Software Processes
اسلاید 1: CSEB233 Fundamentals of Software EngineeringModule 2: Software ProcessesBadariah Solemon 2010
اسلاید 2: ObjectivesTo describe types of process flows.To explain software process patterns.To identify several process assessment and improvements frameworksTo analyze prescriptive and specialized software process models.To select a process model for software development project. To determine task set for software process activities.Badariah Solemon 2010
اسلاید 3: A Generic Process ModelA software process:a collection of work activities, actions, tasks, which are performed when software is to be created.A process model or framework is where these activities, actions, and tasks reside, and that defines their relationship with the process and with one another.Also known as an abstract representation of a software process.Badariah Solemon 2010
اسلاید 4: A Generic Process Model (cnt’d)The technical work hierarchy – activities encompassing actions, populated by tasks.Each action is defined by a set of task that defines:the actual work to be completed,the work products to be produced,the quality assurance filters to be applied, andThe milestones that will be used to indicate the project and product progress.Badariah Solemon 2010
اسلاید 5: Process Activities: Framework and UmbrellaFramework activities : generic activities that are applicable to all software projects, regardless of their size or complexity.Include communication; planning; modeling, construction; and deployment.Umbrella activities:complementary activities applied throughout a software project and help manage and control progress, quality, change, and risk.Include project tracking and control; risk management; software quality assurance (SQA); technical reviews; configuration management (CM); etc.Badariah Solemon 2010
اسلاید 6: Process FlowDescribes how the framework activities and the actions and tasks that occur within each activity are organized with respect to sequence and time.The flows:Linear – execute the framework activities in sequence.Iterative – repeats one or more of the activities before proceeding to the next.Evolutionary – execute the activities in a ‘circular’ manner.Parallel – executes one or more activities simultaneously with other activities.Badariah Solemon 2010
اسلاید 7: Process FlowBadariah Solemon 2010
اسلاید 8: Process Patterns It would be useful if proven solution to the problems, encountered as project team moves through a software process, were readily available , which can be reused in another project. In more general terms, a process pattern provides you with a template [Amb98]—a consistent method for describing problem solutions within the context of the software process.A process pattern describes a process-related problem that is encountered during software engineering work, identifies the environment in which the problem has been encountered, and suggests one or more proven solutions to the problem. Badariah Solemon 2010
اسلاید 9: Process Assessment and ImprovementApproaches:Standard CMMI Assessment Method for Process Improvement (SCAMPI) :Is used to identify strengths, weaknesses, and ratings relative to SEI CMMI appraisal reference model, which is applicable to internal process improvement and external capability determination.CMM-Based Appraisal for Internal Process Improvement (CBA IPI):provides a diagnostic technique for assessing the relative maturity of a software organization; uses the SEI CMM as the basis for the assessment [Dun01]. However, CMM has been retired by SEI since the introduction of CMMI group of standards.SPICE (ISO/IEC15504):standard that defines a set of requirements for software process assessment. The intent of the standard is to assist organizations in developing an objective evaluation of the efficacy of any defined software process. [ISO08]ISO 9001:2000 for Software:a generic standard that applies to any organization that wants to improve the overall quality of the products, systems, or services that it provides. Therefore, the standard is directly applicable to software organizations and companies. [Ant06]Badariah Solemon 2010
اسلاید 10: Prescriptive Process ModelsPromote an orderly, structured approach to SEThat leads to a few questions …If prescriptive process models strive for structure and order, are they inappropriate for a software world that thrives on change? Yet, if we reject traditional process models (and the order they imply) and replace them with something less structured, do we make it impossible to achieve coordination and coherence in software work?Badariah Solemon 2010
اسلاید 11: Prescriptive Process Models (cnt’d)Waterfall Model – represents elements of a linear process flowV Incremental Model – combines elements of linear and parallel process flowsEvolutionary Model – follows the evolutionary process flow that combines elements of linear and iterative process flowsPrototypingSpiralConcurrent Model – combines elements of iterative and parallel process flowsBadariah Solemon 2010
اسلاید 12: The Waterfall Model* Also known as the classic SDLC* The original Waterfall model proposed by Winston Royce in 1970 made provision for feedback loops, but many organizations apply this model as if it were strictly linear.Represents a linear process flow from communication through deployment.Badariah Solemon 2010
اسلاید 13: The V-ModelA variation in the representation of the Waterfall model.Illustartes how V&V actions are associated with earlier SE action.In reality, there is no fundamentals difference between the Waterfall model and the V-model.Badariah Solemon 2010
اسلاید 14: The Waterfall Model: An AnalysisCharacteristics Strengths Weaknesses Applicability It suggests a systematic, sequential approach to SE, staring from requirements specification going through planning, modeling, construction, testing, deployment and support of the completed system.Each major activity is marked by milestones and deliverables (artifacts i.e. documents).Simple and easy to use/explain to customers.The staged development cycle enforces discipline: every phase has a defined start and end point, and progress can be conclusively identified (through the use of milestones)Real projects rarely follow the linear flow that the model proposes. Although iteration is indirectly allowed, changes are costly, involve significant rework and can cause confusion to project team and involve.The model requires the customer to state all requirements explicitly, which is often very difficult to achieve.The working software will not available until late in the project, which can be disastrous for late discovery of major defects. Leads to “blocking states” in which some project team members must wait for others to complete dependent tasks.When requirements are well understood and unlikely to change radically during system development (e.g.: in a well-defined enhancement to an existing system).When software development technologies and tools are well known.The work tasks in the project are to proceed to completion in a linear manner.Badariah Solemon 2010
اسلاید 15: The Incremental ModelBadariah Solemon 2010
اسلاید 16: The Incremental Model (cnt’d)Badariah Solemon 2010Rather than deliver the software product as a single delivery, the development and delivery is broken down into increments with each increment delivering part of the required functionality.User requirements are prioritised and the highest priority requirements are included in early increments.Once the development of an increment is started, the requirements are frozen though requirements for later increments can continue to evolve.
اسلاید 17: The Incremental Model: An AnalysisAsk the students to analyze this process model and to discuss their findings in class. Badariah Solemon 2010
اسلاید 18: The Evolutionary Model: PrototypingcommunicationQuickplanModelingQuick designConstructionof prototypeDeploymentdelivery &feedbackBadariah Solemon 2010
اسلاید 19: The Evolutionary Model: Prototyping (cnt’d)Badariah Solemon 2010Using this process model, a prototype (an early approximation of a final software product) is built, tested, and then reworked as necessary until an acceptable prototype is finally achieved from which the complete software product can now be developed.Although it can be implemented as a stand-alone process model, it is more commonly used as part of other process models.The main purpose of the model is to help better understand what it is to built when requirements are fuzzy.
اسلاید 20: The Prototyping Model: An AnalysisAsk the students to analyze this process model and to discuss their findings in class. Badariah Solemon 2010
اسلاید 21: The Evolutionary Model: SpiralBadariah Solemon 2010
اسلاید 22: The Evolutionary Model: Spiral (cnt’d)Badariah Solemon 2010A process model that combines the iterative nature of prototyping with the systematic aspects of waterfall model.The spiral model can be thought of as a repeating waterfall model that emphasizes risk assessment and that is executed in an incremental fashion.Each loop/pass through the spiral model consists of risk assessment and other framework activities from communication through deployment.
اسلاید 23: The Spiral Model: An AnalysisAsk the students to analyze this process model and to discuss their findings in class. Badariah Solemon 2010
اسلاید 24: The Concurrent Process ModelBadariah Solemon 2010
اسلاید 25: The Concurrent Process Model (cnt’d)Badariah Solemon 2010A process model that combines the iterative and parallel elements of any of the prescriptive process models.In this process model, all SE activities (framework or umbrella activities) exist concurrently but reside in different states.
اسلاید 26: The Concurrent Model: An AnalysisAsk the students to analyze this process model and to discuss their findings in class. Badariah Solemon 2010
اسلاید 27: Specialised Process ModelsComponent based software development (CBSD)the process to apply when reuse is a development objectiveFormal methodsemphasizes the mathematical specification of requirements, which can demonstrate software correctness but are not widely used.Aspect-oriented software development (AOSD)provides a process and methodological approach for defining, specifying, designing, and constructing aspectsUnified Processa “use-case driven, architecture-centric, iterative and incremental” software process closely aligned with the Unified Modeling Language (UML)Badariah Solemon 2010
اسلاید 28: Specialised Process Models (cnt’d)Agile ProcessAn iterative approach to requirements specification, construction and deployment, which support rapid changes to requirements.Personal Process ModelEmphasizes the need to record and analyze errors each individual practitioner made, so that he/she can develop a strategy to eliminate them.Team Process ModelBuild self-directed teams that plan and track their work, establish goals, and own their processes and plans. These can be pure software teams or integrated product teams (IPT) of three to about 20 engineers. Show managers how to coach and motivate their teams and how to help them sustain peak performance. Badariah Solemon 2010
اسلاید 29: Agile DevelopmentCombines a philosophy and a set of development guidelines.The philosophy encourages:customer satisfaction and early incremental delivery of software;small, highly motivated project teams;informal methods;minimal SE work products; andoverall development simplicity.The development guidelines:stress delivery over analysis and design, andactive and continuous communication between developers and customersBadariah Solemon 2010
اسلاید 30: The Agile ManifestoValue individuals and interactions over process and toolsPrefer to invest time in producing working software rather than in producing comprehensive documentationFocus on customer collaboration rather than contract negotiationConcentrate on responding to change rather than on creating a plan and then following itWhy?The modern business environment is fast-paced and ever-changing. This process model has been demonstrated to deliver successful systems quickly.Badariah Solemon 2010
اسلاید 31: The Agile PrinciplesOur highest priority is to satisfy the customer through early and continuous delivery of valuable software.Welcome changing requirements, even late in development. Agile processes harness change for the customers competitive advantage. Deliver working software frequently, from a couple of weeks to a couple of months, with a preference to the shorter timescale. Business people and developers must work together daily throughout the project. Build projects around motivated individuals. Give them the environment and support they need, and trust them to get the job done. The most efficient and effective method of conveying information to and within a development team is face–to–face conversation.Badariah Solemon 2010
اسلاید 32: The Agile Principles (cnt’d)Working software is the primary measure of progress. Agile processes promote sustainable development. The sponsors, developers, and users should be able to maintain a constant pace indefinitely. Continuous attention to technical excellence and good design enhances agility. Simplicity – the art of maximizing the amount of work not done – is essential. The best architectures, requirements, and designs emerge from self–organizing teams. At regular intervals, the team reflects on how to become more effective, then tunes and adjusts its behavior accordingly.Badariah Solemon 2010
اسلاید 33: Agile: Human Factorsthe process molds to the needs of the people and team, not the other way aroundkey traits must exist among the people on an agile team and the team itself:Competence.Common focus.Collaboration.Decision-making ability.Fuzzy problem-solving ability.Mutual trust and respect.Self-organization.Badariah Solemon 2010
اسلاید 34: The Agile Process ModelsAlso known as approaches to agile software engineering, which include:Extreme Programming (XP)Industrial XPScrumAdaptive Software Development (ASD)Dynamic Systems Development Method (DSM)CrystalFeature Driven Development (FDD)Lean Software Development (LSD)Agile Modeling (AM)Agile Unified Process (AUP)Badariah Solemon 2010
اسلاید 35: The Extreme Programming (XP)The most widely used approach to agile SE.Badariah Solemon 2010
اسلاید 36: The XP: ActivitiesXP PlanningBegins with the creation of “user stories”Agile team assesses each story and assigns a costStories are grouped to for a deliverable incrementA commitment is made on delivery dateAfter the first increment “project velocity” is used to help define subsequent delivery dates for other incrementsBadariah Solemon 2010
اسلاید 37: The XP: Activities (cnt’d)XP DesignFollows the KISS principleEncourage the use of CRC cards (see Chapter 8)For difficult design problems, suggests the creation of “spike solutions”—a design prototypeEncourages “refactoring”—an iterative refinement of the internal program designXP CodingRecommends the construction of a unit test for a store before coding commencesEncourages “pair programming”XP TestingAll unit tests are executed daily“Acceptance tests” are defined by the customer and executed to assess customer visible functionalityBadariah Solemon 2010
اسلاید 38: The Extreme Programming (XP): An AnalysisAsk the students to analyze this process model and to discuss their findings in class. Badariah Solemon 2010
اسلاید 39: Selecting a Process ModelAnalyze the sidebars in pages 45 and 47.What are the lesson-learned from these sidebars?Badariah Solemon 2010
اسلاید 40: Selecting a Process ModelFactors to consider:The characteristics of the problems to be solved.Such as complexity of the problem, etcE.g.: simple with clear, stable requirements, complex with changing, unstable requirements, etc.The characteristics of the projectSuch as the customers who have requested the product and the people who will do the work, etc.E.g.: Uncertain requirements, breakthrough technology The characteristics of the product.Such as quality attributes or metric of the product, product domain, etcThe project environment in which the software team worksSuch as political, cultural, language ,etc.Badariah Solemon 2010
اسلاید 41: Key Questions in Determining Task SetBadariah Solemon 2010Different projects requires different task sets. The tasks should be selected based on problems and project characteristics.Q: What actions are appropriate for a framework activity, given:the nature of the problem to be solved;the characteristics of the people doing the work; andthe stakeholders of the project?Q: What work tasks (task set) that these actions should encompasses of?
اسلاید 42: ExampleBadariah Solemon 2010Nature of the problems and project : A small software project requested by one person (at a remote location) with simple, straightforward requirements. Actions:Communication action: develop requirementsTask set:Make contact with stakeholder via telephone.Discuss requirements and take notes.Organize notes into a brief written statement of requirements.E-mail to stakeholder for review and approval.
اسلاید 43: Process Management Tools Also known as process modeling tools or process technology.Allows a team to define and manage the elements of a process model (activities, actions, task, work products, milestones, and QA points/filters).Such tools also provide detailed guidance on the content of each process element.The tools may also provide standard project management tasks such as estimating, scheduling, tracking and control.Example:Igrafx Process Tools (www.micrografx.com)Badariah Solemon 2010
اسلاید 44: Selecting a Process Model: an ExerciseThe project:Assume that you are in charge of a project to create a portal for the Shah Alam district of Selangor state. This portal would include a homepage with links to a wide range of discounted travel packages to major destinations in Selangor, links to certain featured places like golf courses, shopping complexes and places to eat, links to the detailed map of Selangor, and links to news and events listing. It also includes a bulletin board and chat room feature where tourists (international and local tourists) can exchange information. The portal should also provide Automated Teller Machine (ATM) locator, timezone converter, and currency converter.Select a software process model that you would recommend to be implemented in the above mentioned project. Why is the software process model selected? Badariah Solemon 2010
اسلاید 45: SummaryThere are four types of process flows – linear, iterative, evolutionary, and parallel.Software process patterns may suggest one or more proven solutions to the problem from other projects, which can be reused in another project. There are several process assessment and improvements frameworks that can be exercised by practitioners.The analyses of prescriptive and specialized software process models would help you select the most appropriate process model for a software development project, which can be proceeded with the identification of task set for the project. Badariah Solemon 2010
اسلاید 46: References and creditContents in the slides are adapted from the book and the slides that accompanied the book by R.S. Pressman, Software Engineering: A Practitioner’s Approach, 7th. Edition, McGraw Hill, 2009.Badariah Solemon 2010
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