Software Engineering 3156AdministriviaReview: ConcurrencyRPISBasic Reuse: LibrariesImpediments to ReuseSuccessful Reuse: ObjectsReuse: FrameworksReuse: Design PatternsPortability PitfallsLanguage PortabilityInteroperabilityCORBACOMScalabilityRational Development SuiteReview: XMLImportant PointWhere Is It?Software Engineering 31561-Oct-01#7: RPIS and ProjectPhil Gross2AdministriviaGroups and questionnaires are locked–Talk to Janak or me directly for changes3Review: ConcurrencyThreads (lightweight processes)Ability to run concurrent sets of code in one processJava: Class should implement Runnable–Then create new Thread on this class and start() itRace conditions (fix with locks)Deadlock (fix with timeout [or cycle detection])4RPISReusabilityPortabilityInteroperability(Scalability)Things to keep in mind early–So you’re not trying to force it in later5Basic Reuse: LibrariesLibraryAPISystem Call6Impediments to ReuseLack of trust / NIHLogistics of reuseMismatch of features (Kangaroos)Not to mention Ariane 5 (8.3.6)7Successful Reuse: ObjectsWell, that was the intention in any caseTypical language-level objects need some helpDiscovered somewhat by accident: VBXLead to JavaBeans and the COM familyWindows uses this pretty successfully8Reuse: FrameworksHigh-levelFramework gives you a generic body into which you add your particular codeExample: MFCProblems: bloat, steep learning curve9Reuse: Design PatternsChristopher Alexander in 1977Gang of Four in 1995Ways of organizing objects in order to solve frequently reoccurring problemsDesign it to be flexible, extensible, scalable, portable, etc. from the beginningGive a vocabularyAntipatterns: known bad ways of doing things10Portability PitfallsHardwareOSNumericsCompilersLibrariesBut, you have to do it: software lasts longer than hardware11Language PortabilityJava and C#Java uses a JVM–Write once, run anywhere, sorta, kindaC#: mobile data, not code–XML everywhereWinner as yet unknown, but betting against Microsoft is historically a losing proposition12InteroperabilityCOM and CorbaBoth define abstract servicesAllow programs in any language to access services in any language in any locationObject-ish13CORBAInternational standardTransport independentObject orientedGood for distributed applicationsQuite complex14COMMicrosoft proprietaryMicrosoft proprietary transportObject based (weaker than oriented)Impossibly complexWorks really, really well with Windows (surprise!)Vast quantities of off-the-shelf components15ScalabilityJust keep it in mind–Familiarity with patterns can helpDon’t worry about scaling beyond abilities of machine–Just avoid unnecessary barriers–Plus maybe graceful overload handlingFrom single connection, to forking processes, to threads, to thread pool16Rational Development SuiteName makes jokes too easyInterface is flakySoftware is incredibly bloatedPoor advertisement for software engineeringAnd yet…17Review: XMLXML Schema is like a classAn individual message is like an instance of that classSchema is itself defined with XML syntaxMade up of elements, aggregated with sequences or choices18Important PointForgot to mention this last timeXML Schema Primer 0Read itNo, really, read itRead and understand, and you have a sweet item for your resumePlus a chance of understanding the requirements…19Where Is It?http://www.w3.org/TR/xmlschema-0/ More than the textbook, this is required readingLike, right nowAn example to kick things