The software development lifecycle for IT
- 2. LIST OF CONTENTS Software Development Lifecycle Agile Methodologies (Scrum, Kanban) Waterfall Model Iterative Development Choosing the right Methodologies
- 3. Bringing a computer programming project to market is time consuming and effort. The key to completing in on time, within budget, and ensuring that it meets user requirements, requires planning. The Software Development Lifecycle describes the steps in this process, and programmers must be conversant with this process. In this section, you will look into the steps involved in planning, analyzing and designing a software application.
- 4. SDLC Software Development Lifecycle Software development is a time-consuming effort. It can take months, and even years, to develop an application. AAA games typically take 1 to 2 years to bring a game to the market, while mobile apps take 3 to 5 months to develop. The steps in getting an app to the market are described by the SDLC (Software Development Lifecycle). The SDLC breaks down the process to bring an application to market into 7 phases. The purpose of phase in the SDLC can encapsulated in a phrase which indicates the basic rationale of that phase. The software development process starts when a customer requests an application, or a perceived need is detected in the marketplace and ends when the app has been deployed. The first, second and third phases in the SDLC are the Planning, Analysis and Design Phases.
- 5. Figure 2. The purpose of each phase in the SDLC The Planning phase decides whether the app should be developed or not. Various stakeholders in the project are assembled and the reasons for developing the app are discussed. This phase examines the business aspects of the proposed app and determines scope of the project, along with preliminary cost estimates. Feasibility studies are also conducted, and a tentative timeline is proposed. PLANNING PHASE The Analysis phase is commenced after the decision to develop the app has been made. In this phase, the requirements of the proposed app are finalized. This phase is performed by members of the development team, business analysts, Subject Matter Experts (SMEs), customers and end-users who will ultimately use the app. The SMEs provide subject matter expertise about the app requirements, and the marketplace for the app. The next phase, the Design phase, depends upon the accuracy of the requirements gathered in this phase, which ends with the creation of a high- level design document. ANALYSIS PHASE
- 6. Design Phase Phase 3 of the SDLC is the Design phase. In this phase, the team decides upon the building blocks that will be used to build the app. The architecture of the application is decided. This includes decisions about the application frameworks, database software, and development of function specifications. For a web app, this includes web site design, and for a mobile app, it includes screen layouts. Server configurations are also finalized. Decisions about programming language may be made in the Design phase or deferred until the Coding phase. DESIGN PHASE
- 7. FIGURE 3. THE FIRST 3 PHASES OF THE SDLC. CASE STUDY To understand the SDLC better, a case study approach is used to demonstrate the use of the SDLC. Consider a local pizzeria that needs to build a web app that allows its customers to place orders for various types of pizzas that the pizzeria makes via a website. The customer must be allowed to make payments via the web app and specify the time that they will pick up the pizza. FIGURE 4. Case study example.
- 8. Planning Phase In this phase, there are 3 sets of people involved. The first are the members of the design team. They bring in technical and software expertise. The customer is the pizzeria, while the pizzeria’s customers are those who place orders for their product. These are the end- users of the app. It is the responsibility of both the design team and the pizzeria team to correctly understand and anticipate the requirements of the end- users, the pizzeria’s customers. Using focus groups of potential end-users will help refine requirements. Many questions must be answered in the Analysis phase. These questions will need be viewed by both the client and the end-user. Answers to these questions impact the design of the application. The requirements from the customer are stated in business terms. The Pizzeria’s offerings (pizzas) and their current mode of doing business must be understood, along with other information. If feasibility studies and costing estimates have indicated that building the app is a sound business decision, the project moves ahead. The Design phase commences after the Analysis phase has concluded. The Design document contains various information items along with clarifying details. The Database Management Software is selected, along with a design of the database to hold information. Application architecture is finalized. This includes determining if cloud architecture will be used or whether the Pizzeria will maintain hardware. Decisions to create the frontend from scratch or use a Content Management system is made, and frameworks are selected for the back end. In addition to this high-level view, detailed documents are created showing screen-shots of proposed front-end views and functional specifications for front-end logic and back- end programs. These functional specifications are implemented in the Coding phase. Analysis Phase Design Phase
- 9. FIGURE 5 . Customer requirement — Details. Many questions must be answered in the Analysis phase. These questions will need be viewed by both the client and the end-user. Answers to these questions impact the design of the application.
- 10. FIGURE 6. High level Design Document. Items to be finalized in the Design phase. FIGURE 7. Completed High- level Design Document.
- 11. UNCOVERING ADDITIONAL FACTS: What Does SDLC Stand for? This lesson discusses the Software Development Lifecycle, abbreviated to SDLC. However, there is another process that is also abbreviated to SDLC, and it is the System Development Lifecycle. The System Development Lifecycle is used as a tool to plan IT projects, and it includes hardware and software. It is considered a superset of the Software Development Lifecycle. FIGURE 8. Categories of SDLC Implementations. In this section you will learn about the various SDLC implementations and understand how each implementation allocates software development tasks amongst team members. SDLC Implementations The SDLC is a high-level model that depicts all the phases in a software development effort. There are many implementations of the SDLC model. Though the steps in the SDLC model are universal, they are implemented differently in each of the SDLC variants. SDLC Models can be classified by categories. These categories are Predictive Models, Adaptive Models and Agile Models.
- 12. The oldest of these models is the Predictive model. In this model, the SDLC phases are completed one after the other, with no backward movement. For example, the Design Phase is completed before the Coding Phase is stared. If there needs to be a change in the app’s design, it cannot be incorporated once the Coding phase has commenced. This can lead to the development of apps that do not meet customer or end- user needs. Predictive Models The Waterfall Model: The most popular Predictive model, and one the earliest SDLC implementations, is the Waterfall model. It is a sequential model where a phase is started only after the previous phase has been completed. In this model, it is critical that requirements be correctly and accurately identified in the Analysis phase. Once the Design phase starts, modifications cannot be incorporated since the Waterfall model does not permit backward phase movements. If a project’s requirements are well defined, and the scope of the project is small, the Waterfall model can be used to successfully. System design and Development is relatively easy, and the scope and cost of the project can be predicted early in the process. However, if the project requirements are unclear and evolving, the Waterfall model’s shortcomings become very evident. It does not allow for an iterative approach where changes are incorporated continuously throughout the lifetime of the development effort. Waterfall Model The second SDLC category is the Adaptive Model. This is also referred to as the Iterative Model. Here, the app is built incrementally. The first build creates a small section of the software that is functional and useful. If it does not meet customer requirements, it is modified, and the process is repeated till it is finalized, making this an iterative process. Once a section has been completed, the next increment is developed. This model allows for changes to be made during the Coding phase, and this leads to applications that meet customer need more closely than those built using predictive models. Adaptive Model
- 13. The third implementation of the SDLC is the Agile model. In 2001, seventeen software developers met in Snowbird, Utah, and developed the Manifesto for Agile Software Development, which is commonly referred to as the Agile Manifesto. This document did not contain detailed implementation plans but placed emphasis on an iterative approach to software development. The premise was that while tools and processes are important, people and interactions are more important. It incorporates elements of the Adaptive model with emphasis on speed of delivery of software. Agile projects are implemented in small increments by compact self-managed teams. The Agile model does not believe in designing the entire app before starting the Coding phase. Instead, an incremental and iterative approach is used. The project is broken into smaller pieces and each of these is competed in small sections of time. The customer is part of the development process and provides feedback each step of the way, allowing for changes to be incorporated as the app is being built. In Agile, multiple iterations are performed. An iteration can be a re-working of existing code that needs to be changed due to changes in user requirements, or it can mean the development of new software modules. Each iteration runs for a few weeks. However, the Agile approach has its drawbacks. Users must commit time towards the development process, and it can be difficult to predict costs for the project. Agile Model The Scrum Model. One of the most popular variations of the Agile methodology is the Scrum Model. Scrum emphasizes simplicity and frequent interactions between developers and customers. There are 3 main roles in a Scrum project. The Product Owner is the interface between the customer and the development team. This person assembles customer requirements, referred to as stories, and places them in the product backlog. The Scrum Master is the person who ensures that the development team can work without any obstacles. Scrum teams are self- organizing, and do not need a formal team leader or project manager. Team members self-select roles during the Coding phase based upon their competencies. The success of the Scrum methodology rests upon the fact that team members feel empowered to perform tasks that fits Scrum Model
- 14. their skill set best. Scrum projects are broken into smaller timeboxed events called sprints. A sprint is a development effort that lasts 3-4 weeks. A sprint starts with a sprint planning meeting. At this meeting, sprints are removed from the product backlog and placed in the sprint backlog. The Development team begins coding and testing the assigned sprint. Daily scrum meetings are held at the start of business day. The meeting is a standing-only meeting which lasts 10-15 minutes, where the team discusses their progress during the previous day. Once a sprint is completed, it is reviewed and presented to the Product Owner. If the Product owner accepts the sprint, the sprint is ended, and it is moved into production. A sprint retrospective is also performed to review the sprint completion process to see if any lessons can be learned from the process. FIGURE 11. Roles in a Scrum project. FIGURE 12. Steps in a Sprint.