Slide 1RemindersWho Invented the Internet?Who Invented Networking?What is a Network?Beacon Chain NetworkingPony ExpressChappe’s Semaphore NetworkGovernment and NetworkingMeasuring NetworksLatency and BandwidthImproving LatencyHow many transfer points between here and California?Slide 14tracertSlide 16BandwidthImproving BandwidthMorse CodeCircuit SwitchingPacket SwitchingCircuit and Packet SwitchinginternetworkThe First internetFirst Use of InternetOkay, so who invented the Internet?The Modern InternetThe World Wide WebThe “Desk Wide Web”Slide 30Slide 31World Wide Web SuccessHyperText Transfer ProtocolHTML: HyperText Markup LanguageHTML Grammar ExcerptPopular Web Site: Strategy 1 Static, Authored Web SitePopular Web Site: Strategy 2 Dynamic Web ApplicationsSlide 38Dynamic Web SitesDynamic Web SiteSlide 41Processing a GET RequestUsing a DatabaseSlide 44SQLChargeSlide 47David Evanshttp://www.cs.virginia.edu/evansCS150: Computer ScienceUniversity of VirginiaComputer ScienceLecture 33: Lecture 33: NetworkingNetworkingMemex MachineVannevar Bush, As We May Think, LIFE, 19452Lecture 33: NetworkingReminders•Before midnight tonight: email me your idea and/or team request for ps9•Wednesday’s class: Gary McGraw3Lecture 33: NetworkingWho Invented the Internet?4Lecture 33: NetworkingWho Invented Networking?5Lecture 33: NetworkingWhat is a Network?A group of three or more connected communicating entities6Lecture 33: NetworkingBeacon Chain NetworkingThus, from some far-away beleaguered island, where all day long the men have fought a desperate battle from their city walls, the smoke goes up to heaven; but no sooner has the sun gone down than the light from the line of beacons blazes up and shoots into the sky to warn the neighboring islanders and bring them to the rescue in their ships. Iliad, Homer, 700 BCChain of beacon’s signaled Agammemnon’s return (~1200BC), spread on Greek peaks over 600km.7Lecture 33: NetworkingPony Express•April 1860 – October 1861•Missouri to California–10 days–10-15 miles per horse, ~100 miles per rider•400 horses total (not per station like Kahn’s)8Lecture 33: NetworkingChappe’s Semaphore NetworkMobile Semaphore Telegraph Used in the Crimean War 1853-1856 First Line (Paris to Lille), 17949Lecture 33: NetworkingGovernment and NetworkingChappe wanted a commercial networkAnyone performing unauthorized transmissions of signals from one place to another, with the aid of telegraphic machines or by any other means, will be punished with an imprisonment of one month to one year, and a fine of 1,000 to 10,000 Francs. The use of novel methods that modify established habits, often hurts the interests of those who profit the most from the older methods. Few people, with the exception of the inventors, are truly interested in helping projects succeed while their ultimate impact is still uncertain. . . . Those in power will normally make no effort to support a new invention, unless it can help them to augment their power; and even when they do support it, their efforts are usually insufficient to allow the new ideas to be fully exploited. (Claude Chappe, 1824)French Law passed in 1837 made private networking illegal10Lecture 33: NetworkingMeasuring Networks•LatencyTime from sending a bit until it arrives seconds (or seconds per geographic distance)•Bandwidth How much information can you transmit per time unitbits per second11Lecture 33: NetworkingLatency and Bandwidth•Napoleon’s Network: Paris to Toulon, 475 mi•Latency: 13 minutes (1.6s per mile)–What is the delay at each signaling station, how many stations to reach destination–At this rate, it would take ~1 hour to get a bit from California•Bandwidth: 2 symbols per minute (98 possible symbols, so that is ~13 bits per minute–How fast can signalers make symbols–At this rate, it would take you about 9 days to get ps8.zip12Lecture 33: NetworkingImproving Latency•Less transfer points–Longer distances between transfer points–Semaphores: how far can you see clearly •Curvature of Earth is hard to overcome–Use wires (electrical telegraphs, 1837)•Faster transfers–Replace humans with machines•Faster travel between transfers–Hard to beat speed of light (semaphore network)–Electrons in copper: about 1/3rd speed of light13Lecture 33: NetworkingHow many transfer points between here and California?14Lecture 33: Networking15Lecture 33: NetworkingK:\>tracert www.cs.berkeley.eduTracing route to hyperion.cs.berkeley.edu [169.229.60.105]over a maximum of 30 hops: 1 3 ms 3 ms 4 ms 128.143.69.1 2 <1 ms <1 ms <1 ms carruthers-6509a-x.misc.Virginia.EDU [....] 3 <1 ms <1 ms <1 ms new-internet-x.misc.Virginia.EDU [128.....] 4 4 ms 4 ms 4 ms nwv-nlrl3.misc.Virginia.EDU [192.35.48.30] 5 5 ms 5 ms 5 ms nlrl3-router.networkvirginia.net [192.7...] 6 18 ms 18 ms 18 ms atla-wash-64.layer3.nlr.net [216.24.186.20] 7 43 ms 43 ms 42 ms hous-atla-70.layer3.nlr.net [216.24.186.8] 8 73 ms 73 ms 73 ms losa-hous-87.layer3.nlr.net [216.24.186.30] 9 72 ms 72 ms 72 ms hpr-lax-hpr--nlr-packenet.cenic.net [137..] 10 80 ms 81 ms 81 ms svl-hpr--lax-hpr-10ge.cenic.net [137.16...] 11 145 ms 81 ms 81 ms hpr-ucb-ge--svl-hpr.cenic.net [137.164....] 12 81 ms 81 ms 81 ms g3-12.inr-201-eva.Berkeley.EDU [128.32....] 13 81 ms 82 ms 83 ms evans-soda-br-5-4.EECS.Berkeley.EDU [...] 14 83 ms 84 ms 83 ms sbd2a.EECS.Berkeley.EDU [169.229.59.226] 15 83 ms 84 ms 83 ms hyperion.CS.Berkeley.EDU [169.229.60.105]Trace complete.tracertUVaUCBAtlanta  Houston  LA?16Lecture 33: Networking>>> cvilleberkeley = 3813 # kilometers>>> seconds = 84.0/1000>>> speed = cvilleberkeley / seconds>>> speed45392.857142857138>>> light = 299792.458 # km/s>>> speed / light0.15141427321316114Packets are traveling average at 15% of the speed of light (includes transfer time through 15 routers)17Lecture 33: NetworkingBandwidthHow much data can you transfer in a given amount of time?18Lecture 33: NetworkingImproving Bandwidth•Faster transmission–Train signalers to move semaphore flags faster–Use something less physically demanding to transmit•Bigger pipes–Have multiple signalers transmit every other letter at the same time•Better encoding–Figure out how to code more than 98 symbols with semaphore signal–Morse code (1840s)19Lecture 33: NetworkingMorse CodeRepresent