CS 501: Software EngineeringAdministrationProject Concept: Legal Information InstituteProject Concept: ParMETISProject Concept: Public Key InfrastructureProject Concept: Data Tracking System for the Web LibraryProject Concept: Revision Control SystemProject Concept: Map & GIS LibraryProject Concept: Reference Statistics for Olin LibraryProject Concept: Water Distribution in Honduran VillagesProject Concept: Small Hotels and Bed & BreakfastsA Classic BookSoftware ProcessVariety of Software ProcessesBasic Process Steps in all Software DevelopmentFeasibility and PlanningRequirementsSystem and Program DesignImplementation and TestingAcceptance Testing and ReleaseOperation and MaintenanceSequence of ProcessesProcess 1: Sequential The Waterfall ModelSlide 24Discussion of the Waterfall ModelModified Waterfall ModelProcess 2: Iterative Refinement (Evolutionary Development)Iterative RefinementSlide 29Process 3: Phased DevelopmentIterative Refinement + Waterfall Model: Graphics for BasicSlide 32Slide 33Observations about Software ProcessesThree Project Presentations: Sequential OptionThree Project Presentations: Iterative Option1CS 501 Spring 2006CS 501: Software EngineeringLecture 2Software Processes2CS 501 Spring 2006Letter "l"AdministrationProject teamsAny short notices to class?Course team email addressWhen you have formed your team and reached agreement with your client, please send a message to [email protected] with the names of the team, the client's name, and the topic of the project.3CS 501 Spring 2006Project Concept: Legal Information Institute4CS 501 Spring 2006Project Concept: ParMETIS5CS 501 Spring 2006Project Concept: Public Key Infrastructure6CS 501 Spring 2006Project Concept: Data Tracking System for the Web Library7CS 501 Spring 2006Project Concept: Revision Control System8CS 501 Spring 2006Project Concept: Map & GIS Library9CS 501 Spring 2006Project Concept: Reference Statistics for Olin Library10CS 501 Spring 2006Project Concept: Water Distribution in Honduran Villages11CS 501 Spring 2006Project Concept: Small Hotels and Bed & Breakfasts12CS 501 Spring 2006A Classic BookFrederick P. Brooks, Jr. The Mythical Man Month. Addison-Wesley, 1972.13CS 501 Spring 2006Software ProcessFundamental Assumption: Good processes lead to good software Good processes reduce risk Good processes enhance visibility14CS 501 Spring 2006Variety of Software ProcessesSoftware products are very varied...Therefore, there is no standard process for all software engineering projectsBUT successful software development projects all need to address similar issues.This creates a number of process steps that must be part of all software projects15CS 501 Spring 2006Basic Process Steps in all Software Development• Feasibility and planning• Requirements• System and program design• Implementation and testing• Acceptance testing and release• Operation and maintenanceIt is essential to distinguish among these aspects and to be clear which you are are doing at any given moment. Do not confuse requirements and design.16CS 501 Spring 2006Feasibility and PlanningA feasibility study precedes the decision to begin a project.• What is the scope of the proposed project?• Is the project technically feasible?• What are the projected benefits?• What are the costs, timetable?A feasibility study leads to a decision: go or no-go.17CS 501 Spring 2006RequirementsThe requirements define the function of the system FROM THE CLIENT'S VIEWPOINT.The requirements establish the system's functionality, constraints and goals by consultation with the client and users. They are then defined in a manner that is understandable by both the client and the development staff.This phase is sometimes divided into:• Requirements analysis• Requirements definition• Requirements specification18CS 501 Spring 2006System and Program DesignThe design describes the system FROM THE SOFTWARE DEVELOPERS' VIEWPOINT System design: Partition the requirements to hardware or software systems. Establishes an overall system architectureSoftware design: Represent the software system functions in a form that can be transformed into one or more executable programs• Unified Modeling Language (UML)19CS 501 Spring 2006Implementation and TestingCodingThe software design is realized as a set of programs or program units. (Written specifically, acquired from elsewhere, or modified.) TestingIndividual components are tested against specifications. The individual program units are integrated and tested against the design by the development staff as a complete system.20CS 501 Spring 2006Acceptance Testing and ReleaseAcceptance testingThe complete system is tested against the requirements by the client.Delivery and releaseThe complete system is delivered to the client and released into production.21CS 501 Spring 2006Operation and MaintenanceOperation: The system is put into practical use.Maintenance: Errors and problems are identified and fixed.Evolution: The system evolves over time as requirements change, to add new functions or adapt the technical environment.Phase out: The system is withdrawn from service.This is sometimes called the Software Life Cycle22CS 501 Spring 2006Sequence of ProcessesEvery software project will include these basic processes, in some shape or form, but:• They may be formal or informal• They may be carried out in various sequencesMajor alternatives• Sequential: Complete each process step before beginning the next (but see the next few slides). Waterfall model.• Iterative: Go quickly through all process steps to create a rough system, then repeat them to improve the system. Iterative refinement.23CS 501 Spring 2006Process 1: Sequential The Waterfall ModelRequirementsSystem designTestingOperation & maintenanceProgram designCodingAcceptance & releaseRequirementsDesignImplementationFeasibility study24CS 501 Spring 2006Sequence of ProcessesA pure sequential model is impossibleExamples: • A feasibility study cannot create a proposed budget and schedule without a preliminary study of the requirements and a tentative design.• Detailed design or implementation usually reveals gaps in the requirements specification.The plan must allow for some form of iteration.25CS 501 Spring 2006Discussion of the Waterfall ModelAdvantages:• Process visibility• Separation of tasks• Quality control• Cost controlDisadvantages:Each stage in the process reveals new
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