lesson2.pptx

SOFTWARE PROCESS Software Processes is a coherent set of activities for specifying, designing, implementing and testing software systems. A software process model is an abstract representation of a process that presents a description of a process from some particular perspective There are many di...

SOFTWARE PROCESS Software Processes is a coherent set of activities for specifying, designing, implementing and testing software systems. A software process model is an abstract representation of a process that presents a description of a process from some particular perspective There are many different software processes but all involve: Specification – defining what the system should do; Design and implementation – defining the organization of the system and implementing the system; Validation – checking that it does what the customer wants; Evolution – changing the system in response to changing customer needs. Types of Software Process Model Software processes, methodologies and frameworks range from specific prescriptive steps that can be used directly by an organization in day-to-day work, to flexible frameworks that an organization uses to generate a custom set of steps tailored to the needs of a specific project or group. In some cases a “sponsor” or “maintenance” organization distributes an official set of documents that describe the process. There are many software development life cycle models that have been developed in order to achieve different required objectives. The models specify the various stages of the process and the order in which they are carried out. The most used, popular and important SDLC models are given below: Waterfall model V model Incremental model RAD model Agile model Iterative model Spiral model Prototype model Waterfall Model The waterfall model is a breakdown of project activities into linear sequential phases, where each phase depends on the deliverables of the previous one and corresponds to a specialization of tasks. The approach is typical for certain areas of engineering design. The V-model represents a development process that may be considered an extension of the waterfall model and is an example of the more general V-model. Instead of moving down in a linear way, the process steps are bent upwards after the coding phase, to form the typical V shape. The V-Model demonstrates the relationships between each phase of the development life cycle and its associated phase of testing. The horizontal and vertical axes represent time or project completeness (left-to-right) and level of abstraction (coarsest-grain abstraction uppermost), Incremental model The incremental build model is a method of software development where the model is designed, implemented and tested incrementally (a little more is added each time) until the product is finished. It involves both development and maintenance. The product is defined as finished when it satisfies all of its requirements. Each iteration passes through the requirements, design, coding and testing phases. Iterative Model An iterative life cycle model does not attempt to start with a full specification of requirements by first focusing on an initial, simplified set user features, which then progressively gains more complexity and a broader set of features until the targeted system is complete RAD model Rapid application development was a response to plan-driven waterfall processes, developed in the 1970s and 1980s, such as the Structured Systems Analysis and Design Method (SSADM). Rapid application development (RAD) is often referred as the adaptive software development. Spiral model The spiral model, first described by Barry Boehm in 1986, is a risk-driven software development process model which was introduced for dealing with the shortcomings in the traditional waterfall model. A spiral model looks like a spiral with many loops. The exact number of loops of the spiral is unknown and can vary from project to project. Agile model Agile is an umbrella term for a set of methods and practices based on the values and principles expressed in the Agile Manifesto that is a way of thinking that enables teams and businesses to innovate, quickly respond to changing demand, while mitigating risk.  12 PRINCIPLES OF AGILE 1.Satisfy customers through early and continuous delivery of valuable work. 2.Break big work down into smaller tasks that can be completed quickly. 3.Recognize that the best work emerges from self- organized teams. 4.Provide motivated individuals with the environment and support they need and trust them to get the job done. 5.Create processes that promote sustainable efforts. 6.Maintain a constant pace for completed work. 7. Welcome changing requirements, even late in a project. 8. Assemble the project team and business owners on a daily basis throughout the project. 9. Have the team reflect at regular intervals on how to become more effective, then tune and adjust behavior accordingly. 10. Measure progress by the amount of completed work. 11. Continually seek excellence.  COPING WITH CHANGE Change is inevitable in all large software projects. The system requirements change as businesses respond to external pressures, competition, and changed management priorities. As new technologies become available, new approaches to design and implementation become possible. Therefore whatever software process model is used, it is essential that it can accommodate changes to the software being developed. THE FOUR CORE VALUES OUTLINED IN THE AGILE MANIFESTO Individual interactions are more important than processes and tools. People drive the development process and respond to business needs. They are the most important part of development and should be valued above processes and tools. If the processes or tools drive development, then the team will be less likely to respond and adapt to change and, therefore, less A focus on working software rather than thorough documentation. Before Agile, a large amount of time was spent documenting the product throughout development for delivery. The list of documented requirements was lengthy and would cause long delays in the development process. While Agile does not eliminate the use of documentation, it streamlines it in a way that provides the developer with only the information that is needed to do the work -- such as user stories. The Agile Manifesto continues to place value on the process of documentation, but it places higher value on working software. Collaboration instead of contract negotiations. Agile focuses on collaboration between the customer and project manager, rather than negotiations between the two, to work out the details of delivery. Collaborating with the customer means that they are included throughout the entire development process, not just at the beginning and end, thus making it easier for teams to meet the needs of their customers. For example, in Agile, the customer can be included at different intervals for demos of the product. However, the customer could also be present and interact with the teams daily, attend all meetings and ensure the product meets their desires. A focus on responding to change. Traditional software development used to avoid change because it was considered an undesired expense. Agile eliminates this idea. The short iterations in the Agile cycle allow changes to easily be made, helping the team modify the process to best fit their needs rather than the other way around. Overall, Agile software development believes change is always a way to improve the project and provide additional value. The Agile software development cycle The Agile software development cycle can be broken down into the following six steps: concept inception iteration/construction release production retirement Types of Agile methodologies The goal of every Agile methodology is to embrace and adapt to change while delivering working software as efficiently as possible. However, each method varies in the way it defines the steps of software development. The most widely used Agile methods include the following: Scrum Lean software development Extreme programming Crystal Kanban Dynamic systems development method Feature-driven development Scrum is a lightweight Agile framework that can be used by project managers to control all types of iterative and incremental projects. In Scrum, the product owner creates a product backlog that allows them to work with their team to identify and prioritize system functionality. Lean software development is another iterative method that places a focus on using effective value stream mapping to ensure the team delivers value to the customer. It is flexible and evolving; it does not have rigid guidelines or rules. The Lean method uses the following primary principles: Increasing learning Empowering the team Fostering integrity Removing waste Understanding the whole Making decisions as late as possible Delivering the product as fast as possible The extreme programming (XP) method is a disciplined approach that focuses on speed and continuous delivery. It promotes increased customer involvement, fast feedback loops, continuous planning and testing and close teamwork. Software is delivered at frequent intervals -- usually every one to three weeks. The goal is to improve software quality and responsiveness when faced with changing customer requirements. Crystal is the most lightweight and adaptable methodology. It focuses on people and the interactions that occur while working on an Agile project as well as business-criticality and priority of the system under development. The Crystal method works off the realization that every project possesses unique characteristics that require a slightly tailored set of policies, practices and processes. As a result, it is made up of a collection of Agile process models, such as Crystal Orange, Crystal Clear and Crystal Yellow. Each model has its own unique characteristics that are driven by different factors, including project priorities, team size and system criticality. Kanban uses a highly visual workflow management method that allows teams to actively manage product creation -- emphasizing continuous delivery -- without creating more stress in the software development lifecycle (SDLC). It has become popular among teams also practicing Lean software development. The dynamic systems development method (DSDM) is a response to the need for a common industry framework for rapid software delivery. The DSDM is based on eight key principles; failing to abide by any one of the principles introduces risk to successful completion of the project. The DSDM eight principles are as follows: 1.Collaboration 2.On-time delivery 3.Demonstrated control 4.Continuous, clear communication 5.A constant focus on the business need 6.Iterative development 7.Creation in increments from firm foundations 8.Refusal to compromise quality feature-driven development (FDD) blends software engineering best practices -- such as developing by feature, code ownership and domain object modeling -- to create a cohesive, model-driven, short-iteration process. FFD begins by defining an overall model shape, which in turn creates a feature list. The method then proceeds with iterations that last two weeks and focus on planning by feature, designing by feature and building by feature.