StandardsObjectivesSlide 3What are standards?De jure and de facto standardsDe jure and de facto standards (cont’d)Examples of de jure and de factoGray-area StandardsAnother spectrumOpen vs. closed standardsWhy use standards?Why use standards? (cont’d)Drawbacks of standardsOverspecification vs. underspecificationTwo different kinds of underspecificationWhen to adopt a standard?When to adopt a standard? (cont’d)Slide 18Slide 19IEEE 1471IEEE 1471 (cont’d)Department of Defense Architecture FrameworkDoDAF (cont’d)Slide 24Slide 25DoDAF ExamplesDoDAF Examples (cont’d)Slide 28Slide 29Slide 30DoDAF TakeawaysThe Open Group Architecture FrameworkTOGAF Part 1: ADMTOGAF Part 2: Enterprise ContinuumTOGAF Part 3: TOGAF Resource BaseTOGAF TakeawaysRM-ODPUMLUML TakeawaysSysMLSysML DiagramsStandard UML ToolsArgoUML – a UML toolTelelogic System ArchitectRational Unified ProcessModel-Driven ArchitectureOverall TakeawaysCopyright © Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy. All rights reserved.StandardsSoftware ArchitectureLecture 262Foundations, Theory, and PracticeSoftware ArchitectureSoftware ArchitectureObjectivesConceptsWhat are standards?Why use standards?And why not? (drawbacks)Deciding when to adopt a standardPrevalent Architectural StandardsConceptual standardsNotational standardsStandard toolsProcess standards3Foundations, Theory, and PracticeSoftware ArchitectureSoftware ArchitectureObjectivesConceptsWhat are standards?Why use standards?And why not? (drawbacks)Deciding when to adopt a standardPrevalent Architectural StandardsConceptual standardsNotational standardsStandard toolsProcess standards4Foundations, Theory, and PracticeSoftware ArchitectureSoftware ArchitectureWhat are standards?Definition: a standard is a form of agreement between partiesMany kinds of standardsFor notations, tools, processes, organizations, domains There is a prevalent view that complying to standard ‘X’ ensures that a constructed system has high qualityThis is almost never strictly trueBut that doesn’t mean standards are worthless!Here, we will attempt to put standards in perspective5Foundations, Theory, and PracticeSoftware ArchitectureSoftware ArchitectureDe jure and de facto standardsSome standards are controlled by a body considered authoritativeANSI, ISO, ECMA, W3C, IETFThese standards are called de jure (“from law”)De jure standards usuallyare formally defined and documentedare evolved through a rigorous, well-known processare managed by an independent body, governmental agency, or multi-organizational coalition rather than a single individual or company6Foundations, Theory, and PracticeSoftware ArchitectureSoftware ArchitectureDe jure and de facto standards (cont’d)Some standards emerge through widespread awareness and useThese standards are called de facto (“in practice”)De facto standards usuallyare created by a single individual organization to address a particular needare adopted due to technical superiority or market dominance of the creating organizationevolve through an emergent, market-driven processare managed by the creating organization or the users themselves, rather than through a formal custodial body7Foundations, Theory, and PracticeSoftware ArchitectureSoftware ArchitectureExamples of de jure and de factoDe jure standardsUML (managed by OMG)CORBA (also managed by OMG)HTTP protocol (managed by IETF)De facto standardsPDF format (managed by Adobe)May become de jure through ISOWindows (managed by Microsoft)There is a substantial gray area between these two8Foundations, Theory, and PracticeSoftware ArchitectureSoftware ArchitectureGray-area StandardsHTMLOfficially standardized by W3C, indicating de jureFlavors and browser-specific extensions developed by Microsoft, Netscape, and others, creating de facto variantsNone of these has power to force users to use standardJavaScriptDeveloped by Netscape; copied (as JScript) by MicrosoftAfter substantial adoption and possibly under threat of forking/splintering, Netscape submits it to ECMANow standardized as ECMAScript (de jure)JavaScript and variants continue to be developed as compatible extensions of ECMAScript9Foundations, Theory, and PracticeSoftware ArchitectureSoftware ArchitectureAnother spectrumStandards (whether de jure or de facto) can be:OpenAllow public participation in the standardization processAnyone can submit ideas or changes for reviewClosed (a.k.a. proprietary)Only the custodians of a standard can participate in its evolution10Foundations, Theory, and PracticeSoftware ArchitectureSoftware ArchitectureOpen vs. closed standardsAnother spectrum with a gray areaSome standards bodies have high barriers to entry (e.g., steep membership fees, vote of existing membership)Some standards (e.g., Java) have aspects of bothSun Microsystems is effectively in control of Java as a de facto standardThere is an open “community process” by which external parties can participate in a limited way11Foundations, Theory, and PracticeSoftware ArchitectureSoftware ArchitectureWhy use standards?Standards are an excellent way to create and exploit network effectsA network effect exists if the value of participation increases as the number of users of the standard increasesOther network effects:TCP/IP, HTTP & HTML, UML… versus 12Foundations, Theory, and PracticeSoftware ArchitectureSoftware ArchitectureWhy use standards? (cont’d)To ensure interoperability between products developed by different organizationsUsually in the interest of fostering a network effectTo carry hard-won engineering knowledge from one project to anotherTo take advantage of hard-won engineering knowledge created by othersAs an effort to attract tool vendorsTo create economies of scale in toolsTo attempt to control the standard’s evolution in your favor13Foundations, Theory, and PracticeSoftware ArchitectureSoftware ArchitectureDrawbacks of standardsLimits your agilityRemember that doing ‘good’ architecture-based development means identifying what is important in your projectStandards often attempt to apply the same techniques to a too-broad variety of situationsThe most widely adopted standards are often the most general14Foundations, Theory, and PracticeSoftware