Presentation on theme: "Systems Development Life Cycle (SDLC)"— Presentation transcript:
1 Systems Development Life Cycle (SDLC) Minder Chen, Ph.D.Professor of MISMartin V. Smith School of Business and EconomicsCSU Channel Islands
2 Problems/Opportunities Life CycleStages: Planning Analysis Design ImplementationWhatProblems/OpportunitiesRequirementsSoft/People SkillsHowSolutionsSpecificationsTechnical SkillsVisibility: Deliverables/DocumentationMethodology*:Process (Life Cycle)Techniques (Modeling)Use modelingtechniques*A system development methodology is a framework that is used to structure, plan, and control the process of developing an information system.DataProcessUIPrototypingCodingProgrammingImplementationUI: User Interface
4 SDLC Waterfall Model Planning Analysis Design Implementation Operation Identify & prioritize IS development projectsPlanningAnalysisDesignImplementationOperationRequirementsAS-IS vs. TO-BELogical and physical Design specificationProgrammingTestingTrainingInstallationBug fix and UpgradesIT Service Management (ITIL standard)
5 Deliverables/Documentations of SDLC Stages/Phases
15 Adding More People Brook's Law: Adding developers to a late project will make it later.
16 Design: Cohesion and Coupling Divide and Conquer for effective teamworkSoftware Design CriteriaModularization: Simple, stable, and clearly defined interface for each module, no need to understand the internal structure or design of the module to use it.Good design is a system that has low coupling between modules and high cohesion within modules
17 Stubs and DriversThe most common build problem occurs when one component tries to use another component that has not yet been written. This occurs with modular design because the components are often created out of sequence.DriverModule MModule 1Module 2StubModule 2Stubs are non-functional components that provide the class, property, or method definition used by the other component. Stubs are a kind of outline of the code you will create later.To test two components that need to work together through a third component that has not been written yet, you create a driver. Drivers are simply test components that make sure two or more components work together. Later in the project, testing performed by the driver can be performed by the actual component.
18 General Systems Theory: Abstract Thinking Source:
19 Testing Test plan objectives Test plan covers Test cases Is thoroughly testedMeets requirementsDoes not contain defectsTest plan coversToolsWhoScheduleTest result analysisWhat is being tested?Test casesAutomated testingReproducibleMeasurableSource:Developing Web Applications with Microsoft Visual Basic .NET and Microsoft Visual C# .NET
20 Types of Tests Test type Objectives Unit test Each independent piece of code works correctlyIntegration testAll units work together without errorsRegression testNewly added features do not introduce errors to other features that are already workingLoad test (also called stress test)The product continues to work under extreme usagePlatform testThe product works on all of the target hardware and software platforms
21 Regression and Regression Test Regression testing is the process of validating modified parts of the software and ensuring that no new errors are introduced into previously tested code.Unit and integration tests form the basis of regression testing. As each test is written and passed, it gets checked into the test library for a regularly scheduled testing run. If a new component or a change to an existing component breaks one of the existing unit or integration tests, the error is called a regression.
22 Reasons for Project Failures Primary reasons for project failure includeUnclear or missing business requirementsSkipping SDLC phasesFailure to manage project scopeScope creep – occurs when the scope increasesFeature creep – occurs when extra features are addedFailure to manage project planChanging technology
23 European Space Agency rocket failure (June 4, 1996) Montclair State University ERP systemMinnesota’s Department of Human Services project called HealthMatchFord Motor Co. Purchasing SystemAvis Europe ERPUK Inland RevenueFBI Virtual Case FileDenver Airport Automated Baggage SystemCargo Management Reengineering - Australian CustomsPersonnel Management Key Solution – Department of DefenseHouse of Representatives Payroll SystemDMV - California (1994)FoxMeyer ERPSainsbury's SCM system automationCanadian national firearm registration systemU.S. Department of Homeland Security's "virtual fence"U.S. Census Bureau handheld devicesNational Programme for ITOverstock.com's ERP SYSTEMDepartment of Family and Community Services
24 Successful Principles for Software Development Primary principles for successful agile software development include:Slash the budgetIf it doesn’t work, kill itKeep requirements to a minimumTest and deliver frequentlyAssign non-IT executives to software projects
26 The Ten Essentials of RUP Develop a VisionManage to the PlanIdentify and Mitigate RisksAssign and Track IssuesExamine the Business CaseDesign a Component ArchitectureIncrementally Build and Test the ProductVerify and Evaluate ResultsManage and Control ChangesProvide User SupportSource:
30 Agile software development (Agile) ProsMinimizes feature creep by developing in short intervals resulting in miniature software projects and releasing the product in mini-increments.ConsShort iteration may add too little functionality, leading to significant delays in final iterations. Since Agile emphasizes real-time communication (preferably face-to-face), using it is problematic for large multi-team distributed system development. Agile methods produce very little written documentation and require a significant amount of post-project documentation.Extreme Programming (XP)Lowers the cost of changes through quick spirals of new requirements. Most design activity occurs incrementally and on the fly.Programmers must work in pairs, which is difficult for some people. No up-front “detailed design” occurs, which can result in more redesign effort in the long term. The business champion attached to the project full time can potentially become a single point of failure for the project and a major source of stress for a team.Joint application design (JAD)Captures the voice of the customer by involving them in the design and development of the application through a series of collaborative workshops called JAD sessions.The client may create an unrealistic product vision and request extensive gold-plating, leading a team to over- or under-develop functionality.Lean software development (LD)Creates minimalist solutions (i.e., needs determine technology) and delivers less functionality earlier; per the policy that 80% today is better than 100% tomorrow.Product may lose its competitive edge because of insufficient core functionality and may exhibit poor overall quality.Rapid application development (RAD)Promotes strong collaborative atmosphere and dynamic gathering of requirements. Business owner actively participates in prototyping, writing test cases and performing unit testing.Dependence on strong cohesive teams and individual commitment to the project. Decision making relies on the feature functionality team and a communal decision-making process with lesser degree of centralized PM and engineering authority.ScrumImproved productivity in teams previously paralyzed by heavy “process”, ability to prioritize work, use of backlog for completing items in a series of short iterations or sprints, daily measured progress and communications.Reliance on facilitation by a master who may lack the political skills to remove impediments and deliver the sprint goal. Due to relying on self-organizing teams and rejecting traditional centralized "process control", internal power struggles can paralyze a team.
32 Coincidental cohesion (worst)Coincidental cohesion is when parts of a module are grouped arbitrarily; the only relationship between the parts is that they have been grouped together (e.g. a “Utilities” class).Logical cohesionLogical cohesion is when parts of a module are grouped because they logically are categorized to do the same thing, even if they are different by nature (e.g. grouping all mouse and keyboard input handling routines).Temporal cohesionTemporal cohesion is when parts of a module are grouped by when they are processed - the parts are processed at a particular time in program execution (e.g. a function which is called after catching an exception which closes open files, creates an error log, and notifies the user).Procedural cohesionProcedural cohesion is when parts of a module are grouped because they always follow a certain sequence of execution (e.g. a function which checks file permissions and then opens the file).Communicational cohesionCommunicational cohesion is when parts of a module are grouped because they operate on the same data (e.g. a module which operates on the same record of information).Sequential cohesionSequential cohesion is when parts of a module are grouped because the output from one part is the input to another part like an assembly line (e.g. a function which reads data from a file and processes the data).Functional cohesion (best)Functional cohesion is when parts of a module are grouped because they all contribute to a single well-defined task of the module (e.g. tokenizing a string of XML).
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