- SDLC Tutorial
- SDLC or the Software Development Life Cycle is a process that produces software with the highest quality and lowest cost in the shortest time possible. SDLC provides a well-structured flow of phases that help an organization to quickly produce high-quality software which is well-tested and ready for production use.
- The SDLC process provides Information Technology (IT) project managers with the tools to help ensure successful implementation of systems or applications that satisfy strategic and business objectives. SDLC documentation provides a mechanism to ensure that executive leadership, functional managers.
Systems Development Life Cycle Checklists The System Development Life Cycle (SDLC) process applies to information system development projects ensuring that all functional and user requirements and agency strategic goals and objectives are met. The SDLC provides a structured and standardized process for all phases of any system development effort.
- SDLC Useful Resources
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Software Development Life Cycle (SDLC) is a process used by the software industry to design, develop and test high quality softwares. The SDLC aims to produce a high-quality software that meets or exceeds customer expectations, reaches completion within times and cost estimates.
SDLC is the acronym of Software Development Life Cycle.
It is also called as Software Development Process.
SDLC is a framework defining tasks performed at each step in the software development process.
ISO/IEC 12207 is an international standard for software life-cycle processes. It aims to be the standard that defines all the tasks required for developing and maintaining software.
What is SDLC?
SDLC is a process followed for a software project, within a software organization. It consists of a detailed plan describing how to develop, maintain, replace and alter or enhance specific software. The life cycle defines a methodology for improving the quality of software and the overall development process.
The following figure is a graphical representation of the various stages of a typical SDLC.
A typical Software Development Life Cycle consists of the following stages −
Stage 1: Planning and Requirement Analysis
Requirement analysis is the most important and fundamental stage in SDLC. It is performed by the senior members of the team with inputs from the customer, the sales department, market surveys and domain experts in the industry. This information is then used to plan the basic project approach and to conduct product feasibility study in the economical, operational and technical areas.
Planning for the quality assurance requirements and identification of the risks associated with the project is also done in the planning stage. The outcome of the technical feasibility study is to define the various technical approaches that can be followed to implement the project successfully with minimum risks.
Stage 2: Defining Requirements
Once the requirement analysis is done the next step is to clearly define and document the product requirements and get them approved from the customer or the market analysts. This is done through an SRS (Software Requirement Specification) document which consists of all the product requirements to be designed and developed during the project life cycle.
Stage 3: Designing the Product Architecture
SRS is the reference for product architects to come out with the best architecture for the product to be developed. Based on the requirements specified in SRS, usually more than one design approach for the product architecture is proposed and documented in a DDS - Design Document Specification.
This DDS is reviewed by all the important stakeholders and based on various parameters as risk assessment, product robustness, design modularity, budget and time constraints, the best design approach is selected for the product.
A design approach clearly defines all the architectural modules of the product along with its communication and data flow representation with the external and third party modules (if any). The internal design of all the modules of the proposed architecture should be clearly defined with the minutest of the details in DDS.
Stage 4: Building or Developing the Product
In this stage of SDLC the actual development starts and the product is built. The programming code is generated as per DDS during this stage. If the design is performed in a detailed and organized manner, code generation can be accomplished without much hassle.
Developers must follow the coding guidelines defined by their organization and programming tools like compilers, interpreters, debuggers, etc. are used to generate the code. Different high level programming languages such as C, C++, Pascal, Java and PHP are used for coding. The programming language is chosen with respect to the type of software being developed.
Stage 5: Testing the Product
This stage is usually a subset of all the stages as in the modern SDLC models, the testing activities are mostly involved in all the stages of SDLC. However, this stage refers to the testing only stage of the product where product defects are reported, tracked, fixed and retested, until the product reaches the quality standards defined in the SRS.
Stage 6: Deployment in the Market and Maintenance
Once the product is tested and ready to be deployed it is released formally in the appropriate market. Sometimes product deployment happens in stages as per the business strategy of that organization. The product may first be released in a limited segment and tested in the real business environment (UAT- User acceptance testing).
Then based on the feedback, the product may be released as it is or with suggested enhancements in the targeting market segment. After the product is released in the market, its maintenance is done for the existing customer base.
SDLC Models
There are various software development life cycle models defined and designed which are followed during the software development process. These models are also referred as Software Development Process Models'. Each process model follows a Series of steps unique to its type to ensure success in the process of software development.
Following are the most important and popular SDLC models followed in the industry −
- Waterfall Model
- Iterative Model
- Spiral Model
- V-Model
- Big Bang Model
Other related methodologies are Agile Model, RAD Model, Rapid Application Development and Prototyping Models.
The Software Development Life Cycle (SDLC) is a terminology used to explain how software is delivered to a customer in a series if steps. These steps take software from the ideation phase to delivery.
We’ve broken down everything you need understand the SDLC from a high level, including:
History of the SDLC
The profession of “software developer” has existed since the first computers, and their operators, as far back as the days of ENIAC and vacuum tubes. Practices and methods for developing software have evolved over the decades since the invention of the computer.
Those methods have adapted to the state of the art in computer hardware, development tools, and modern thinking about the organizational management of software development teams. With this progress, new methods of software development have grown out of private and public software development efforts around the world.
These methods vary widely in approach, yet they share a common goal: to develop software as cheaply, efficiently, and effectively as possible.
What is the SDLC?
Software is a complex product that is developed and delivered through a series of steps. That is the one thing all the various methods have in common: one way or another, software, like all products, starts as an idea. The idea then becomes a document, or perhaps a prototype, depending on the method in use.
Whether a document, diagram, or working software, the artifact created in one step becomes the input to the next step. Eventually, the software is delivered to the customer. The sequence of steps used by these methods is commonly referred to as the Software Development Lifecycle (SDLC.)
How does the SDLC work?
The process of software development is a never-ending cycle. The first release of a software application is rarely “finished.” There are almost always additional features and bug fixes waiting to be designed, developed, and deployed.
Reports from error monitoring software about usability and bugs feed back into the process of software development, and become new feature requests and improvements to existing features. This is why the Software Development Life Cycle is the most general term for software development methods. The steps of the process and their order vary by method. Regardless of method, they typically run in cycles, starting over with each iteration.
Benefits of the SDLC
“If you fail to plan, you are planning to fail” - Benjamin Franklin
It’s very difficult to carry out a complex, team effort such as software development without some kind of plan. Each software development methodology (several will be detailed below) is a plan framework for how to develop software. There is much debate about which method is best overall, which is best suited to a particular type of software, and how to measure success in software development. One thing, however, is certain: any plan is better than no plan.
Without some kind of structured plan, software development teams tend to devolve into a “herd of cats.” Developers don’t know what they’re supposed to create. Project managers have no idea how much progress is made towards completion of a project. Without a plan, the business doesn’t even have a way to decide whether the final product meets their requirements.
A formally defined method for software development in the form of the SDLC achieves a number of benefits:
- A common vocabulary for each step
- Defined communication channels between development teams and stakeholders
- Clear roles and responsibilities among developers, designers, business analysts, and project managers
- Clearly-defined inputs and outputs from one step to the next
- A deterministic “definition of done” that can be used to confirm whether a step is truly complete
The Seven Phases of the SDLC
These steps are (very) roughly the same from one methodology to another. They tend to occur in this order, though they can also be mixed together, such that several steps occur in parallel.
As we’ll discuss later, Agile methods tend to “wind together” all of these steps into a tight, rapidly-repeating cycle. Waterfall methods tend to take each of these steps in turn. Outputs from one become inputs to the following step.
1. Planning
The planning phase involves aspects of project and product management. This may include:
- Resource allocation (both human and materials)
- Capacity planning
- Project scheduling
- Cost estimation
- Provisioning
The outputs of the planning phase include: project plans, schedules, cost estimations, and procurement requirements. Ideally, Project Managers and Development staff collaborate with Operations and Security teams to ensure all perspectives are represented.
2. Requirements
The business must communicate with IT teams to convey their requirements for new development and enhancement. The requirements phase gathers these requirements from business stakeholders and Subject Matter Experts (SMEs.)
Architects, Development teams, and Product Managers work with the SMEs to document the business processes that need to be automated through software. The output of this phase in a Waterfall project is usually a document that lists these requirements. Agile methods, by contrast, may produce a backlog of tasks to be performed.
3. Design and prototyping
Once the requirements are understood, software architects and developers can begin to design the software. The design process uses established patterns for application architecture and software development. Architects may use an architecture framework such as TOGAF to compose an application from existing components, promoting reuse and standardization.
Developers use proven Design Patterns to solve algorithmic problems in a consistent way. This phase may also include some rapid prototyping, also known as a spike, to compare solutions to find the best fit. The output of this phase includes:
- Design documents that list the patterns and components selected for the project
- Code produced by spikes, used as a starting point for development
4. Software development
This phase produces the software under development. Depending on the methodology, this phase may be conducted in time-boxed “sprints,” (Agile) or may proceed as a single block of effort (Waterfall.) Regardless of methodology, development teams should produce working software as quickly as possible. Business stakeholders should be engaged regularly, to ensure that their expectations are being met. The output of this phase is testable, functional software.
5. Testing
The testing phase of the SDLC is arguably one of the most important. It is impossible to deliver quality software without testing. There is a wide variety of testing necessary to measure quality:
- Code quality
- Unit testing (functional tests)
- Integration testing
- Performance testing
- Security testing
The best way to ensure that tests are run regularly, and never skipped for expediency, is to automate them. Tests can be automated using Continuous Integration tools, like Codeship, for example. The output of the testing phase is functional software, ready for deployment to a production environment.
6. Deployment
The deployment phase is, ideally, a highly automated phase. In high-maturity enterprises, this phase is almost invisible; software is deployed the instant it is ready. Enterprises with lower maturity, or in some highly regulated industries, the process involves some manual approvals. However, even in those cases it is best for the deployment itself to be fully automated in a continuous deployment model. Application Release Automation (ARA) tools are used in medium and large-size enterprises to automate the deployment of applications to Production environments. ARA systems are usually integrated with Continuous Integration tools. The output of this phase is the release to Production of working software.
7. Operations and maintenance
The operations and maintenance phase is the “end of the beginning,” so to speak. The Software Development Life Cycle doesn’t end here. Software must be monitored constantly to ensure proper operation. Bugs and defects discovered in Production must be reported and responded to, which often feeds work back into the process. Bug fixes may not flow through the entire cycle, however, at least an abbreviated process is necessary to ensure that the fix does not introduce other problems (known as a regression.)
Software Development Life Cycle infographic
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