Software lifecycle - definition & overview

The software lifecycle, sometimes referred to as the software development lifecycle (SDLC) can be summarized as the set of steps, tasks, activities, and processes required to develop a new application. The software lifecycle can be defined in many different ways, and each development team is free to customize its own development process to fit its unique needs and circumstances.

The software lifecycle is both descriptive and prescriptive. It describes how a software application is developed, beginning with the initial identification of a need, demand or market opportunity and finishing with the operation and maintenance of the application by developers. The model also serves as a methodological framework for software developers pursuing a structured approach to application development. While the software lifecycle can be represented in different ways, we choose this eight-step model that covers the most important activities of software development.

Demand identification

The first step of a successful software development project is demand identification. Before a team of developers can begin to collect user needs to start establishing requirements, they must first choose a target user for the application. This entails the identification of a target market, a market opportunity, or some unmet demand in the marketplace. Demand identification is about finding a customer or user base whose needs you can address through the development of the application.

Demand identification can happen from market research or when a firm interacts with its existing users and customers.

Requirements engineering/capturing user needs

Once a software development team identifies a need for an application in the marketplace, the next step is to understand the specific needs of users. This process is called requirements engineering and its purpose is to establish the "scope of work" for the project and to understand and detail the features and functions that users will expect in the application.

Software and code design

Once a scope of work has been clearly defined through the requirements engineering process, the project team will create a thorough scope-of-work document that includes all of the user requirements captured by the customer. The next step is to design the application. A systems designer will create specifications for the software, establish specifications for the hardware it will run on and define the overall system architecture for the creation of the application.

Software designers sometimes put forward more than one proposed architecture for the application in a document known as a Design Document Specification (DDS). This document can be presented to stakeholders who would formally assess each plan based on time, budget and risk to determine how best to proceed.

Programming

In the programming stage of the software lifecycle, teams of software developers work together to write the application code by the specifications created during the design stage. Teams of programmers are not only responsible for writing code, but they may also be responsible for producing documentation, writing unit and functional test scripts for the code and ensuring that it is free from bugs.

The programming stage begins to introduce increased variability in how projects are delivered. Some projects are coded with a monolithic architecture and others are coded using a microservices architecture. Some development teams work in the agile paradigm and may code individual features of the application in condensed time blocks known as sprints. Others do all of the code development for the whole application at once during the programming stage.

Testing and integration

Once programming teams have completed all of the features or modules necessary for the application, the modules must be tested and integrated to create a stable version of the final product. The software can be tested in many different ways, but at the minimum, there should be:

• Unit testing - A unit test ensures that a single module or piece of code is functioning correctly. These are the simplest type of functional testing.
• Integration testing - Once all of the modules of an application have been integrated, integration testing is used to verify and validate their combined functionality.
• User acceptance testing (UAT) - UAT puts the application in front of clients and verifies that the end-to-end process flow of the application matches the business requirements set forth by the customer early in the software lifecycle.

A large application produced by separate development teams can face significant challenges in the integration stage. New working methods like continuous integration and continuous delivery are being used to reduce the time spent in the integration stage of the SDLC.

Documentation

Before the software application can be made available for users, developers may prepare some documentation to describe the functioning of the application and help users navigate the interface to take full advantage of its features. Project documentation can also include test scripts and APIs.

Deployment

When all errors have been detected and removed, the newly developed application can be deployed to a production environment and made available for users. An increasing number of organizations are choosing to deploy applications into public and hybrid cloud environments, taking advantage of the low IT infrastructure costs made possible by dedicated cloud service providers.

Operations and maintenance

Software development teams working in the DevOps paradigm may also be responsible for maintaining and operating the applications they build, including producing patches and updates, releasing new improvements and producing changes in response to user needs and requests. Application maintenance is the most costly portion of the software lifecycle, beginning once the software is deployed and continuing throughout the entire operational lifespan of the application.

Application developers are increasingly relying on cloud-based infrastructure and platforms to supply critical functionalities throughout the software lifecycle. Sumo Logic's cloud-native analytics platform is a natural addition to any cloud developer's tool suite.

With Sumo logic's log aggregation and security intelligence capabilities, developers can leverage operational and business insights that drive application performance and customer satisfaction while maintaining the security posture of public cloud environments.