Business Information Systems
Business Information Systems ISM 50
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This 64 page Class Notes was uploaded by June Dickinson on Monday September 7, 2015. The Class Notes belongs to ISM 50 at University of California - Santa Cruz taught by John Musacchio in Fall. Since its upload, it has received 74 views. For similar materials see /class/182167/ism-50-university-of-california-santa-cruz in Information Systems Management at University of California - Santa Cruz.
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Date Created: 09/07/15
ISM 50 Business Informa rion Sys rems Lec rur39e 12 Ins rr39uc ror39 John Musacchio UC San ra Cr39uz May 11 2006 AnnouncemenTs Read Messerschmi r r Ch 7 for39 Tuesday Pr39esen rer39s for39 Tuesday 1 Danny Macias Walmar39T 1 Isaac Bejar39 Ebaycom l Sources You should ciTe aT leasT 5 nonweb sources a Ideally a loT more I If an arTicle is available online and also in prinT you should ciTe The prinT versionllll El Why I Only ciTe a websiTe if you are sure There is no prinT version of The maTerial available 1 Your ciTaTion of The prinT version may also indicaTe a websiTe where The same arTicle is available l Citing Sources More Than Thir ry words verba rim mus r be ci red Any fac rs or figures Tha r are no r your own mus r be ci red in The body of The Tele 1 Ebay39s revenues in US Revenues in 2002 were 139 billion 1 1 Ebay 2005 Annual ReporT Any Tables of figures mus r be ci redll l Citing Sources STYLE1 Companies that have deployed Internet Technology have been confused by distor39ted market signals often of their39 own creationquot1 1M Por39ter39 Strategy and the In tquot Harvard Business Vew March 2001 pp 331 Footnote at page bottom FOOtnOte IDdlcatOF STYLE 2 Citation indicator Companies that have deployed Internet technology have been confused by distorted market signals often of their own creation 1 References 1 M Por39ter39 Strategy and the Internetquot Harvard 3 Mess Review March 2001 pp 331 Matches reference number in References section at the end of text STudenT Talks I Mia Zer39cher39 Home DepoT Tallis Salama rian Coca Cola l Wha r problems did The micro era produce Desk rops are expensive To mainTain a TCO for windows PC 9900 I Every PC had a Io r of sof rware Tha r had To be main rained 1 Office Windows e rc Small differences like The order in which sof rware is ins ralled could make differen r PCs behave differen rly 5un39s Vision Thin Clien r model Applica rion Servers wi rh Applica rions wri r ren in Java NCs could re rrieve applica rions from applica rion server as needed Applica rions compa rible wi rh any NC hardware and OS Applica rions could be fixed added updaTed a r The server eve ra rher Than main raining each PC Micr39oso Vision Keep fo rclien rquot model I Add some feo rur39es To Windows To reduce administration cos rs I r A EllIUD El n Netlncome3558 4764 7624 7629 10313 18540 9270 5870 A 1995 13939 34290 3880 1060 Today 3Tier model common Sun39s version of 4Tier model no rcommon NTier model where Webserver and Applica rion Server on separa re equipmen r also common Sun39s hardware business no r s rrong a Linux on cheap PCs mos r common servers 1 MicrosofT desk rops replacing Sun works ra rions l Today I Java 1 Common in Server implemen ra rions I Example Java Ser39vle r implemen ring applica rion logic in a banking applica rion a OfTen used To push simple apple rs on ro clien r 1 NOT common I For39 quotbigquot desk rop applica rions Office Sui re in Java no r popular39 a MicrosofT is s rill in business l ArchiTecTure ConcepTualizaTion u Wha r is if you are Trying To do Example Concep r a Small HHC for fligh r a r rendan rs u HHC rells fligh r a r rendan rs which passengers are higher priori ry I Who paid The highes r fares I Who has been a more valuable cus romer in pas r u Fligh r a r rendan r discriminates based on This I Free drinks meals and pillows To valuable cus romers I Ignore less valuable cus romers Example ConcepT Ar39chiTecTur39e How do you begin To orchi rec r o solu rion for39 a problem like This I Break i r in ro modules Ar39chi rec rur39e Vq HEADQUARTERS C a rem DEE m Airline Datasener Wireless Link HHC Architecture HHC Application l i Palm OS l T Networking Infrastructure Aina on With HHC Server User Interface Data Management When a module is composed of submodules the architecture is hierarchical HHC Architecture HHC Application l i Palm OS l T Networking Infrastructure ad g Communication With HHC Server User Interface data management We are using a layered arch39fecfure as well Allows reuse of previously built infrastructure l GranulariTy Tradeoff I How big should we make The modules 1 Many simple small ones 1 Or39 a few complica red big ones I This aspec r of modulari ry is called granularity Which is better I HHC s er39ver Computation Communication HHC Server Appllcatlon of key statistics with HHC Windows OS Communication with airline database Networking Infrastructure Standard Database queries SQL relayed to DBMS via 08 and infrastructure Again we see layering and hier39ar39ch Between each module we specify an interface Data server Standard Database queries SQL from HHC Server DBMS Database Our architecture makes use of the Existing interface of the airline database so we don t need to redesign it A simple interface from within our39 HHC Server Architecur e Compute Mean and List of numbers Variance Computation 4 of key statistics Variance of key statistics With HHC with airline database lInterfaces N numbers of Float type Computation of key statistics Compute Mean and Variance 2 Numbers of float type that signify Mean Variance Interface specifications are often made precise by using data es Example type float a A number with a decimal place 1 Has a certain allowable range and precision l More on DaTa Types DaTa passing an inTer39face is ofTen specified in Terms of a limiTed number of sTandar39d daTa Types DaTa Type 2 range of values and allowable manipulaTion DaTa Type does nof presume a specific r39epr39esenTaTion To allow heTer39ogeneous planor39ms a RepresenTaTion musT be known when daTa passes a specific module inTer39face Example daTa Types InTeger u naTur39al number beTween 32767 and 32768quot 1 Could be r39epr39esenTed in many ways by 16 biTs I since 2 65536 FloaT a number of The form m10 32768 where m is in The range 32767 To 32768 and n is in The range 255 To 256quot 1 Could be r39epr39esenTed by 168 24 biTs More dam Types Charac rer39 a values assuming 12 and AZ plus space and punc rua rion marksquot could be represented by 7 or39 8 bi rs Charac rer39 s rr39ing a collec rion of n charac rer39s where n is cus romizablequot could be represented by 7n bi rs I Compound dam Types Programmerdefined composi rion of basic da ra Types Example Employee String name String address Integer year39of bir rh e rc Interfaces PARAMETERS N numbers of 39lfloat type 0 Compute Mean and Variance 9 2 Numbers of float Computation 3 type that signify of key statistics 399 3 Mean Variance av INTERFACE RETURNS Module B Implementation Compute Mean and Variance Module A Implementation 1 Computation of key statistics One module should not be concerned with other module s Implementation 1 9 Separation of concernsquot n One module should see the other only through its interface implementation details hidden 1 9 Abstraction Module B Implementation Compute Mean and Variance a ModuleA I p 0 mplementation2 6P P Computation l N of key statistics SHIV 2er i1 MEAN SUM 1V N VARIANCE 2mi MEAN2 1 Though different this implementation is ok too I We can choose the implementation details however39 we want as long as we comply with the agreed interface Module B Implementation Compute Mean and Variance A Module A Computation N of key statistics 2 33 711 I lljust take it from B I Should he use it a Noun Why Either A should compute SUM himself or sit down with B and redesign the interface l EncapsulaTion The designer of B migh r Take measures To hide SUM from A so Tha r A is no r able To viola re The agreed in rerface 1 Example B does no r declare quotSUMquot as a global variable Making a modules implemen ra rion de rails inaccessible To o rher modules is called encapsulation lInterfaces PARAMETERS N numbers of 39lfloat type a 0 Module A Module B Compute Mean and Variance Q Computation of key statistics 2 Numbers of float 3 type that signify 5 3 Mean Variance av This si module INTERFACE RETURNS mile interface example allows for only one action of 1 Action is Compute mean and variancequot Other examples are possible Possible sof rware inTerface action 1 Menu of actions acuon39z action3 Example Ac rion 1 CompuTe mean AcTion 2 CompuTe variance AcTion 3 CompuTe mode ETc lProTocol In addi rion To a romic ac rions an in rer39face may define pr39o rocols a Pr39o rocol fini re sequence of ac rions required To achieve a higher level funcTion a One ac rion can be shared by mulTiple pr39o rocols a MulTiple modules may par ricipa re in a pr39o rocol l Protocol Example Hello I m the HHC of Airplane1234 Hello I m the ate 32 sen These were the unruly passengers on last flight Passengers noted Tell me about the passengers of my next flight Might be passed As an array of a Return Passenger compound data type Data passenger which in turn Tell me about the weather lts conlliosleil Of Standdard at my next destination ypes l e In eger39 an string Return Weather Data Another Interface Example Automatic teller machine ATM What is the interface between this machine and the customer STeps Define available ac rions Define for each higher level func rion a proTocol a Single ac rion or39 a fini re sequence of ac rions Interface building blocks Message on screen or printed a Menu of actions or returns from an action a Touch selection of action Keypad a Input parameters to an action Card reader a Authentication input parameters Money output slot a Returns money AcTion auThenTicaTion Parame rer39s Infernal func rionali ry Returns l AcTion auThenTicaTion Par39ameTer39s a Iden ri ry card in slo r u Ins ri ru rion card in slo r a PIN Typed on keypad In rer39nally i r con rac rs insTiTuTian and ma rches agains r I l S da rabase Ins rl ru rlon no red for39 all subsequenT GC l IOl lS example of sTaTe Refurns a Screen message Invalid PINquot or39 menu of available ac rions AcTion specifyaccounT Parame rer39s Infernal func rionali ry Returns AcTion specifyoccounT Por39ome rer39s a Accoun r Touch screen from menu of choices In rer39nolly choice no red for39 all subsequen r oc rions ono rher39 example of s ro re Returns El None l AcTion amounT Parame rers a Dollarsandcen rs Typed on keypad In rernally amoun r no red ano rher example of s ra re Re rurns a Success or failure sTaTe dependen r for example for a wi rhdraw failure when dollarsandcenTs exceeds balance ProTocol cashwiThdmwal Wha r is The sequence of actions Protocol cashwithdmwal failure other objectives no accounts balance exceeded More on layering by David G Messer39schmi r r l Goals Unders rand be r rer39 a how layering is used in The infras rr39uc rur39e a how if con rains complexi ry a how if coordina res suppliers 1 how if allows new capabili ries To be added incremenTally lIm erac rion of layers IIIIIIIII 177 Each layer provides services to the layer above by utilizing the services of the layer below and adding capability TTTT IIIIIIII Host A Host B Layering Three Types of sofTware services storagea eoneum ency presentation Part of Microsoft vs DOJ dispute Microsoft DO DOSitiOH position GETMIimrru Imm quot Emmi Infrastructure Major layers Data and information Assumes structure and interpretation Ignores structure and interpretation l DaTa and informaTion in layers I The infr39as rr39uc rur39e should deal with da ra a or39 a r mos r minimal s rr39uc rur39e and in rer39pr39e ra rion The applica rion adds addi rional s rr39uc rur39e and in rer39pr39e ra rion This yields a separ39a rion of concerns l Package file message In The simplesT case The infrasTrucTure deals wiTh a package of daTa nonsTandard Terminology a collecTion of biTs a specified number and ordering The objecTive of The infrasTrucTure is To sTore and communicaTe packages while mainTaining daTa inTegriTy File for sTorage message for communicaTion DaTa inTegriTy Re rain The a values a order39 a number of biTs in a package I Example 1 Bob sends a letter to Alice lt Q Alice Envelope I Envelope I US Postal Service I I UK Royal Mail Shipping Container I Shipping Container ABC Airlines w I Example 2 Web page gt Application Operating SYStem File system Network Fragmentatlon l Example 3 Passenger Information HHC Server Application HHC Client Application message message I Windows OS I l Palm 05 l Networking Infrastructure COlleCtlon 0f PaCketS Networking Infrastructure Contains TCPIP WiFi Contains TCPIP WiFi Example 3 Network Infrastructure Expanded I HHC ServerApplication Passenger Information message I Windows OS I TOP transport layer I Packets Packets I WiFi Link Layer I Radio Signals WiFi Physical Layer I Networking Infrastructure V 4 HHC ClientApplioation A message Palm OS TCP transport layer I WiFi Link Layer I WiFi Physical Layer I I Networking Infrastructure I Example 4 HEADQUARTERS DE E D Airline Datasener Send me today s HHC Server Application ight informationquot DBMS message message Windows os I Unix OS I Networking Infrastructure COHeCtion 0f PaCKetS Networking Infrastructure Layers within TCPIP WiFi Layers within TCPIP WiFi InformaTion in The infrasTrucTure Some rimes if is appropria re for39 The infras rr39uc rur39e To assume s rr39uc rur39e and in rer39pr39e ra rion for39 da ra a To add capabili ries widely useful To applica rions a To help applica rions deal wi rh he rer39ogeneous planorms where r39epr39esen ra rions differ AT mos r da ra Types
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