CS 501: Software EngineeringAdministrationProject Concept: Institutional Repository Submission SystemProject Concept: Library of Congress ClassificationsProject Concept: Legal Information InstituteProject Concept: Automated Statistics Gathering and Reporting SystemProject Concept: Revision Control SystemProject Concept: RingtonesProject Concept: Automatic TeX SystemProject Concept: The Johnson Graduate School of Management LibraryA Classic BookSoftware ProcessVariety of Software ProcessesBasic Process Steps in all Software DevelopmentFeasibility and PlanningRequirements Analysis and DefinitionSystem and Program DesignImplementationAcceptance and ReleaseOperation and Maintenance: Software Life CycleCombining the Process StepsSequence of ProcessesProcess 1: Sequential The Waterfall ModelDiscussion of the Waterfall ModelModified Waterfall ModelProcess 2: Iterative Refinement (Evolutionary Development)Iterative RefinementSlide 28Process 3: Phased DevelopmentIterative Refinement + Waterfall Model: Graphics for BasicSlide 31Slide 32Observations about Software ProcessesProject Presentations: Sequential OptionProject Presentations: Iterative Option1CS 501 Spring 2005CS 501: Software EngineeringLecture 2Software Processes2CS 501 Spring 2005AdministrationCourse team email [email protected] teamsAny short notices to class?Letter "l"3CS 501 Spring 2005Project Concept: Institutional Repository Submission SystemQuickTime™ and aTIFF (LZW) decompressorare needed to see this picture.4CS 501 Spring 2005Project Concept: Library of Congress ClassificationsQuickTime™ and aTIFF (LZW) decompressorare needed to see this picture.5CS 501 Spring 2005Project Concept: Legal Information Institute6CS 501 Spring 2005Project Concept: Automated Statistics Gathering and Reporting SystemQuickTime™ and aTIFF (LZW) decompressorare needed to see this picture.7CS 501 Spring 2005Project Concept: Revision Control SystemQuickTime™ and aTIFF (LZW) decompressorare needed to see this picture.8CS 501 Spring 2005Project Concept: RingtonesQuickTime™ and aTIFF (LZW) decompressorare needed to see this picture.9CS 501 Spring 2005Project Concept: Automatic TeX SystemQuickTime™ and aTIFF (LZW) decompressorare needed to see this picture.10CS 501 Spring 2005Project Concept: The Johnson Graduate School of Management LibraryQuickTime™ and aTIFF (LZW) decompressorare needed to see this picture.11CS 501 Spring 2005A Classic BookFrederick P. Brooks, Jr. The Mythical Man Month. Addison-Wesley, 1972.12CS 501 Spring 2005Software ProcessFundamental Assumption: Good processes lead to good software Good processes reduce risk Good processes enhance visibility13CS 501 Spring 2005Variety 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 projects14CS 501 Spring 2005Basic Process Steps in all Software Development• Feasibility and planning• Requirements• Design• Implementation• Acceptance 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.15CS 501 Spring 2005Feasibility 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.16CS 501 Spring 2005Requirements Analysis and DefinitionThe requirements analysis and definition establish the system's services, constraints and goals by consultation with users. They are then defined in a manner that is understandable by both users and development staff.This phase can be divided into:• Requirements analysis• Requirements definition• Requirements specificationRequirements define the function of the system FROM THE CLIENT'S VIEWPOINT.17CS 501 Spring 2005System and Program DesignSystem 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)The design describes the system FROM THE SOFTWARE DEVELOPERS' VIEWPOINT18CS 501 Spring 2005ImplementationProgrammingThe 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 as a complete system.19CS 501 Spring 2005Acceptance and ReleaseAcceptance The complete system is tested against the requirements by the client.Delivery and releaseThe complete system is delivered to the client and released into production.20CS 501 Spring 2005Operation and Maintenance: Software Life CycleOperation: 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.21CS 501 Spring 2005Combining the Process StepsRequirementsOperation andMaintenanceImplementationDesignFeasibility andPlanningThere are many ways to combine the processes22CS 501 Spring 2005Sequence 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 sequencesExamples: • 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.23CS 501 Spring 2005Process 1: Sequential The Waterfall ModelRequirements analysisSystem designTestingOperation & maintenanceProgram designCodingAcceptanceRequirementsDesignImplementationFeasibility study24CS 501 Spring 2005Discussion of the Waterfall ModelAdvantages:• Process visibility• Separation of tasks• Quality control• Cost controlDisadvantages:Each stage in the process reveals new understanding of the
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