What is system development life cycle?The system development life cycle is a project management model that defines the stages involved in bringing a project from inception to completion. Software development teams, for example, deploy a variety of systems development life cycle models that include waterfall, spiral and agile processes. Show
What are system development life cycle stages?Systems development life cycle phases include planning, system analysis, system design, development, implementation, integration and testing, and operations and maintenance. What is system development life cycle iteration?Iteration is what is system development life cycle’s greatest advantage, enabling faster development of systems by moving ahead with development without requiring full specifications upfront. Additional specifications can be introduced as the development process is repeated, producing new versions of the system at the end of each iteration. What is system development life cycle security?Security is critical when the intent of the system development life cycle is to produce software applications. Software is the most-attacked part of the security perimeter, and more than half of all successful security breaches begin with an attack on an application. What is system development life cycle testing?Testing is required during the system development life cycle to ensure that applications are free of flaws and vulnerabilities. Ideally, testing should happen at every stage of the SDLC, but because it adds unacceptable delay to development processes, it is often given short shrift or postponed until the later stages of the life cycle. What is a system development life cycle testing provider?A security testing provider offers tools that enable developers to perform tests on applications and development and production. As one of the industry’s leading providers of application security testing solutions, Veracode offers a cloud-based subscription service that makes it easy for developers to embed security into all stages of the system development life cycle. With Veracode, developers can find and fix flaws at the most cost-efficient point in the development process and produce more secure software with every release. Learn more about “What is system development life cycle?”, about what is an application and Veracode solutions for secure devops. Jumping into software development without a pre-defined plan is a recipe for overbudgeting, delays, and costly failures. Instead of rushing into a project, more and more companies are turning to SDLC strategies that enable them to ship high-quality software as quickly, safely, and cost-effectively as possible. This article goes through everything a company needs to know to adopt SDLC-based software development. We explain how SDLC strategies work, dive deep into each typical phase of a product's life cycle, and present the market's most reliable SDLC methodologies. An SDLC (software development life cycle) is a big-picture breakdown of all the steps involved in software creation (planning, coding, testing, deploying, etc.). Companies define custom SDLCs to create a predictable, iterative framework that guides the team through all major stages of development. The character and the exact number of phases in an SDLC vary between businesses and projects. The most common models are variations on the following steps:
An SDLC strategy enables a business to set a tried-and-tested foundation for every software-related project. Teams develop high-quality products with more speed and consistency while the company maximizes its ROI by boosting its ability to:
SDLC models are the basis of every DevOps pipeline. If you are considering a transition to DevOps, ensure the team has a firm grasp of SDLC strategies before you introduce radical workflow changes. How SDLC WorksAn SDLC outlines each stage of software development, breaking down the process into separate phases that have individual:
The exact number and nature of steps depend on the business and its product goals. On average, most companies define SDLCs with five to seven phases, although more complex projects reach ten or more stages. Each step in an SDLC results in an output (document, diagram, working software, etc.) that acts as the necessary input for the next step. Despite this funnel-like approach, modern SDLC strategies are not strictly linear. The team often goes back a step or two in the SDLC to perform fixes or make improvements. A product's SDLC must be a living process that the team regularly updates (or at least reviews). Keeping an SDLC up to date takes a combined effort of business analysts, developers, QA staff members, and stakeholders. SDLC strategies have been around since the 1960s, and most of its core concepts have evolved over time. The most significant change occurred in the testing phase. Whereas testing is traditionally a separate SDLC stage, teams nowadays prefer integrating security activities throughout the life cycle to create more reliable software that's secure by design. Ensuring every phase of the SDLC accounts for security is vital, but do not overlook the value of a dedicated testing phase. There's no reason not to have a separate stage for in-depth testing even if other SDLC steps have some built-in security analysis. SDLC PhasesWhile every SDLC is unique, all life cycles go through similar steps. Let's take a close look at every typical phase of an average software development life cycle. Requirements AnalysisThe first step of any SDLC is to define the project's requirements. Some critical questions during this stage are:
This stage requires a combined effort of business analytics, operations, leadership, development, and security teams. In some use cases, asking end users for input is also a valuable source of info. All the data gathered in this stage goes into a Software Requirement Specification (SRS) document. An SRS file includes all the software, hardware, security, and network specifications for the upcoming product, but the file also contains info concerning:
The output of this step: An SRS document that defines project goals and scope, plus provides product requirements and rough project estimations (budget, resources, deadlines, etc.). Feasibility StudySenior business analysts perform a feasibility study to determine the software's viability. The usual approach is to focus primarily on these five factors:
Analysts add the findings of this phase to the existing SRS document, after which a team of decision-makers reviews the report to approve:
The higher management either signs off on the project or asks the team to go back a step in the SDLC and come up with a new suggestion. The output of this step: An expanded SRS document approved by higher management. Design PlanOnce there is an approved project direction, the team starts creating a design plan that explains all major aspects of the new product, including its:
The team gathers this info in the Design Document Specification (DDS). A stakeholder reviews the DDS and approves a direction based on the following factors:
Some companies decide to create a prototype during this SDLC stage. While time-consuming, prototyping is much less expensive than making radical changes after the development phase. The output of this step: A detailed DDS that lists all the info developers require to code the product. Software DevelopmentThe development team gets familiar with the DDS and starts working on the code. Typically, this step is the most time-consuming phase of SDLC, so we recommend using agile methodologies to speed up coding. This phase results in operational software that meets all the requirements listed in the SRS and DDS. While the code still awaits advanced testing, the team should already put the product through basic tests (such as static code analysis and code reviews for multiple device types). The output of this step: Source code of a testable, fully functional software. In-Depth Software TestingThe software that comes out of the previous SDLC phase now goes through extensive testing. Companies have a wide variety of testing methods to evaluate the new product, such as:
Most teams rely on automated tests to speed up this phase, but some manual examinations are also valuable (penetration tests are a good example). If the team discovers a defect, the code goes back a step in its life cycle, and developers create a new, flaw-free version of the software. The testing stage ends when the product is stable, free of bugs, and up to quality standards defined in the previous phases. The output of this step: A thoroughly tested version of the product ready for a production environment. Software DeploymentThe product leaves the testing phase and is ready to go into production. Some projects require the team to write user manuals or create instructional videos before the software becomes available to end users. Ideally, the deployment phase happens automatically (typically as a part of CI/CD). Companies with lower maturity or in some highly regulated industries may require manual approvals during this SDLC stage. Most companies deploy new software to a small percentage of users (10 to 15%) and slowly phase it into the rest of the customer base. Gradual introduction means you limit the impact on the UX if there's an overlooked issue with the product. The output of this step: A fully functional and tested product that's available to end users. Product Maintenance and EnhancementEvery shipped piece of software requires periodic reviews and updates based on user feedback. The most common activities during this stage are:
Whenever a user reports a bug or the team discovers a new flaw, the product moves back through its SDLC as many steps as necessary. Some severe defects require updates in the design stage, while most problems take the app back to the development stage. The output of this step: A fully monitored product that continuously sees improvements. Other less common SDLC phases that are still worth knowing are dedicated steps for deconstructing apps, retiring software, and writing documentation. SDLC MethodologiesDifferent SDLC methodologies (or models) prioritize different aspects of product creation and measure success in unique ways. Let's look at the most popular SDLC methodologies you can adopt at your company. WaterfallThe waterfall is the oldest and the most straightforward SDLC model on the market. This strategy (also known as the linear sequential model) takes a product through a one-way funnel with the following steps:
Waterfall phases run sequentially, and every stage depends directly on the outcome of the previous phase (i.e., each step "waterfalls" into the next one). In a true waterfall model, the team never goes back a step after finishing a phase, so the model's success rests on the team's ability to avoid mistakes. Pros of this model:
Cons of this model:
V-Shaped ModelThe V-shaped model (also known as the Verification and Validation Model) requires the team to run coding and testing tasks in parallel.
Each verification phase has an assigned validation stage, which makes the model's diagram appear as the letter V (the base of the V is the coding phase). The verification phase consists of the following steps:
The validation stage has the following steps:
A true V-shaped model does not have a dedicated testing phase since each development stage has its own QA sequence. Pros of this model:
Cons of this model:
Prototype ModelThe prototype model requires the team to create a working product prototype during the traditional design phase. When compared to the end-result software, a prototype has the following traits:
Companies opt for this model to get valuable early feedback from customers. Users offer input on the prototype, developers implement the requested changes, and the team creates a better version of the prototype. This process goes on until customers have no more negative feedback, after which the team gets a customer-driven requirements analysis and starts developing the final product. Pros of this model:
Cons of this model:
Spiral ModelThe spiral model is a risk-driven SDLC strategy. This model emphasizes the repetition of its four core stages:
The idea is to go through these stages repeatedly while making gradual improvements at each pass. The team continuously analyzes needs and makes prototypes while going through the same four-step cycle. Pros of the model:
Cons of the model:
Iterative Incremental ModelThe iterative incremental model requires the team to quickly deploy an incomplete version of the software at the end of each development cycle. The first iteration is a far-from-perfect product that meets a small set of software requirements, and every subsequently deployed version expands the product with more functionality. Each iteration goes through the following phases:
Each iteration goes through verification and requires either user or stakeholder feedback. The last iteration deploys a product version that went through rigorous testing and meets all the requirements specified in the DDS. Unlike the spiral SDLC methodology (which is similar in concept), the iterative incremental model deploys each software version to production. Pros of this model:
Cons of this model:
Agile ModelThe agile methodology relies on ongoing release cycles that make small, incremental changes to the previous release. Builds evolve as teams add new features and improvements with each deployment. The agile model requires the team to work in sprints that last for 2 to 4 weeks, each with unique requirements and goals. At the end of a sprint, the product owner verifies the code and greenlights its deployment to users. The team then gathers feedback and starts preparing for the next sprint. Unlike the iterative incremental model, an agile SDLC does not rush the team to deploy the product to customers. Instead, the emphasis is on finding the balance between quality and speed. The agile approach requires the team to perform testing at the end of each sprint to ensure no potential exploits end up in production. Pros of this model:
Cons of this model:
Big Bang ModelThe big bang model is a high-risk SDLC type that throws most of its resources at development without requiring an in-depth analysis at the start of the cycle. A big bang starts with little planning and quickly moves to the coding stage. In many cases, developers are the only ones responsible for figuring out requirements, writing code, and checking the validity of a finished product. Pros of this model:
Cons of this model:
Remember that you do not have to pick only one of the models discussed above—many companies benefit from combining two or more SDLC methodologies into a unique hybrid model that fits their specific use case. Benefits of SDLCA well-defined software development life cycle that fits business needs leads to various benefits, including:
Adopting an SDLC strategy also lowers your team's technical debt since developers take little to no shortcuts during software creation. SDLC Best PracticesBelow is a look at a few best practices you should consider when adopting SDCL at your company:
SDLC Frequently Asked QuestionsLooking for a few more quick takeaways? Let's answer the most frequently asked questions concerning SDLC. Why is SDLC Important?An SDLC outlines a detailed, step-by-step plan for software development. The practice speeds up decision-making during product creation and minimizes risks while keeping all teams (and stakeholders) on the same page. What Is the Secure SDLC (Software Development Life Cycle)?Secure SDLC (or SSDLC) is a software life cycle with fully integrated security checks at every phase. Teams start thinking about security risks and measures during the first stage of the SDLC. SDLC vs. AgileAn SDLC is a conceptual outline of the software creation process, while Agile is a project management methodology that focuses on a cyclical, iterative progression while building software. SDLC vs. DevOpsDevOps is a set of practices and philosophies that combines software development and IT operations. This practice takes SDLC concepts to the next level by introducing high levels of automation and focusing on smaller software releases. SDLC vs. STLCAn SDLC defines a sequence of activities during software creation, whereas STLC (Software Testing Life Cycle) refers to a step-by-step list of activities required for reliable software testing. SDLC vs. CI/CDCI/CD (Continuous Integration and Continuous Delivery) is a set of practices and methods that speed up software delivery by introducing automation into an SDLC. CI/CD is an enhancement to your SDLC, not a potential replacement. The De-Facto Method of Creating Modern SoftwareCompanies are under more pressure than ever to deliver high-quality products in often unrealistically short time frames. In such a market, approaching software creation in any way that does not involve a pre-defined SDLC is not a business-wise move. Start building your development around a strict life cycle and stay a step ahead of competitors still relying on an old-school approach to product design. Andreja Velimirovic Andreja is a content specialist with over half a decade of experience in putting pen to digital paper. Fueled by a passion for cutting-edge IT, he found a home at phoenixNAP where he gets to dissect complex tech topics and break them down into practical, easy-to-digest articles. |