Software Development Life Cycle (SDLC) is a detailed plan outlining and defining tasks performed in every stage of software development. It is a conceptual framework showing the processes involved in planning, building, executing, and maintaining the software.
The main goal of SDLC is to create and deliver a high-quality product or service, which will meet your customer’s needs. It covers software’s complete life cycle, from its inception through to deployment and maintenance.
The development team follows the SDLC structure to produce quality software that meets deadlines and surpasses customer expectations and cost estimates.
To fully understand SDLC, this article covers a comprehensive definition of the software development life cycle, its phases and models, and best practices.
Table of Contents
What Is SDLC (Software Development Life Cycle)?
SDLC is a process model comprising cumbersome activities involved in requirement identification, implementation, execution, and maintenance of software.
When developing software, programmers have to draft a project idea, take it through the various stages of development, test, and release it.
While some steps may be combined, project leaders use the SDLC model to analyze every stage in detail. As the demand for software and developers keeps rising, this practice is now becoming commonplace as it enhances the development process.
This framework enables companies to reduce their software development costs, lower the delivery time, and meet the design requirements as per customer’s needs.
SDLC enables developers to achieve these goals by determining areas of inefficiencies and blotted costs and taking the necessary action for the smooth running of projects.
This phase entails gathering all the relevant information from the customer to ensure the product developed meets their expectations.
The customer may not have a complete idea of what the software will look like but any ambiguities should be cleared by collaborating with software engineers and the sales department.
The most essential information to be provided includes details about the product, its purposes, and how it should work.
At this stage, the software developers should design the terms of the project by creating target goals, project teams, and leadership structure.
The developers should also calculate material costs and labor, while communicating and obtaining feedback from project stakeholders (customers, sales reps., and subject matter experts).
With this knowledge, the developers should conduct an analysis to determine if developing the product or software is feasible.
The software engineers should also document the ideas about the product in a Software Requirement Specification (SRS) document. The contents of this document should be clear to the developers, and the customer should be able to use it for future reference.
2. Design
This phase entails designing the system architecture and outlining the functionalities of each module. The developers also design the interaction between the software and third-party modules.
Creating the ideal software requires using the requirements in the SRS document as inputs into the process. The main output derived is the software architecture, which is used for executing the system development.
The design phases comprise the following aspects:
Architecture: specifies the software’s programming language, industry practices, templates to be used, and the overall product design.
User interface: outlines the interaction between the software and the input by customers.
Platforms: the applications or platforms on which the software will operate, including Windows, Linux, iOS, or gaming consoles.
Programming: the programming language, problem-solving techniques, and task execution.
Communications: specifies the mode of communication between the application and other assets, such as the central server.
Security: outlines the techniques for securing the application, including password protection and SSL traffic encryption.
Developers can also develop prototypes at the design stage. A prototype demonstrates the basics of the end product; it is an earlier version of the software, which the developers can show to stakeholders.
The owners of the software can then propose changes to be made to the application, making it easier to rewrite code rather than making reviews during the development stage.
3. Software Development or Coding
The development phase of the software development life cycle starts once the developers have the design document and prototype of the end product.
The design is written into a code, and the product is built according to the company’s set standards. The developers adhere to the best guidelines and practices to ensure they apply programming tools to develop a high-quality product.
Identifying and fixing glitches and errors during this phase is crucial as any problems during the development phase can affect the running of the application. It is also essential to note down useful tutorials about complex tasks to guide users during the first launch.
A written document in the form of troubleshooting guides or user guides can help users resolve technical issues that may arise during testing or deployment.
This phase of the software development life cycle precedes the execution of the final product. It starts after coding is complete and the modules are made available for testing.
The developers can automate some aspects of product testing, such as security testing.
For complex deployments, developers may require a practical scenario, such as a simulated production environment. The objective of testing is to ensure that every component of the software is working as expected and in sync with other parts linked to it.
Performance tests are done to detect and rectify processing lags and hangs while minimizing the number of glitches likely to affect users.
Reference is made to the SRS document to test and retest the software until the product meets the customer’s standards.
Successful product testing indicates the product’s performance is satisfactory, hence, a good usage rate.
5. Deployment
The developers release or launch the final version of the software in the production environment.
Prior to this process, User Acceptance Testing (UAT) can be performed to determine if the software is acceptable or not. It is done after the completion of system, functional, and regression testing.
The main objective of UAT is to ensure the software meets the business requirements. It is a process conducted by the end-users who understand the business strategy.
When the product is deployed through UAT, the developers create a replica of the production environment, and both the software engineers and the customer perform the testing.
The customer signs off the go-live once they are satisfied the software meets the business expectations.
6. Maintenance
Following the release of the software, frequent maintenance should be done to change the system architecture to meet the future needs of the market or customer.
Maintenance may require altering the existing code or adding a new one. It is essential for developers to fix system glitches and to enhance the product’s standards to avoid exposure to glitches and virus attacks.
Software development is streamlined using different models. Developers can choose to follow any of the popular models in the software development life cycle.
Software Development Life Cycle Models
An SDLC model describes the methodology used in software development. The main software development life cycle models include:
a. Waterfall model
Also known as the linear sequential model, the waterfall model comprises six phases. Each stage follows the other in a sequential manner with the outcome for one phase being input for the next.
Every phase is evaluated for feasibility and continuity before proceeding. The model’s stages include:
Requirement gathering and feasibility analysis. The developers create the SRS document, which acts as the input for the next phase.
System design and software architecture. This phase entails creating documents for the implementation and coding phases.
Implementation. Here, the developers write down the code for software development. They develop the software in preparation for testing.
Testing. The developers test the developed code for any defects. Any system glitches are monitored using the defect tracking tool and retested after fixing. Other activities, such as regression testing, retest, and bug logging continue until the go-live state.
Deployment. Software developers launch the developed code in the production environment following sign off by the customer.
Maintenance. The developers resolve any issues with the code or implement improvements when necessary.
The V-shaped model is also known as the validation or verification model. Here, developers perform software development (verification) and testing (validation) in parallel.
The main difference between the v model and the waterfall model is that in the former, test planning and testing are done at an early stage.
The verification phase comprises the following stages:
Requirement analysis – the developers gather all the necessary information and analyze it to ensure all the requirements are available to meet the needs of the customer and system design.
System design – this process entails architecture, creating system components, and writing down a design document.
High-level design – this stage involves defining the technicalities involved between the verification and validation modules. It outlines the modules’ architecture/design.
Low-level design – this stage defines the design or architecture of the individual system components.
Coding – the software engineers write and develop the code at this stage.
The validation phase comprises the following steps:
Unit testing – developers perform unit testing at the low-level design stage. They use the unit test cases to detect any lags or hangs on individual components.
Integration testing – this testing is performed by testers on integrated modules. It is done at the high-level design stage using integration test cases.
System testing – this testing is performed on the entire system to test its functionality. It is done at the system design stage.
Acceptance testing – the developers and the customer perform this test in the customer’s environment to confirm that the system meets the business requirements.
c. Prototype model
The system developers create a prototype in the requirement phase after which it is evaluated by end-users before developing the actual software.
The feedback obtained from the customer helps developers to alter the prototype to meet user requirements.
Once the feedback is implemented, the customer reviews the prototype once more for any changes. The process is repeated until the users accept the model.
Prototypes are created using dummy functions; hence, they have limited performance and functional capabilities relative to the final product. Once all the requirements have been obtained and the prototype is approved by the customer, a quick design is created.
The customer evaluates the design for any modifications, the developers proceed to create the actual software. The actual system is developed using the waterfall model technique.
d. Spiral model
The spiral model of the software development life cycle follows the iterative and prototype models. Developers use 4th generation programming languages, risk analysis, and rapid application prototyping techniques to the waterfall model.
The developers also design the system requirements for creating a preliminary system. The initial prototype is tested, and its results are used to create a second prototype. Other prototypes follow until the customer’s requirements are met.
The final prototype is used as the basis for creating the system. Once complete, the software is evaluated and tested by both the developers and end-users.
The spiral model comprises the following stages:
Planning – this stage entails requirement gathering from the customer and documentation. The SRS document is created for use in the next phase.
Risk analysis – the developers select the best solution based on an analysis of the risks involved. A prototype is developed based on the results of the analysis.
Engineering – the developers write a code and create a system while keeping in mind the risks identified in the previous phase. For instance, if a remote database causes delays in accessing data, the developers can create a system that addresses the issue of data speeds by building a prototype with a subsystem of the data access system.
Evaluation – the customer evaluates the final prototype of the developed system and prepares for the next iteration.
e. Iterative and Incremental Model
This software development life cycle model requires developers to implement a part of the software, after which it is reviewed and additional features are added.
The parts are developed and released in groups of iterations. This practice helps reduce the development risks significantly because the customer provides feedback after the completion of every part.
However, this model demands good planning, early definition of the complete system, and well-outlined module interfaces.
The iterative model is an incremental framework where product features are added on an incremental basis. Therefore, the final product comprises complete iterations.
The iterative and incremental model is made up of the following phases:
Inception – the requirements and scope of the project are outlined and defined.
Elaboration – the product’s working architecture is provided, covering the non-functional requirements and risks determined during the inception stage.
Construction – the code is created and the system architecture is developed through the stages of analysis, design, implementation, and testing.
Transition – the product is launched in the production environment.
f. Big Bang model
The big bang model has no defined structure. Instead, the developers design and develop a product according to the customer’s budget. The main downside of this approach is that the software may not meet the customer’s needs.
There is also no planning and scheduling done when using the big bang model. The requirement analysis, coding, and development are done by the developer as per his interpretation and understanding.
If you’re using the big bang model in the software development life cycle, ensure your project is small to minimize the magnitude of the risk involved. Keep in mind that no testing is done when using this model, which could contribute to project failure.
The model is ideal for small, simple projects.
g. Agile model
The agile model comprises the elements of the iterative and incremental model. The agile model seeks flexibility in product development rather than in the requirements.
The scope of system development entails small incremental builds, which are developed by adding features as per the customer’s requirements. The next build is based on the functionalities of the previous output.
Iterations in the agile model are known as sprints, with each sprint lasting 2-4 weeks. The customer must verify the product at the end of every iteration before delivery.
Suggestions from the customer are used to enhance the next sprint. The developers perform tests on each sprint to minimize the risk of project failure.
Software Development Life Cycle Best Practices
Continuous integration
The objective of continuous integration (CI) is to ensure every component of SDLC is compatible with other parts. Incorporating CI reduces problems when combining parts of the product at the end of development.
Different teams should use similar programming languages and libraries to minimize inconsistencies and conflicts in project execution. This practice also eliminates the problem of duplication of work.
SDLC management systems
Developers should use SDLC management systems to manage and control every step of the development cycle. Such systems improve the transparency of the phases of the development process, leading to high-quality outputs.
SDLC management systems also add metrics or KPIs to the development process, such as bug-tracking, analytics, and work management, which help improve the functionalities of the system parts.
Conclusion
Software Development Life Cycle (SDLC) is a detailed framework showing the processes involved in planning, building, executing, and maintaining the software.
It comprises cumbersome activities involved in requirement identification, implementation, execution, and maintenance of software.
While some steps can be combined, project leaders use the SDLC model to analyze every stage of the development process in detail.
The benefit of using SDLC is that it helps minimize risks and inefficiencies in software development, lower software development costs, manage the delivery time, and ensure the final product meets the customer’s requirements.
The main phases of SDLC include requirement extraction and analysis, design, coding, product testing, deployment, and maintenance.
The models used in the development process include the waterfall model, v-shaped, prototype, spiral, iterative incremental, big bang, and agile models.
Developers can use either of these frameworks, but they should observe the best practices of continuous integration and SDLC management systems for proper management and control of the development process.
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Jamsheer K, is the Tech Lead at Acodez. With his rich and hands-on experience in various technologies, his writing normally comes from his research and experience in mobile & web application development niche.
