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The Software Development Life Cycle: Phases And Methodologies

The Software Development Life Cycle: Phases And Methodologies

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In IT and everywhere else, great projects start with a great vision. Like any other complex process, software development takes a lot of planning, preparation, and delegating tasks at different stages to teams or team members –  especially, if you have several simultaneous processes.

 

Sometimes, it’s necessary to involve external specialists to help answer specific user needs. These experts have to be filled in as quickly as possible so they can do their job. For all this to go smoothly, you’ll need a strict framework that makes the entire software development process effective and lets the development team generate the best possible results in the shortest time.

 

This is, basically, what the Software Development Life Cycle (SDLC) stands for: defining the tasks performed each step of the way. It helps the core team get a clear idea of what they need to do, highlights problems and lays out every phase of the development process before a single line of code is written. It saves everyone time and effort and helps them reach their goal faster.

 

Explaining the Software Development Life Cycle

An SDLC is basically a regulated framework, a methodology for planning and controlling the creation, testing, and delivery of high-quality software. Some mistakenly call the software development life cycle a management methodology, which it isn’t. It’s not about management. It’s all about planning, designing, building, testing, and delivering a product. Basically, it’s a to-do list for the development team, which consists of a number of clearly defined work phases. These include analyzing user requirements, designing the software, coding it, documenting and testing what has been done, and operating and maintaining the software.

 

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Creating a mapped-out software development life cycle offers numerous perks for everyone involved.

 

Developers have a clear understanding of what they should do and why, as well as what problems they should solve. Hopefully, we all can agree that the goal can be reached sooner, the product can be implemented faster and with fewer difficulties when the goal is clear to everyone.

 

If difficulties arise, they’re much more visible. Deviations from the main road are much clearer when the road is brightly illuminated. On top of that, since a clear framework allows us to see the big picture and possible bugs, developers can choose a path that will make development easier and serve their purposes. This way (depending on the SDLC), the team will be able to keep working at a quick pace, instead of testing and retesting software glitches that would hinder or postpone the implementation. Generally, the whole process will become more efficient, as the software development life cycle helps you anticipate mistakes and avoid typical pitfalls.

 

A software development life cycle demands detailed documentation of development when necessary, structure, and coding. Documenting the development process in great detail will allow you to outsource maintenance to another company more easily or replace a team member in the process. This way, you won’t waste time updating the new team or team member if someone else can’t do the work due to illness or incompetence.

 

To give you a more complete picture and help you get the best from an SDLC, you should remember the typical software development life cycle phases.

 

Phases of SDLC

How do you actually cycle through the SDLC? There are six universal phases in the  software development life cycle. Knowing them will make workflow planning easy as pie, and the whole process will become more transparent.

 

a) Requirement gathering and analysis is the first, and the most basic stage of the SDLC. This is when you gather requirements from your client, analyze product feasibility and user needs, envision development and improvements that can be made, and investigate new, better ways to create the product.

 

If you need to improve or modify existing software, you’ll have to find underlying problems and ways to prevent them. If you’re working on an entirely new product, this is the phase that involves the most research and input from you as a developer, as well as from your client or the rest of the team. Jot down ideas on paper or flip charts, as visual aids always help you keep your thoughts together and everyone on the same page.

 

Documenting all your findings will help you track what has already been taken into consideration and refine requirements throughout the development process. Define roles and corresponding tasks. Create a blueprint for the various work processes that will be involved during development.

 

techniques-imageb) Design is the phase that comes next. Based on the requirements and the detailed analysis you carried out, now you can design the software. Logical design is turning your vision into a physical design. That said, the business requirements you identified earlier must be transformed into a software architecture that brings value to the customer. Elements like input and output, forms and databases, codification schemes and processing specifications should be laid out in great details.

 

The software design process can be facilitated using tools and techniques like flowcharts, data flow diagrams (DFD), data dictionaries, structured English, decision table, and decision trees.

 

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c) Implementation, or coding, is the phase when your team works on the the actual software and translates software specs and requirements into computer code. Physical software specifications are transformed into a solid working and reliable solution. This part requires good management, as each team member is assigned tasks according to his or her skill set. The work of every participant in the process should be closely supervised so that elements created by different people can function properly when combined together. Of course, well-written code substantially reduces the number of test runs and maintenance-related problems.

 

 

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d) Testing, however, is vital, and there’s no way around it. This stage allows the development team to see whether everything works as intended. This is the vital phase when they detect potential errors and see if the software meets the initial business goals. QA engineers design and carry out test cases and evaluate exit criteria (by following the scope set in the planning phase). They create bug reports describing detected defects and report to the stakeholders on the test findings and the completion status. Testing may be repeated to check for errors. Stakeholders can also participate in the acceptance testing to give feedback from a user’s point of view and see if the software fulfills their requirements.

 

 

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e) One of the final stages is deployment. If you’re not responsible for maintenance, this might be the final phase for you. This is the step when different users run the software. The main goal of this phase is to make sure that the software is indeed operational in a live environment. You can say that this is when you let your brainchild out into the wild. If it runs smoothly and the way it was intended in the first place, then consider your software ready to be launched.

 

To deploy your software, set up a schedule and deployment stages. Discuss all the user benefits at each stage to see if they’re delivered as planned, and all the communication channels for support and maintenance communication.

 

A post-deployment review is will point out the software’s bugs, if there are any. Other than that, you may need to provide some instructions for future users.

 

f) Congratulations! You’ve reached the final phase of the software development life cycle: maintenance. If you successfully arrived at this point, your product must have been deployed at expected quality level. In most cases, maintenance is the longest- lasting phase, and can be a tricky one. Your task now is to keep the software operational, ensure it meets the scope of future enhancements, and works well with updates in other related software or hardware.

 

 

There are two types of maintenance. With corrective maintenance, you fix defects that may arise and are rooted in production. It’s virtually impossible to create a perfect product in one go. Some problems become visible only when software is used by a large number of users or across a larger geographic or demographic area.

 

 

Adaptive maintenance allows you to add requirements you didn’t have in the original plan; users can show the need for them only after they have fully switched to the software.

 

 

All these phases are vital parts of the development process, and can be arranged and worked through in different order. Depending on how the team managers organize the developers’ work, there are several SDLC methodologies.

 

Software Development Life Cycle Methodologies

There are always many ways to reach a goal. In our case, we have five major SDLC methodologies that define the framework of a development team.

 

a) Waterfall Model. Waterfall is the oldest and basically the most straightforward methodology. It’s all pretty much on the surface: you complete a level, you go to the next one. Waterfall is a methodology that is the easiest to manage, however, it can be be prone to delays. Due to its nature, every phase should be reviewed and signed off on before the team can start the next one.


Another major drawback is that if you’ve completed a phase and moved on to the next one, you can’t really go back and fix something until the maintenance phase.

 

In order for Waterfall to work well, you should know all the requirements before the development process starts. However, if the project doesn’t require a lot of flexibility and has a tight schedule, Waterfall is the go-to methodology for completing the development efficiently and in time.

 

waterfall-model-imageb) V Model. This one is also known as the the Verification and Validation model. It’s a sequential model like Waterfall, which means that all of the work products and activities for a given phase are completed before the next phase begins. However, there’s a short step forward from the Waterfall methodology – this time, the testing team gets involved during the early phases of the SDLC, rather than at the end of the project, which reduces the amount of potential reworking.

 

Once the development and the test teams receive the requirements, they both start their work. While developers are working on the System Requirement Specification (SRS), the testers work on the Business Requirements Specification and prepare the Acceptance Test Plan (ATP) and the Acceptance Test Cases (ATC), etc. So, by the time the developers finish the product, the testers are ready with all the required artifacts (such as the ATP and ATC).

 

It’s still good for projects with little to no unknown specs, as it’s still difficult to go back a step and fix or add something. Every phase must be signed off on before the team can move to the next one. Each of them has a corresponding testing activity.

 

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c) Iterative Model. This model works like a kind of snowball. The team develops software in small portions, adding functionality at each step. They group features (according to priority, for example), and then carry out various project phases for each group. This way, you get a viable product fairly early in the development process, and introducing changes along the way is less expensive.

 

Straightforward as it may be, the Waterfall model requires all the info about the future product at the initial stage. With the Iterative model, it’s possible to add new requirements as you go.

 

So, basically, you start with a small set of features, test them, evaluate, refine them or move on. You repeat the process until all the requirements are implemented and work perfectly. Be careful though – don’t let the process get stalled by repeating the same phases too many times.

 

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d) Spiral Model. Being the most flexible, this model borrows from the Iterative model by following the repetitive principle but is also structured and systematic, like the Waterfall model. The Spiral Model pays a lot of attention to risk management. Here, a project starts on a very small scale, explores risks, handles them, and then decides whether it’s okay to move on to the next step, i.e., to the next iteration of the spiral.

 

Basically, a project goes through four stages (identification, design, build, evaluation and risk analysis) again and again in a “spiral” until it’s completed. This way, multiple rounds of refinement and changes are possible.

 

With this model, you can build highly customized software and incorporate user feedback in the early stages. It also allows for more realistic estimates (budget, schedules, etc.) But beware – you may get into an endless spiral. The cost and time needed to complete the product may also be higher than it is with other models.

 

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e) Agile Model. The Agile model is another iterative model with very short iterations of 2-4 weeks. It advocates for collaborative effort of self-organizing cross-functional teams. For this methodology, everyone works with everyone – customers, developers and testers work together throughout the project. Agile methods prefer personal communication over documentation, and emphasizes individuals and interactions over processes and instruments. Responding to change is more important than following a plan.

 

With the Agile model, the whole development process is broken down into small timeboxes that minimize upfront planning. In this time, a cross-functional team works in all directions – planning, analysis, design, coding, and testing. At the end of this iteration, a working product is presented to the stakeholders. One iteration doesn’t necessarily add enough functionality to guarantee a market release, but still, there’s a working product at the end of each iteration.

 

The team reevaluates project priorities after each iteration to make sure the product fulfills all of the customer’s (new and old) requirements. Because of its practical approach, it has become one of the most widely adopted SDLC methodologies.

 

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Aligning SDLC with Project Management

As we review all of the methodologies and phases, it may seem that the software development life cycle is some sort of project management “silver bullet”. This is actually a misconception, common even among many professionals working in the field . The truth is, SDLC is just a framework for planning, controlling, creating, testing, and delivering software. It’s like a checklist you tick off on your way to the goal. It’s a path description that aims to realize a product’s requirements.

 

Project management, in turn, is less about technology, and more about the application of knowledge and skills. A project manager needs to know his techniques to make sure the product meets requirements through careful planning and organizing the team, controlling and supervising the development process, and overseeing resources, be they human, financial, or time.

 

Similar to SDLC, traditional project management has its own phases. They’re also called “process groups”, and include Initiating, Planning, Executing, and Closeout. Project managers, standing between the stakeholders and the development team, must translate the languages these groups speak for the other side. They identify requirements, balance stakeholder needs, expectations, and concerns, as well as competing constraints such as scope, quality, schedule, budget, risk, and resources.

 

Good project managers should know how to combine managerial practices with SDLC. They have to communicate the status of a project to a variety of stakeholders. Since they all have different project information needs, there must be a way – like including certain milestones – to report in a manner that is meaningful for both project management and SDLC. To do so, these two life cycles must be aligned.

 

For example, take Initiation – the first phase of project management – the part where the initial project scope and schedule are settled. The SDLC phase that corresponds to this is Requirement gathering. Both of these depend on the amount and complexity of the requirements. The next stage is Planning, which requires greater precision in size, complexity and impact estimation. This is only possible after the Design phase and its activities are settled, and there’s a clear understanding of the next steps in development. Execution incorporates several SDLC phases at the same time – Implementation (Coding), Testing, and Deployment. The Closeout is a standalone phase not directly related to the SDLC phases.

 

 

Software Development Life Cycle and Management Phases

sdlac-and-management-phases

 

To move from theory a bit more deeply into details, let’s see how project management differs for the Waterfall and Agile models. Stemming from the ’50s, the Waterfall Model is the oldest one, and has now serious competition in form of the Agile Model, which has largely replaced it.

 

Above, we explained how both of these models work, but what about the managerial perspective? Waterfall follows a strict plan and requires very detailed documentation; this is the part the project manager is responsible for. It may sound like a heavy workload – but it pays off, as the process is absolutely independent from any of the team members so they can be moved or replaced.

 

With Agile, development is divided into short stages; at the end of each, a small module of the final product is presented to users for review. This way, changes are easier to make along the way. Since this model values a well-functioning product and a satisfied customer over transparent documentation, it requires a creative (to some extent) and quick-thinking project manager.

 

Both of these models coexist quite peacefully, and choosing one or the other mainly depends on your company and the product you develop. For example, Agile works better for developmental and non-sequential projects, while Waterfall is a comfortable framework for projects with fixed requirements and scope, and where the technology is very clear and reliable, and the product is familiar and stable.

 

Antoine de Saint-Exupéry once said, “A goal without a plan is just a wish.” Knowledge of the software development life cycle and all its phases and methodologies gives you an endless and powerful set of tools to develop innovative software fast and cost-effectively. Whatever your project will be – whether it’s a request from a client or something your own startup is eager to achieve – you need to have a good plan. There must be a sturdy ladder that leads you to the top.

 

 

 

Read more by QA Lead @ Django Stars

    Ira is a perfect example of diligence and assertiveness. Having a 3 years experience she is already a certificated QA engineer and Scrum specialist. Passionate and attentive to the details she will find even the most hidden bug in your application.

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