Understanding the Software Development Life Cycle

February 3, 2021

In the current digital era, many software applications are being developed to solve various real-life problems. For software developers, understanding the software development life cycle (SDLC) facilitates the effective planning and delivery of high-quality software products. This article takes you through the software development life cycle, providing an overview of the process and limitations of various implementations of the SDLC.

What is Software Development Life Cycle (SDLC)?

The software development life cycle (SDLC) refers to the process followed by software developers to develop high-quality software products. The SDLC provides a framework that outlines the tasks that need to be performed in each phase of software development. Organizations can use the SDLC process to provide structure when designing and building of applications.

This life cycle provides an effective plan for various activities in software development such as designing, building (developing), and maintaining software applications. It also provides a methodology for enhancing the quality of software applications in an organization. Organizations can choose an effective software development strategy from a variety of SDLC process models.

Various people in the organization can use the SDLC such as software engineers, developers, and cross-function teams. Developers and software engineers use it to create effective plans and designs. They also apply the various SDLC stages to develop innovative software products. Cross-function teams use the SDLC to collaborate across different software development stages.

Importance of SDLC

The software development life cycle adds value to software development in the following ways:

  • It provides an effective framework and method to develop software applications.
  • It helps in effectively planning before starting the actual development. SDLC allows developers to analyze the requirements.
  • It helps in reducing unnecessary costs during development. During the initial phases, developers can estimate the costs and predict costly mistakes.
  • It enables developers to design and build high-quality software products. This is because they follow a systematic process that allows them to test the software before it is rolled out.
  • It provides a basis when evaluating the effectiveness of the software. This further enhances the software product.

An Overview of SDLC stages

Requirements collection

This is the first phase of software development that involves getting the requirements from clients. Business analysts meet with the clients and collect their requirements (concerning the software being developed). These analysts use the collected information to prepare the business requirement specification (BRS). A requirement specification document is then prepared to provide guidelines for other phases in the SDLC.

Feasibility study

This phase involves analyzing the feasibility of the plans and requirements made in the first stage. The following are some of the questions that need to be answered in this phase:

  • Economic feasibility: Are there enough funds to invest in the development of the software?
  • Legal feasibility: Is the company able to comply with related regulations?
  • Operational feasibility: Is it possible to meet the workflow and operational requirements set in the requirement stage?
  • Technical feasibility: Does the organization have the necessary technology and human resources for the SDLC process?
  • Schedule feasibility: Can the development process be completed on time?

These questions should be answered carefully and documented before going to the next phase.

Design

In this phase, the developers are required to refer to the requirements document to design an appropriate architecture for the software. The designs created by the development team should be documented. The documents used for documenting the designs are known as design document specifications (DDS). These document should be reviewed by various stakeholders of the organization.

The final design is then selected based on certain parameters such as risk, modularity, robustness, time constraints, and budget. This design provides the blueprint of the software application being developed.

Software development

This is the implementation stage that involves developing the software. Here, the design of the product is transformed into reality by the software developers involved. The design document specification provides a guideline for the source code. Various programming languages can be used. These may include languagues such as PHP, Java, C++, Pascal, C, etc. The language chosen depends on the type of software being developed, the business use-case among other constraints.

Testing

In this phase, the software is sent to a testing environment where it is tested by test engineers. Testing is done to establish whether the software functions as intended based on the requirements given in the first phase. If the test engineers discover some defects, the developers go back and fix them. The software is tested further to check whether there are other defects.

Deployment

After ensuring that all customer requirements have been met, the developers deploy the software for use. Before actual deployment, the software should be documented for future reference. Ownership should also be transferred to the client. The deployment strategy depends on the specifications of the customer. It can be deployed in a data center or a client premise.

Sometimes software deployment can be done in stages. It may first be deployed to a limited customer segment to conduct user acceptance testing (UAT). The client will collect feedback from the initial users and suggest further enhancements. The enhanced product will then be deployed to the entire target market.

Maintenance

This phase involves solving issues faced by the customers when they use the software. When an issue is solved by the developers or software engineers, the software is tested to ensure it functions well. The software is then handed back to the customer for use. In the maintenance phase, the software can be enhanced to add other new features. It can also be upgraded to establish a new version of the system.

Software development process models

SDLC models are the methodologies employed by organizations in the development of software. These methodologies depend on the objectives of an organization. The main types of SDLC process models include waterfall, spiral, iterative, agile, and V-model.

Waterfall model

This model consists of various stages with inputs and outputs. The next stage cannot begin without the completion of the initial phase. Each phase uses the output of the previous phase as the input. The software product is tested once all the stages have been completed.

Waterfall Model

Image Source: Wikimedia

Advantages

  • It is a simple model that can be followed by developers in developing software.
  • It is easy to implement this model.
  • All the phases are clearly defined.
  • It works well in short projects.

Disadvantages

  • It is not ideal for complex software development projects.
  • It consumes a lot of time because each phase should be completed before moving to the next one.
  • It does not enhance customer integration during the development process.

Iterative model

In this model, software development is first done on a small scale. In every single iteration, additional features are designed and added to the software. Each iteration involves coding and testing the software product. This cyclical process produces a software product in every cycle. This software has more features than the previous cycle.

Iterative Model

Image Source: Professional QA

Advantages

  • It is easy to measure progress in this model.
  • It is possible to produce working functionalities early in the process (lifecycle).
  • It improves risk management because high-risk sections can be handled first.
  • It allows customers to change requirements easily.

Disadvantages

  • Following this model may require enhanced resources.
  • It requires a lot of attention from the management.
  • It is not ideal for small projects.

V-Model

This model is an extension of the waterfall model. The development and testing stages are organized in a parallel way. This model consists of the verification stage on one side, and the validation or testing stage on the other side. These two sides are joined through coding.

V-Model

Image Source: Professional QA

Advantages

  • It is ideal for small projects where all the requirements are well-understood.
  • It is a simple model that can be used easily by developers.
  • Every phase consists of a review process and certain deliverables, which makes it easier to manage.
  • It promotes high-discipline in software development since there is a step-by-step completion of phases (one at a time).

Disadvantages

  • It is not ideal for complex projects.
  • It is difficult to change the functionality of an application once it gets to the testing stage.
  • It is characterized by high risk.

Spiral model

This model combines aspects of the iterative and waterfall models. It goes beyond these models by paying more attention to risk analysis. It allows the software to be refined or released incrementally through iterations that exist on a spiral.

The software development process moves to the next step based on the evaluation done by the customer. The process moves along the spiral to the next phase.

Spiral Model

Image Source: Ultimate SDLC

Advantages

  • It allows an easier way to change requirements.
  • It improves risk management because the risky sections can be handled first.
  • In this model, prototypes can be used extensively.
  • It allows the accurate documentation of requirements.

Disadvantages

  • Managing this model is complex.
  • The completion time of the project is uncertain.
  • It may require excessive documentation because of huge intermediate phases.

Agile model

This is a combination of incremental and iterative models with more of a focus on customer satisfaction and adaptability. In this model, the development process is divided into incremental sections in iterations. In every iteration, cross-functional units work on areas such as planning, requirement analysis, design, coding, and testing. When each iteration ends, the product is shown to the customer and other stakeholders. The final product should meet all the specifications given by the customer.

Agile Model

Image Source: Tutorials Point

Advantages

  • It provides a realistic approach to the development of software.
  • It requires minimum resources.
  • It provides greater flexibility to software developers.
  • It requires little planning.

Disadvantages

  • The final product depends on the customer. If the customer is not clear on what is needed, the development team may move in the wrong direction.
  • It does not generate adequate documentation.
  • Inadequate documentation hinders technology transfer to new members.

Limitations of SDLC

  • It is difficult to estimate the actual cost of the entire project and the project overruns.
  • It may lead to an increase in the cost of software development especially if the customer requirements are not understood properly.
  • It consists of specific requirements and phases that need to be completed, which increase the time taken in the software development.
  • Sometimes the input of users may be limited.
  • The execution of SDLC phases depends on factors, such as customer requirements and the availability of funds.

Conclusion

The software development life cycle is a resourceful tool for developing high-quality software products. This tool provides a framework for guiding developers in the process of software development. Organizations can use various SDLC strategies such as waterfall, V-model, iterative, spiral, and agile models.

A suitable SDLC model can be selected based on the customer requirements and the objectives of an organization. The benefits of SDLC in software development can be realized if developers understand the customer requirements and strictly follow the documented plan.

Resources


Peer Review Contributions by: Adrian Murage


About the author

Onesmus Mbaabu

Onesmus Mbaabu is a Ph.D. candidate pursuing a doctoral degree in Management Science and Engineering at the School of Management and Economics, University of Electronic Science and Technology of China (UESTC), Sichuan Province, China. His interests include economics, data science, emerging technologies, and information systems. His hobbies are playing basketball and listening to music.

This article was contributed by a student member of Section's Engineering Education Program. Please report any errors or innaccuracies to enged@section.io.