What is the software development life cycle?

Fri, 04/05/2019 - 14:00

The software development life cycle works by reducing the cost of software development, while at the same time improving quality and reducing production time. How is this happen? The SDLC accomplishes these divergent goals by simply following a plan that eliminates typical pitfalls associated with software development projects.

It all starts with an assessment of the existing system for the presence of flaws. Then it finds new system requirements. In addition, the software creation goes through various stages:

  • Design;
  • Development;
  • Testing;
  • Deployment.

When you can see costly mistakes in advance, such as the inability to request an offer from an end user, the SDLC can eliminate after-the-fact corrections and over-processing.

Since now we're familiarized with the work of SDLC, let's take a look at the various methodologies used for this purpose.

Software Development Models

Waterfall model:

Probably the simplest and oldest model of SDLC. In this methodology, you first complete one phase and then begin another. From the name it is clear that each of the phases contains its own microplan, and each phase of the "waterfalls" moves into another phase. But, this model has a drawback - even some small details that remain unfinished can stop the whole process. There is no need to consider past problems that may arise in the next stage.

Agile Model:

The Agile model divides the product into various cycles and delivers a functional product instantly. This model generates a sequence of releases. When each release is tested, it returns information which is then included in another version.

Speaking about the lack of this model and, as suggested by Robert Hough, during the validity of this model, an increased emphasis on interaction with consumers can lead the entire project in a completely wrong direction in some cases.

Iterative Model:

This model focuses on repetition. In this model, software engineers have developed the version instantly and, apparently, still quite cheap, then the version is tested and improved using consistent and fast versions. But if you do not constantly monitor this model, it can instantly consume resources.

After each iteration the development team can work on risk management, preparing for the next iteration. Since the cycle includes a small part of the entire software development process, it becomes easier to deal with the development process, but it requires more resources.

V-shaped model:

This model is an extended model of the waterfall methodology. The SDLC model is tested at every stage of development. Just like a waterfall, the process of a V-shaped model can easily run into obstacles. The model uses a V-shaped model, which usually focuses on validation and verification.

But there is a huge advantage of this model - you can test the software at each stage and in the reverse order. This is not like a waterfall model, where, if the previous stage is completed, you cannot go back to correct what went wrong.

Big Bang Model:

This is a high-risk software development life cycle model that devotes most of its resources to development and is great for small projects. However, there is no stage for detailed requirements determination. This is the simplest model, requiring less planning and more tools and programs.

Spiral model:

This is one of the most flexible models of the software development life cycle, which is similar to an iterative model in terms of repetition. This model again and again goes through the stages of planning, assembly, design and testing, and at each stage it is constantly being improved. The spiral model takes into account risk, which often goes unnoticed by various other models.


This model is a combination of operations and development functions, allows you to create a structure that is focused on communication and collaboration. Its goal is to automate processes and create an environment focused on continuous development.

Phases of the software development life cycle

A strong SDLC strategy offers high-quality software, reduces resources and time, and reduces vulnerability. It not only focuses on software support and development, but also provides benefits when it comes time to decommission the code.

Phases involved in the software development life cycle:

Stage 1 - Plan

As with any other project planning, the main step in the SDLC is the planning of the complete planning process. At this stage, the organization determines the content, the topic of release and the timing. Typically, this includes activities such as collecting end-user requirements, defining user histories and scheduling release dates.

Some of the highlights that need to be considered at this stage include:

  • to ensure that the application meets business requirements;
  • engage in threat modeling or safe design;
  • selection of libraries and language to be used throughout the development process;
  • comparison of test cases with functional and business requirements.

This is the stage to identify new software requirements along with its cost. At this stage, the associated risks are also detailed and sub-plans are proposed to mitigate these risks. These are some of the questions that need to be answered at this stage. Who will use the system? What data will enter the system and what data should be the output of the system?

Stage 2 - Code and Build

This stage includes the design itself, as well as the writing of the application. All this is done in attempt to meet the requirements established in the planning process.

Before writing, the team analyzes whether the software can satisfy all user requirements. In other words, this stage consists in determining whether the project is practically, financially and technologically feasible for the development of the organization. To do this, developers use different algorithms to make a conclusion about the feasibility of a software project.

Some of the highlights that need to be considered at this stage include:

  • Developer Training on Secure Coding Rules;
  • correction and search for defects and other vulnerabilities in the program code when it is written;
  • safe use of open source components;
  • by reducing unproductive time, developers usually spend in anticipation of test results.

At this stage, the code is created and integrated. This is the main focus of developers and it is one of the longest stages of the entire software development life cycle.

Stage 3 - Test

This is the phase that can complete the steps you have taken in the previous phases. At this stage, QA engineers test the code in terms of requirements to ensure that the product handles them correctly and works as expected. At this stage, all types of testing are conducted, including UX testing, performance, and functional testing.

Some of the highlights that need to be considered at this stage include:

  • Testing applications for security policy using various testing methods.
  • Conducting a comprehensive and complete set of functional blocks, performance testing and integration using similar protocols and the language of the tested systems.

Stage 4 - Deployment

At this stage, software developers implement the product. This is the release phase in which software is deployed on production servers. This includes managing, packaging and deploying various complex releases in a variety of environments, including clouds and private data centers, as well as public cloud resources.

Some of the highlights that need to be considered at this stage include:

  • track the progress of the release, including its components;
  • the transition from manual release processes to an automated process, in which software release usually depends on a business decision;
  • the inclusion of security testing as one aspect of final quality checks.

At this stage of the deployment the developed software is checked for problems related to adaptability, portability, and integration so that they can be fixed immediately and without further action. The complexity of the deployment is usually determined by the size of the project.

Stage 5 - Maintenance

At this stage, your product is already being used by consumers. This phase involves monitoring and maintaining the application and its performance.

It is very important to provide the best user experience and ensure continuous improvement. To make operational data available to testers and developers, an organization creates feedback loops.

Some of the highlights that need to be considered at this stage include:

  • continuous testing and monitoring of applications during production;
  • re-evaluate applications for safety, performance, and user convenience as they change or update.

It is clear that newly developed software should be carefully evaluated for stability and performance. For this, organizations use APM (Application Performance Management), as well as journals and other similar metrics collection tools. If a problem is reported, the development team accepts it for corrections or as ongoing software maintenance efforts. The step confirms the functionality of the software in terms of fewer errors and greater efficiency.

Benefits of creating a software development life cycle

Currently, software development environment requires complex and elegant solutions. This means that developers must manipulate several tools as well as technologies, creating code that will provide an effective level of digital business.

In addition, teams need to solve a number of problems including mobile, coding for APIs and cloud environments. There are many tools with lack of flexibility and some of them have a steeper course of study.

Thus, it is crucial to fully implement tools that detect application security vulnerabilities and include metrics and risk data in a more automated way. Any organization that seeks to implement an integrated approach to embed protection and security in their SDLCs reduces risks, speeds development, and reduces costs.

They continue to develop better and new applications, constantly updating current software without compromising security.

In other words, the organization achieves the best level of protection. However, SDLC, if done correctly, can provide the highest level of documentation and control by management.

Developers understand what they need to build and why. Each involved party can agree in advance with the goal and make a clear plan for achieving it. Everyone knows the necessary resources and costs.

However, there are many pitfalls that can turn the implementation of the software development life cycle into an obstacle to development, and not as an auxiliary tool. Failure to comply with the requirements of all users, customers and stakeholders can lead to a wrong and poor understanding of system requirements from the outset. In other words, the advantages of SDLC exist only when the complete plan is strictly executed.


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