Software Development Life Cycle(SDLC) is a series of phases which is the process for building and delivering software systems. SDLC has distinct 6 stages: planning, analysis, design, implementation, testing, and maintenance.
As a brief description let’s see what is happening in each step. SDLC starts with requirement gathering a.k.a planning. Then step 2 is to analyze collected requirements for feasibility and validity. The next step includes the designing of requirements and helps in defining the overall software architecture. Then the coding starts and that is the most important stage for the developers. And various types of testings should be done. All the bugs and enhancements are reported to the developers. At last, maintenance starts. And this should be done from time to time. And if there is any issue the SDLC again starts from phase 1.
For a successful software project, a software engineer needs to choose the best SDLC model based on the project context and business requirements. So software engineers should have a piece of proper knowledge about SDLC models and their pros and cons.
Types of Software Development Life Cycles
- Waterfall model
- V model
- Spiral model
- Agile model
- Iterative model
This is one of the oldest surviving SDLC methodologies. If follows a straightforward approach which any phase in the development process begins only if the previous phase is complete. If the customer has very clear documented requirements this method can be used in development.
- Easy to explain to the users since each stage has well-defined starting and ending points.
- Needs and outcomes are clear. One gets one has planned.
- Verification at each stage ensures early detection of errors or misunderstandings.
- All potential development issues are researchable and manageable in the design phase.
- Doesn’t take into account changes due to the business plans or market influences during the planning process.
- Lacks flexibility because the model is incapable to cater to new developments or changes made in the requirements occurring after the original consultation.
- Very difficult to conceptualize client needs in terms of a functional specification during the requirements phase.
- takes much longer to make the final delivery.
This is an extension of the waterfall method where V model introduces testing at the end of the each step in development. So, the process steps are bent upwards after the implementation and coding phase, to form the typical V shape. This method is mostly used when Software requirements and Software development technologies and tools are clearly known.
- Higher success chances because development of test plans early on during the life cycle.
- Verification and validation of the product in the early stages of product development.
- An apt fit for small projects with easily understandable requirements and easy to use.
- Saves a lot of time as planning and designing related to testing is done way before the actual coding takes place.
- Adjusting scope is difficult and expensive.
- The model doesn’t provide a clear path for problems found during testing phases.
- Costly and required more time, in addition to a detailed plan
- Less flexible like waterfall model.
- Requirement and test documents need to be updated if any changes had to be made amid the software development
The Spiral model enables the project development teams to build a highly customized product and it is considered to be one of the most flexible SDLC methods. Spiral methodology passes through four phases repeatedly until the project is completed. And they are planning, risk analysis, engineering, and evaluation. Each iteration of the Spiral methodology begins with foreseeing potential risks as well as the best way to avoid or mitigate the same. This model is used in the large applications and systems which built-in small phases or segments.
- Early involvement of developers.
- Manages risks and develops the system into phases.
- Able to accommodate new changes or functionality at a later stage of the development.
- As the prototype build is done in small increments, cost estimation becomes easy.
- Emphasizes on customer feedback.
- Faster development and systematic addition of features.
- High risk of not meeting budget or schedule deadlines
- Impractical for small projects
- Much more documentation due to intermediate phases
- High cost and time to reach the final product.
- Needs special skills to evaluate the risks and assumptions.
- Highly customized limiting re-usability
Agile methodology is based on an incremental and iterative approach where requirements and solutions evolve through collaboration between cross-functional teams. A Scrum is a form of implementation of the Agile methodology that helps development teams to structure complex project requirements. This can be used with any type of the project, but it needs more engagement from the customer and to be interactive. Also, we can use it when the customer needs to have some functional requirement ready in less than three weeks and the requirements are not clear enough. This will enable more valuable and workable piece for software early which also increase the customer satisfaction.
- Capable of accommodating new changes or enhancements occurring during the development phase without the budget constraint
- Engages projects managers and business stakeholders as well as get their feedback throughout the entire software development process
- Fast development and testing enable for recognizing existing gaps in the requirements or technologies being used.
- Helps development teams in identifying as well as addressing minor issues before they can evolve into bigger ones
- Saves a great amount of cost and time thanks to the lesser documentation requirement.
- The end result is the high-quality software in the least possible time duration and satisfied customer.
- Almost impossible to determine the effort estimation at the very beginning of the software development for full-size and complex projects.
- High-risk probability when clients/end-users are unsure about requirements.
- Necessitates experienced resources.
- Puts less emphasis on designing and documentation processes.
- The ability and collaboration of the customer to express user needs.
This model starts with an initial planning and ends with deployment with the cyclic interactions in between. The basic idea behind this method is to develop a system through repeated cycles and in smaller portions at a time, allowing software developers to take advantage of what was learned during the development of earlier parts or versions of the system.
- Capacity to plan parallel development.
- Cost-effective to change the scope or requirements.
- Each iteration is easy to manage.
- Easily adapts to the ever-changing needs of the clients as well as the project.
- Requires less time for documentation and gives more time for designing.
- Less corrections because of identifying the functional or design flaws at the earliest.
- As not all requirements are gathered at the very beginning of the project, it is highly likely for system architecture or design issues to spring up.
- Demands added management attention.
- Each iteration is rigid.
- Not suitable for smaller projects.
- Requires comparatively number of resources and heavy documentation.
- Skill analysis requires highly skilled resources.