What is the software development life cycle?
The software development life cycle, also known as SDLC or systems development life cycle, is a clearly defined and highly organised methodical process for developing and refining software.
The software development life cycle is generally described in the following seven stages, although there are multiple variations of the software development life cycle which combine some of the steps:
- Design and prototyping
- Operations and maintenance
How the Software Development Life Cycle Works
The software development life cycle works by providing a structured framework encompassing every task necessary for the development of software for development teams to follow.
This helps to reduce time and resource waste whilst ensuring that the project remains efficient and stays on track.
What is the importance of the software development life cycle?
The software development life cycle is key for building software and ensuring the quality and correctness of the software built. It also helps to provide a framework for a standard set of activities and deliverables.
If you are considering investing in an embedded software solution or mobile app that provides an exceptional user experience, then you will want to know the stages that are involved in building such a specialist product.
This article will outline the software development framework and cover a detailed plan for building, deploying and maintaining the software as well as some of the common models utilising the SDLC.
Can software be developed without the software development life cycle?
Deviating from an SDLC methodology can result in a product that doesn’t meet the needs of users or match the quality standards expected within the industry so developing software in this way without the SDLC is not advised.
However, in some cases such as if you’re developing a small project at home for your own use, a formal SDLC process is not always necessary, although your actions are still likely to informally follow an SDLC.
For professional, large projects, it’s far too risky to attempt software development without the SDLC and doing this would likely result in the ultimate failure of the project – wasting time, funds and resources.
The Five Software Development Life Cycle Stages
The five software development life cycle stages include planning and analysis, design and prototyping, coding and implementation, QA testing and integration and support and maintenance.
Below, we explore the aims of each stage, what is required and why each one is important.
Planning and Analysis
The first and most important stage of the SDLC is to gather all relevant information in regards to customer expectations, goals and objectives along with a detailed breakdown of what the customer wants to achieve long-term.
At this stage, the project manager will set up a meeting with you to discuss these requirements such as what the purpose of the product is and who will be the end-user. The project manager will also help you to identify any potential gaps in the market.
The meeting will also present a chance to discuss the opportunities and risks of pursuing the project. Clear structured documentation will help the development team to analyse the technical and economical aspects impacting the application development process. Involvement from the development team will help calculate the ROI and determine the overall project cost and timescale for completion.
Example: A customer requires an application that involves a tracking system to monitor and collect data. In this case, the stated requirements will need to be clear about what data the system will need to collect, how it will collect it and what the end results need to be.
Design and Prototyping
During the design phase, the conceptualisation of the solution is created. This determines whether the software architecture is meeting the specific project requirements.
Custom, tailored software design by software architects helps developers set definitive workflows and standards. This stage of the process will be built using the final prototype and mockups, to check the functionality and usability of the solution and potential software development tools that can be used for future development and processes to realise the business needs and objectives.
There are two types of design documents developed in the design and prototyping phase; high-level design and low-level design.
High-level design will include a brief description and an outline about the functionality of each module, interface relationship and dependencies, database tables and complete architecture diagrams.
Low-level design will assess the functional logic of the modules, database tables, complete detail of the interface, address all types of dependency issues, listing of error messages and inputs and outputs for each module.
Coding and Implementation
The implementation phase, also defined as the development and coding phase, is about writing code and converting all the design documentation into actual software, which is the most time-intensive part of the development process.
The newly built and tested application is then moved to the software testing and integration phase to deploy any immediate changes. The software engineering team has to make sure that the code meets all software requirements and specifications.
QA Testing and Integration
The software engineering team will then set out to deploy the software once complete into the testing environment. This is where the quality assurance testing team will set out and use a whole range of frameworks alongside unit testing to conduct a series of tests.
The software quality assurance testing phase is an engineering process that ensures quality with all tests carried out in a robust testing environment, allocating time accordingly to each process, prioritising bug fixes and selecting the release criteria carefully.
These tests include functionality testing, systems integration and user acceptance testing to ensure the code is clean and the business goals have been met. Once the system has been validated and is bug-free, the system will be ready for launch.
Support and Maintenance
During the final stages of the product development phase, there will be the opportunity for ongoing maintenance and support post-launch. Once the customer starts using the deployed system, any issues that may occur will be fixed. Maintenance support can be one of the following, including bug fixing, system upgrades or software enhancements.
There could be several reasons that a software system may need maintenance including improving the design features for better usability or implementing enhancements or accommodating new programs so that different hardware, software, system features and telecommunications facilities can be used.
Software Development Life Cycle Models
In the software industry, the most popular software development life cycle models are the:
- Waterfall SDLC model
- V-shaped SDLC model
- Iterative SDLC model
- Spiral SDLC model
- Big Bang SDLC model
- Agile SDLC model
- Scrum SDLC Model
- XP SDLC Model
- RAD SDLC Model
Learn more about the popular models below.
Waterfall SDLC Model
The waterfall model, also known as the linear-sequential life cycle model, is a sequential software development process in which the steps flow steadily downwards (like a cascading waterfall) through the various stages in the process.
The output of the first stage becomes the input for the subsequent phase, which is referred to as an incremental approach.
Lots of planning and documentation is involved in the waterfall model as every stage is mapped out in detail.
This model is primarily used by government, manufacturing and construction industries.
Although there are various modified waterfall models, the original waterfall model is said to have involved:
- System and software requirements
The waterfall SDLC is best suited for long-term projects such as those lasting longer than 12 months.
Waterfall SDLC Model Pros
- It involves lots of detailed planning, making it simple for each person in the team to understand what needs to be done and when.
- It also ensures that deadlines are realistic and can be met as every step has been planned meticulously.
- It’s easy to manage the tasks involved, especially for larger teams or projects.
Waterfall SDLC Model Cons
- Any mistakes or missed steps can become expensive and time-consuming to fix because the model is based on the idea that everything is completed in sequential order.
- It takes a while for working software to be produced – which can cause some initial concern amongst clients or stakeholders.
- It’s difficult to measure the team’s progress as working software isn’t available to look at until the later stages of the project.
- A deep understanding of customer requirements is needed so that development teams don’t waste time and resources building a product that users don’t want.
- This model isn’t suitable for smaller teams and development projects as too much time would be wasted on research in relation to the scale of the overall task.
V-Shaped SDLC Model
The v-shaped SDLC model, also known as the verification and validation model, is a sequential software development process in which the steps flow in a v-shape, down in a linear fashion and then bent up after the coding stage.
Like the waterfall model, the development team only works on one stage at a time before moving onto the next one in the sequence. However, the main difference between the waterfall model and the v-shaped model is that testing is included in every step.
The v-shaped model is primarily used in the medical device industry. Although there are various versions of the v-shaped model, the original version is said to have involved:
- Requirement analysis
- System design
- Architecture design
- Module design
- Unit testing
- Integration testing
- System testing
- User acceptance testing (UAT)
The v-shaped SDLC model is better suited to development teams working on large projects that also have a deep understanding of any in-house development processes and prioritise testing along the way.
V-Shaped SDLC Model Pros
- Like the waterfall model, the v-shaped SDLC model involves a detailed planning stage which makes it easier to meet deadlines as specific task instructions are outlined in the beginning.
- The focus remains on one task at a time – which means everything is more likely to be completed to a high standard due to a lack of distractions and avoidable disruptions.
- This model is well suited to large development teams.
V-Shaped SDLC Model Cons
- Unfortunately, mistakes or missed steps can become expensive and time-consuming to fix as the model is designed for each stage to be completed in sequence.
- Development teams require a deep understanding of the product and what users need as changes cannot be made once a stage is complete.
- Due to the nature of the model, end-users or clients may grow concerned by how long it takes to produce a working or tangible product.
- It is unsuitable for small teams working on small projects.
Iterative SDLC Model
The iterative SDLC model is a circular development model based on the concept of incremental development, which means that development initially focuses on an initial simplified version (MVP feature sets) and then progressively becomes more complex as the feature sets expand until the entire product is developed – requiring little initial planning in the early stages.
This process is called iterative incremental development because it is said to be completed through repeated cycles (iterative) of small portions (incremental) and includes the following steps:
- Initial planning
- Analysis and design
- Everything again..
- Everything again..
- Everything again until it’s ready…
Iterative SDLC Model Pros
- Planning is less thorough and time-consuming than in the waterfall and v-shaped model which can improve time and cost efficiencies.
- Small changes can be made to the product throughout the progression of development because of this.
- Clients and stakeholders can see working software immediately and will consistently see the improvements the development team makes which builds confidence.
- The team’s progress can be easily managed.
- More than one iteration can be worked on at the same time.
Iterative SDLC Model Cons
- Small changes can be made but any adaptations require a lot of additional management effort, which can decrease overall efficiencies.
- Because of the limited initial plans and documentation, there’s no clear idea of what exactly the final product should be like – the product may evolve into something entirely different to what was originally thought of.
- Architecture bugs and design faults may occur throughout the development process as a result of the lack of formal planning and documentation.
Spiral SDLC Model
The spiral model, also known as the meta-model, subsumes other SDLC models including the waterfall and iterative models and is known to be risk-averse because of the way the spiral model handles risks after software development projects have begun.
In the spiral model, software development is completed by repeatedly passing through phases of iteration called spirals, which are:
- Plan objectives or identify alternative solutions
- Perform risk analysis
- Develop and test next level of product
- Review, evaluate and plan the next phase
Similar to the iterative SDLC model, the spiral SDLC model allows testing at every stage of development. Feedback is also collected at every step so the product can adapt closely to any changes in the market’s needs.
Spiral SDLC Model Pros
- Any additional features and elements can be incorporated into the product throughout the development process and slight changes do not pose a significant inconvenience.
- Tasks can be broken down and prioritised based on the features the audience or end-users are most eager to see.
- Continual improvement can be achieved via the feedback collected from each deployment stage.
- Working software can be seen early on in the life cycle which demonstrates value to both end-users and clients.
Spiral SDLC Model Cons
The spiral SDLC model is definitely one of the more complex methodologies and strict management is required to prevent spirals from continuing indefinitely.
It is also unsuitable for smaller teams and can cause projects to become expensive as a result of all of the repeated testing and deployment stages.
Big Bang SDLC Model
The big bang model is an SDLC model that does not follow a specific set of processes or planning and is very high risk because it adopts a just-do-it approach without analysis or clear requirements.
There is no formal planning or extensive research involved and it is only really suitable for very small teams with very small projects.
Big Bang SDLC Model Pros
- It is the simplest model around, there’s zero planning involved which makes it perfect for small teams or ad hoc side projects, allowing high levels of flexibility.
Big Bang SDLC Model Cons
- It is incredibly high risk. With no plans or formal requirements in place, you can’t imagine what the end result will be like which makes it entirely unsuitable for large or complex projects with many stakeholders.
Agile SDLC Model
The agile SDLC model is a process in which development is completed in small, quick segments or increments. Essentially, it is a mix of interactive and incremental approaches focused on being flexible and adaptable.
The agile model is one of the most widely used models in the technology industry because it gives teams the flexibility of measuring progress regularly, adapting to changing production environments and needs of users, and receiving feedback in real-time by releasing working software and updated feature sets more frequently and getting feedback from the market.
The agile SDLC model is based on four central themes and 12 agile principles which are outlined in the 2001 Manifesto for Agile Software Development.
The four central themes of agile software development are:
- Individuals and interactions over processes and tools
- Working software over comprehensive documentation
- Customer collaboration over contract negotiation
- Responding to change over following a plan
The 12 Agile Principles are:
- Customer satisfaction is the highest priority
- Welcome requirement changes, even late in development
- Deliver working software frequently
- Business people and developers must collaborate daily
- Build projects around motivated individuals
- Face-to-face conversation is the most efficient and effective way to convey information within a development team
- Working software is the primary measure of progress
- Agile processes promote sustainable development
- Agility is enhanced by continuous attention to technical excellence and good design
- Simplicity – the art of maximising the amount of work not done – is essential
- The best architectures, requirements and designs come from self-organising teams
- The team reflects on how to become more effective then adjusts its behaviour accordingly at regular intervals
The agile model works like this:
- Brainstorm and requirements analysis
- Design documentation and prototyping
- Development iterations, demo and feedback
- Quality assurance, testing, iterations, demo and feedback
- Development, production and technical support
Agile SDLC Model Pros
- The product is constantly evolving with feedback, ensuring that it is always meeting the market’s most current requirements.
- Change is actively embraced and so strict, detailed, time-consuming paperwork is kept to an absolute minimum.
- It is best suited for smaller projects and ensures that every team member is always on the same page and kept up to speed as a result of frequent communication. Teams can work together much more efficiently because of this too.
Agile SDLC Model Cons
- There’s no clear idea of what the end product should look like as it’s constantly changing and evolving. Because of this, development teams need to be highly adaptable and skilled for the agile model to work well.
- It can be difficult to pin down a solid finish date because of the constant change and lack of rigid documentation. This can become a concern for clients or stakeholders.
Scrum SDLC Model
The Scrum SDLC model is a subset of the agile SDLC model and adheres to the same principles.
The scrum SDLC model works by splitting development up into 2-4 week-long sprints that the team spends working solely on developing working software.
At the end of each sprint, the software the team works on is deployed so that consumer feedback can be obtained.
The three main roles involved in the scrum model are Product Owner, Scrum Master and Scrum Team.
The Product Owner is responsible for communicating with stakeholders and creating the product backlog which lists every feature the development team needs to create.
The Scrum Master is responsible for breaking the features in the product backlog down into smaller tasks to be completed in each sprint to create the scrum backlog – each task is called a user story.
The Scrum Team is responsible for the development of the actual product – each member is required to be committed, highly experienced and responsible for their own tasks. The Scrum Team comes together to communicate at short daily meetings so that everyone can be updated on progress and any challenges that arise can be discussed and overcome.
After every sprint, the entire team holds a scrum review meeting where previous work is discussed and opportunities for improvement are identified.
The scrum SDLC model works best within small teams of 10 or less so that communication can remain efficient yet concise.
Scrum SDLC Model Pros
- It allows for great flexibility, teams can adapt easily to change whilst still maintaining strict processes.
- Team members are held highly accountable and everyone is responsible for producing high-quality work.
- The daily meetings required foster clear and effective communication which aids overall efficiency.
Scrum SDLC Model Cons
- As a subset of the agile methodology, it doesn’t allow you to have a clear idea of what the final product will look like.
- It’s unsuitable for teams that aren’t experienced or flexible enough to react quickly to changes and pick up new skills/technologies efficiently.
- It can be difficult to make precise time or cost estimates as the product is constantly adapting.
XP (Extreme Programming) SDLC Model
The extreme programming SDLC model is a subset of the agile SDLC model but is based on these five components:
- Simplicity: development teams should approach features and functionality in the simplest way possible (not unlike the MVP stage in startup development)
- Team communication: daily face-to-face communication is crucial
- Feedback: user feedback is collated, assessed and acted on continuously
- Courage: development teams need to be courageous enough to accept and roll with new changes when they occur
- Respect: each member of the development team needs to have respect for each other and form a strong enough bond that each person is more dedicated to the development of the most successful product possible than the last
The XP SDLC model is best suited for highly experienced, small teams of no more than 10 where client specifications are scarce.
XP SDLC Model Pros
- Working software is constantly being deployed which pleases both users and clients.
- Changes, adjustments and adaptations are actively encouraged and embraced. The cost of making these changes is also much lower in comparison to the waterfall SDLC model.
XP SDLC Model Cons
- It requires an experienced, adaptable development team to produce good results.
- The lack of formal documentation means that not only is there no clear idea of what the end product should be like, but that frequent communication is absolutely vital.
RAD (Rapid Application Development) SDLC Model
The Rapid Application Development SDLC model is quite similar to the iterative SDLC model and is made up of different iterations that are referred to as prototypes – each one forming a different function of the overall product.
Each prototype is deployed individually, meaning feedback on each one can be collected throughout the development process.
As well as this, each prototype can be reused on future projects, saving time, money and resources.
Like the agile SDLC model, the RAD SDLC model encourages development teams to embrace change and limits lengthy documentation requirements.
The five phases of the RAD SDLC are:
- Business modelling
- Data modelling
- Process modelling
Each prototype must go through all five phases.
RAD SDLC Model Pros
- Each prototype is reusable which is incredibly cost and time-efficient.
- The constant delivery of prototypes keeps customers engaged and satisfied with the value of the software.
- Development teams can stay in tune with the market because of the feedback collected after each prototype release.
- It is best suited to teams of around eight or less and allows the team’s overall progress to easily be monitored.
RAD SDLC Model Cons
- Development teams must be committed to the product and highly skilled to complete the constant changes.
- It only applies to projects that can be split up into separate prototypes.
What type of approach is best for your project?
In short, the software development life cycle is a structured process that can vary from company to company aiming to deliver the best quality products. It can be shaped or adjusted to the needs of the customer or according to the needs of the project that is being worked on.
It is a foundational model used to arrange a framework and equip every team member engaged in technical and non-technical activities. Other benefits of the software lifecycle processes are that it provides visibility for all those involved in the project, eliminates risks like going over budget and provides a realistic outline of deliverables. Find out more about our software development services.