Software Development Life Cycle (SDLC) Methodologies
Software Development Life Cycle is the application of standard business practices to building software applications. SDLC is a way to measure and improve the development process. It allows a fine-grain analysis of each step of the process. This, in turn, helps companies maximize efficiency at each stage. As computing power increases, it places a higher demand on software and developers. Companies must reduce costs, deliver software faster, and meet or exceed their customers’ needs. SDLC helps achieve these goals by identifying inefficiencies and higher costs and fixing them to run smoothly.
How the Software Development Life Cycle Works
The Software Development Life Cycle simply outlines each task required to put together a software application. This helps to reduce waste and increase the efficiency of the development process. Monitoring also ensures the project stays on track, and continues to be a feasible investment for the company.
Many companies will subdivide these steps into smaller units. Planning might be broken into technology research, marketing research, and a cost-benefit analysis. Other steps can merge with each other. The Testing phase can run concurrently with the Development phase, since developers need to fix errors that occur during testing.
The Seven Phases of the SDLC
In the Planning phase, project leaders evaluate the terms of the project. This includes calculating labor and material costs, creating a timetable with target goals, and creating the project’s teams and leadership structure.
Planning can also include feedback from stakeholders. Stakeholders are anyone who stands to benefit from the application. Try to get feedback from potential customers, developers, subject matter experts, and sales reps.
Planning should clearly define the scope and purpose of the application. It plots the course and provisions the team to effectively create the software. It also sets boundaries to help keep the project from expanding or shifting from its original purpose.
2. Define Requirements
Defining requirements is considered part of planning to determine what the application is supposed to do and its requirements. For example, a social media application would require the ability to connect with a friend. An inventory program might require a search feature.
Requirements also include defining the resources needed to build the project. For example, a team might develop software to control a custom manufacturing machine. The machine is a requirement in the process.
3. Design and Prototyping
The Design phase models the way a software application will work. Some aspects of the design include:
Architecture — Specifies programming language, industry practices, overall design, and use of any templates or boilerplate
User Interface — Defines the ways customers interact with the software, and how the software responds to input
Platforms — Defines the platforms on which the software will run, such as Apple, Android, Windows version, Linux, or even gaming consoles
Programming — Not just the programming language, but including methods of solving problems and performing tasks in the application
Communications — Defines the methods that the application can communicate with other assets, such as a central server or other instances of the application
Security — Defines the measures taken to secure the application, and may include SSL traffic encryption, password protection, and secure storage of user credentials
Prototyping can be a part of the Design phase. A prototype is like one of the early versions of software in the Iterative software development model. It demonstrates a basic idea of how the application looks and works. This “hands-on” design can be shown to stakeholders. Use feedback o improve the application. It’s less expensive to change the Prototype phase than to rewrite code to make a change in the Development phase.
4. Software development
In this stage of SDLC the actual development starts and the product is built. The programming code is generated as per DDS during this stage. If the design is performed in a detailed and organized manner, code generation can be accomplished without much hassle.
Developers must follow the coding guidelines defined by their organization and programming tools like compilers, interpreters, debuggers, etc. are used to generate the code. Different high level programming languages such as C, C++, Pascal, Java and PHP are used for coding. The programming language is chosen with respect to the type of software being developed.
This stage is usually a subset of all the stages as in the modern SDLC models, the testing activities are mostly involved in all the stages of SDLC. However, this stage refers to the testing only stage of the product where product defects are reported, tracked, fixed and retested, until the product reaches the quality standards defined in the SRS.
In the deployment phase, the application is made available to users. Many companies prefer to automate the deployment phase. This can be as simple as a payment portal and download link on the company website. It could also be downloading an application on a smartphone.
Deployment can also be complex. Upgrading a company-wide database to a newly-developed application is one example. Because there are several other systems used by the database, integrating the upgrade can take more time and effort.
7. Operations and Maintenance
At this point, the development cycle is almost finished. The application is done and being used in the field. The Operation and Maintenance phase is still important, though. In this phase, users discover bugs that weren’t found during testing. These errors need to be resolved, which can spawn new development cycles.
In addition to bug fixes, models like Iterative development plan additional features in future releases. For each new release, a new Development Cycle can be launched.
There are various software development life cycle models defined and designed which are followed during the software development process. These models are also referred as Software Development Process Models”. Each process model follows a Series of steps unique to its type to ensure success in the process of software development.
Following are the most important and popular SDLC models followed in the industry −
- Waterfall Model
- Iterative Model
- DevOps Model
- Spiral Model
- Lean Model
- Agile Model
- Prototyping Model
If you answer this question on Stack Exchange, you will know that some experts believe that the Waterfall model is not intended to be a really working SDLC method of software development. However, the debate also involves those following the SDLC model.
The waterfall model is one of the oldest surviving methods of the SDLC. Therefore, any discussion of SDLC methods without them is incomplete. In addition, the Waterfall model follows a simple approach, which is a favorable quality for many software development teams.
Under the waterfall procedure, the project development team must take turns completing each phase. Moreover, there is no reversal. Each subsequent stage of the SDLC process relies on the information obtained from the previous one.
- All potential development issues are researchable and manageable in the design phase
- Each stage of the model has a well-defined starting and ending point, making it easy to manage and monitor
- An easy and transparent testing process as the test scenarios are already detailed in the functional specification
- Needs and outcomes are clear
- Offers a greater degree of accuracy for cost estimation once the requirements are completely defined
- One gets one what has planned. Hence, no surprises upon the completion
- Very easy to understand as technical documentation is an essential aspect of the initial requirements gathering stage
- Compared to iterative methodologies like the Agile model, takes much longer to make the final delivery
- Doesn’t take into account changes due to the business plans or market influences during the planning process
- Lacks flexibility as it is very rigid. This means that 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
The iterative methodology takes the waterfall model and cycles through it several times in small increments. Rather than stretching the entire project across the phases of the SDLC, each step is turned into several mini-projects that can add value as the product evolves.
The iterative approach shares many of the same goals as the agile model, except external customers are less involved and the scope of each increment is normally fixed.
- It allows developers and testers to identify functional or design flaws at the earliest possible. Hence, corrective measures can be made in a limited budget
- 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
- Suitable for agile organizations
- 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
- Skill analysis requires highly skilled resources
DevOps is one of the latest SDLC techniques used by many software companies and IT organizations. As the name implies, the idea behind DevOps is to connect development teams with operational teams to simplify delivery and support.
DevOps emerged from two trends: the application of Agile and Lean models to the operations team and a general shift in business towards understanding the value of collaboration between operations personnel and developers at all stages of the SDLC process.
DevOps is short for developers and operators. Using the DevOps method, developers and operations teams work together to expedite and modify the implementation and creation of highly reliable software products. The key features of the DevOps model are consistent feedback, discipline, process improvement and automation of as many manual processes as possible. Software development updates are shorter but more common.
- Cost and time need to be spent on unplanned work as well as bug fixing is reduced greatly
- Enhances the loyalty rates of the employees
- The entire development process takes less time as both operations and development teams get to know about the potential obstructions simultaneously
- Faster failure recovery rates
- Higher credibility
- High risk of security issues, such as spoofing and man in the middle attacks, as the software development approach, neglects security in favor of speeding up the software development process
Model V denotes a verification and verification model. Although the V model is inspired by the waterfall model, in contrast to it, in which testing is done at the end of the project, testing is introduced at all stages of development. As in the Waterfall model, each subsequent phase of the V model does not begin until the previous one is completely completed.
- Ability to avoid the downward flow of defects
- An apt fit for small projects with easily understandable requirements
- Higher success chances
- Offers great ease and simplicity
- Proactive tracking of potential defects
- Saves a lot of time as planning and designing related to testing is done way before the actual coding takes place
- Even more rigid and less flexible than the Waterfall model
- No early prototype creation is possible as the software is developed during the implementation phase
- Requirement and test documents need to be updated if any changes had to be made amid the software development
The spiral method is considered to be one of the most flexible SDLC models. Commonly used to complete projects, the Spiral model enables project teams to create highly customizable products.
The spiral method goes through four stages of repetition until the project is completed. This allows for many product adjustments. The four stages followed by the Spiral method are planning, risk assessment, design and evaluation.
Each iteration of the spiral method begins with anticipating potential risks and finding the best way to avoid or reduce them.
- 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
- Better risk management with repeated development
- Emphasizes on customer feedback
- Faster development and systematic addition of features
- Demands risk management expertise
- High risk of not meeting budget or schedule deadlines
- Impractical for small projects
- Much more documentation due to intermediate phases
The Lean methodology takes inspiration from lean manufacturing practices and principles. The Lean model follows a set of seven principles, which are:
- Eliminate waste
- Amplify/Refine learning
- Decide as late as possible
- Deliver as fast as possible
- Empower the team
- Conceptual integrity
- See the whole/Operating from the top-level
Project teams working on the Lean model are looking for ways to reduce waste at every step of the entire SDLC process. This often includes skipping unimportant meetings and cutting down on paperwork. In fact, the Lean method is very similar to the Agile method, with some notable differences.
The main difference between the two SDLC methods is the prioritization of customer satisfaction. The Agile model makes the customer a priority from the outset.
In this way, the involved project teams immediately responded to stakeholder feedback throughout the SDLC process. On the other hand, the Lean method prioritizes recycling. This is to create more overall value for customers.
- Applicable across team boundaries as well as the tendency to integrate teams and optimize collaboration. Thus, works well in line with the Agile and DevOps methodologies
- Capable to deliver more functionality in a shorter span of time
- Easily scalable makes it an apt fit as an alternative to contemporary SDLC methodologies designed for carrying out large, complex projects
- Empowers the project development team in terms of the decision-making process. Hence, improves the motivation for doing the job in the best way possible
- Saves cost and time by eliminating the unessential activity
- Demands excellent documentation, especially with respect to business requirements. Failing to it might result in underdeveloped or wrongly developed areas pertaining to insufficient documentation
- Heavily team dependent. This means it is essential to put together an experienced team with a high skill level
- Relatively easy to lose focus
Despite the fact that this agile model has been available for almost a decade, it has only recently become popular. The popularity of the agile method is so great that some organizations even use it for non-software projects. Agile method is based on an incremental and iterative approach. Fast failure is a welcome aspect of agile technology. This creates continuous release cycles. Each of them contains minor changes from the previous release. The composite product is tested at every iteration.
Scrum is an agile implementation technique that helps development teams develop complex project requirements. Scrum teams work on sprints to complete the assigned tasks, which can take 2 to 4 weeks. Daily Scrum meetings are organized to help complete the team monitoring that has so far taken place throughout the project. The Scrum Team Manager is known as the Scrum Master. As always, they have a responsibility to keep the team on track to achieve their goal.
- 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. Hence, it is easy to find alternative pathways
- 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
- 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