use a domain name to do it For example the Uniform Resource Locator URL quot ttpwwwhowstuffworkscomquot contains the domain name howstuffworkscom So does this email address examplehowstuffworkscom Toplevel domain names also called firstlevel domain names include COM ORG NET EDU and GOV Every name in the COM toplevel domain must be unique The leftmost word like www is the host name Once a DNS server resolves a request it caches the IP address it receives Once it has made a request to a root DNS server for any COM domain it knows the IP address for a DNS server handling the COM domain so it doesn39t have to bug the root DNS servers again for that information DNS servers can do this for every request and this caching helps to keep things from bogging down Internet servers make the Internet possible All of the machines on the Internet are either servers or client The machines that provide services to other machines are servers And the machines that are used to connect to those services are clients Any server machine makes its services available using numbered ports one for each service that is available on the server Once a client has connected to a service on a particular port it accesses the service using a specific protocol Protocols are often text and simply describe how the client and server will have their conversation How Web Servers Work The browser breaks the URL into three parts 1 The protocol quothttpquot 2 The server name quotwwwhowstuffworkscomquot 3 The file name quotweb serverhtmquot The browser communicates with a name server to translate the server name quotwwwhowstuffworkscomquot into an IP address which it uses to connect to that server machine The browser then forms a connection to the Web server at that IP address on port 80 Following the HTTP protocol the browser sends a GET request to the server asking for the file httpwwwhowstuffworkscomwebserverhtmquot Note that cookies may be sent from browser to server with the GET request see How Internet Cookies Work for details The server sends the HTML text for the Web page to the browser Cookies may also be sent from server to browser in the header for the page The browser reads the HTML tags and formats the page onto your screen How Web Pages Work The History of HTML ntroduction to C55 Chapter 1 John Hagel What is Web 20 Web Content Management Systems Quinn