The software development life cycle is a software engineering process used to design, develop, test, and deploy software. Each phase of the SDLC is designed to give companies control over their software development with predictable deliverables and visibility into budgets and deadlines.
The goal of adopting an SDLC model is to produce high-quality software at a lower cost in an efficient and productive manner. Currently, the most common SDLC models used in software development include waterfall and agile-based methodologies. The waterfall model was the first process model adopted to manage software development. Introduced in the early s, waterfall follows a linear-sequential development cycle, where each phase is discrete and begins only when the previous phase is completed.
In this model, which came from manufacturing and construction industries, progress flows from the top to the bottom much like a cascading waterfall.
Winston Royce , often credited as the creator of the waterfall model for software engineering, identified the following SDLC phases:. The first step in waterfall is gathering all the customer requirements up front. This is the only stage that involves customers until the software is delivered. This is the software architecture stage and includes both logical and physical design. In this stage, developers produce and test code based on the specifications from the design stage.
The product is maintained. Any bugs or security vulnerabilities are fixed as necessary. Under the traditional waterfall model, the average time between releases is one to two years, regardless of the size of the release. Think back to the pre-SaaS Excel days when major updates meant a complete reimagining of the product and occurred only every two years.
The waterfall model provides a centralized and standardized approach to software development that is easy to manage. In , the Agile Manifesto was published, and the software development life cycle was upended.
Not technically a framework or methodology, the Agile Manifesto is a set of 12 guiding principles focused on leadership, teamwork, and customer satisfaction. Some of the core principles include:. One of the main outcomes of the agile movement was the shorter development cycles. Medium-size companies began seeing the benefit of adopting an agile practice, and eventually enterprise organizations followed suit. There is no one single SDLC model.
They are divided into main groups, each with its features and weaknesses. The SDLC models diversity is predetermined by the wide number of product types — starting with a web application development to a complex medical software.
And if you take one of the SDLC models mentioned below as the basis — in any case, it should be adjusted to the features of the product, project, and company. The most used, popular and important SDLC models are given below:. No matter what type of the models has been chosen, each of them has basic stages which are used by every software development company.
Each software development life cycle model starts with the analysis, in which the stakeholders of the process discuss the requirements for the final product. The goal of this stage is the detailed definition of the system requirements.
Besides, it is needed to make sure that all the process participants have clearly understood the tasks and how every requirement is going to be implemented. Often, the discussion involves the QA specialists who can interfere the process with additions even during the development stage if it is necessary. At the second phase of the software development life cycle, the developers are actually designing the architecture.
All the different technical questions that may appear on this stage are discussed by all the stakeholders, including the customer. Also, here are defined the technologies used in the project, team load, limitations, time frames, and budget. The most appropriate project decisions are made according to the defined requirements.
After the requirements approved, the process goes to the next stage — actual development. Programmers start here with the source code writing while keeping in mind previously defined requirements. The system administrators adjust the software environment, front-end programmers develop the user interface of the program and the logics for its interaction with the server.
The programming by itself assumes four stages. The testing phase includes the debugging process. All the code flaws missed during the development are detected here, documented, and passed back to the developers to fix. The testing process repeats until all the critical issues are removed and software workflow is stable. When the program is finalized and has no critical issues — it is time to launch it for the end users. After the new program version release, the tech support team joins.
This department provides user feedback; consult and support users during the time of exploitation. Moreover, the update of selected components is included in this phase, to make sure, that the software is up-to-date and is invulnerable to a security breach. Waterfall — is a cascade SDLC model, in which development process looks like the flow, moving step by step through the phases of analysis, projecting, realization, testing, implementation, and support.
This SDLC model includes gradual execution of every stage completely. Be smart and write the right types of tests. Learn the strengths and weaknesses of the current system with improvement as the goal. It also details the risks involved and provides sub-plans for softening those risks.
In other words, the team should determine the feasibility of the project and how they can implement the project successfully with the lowest risk in mind. All stakeholders then review this plan and offer feedback and suggestions. Failure at this stage will almost certainly result in cost overruns at best and the total collapse of the project at worst. At this stage, the actual development starts. Also, make sure you have proper guidelines in place about the code style and practices.
For example, define a nomenclature for files or define a variable naming style such as camelCase. This will help your team to produce organized and consistent code that is easier to understand but also to test during the next phase. We fix those issues until the product meets the original specifications. Prefix works with. At this stage, the goal is to deploy the software to the production environment so users can start using the product.
However, many organizations choose to move the product through different deployment environments such as a testing or staging environment. This allows any stakeholders to safely play with the product before releasing it to the market.
Besides, this allows any final mistakes to be caught before releasing the product. Further, as conditions in the real world change, we need to update and advance the software to match. Developers are now responsible for more and more steps of the entire development process. We also see the value of shifting left. When development and Ops teams use the same toolset to track performance and pin down defects from inception to the retirement of an application, this provides a common language and faster handoffs between teams.
Application performance monitoring APM tools can be used in a development, QA, and production environment. This keeps everyone using the same toolset across the entire development lifecycle. This SDLC model is the oldest and most straightforward. With this methodology, we finish one phase and then start the next. The biggest drawback of this model is that small details left incomplete can hold up the entire process.
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