Software Development Life Cycle (SDLC)

Software Development Life Cycle or SDLC is a common word used in software industry. Most of you heard this for the first time when you are in university. So let’s discuss about SDLC in this article.

SDLC is the process that produces software with the highest quality and lowest cost in the shortest time possible. Main goal of the SDLC is to minimize project risks through forward planning and deliver a quality product.

SDLC models were introduced to follow a disciplined and systematic method while designing software. With the software development life cycle, the process of software design is divided into small parts, which makes the problem more understandable and easier to solve. SDLC comprises a detailed description or step-by-step plan for designing, developing, testing, and maintaining the software.

Importance of SDLC

We all know that software development process can be challenging due to reasons like requirement changes, technology upgrades etc. So having a well maintained process is very important. There are some benefits of SDLC.

• It provides a standardized framework that defines activities and deliverables
• It aids in project planning, estimating, and scheduling
• It makes project tracking and control easier
• It increases visibility on all aspects of the life cycle to all stakeholders involved in the development process
• It increases the speed of development
• It improves client relations
• It decreases project risks
• It decreases project management expenses and the overall cost of production

SDLC Phases

SDLC will be different from team to team. But there are common phases. Lets see what are they and their functions.

Planning

Planning is the most important stage. This is where we outline the project. Not only in software development, but before we do any major task we are gonna plan how to do it. So same thing is done here. This typically includes resource allocation, capacity planning, project scheduling, cost estimation, and provisioning.

During the planning phase business requirement gathering is done from clients or stakeholders.

Define Requirements

In this stage, the requirements and information gathered from stakeholders will be converted to well defined requirements in a way that development team can understand. his process guides the development of several important documents: a software requirement specification (SRS), a Use Case document, and a Requirement Traceability Matrix document.

Designing

This is where the designers come up with the best architecture for the product. In this phase we will decide the programming languages, libraries, design patterns, security measures of the product. Design diagrams like sequence diagrams, UMLs, data base design diagrams, flow charts, architectural diagrams will be designed. These are very important before moving to development. These all should be well documented and organized so developers won’t face any trouble.

Development

This is where the requirement is turned to a code and developed. Depending on the complexity of the product the number of developers involved will be changed. Developers build the product according to the design. This phase will take some time and depends on the complexity of the product, experience of the developers etc. It’s important to have a set timeline and milestones so the software developers understand the expectations and you can keep track of the progress in this stage.

Testing

This is where the product will be tested by quality assurance team to ensure that product meets the client requirements. All the kind of testing will be done to ensure the quality of the product. It is important test all the areas of the product. QA team will report bugs during this stage and developers need to fix them.

The types of testing to do in this phase:

• Performance testing: Assesses the software’s speed and scalability under different conditions
• Functional testing: Verifies that the software meets the requirements
• Security testing: Identifies potential vulnerabilities and weaknesses
• Unit-testing: Tests individual units or components of the software
• Usability testing: Evaluates the software’s user interface and overall user experience
• Acceptance testing: Also termed end-user testing, beta testing, application testing, or field testing, this is the final testing stage to test if the software product delivers on what it promises

Deployment

This stage is where the application will be available for end users. Deployment is not end with a one step. Deployment always happen when there is a new version of the product available.

Deployment depends on the product of the nature, tools and client. Some times deployment will happen on stages.

Maintenance

Monitoring and maintenance is important once the product deployed. If there are performance issues, security issues they need to be addressed as quickly as possible. Many products are built using iterative development models that call for constant improvement. Additional features launch new development cycles, where developers, the product owner, and stakeholders start the process all over again. Many products are developed throughout their entire lives.

SDLC Models

There are different types of models being used. Here are some commonly used ones.

• Waterfall Model
• Incremental Model
• Spiral Model
• Evolutionary Prototyping Model
• Agile Model
• RAD Model

Waterfall Model

This is the classic software development model. This process is a sequential process or a linear process where in the output of one phase is input of another phase. So previous phase becomes important to be completed before we move to next phase. Systems that have well-defined and understood requirements are a good fit for the Waterfall Model

Pros:

• Easy to understand, easy to use
• Provides structure to inexperienced staff
• Milestones are well understood
• Sets requirements stability
• Good for management control (plan, staff, track)
• Works well when quality is more important than cost or schedule

Cons:

• Not suitable for the project where requirements are changing
• The high amount of risk and uncertainty
• Small change in one phase leads to big change in each phase, as these phases are dependent on one another and eventually more time is consumed

Suitable Situations:

• Work well for a small project
• When Requirements are very well known and not changing.
• When Product definition is stable

Incremental Model

The process of software development where requirements divided into multiple standalone modules of the software development cycle. In this model, each module goes through the requirements, design, implementation and testing phases. Every subsequent release of the module adds function to the previous release. The process continues until the complete system achieved.

Pros:

• Errors are easy to be recognized
• Easier to test and debug
• More flexible
• Can delivery major risk functions early
• Simple to manage risk because it handled during its iteration
• The Client gets important functionality early
• A customer can respond to each build

Cons:

• Require good planning and designing as there will be multiple iterations
• High cost
• Rectifying a problem in one unit requires correction in all the units and consumes a lot of time

Suitable Situations:

• Requirements of the system are clearly understood
• When demand for an early release of a product arises
• When team is not very well skilled or trained
• When high-risk features and goals are involved

Spiral Model

This is an evolutionary software process model that couples the iterative feature of prototyping with the controlled and systematic aspects of the linear sequential model. It implements the potential for rapid development of new versions of the software. Using the spiral model, the software is developed in a series of incremental releases. During the early iterations, the additional release may be a paper model or prototype. During later iterations, more and more complete versions of the engineered system are produced.

Pros:

• Provides an early indication of insurmountable risks, without much cost
• High amount of risk analysis
• Changes can be introduced later in the life cycle
• Users can be closely tied to all lifecycle steps and can see the system early because of rapid prototyping tools

Cons:

• The model is complex
• Risk assessment expertise is required
• Spiral may continue indefinitely
• Doesn’t work well for smaller projects

Suitable Situations:

• For medium to high-risk projects
• When users are unsure of their needs
• When requirements are complex
• When there are frequent deliveries
• When changes may require at any time

Evolutionary Prototyping Model

In this type, developers build a prototype. This is similar to the actual product. Users will evaluate the prototype and provide feedbacks. Based on those feedbacks developers will do refinements. If user is satisfied on the prototype, it will brought up to the standards as needed for final product. Over time and multiple feedback cycles, the prototype may have more advanced functionality added to it as needed by the client. The process thus results in the finished product.

Pros:

• Requires user involvement
• Customers can “see” the system requirements as they are being gathered
• Developers learn from customers
• Reduce the development time
• Reduce the development cost
• Unexpected requirements accommodated
• Allows for flexible design and development
• Missing functionalities can be easily added
• Result in higher user satisfaction

Cons:

• Too much involvement of the customer
• Insufficient analysis
• The design is of less quality
• The resulting system is harder to maintain. Overall maintainability may be overlooked
• A prototype is a quick-and-dirty” solution
• The customer may want the prototype delivered.
• The process may continue forever

Suitable Situations:

• When requirements are unstable or must be clarified
• For developing user interfaces
• For Short-lived demonstrations
• For the new, original development
• With the analysis and design portions of object-oriented development.

Agile Model

The biggest problem we face in software development is changing requirements. For such Agile is the solution. The agile development model is also a type of Incremental model. In Agile the product is developed in incremental, rapid cycles. This results in small incremental releases with each release building on previous functionality. Each release is thoroughly tested to ensure software quality is maintained.

Pros:

• Is a very realistic approach to software development
• Promotes teamwork and cross-training
• Functionality can be developed rapidly and demonstrated
• Resource requirements are minimum
• Suitable for fixed or changing requirements
• Delivers early partial working solutions
• A good model for environments that change steadily
• Customer feedback at every stage ensures that the end deliverable satisfies their expectations
• No guesswork between the development team and the customer, as there is face to face communication and continuous inputs from the client

Cons:

• Not suitable for handling complex dependencies
• More risk of sustainability, maintainability, and extensibility
• An overall plan, an agile leader, and agile PM practice is a must without which it will not work
• Strict delivery management dictates the scope, functionality to be delivered, and adjustments to meet the deadlines
• Depends heavily on customer interaction, so if a customer is not clear, the team can be driven in the wrong direction
• Since the requirements are ever-changing, there is hardly any emphasis, which is laid on designing and documentation. Therefore, chances of the project going off the track easily are much more

Suitable Situations:

• When requirements are changing.
• When a highly qualified and experienced team is available.
• When a customer is ready to have a meeting with a software team all the time.
• When project size is small

RAD Model

RAD or Rapid Application Development is an adaptive software development model based on prototyping and quick feedback with less emphasis on specific planning. RAD approach prioritizes development and building a prototype, rather than planning. RAD is a concept that products can be developed faster and of higher quality through:

• Gathering requirements using workshops or focus groups
• Prototyping and early, reiterative user testing of designs
• The re-use of software components
• A rigidly paced schedule that refers design improvements to the next product version
• Less formality in reviews and other team communication

Pros:

• Reduced cycle time and improved productivity with fewer people means lower costs
• Time-box approach mitigates cost and schedule risk
• It increases the reusability components
• Greater customer satisfaction
• Fast delivery time
• Reduce the development time

Cons:

• Hard to use with legacy systems
• Requires a system that can be modularized
• Require highly skilled developer and designer
• Not useful when technical risks are high

Suitable Situations:

• When the system should need to create the project that modularizes in a short span time (2–3 months).
• When the requirements are well-known.
• When the technical risk is limited.

So in this article we discussed What is SDLC, it’s benefits and use cases. I hope this is helpful to you and you can learn from this article. Thank you and stay connected.