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. Software Development Life Cycle (SDLC) is the series of stages that software must undergo from its conceptualization (inception) to running smoothly. Two models of SDLC are popular - Waterfall and Agile.
Streamlined development relies on a consistent methodology and a clearly-defined process from getting from point A to point B. If you’re just getting your feet wet in the wide world of development, you need to understand the Software Development Life Cycle or SDLC.
Definition of SDLC
SDLC or the Software Development Life Cycle is a process that produces software with the highest quality and lowest cost in the shortest time. SDLC includes a detailed plan for how to develop, alter, maintain, and replace a software system.
SDLC involves several distinct stages, including planning, design, building, testing, and deployment. Popular SDLC models include the waterfall model, spiral model, and Agile model.
How SDLC Works
SDLC works by lowering the cost of software development while simultaneously improving quality and shortening production time. SDLC achieves these apparently divergent goals by following a plan that removes the typical pitfalls to software development projects. That plan starts by evaluating existing systems for deficiencies. Next, it defines the requirements of the new system. It then creates the software through the stages of design, development, testing, and deployment. By anticipating costly mistakes like failing to ask the end user for suggestions, SLDC can eliminate redundant rework and after-the-fact fixes. Dhirubhai ambani book in gujarati pdf.
Stages and Best Practices of SDLC
Following the best practices and/or stages of SDLC ensures the process works in a smooth, efficient, and productive way.
- Identify the current problems. “What don’t we want?” This stage of SDLC means getting input from all stakeholders, including customers, salespeople, industry experts, and programmers. Learn the strengths and weaknesses of the current system with improvement as the goal.
- Plan. “What do we want?” In this stage of SDLC, the team defines the requirements of the new software and determines the cost and resources required. It also details the risks involved and provides sub-plans for softening those risks. In this stage, a Software Requirement Specification document is created.
- Design. “How will we get what we want?” This phase of SDLC starts by turning the software specifications into a design plan called the Design Specification. All stakeholders then review this plan and offer feedback and suggestions. It’s crucial to have a plan for collecting and incorporating stakeholder input into this document. Failure at this stage will almost certainly result in cost overruns at best and total collapse of the project at worst.
- Build. “Let’s create what we want.” This SDLC stage develops the software by generating all the actual code. If the previous steps have been followed with attention to detail, this is actually the least complicated step.
- Test. “Did we get what we want?” In this stage, we test for defects and deficiencies. We fix those issues until the product meets the original specifications.
- Deploy. “Let’s start using what we got.” Often, this part of the SDLC process happens in a limited way at first. Depending on feedback from end users, more adjustments can be made.
- Maintain. “Let’s get this closer to what we want.” The plan almost never turns out perfect when it meets reality. Further, as conditions in the real world change, we need to update and advance the software to match.
The DevOps movement has changed the SDLC in some ways. 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. APM tools can be used in development, QA, and production. This keeps everyone using the same toolset across the entire development lifecycle.
Read More: 3 Reasons Why APM Usage is Shifting Left to Development & QA
Examples of SDLC in Action
The most common SDLC examples or SDLC models are listed below.
- Waterfall Model. This SDLC model is the oldest and most straightforward. With this methodology, we finish one phase and then start the next. Each phase has its own mini-plan and each phase “waterfalls” into the next. The biggest drawback of this model is that small details left incomplete can hold up the entire process.
- Agile Model. The Agile SDLC model separates the product into cycles and delivers a working product very quickly. This methodology produces a succession of releases. Testing of each release feeds back info that’s incorporated into the next version. According to Robert Half, the drawback of this model is that the heavy emphasis on customer interaction can lead the project in the wrong direction in some cases.
- Iterative Model. This SDLC model emphasizes repetition. Developers create a version very quickly and for relatively little cost, then test and improve it through rapid and successive versions. One big disadvantage here is that it can eat up resources fast if left unchecked.
- V-Shaped Model. An extension of the waterfall model, this SDLC methodology tests at each stage of development. As with waterfall, this process can run into roadblocks.
- Big Bang Model. This high-risk SDLC model throws most of its resources at development and works best for small projects. It lacks the thorough requirements definition stage of the other methods.
- Spiral Model. The most flexible of the SDLC models, the spiral model is similar to the iterative model in its emphasis on repetition. The spiral model goes through the planning, design, build and test phases over and over, with gradual improvements at each pass.
Benefits of SDLC
SDLC done right can allow the highest level of management control and documentation. Developers understand what they should build and why. All parties agree on the goal up front and see a clear plan for arriving at that goal. Everyone understands the costs and resources required.
Several pitfalls can turn an SDLC implementation into more of a roadblock to development than a tool that helps us. Failure to take into account the needs of customers and all users and stakeholders can result in a poor understanding of the system requirements at the outset. The benefits of SDLC only exist if the plan is followed faithfully.
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One of the basic notions of the software development process is SDLC models which stands for Software Development Life Cycle models. SDLC – is a continuous process, which starts from the moment, when it’s made a decision to launch the project, and it ends at the moment of its full remove from the exploitation. There is no one single SDLC model. They are divided into main groups, each with its features and weaknesses.
Evolving from the first and oldest “waterfall” SDLC model, their variety significantly expanded. 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. Let’s explore those stages as this is important for the understanding of the each of SDLC models and the differences between them.
BASIC STAGES OF SOFTWARE DEVELOPMENT LIFE CYCLE
Stage 1. Planning and requirement analysis
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.
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.
Stage 2. Designing project architecture
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.
System Development Life Cycle Models
Stage 3. Development and programming
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 programming by itself assumes four stages
- Algorithm development
- Source code writing
- Compilation
- Testing and debugging
Stage 4. Testing
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.
Stage 5. Deployment
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.
SDLC MODELS
Waterfall SDLC Model
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. This process is strictly documented and predefined with features expected to every phase of this software development life cycle model.
ADVANTAGES | DISADVANTAGES |
---|---|
Simple to use and understand | The software is ready only after the last stage is over |
Management simplicity thanks to its rigidity: every phase has a defined result and process review | High risks and uncertainty |
Development stages go one by one | Not the best choice for complex and object-oriented projects |
Perfect for the small or mid-sized projects where requirements are clear and not equivocal | Inappropriate for the long-term projects |
Easy to determine the key points in the development cycle | The progress of the stage is hard to measure while it is still in the development |
Easy to classify and prioritize tasks | Integration is done at the very end, which does not give the option of identifying the problem in advance |
Use cases for the Waterfall SDLC model:
- The requirements are precisely documented
- Product definition is stable
- The technologies stack is predefined which makes it not dynamic
- No ambiguous requirements
- The project is short
Iterative SDLC Model
The Iterative SDLC model does not need the full list of requirements before the project starts. The development process may start with the requirements to the functional part, which can be expanded later. The process is repetitive, allowing to make new versions of the product for every cycle. Every iteration (which last from two to six weeks) includes the development of a separate component of the system, and after that, this component is added to the functional developed earlier. Speaking with math terminology, the iterative model is a realization of the sequential approximation method; that means a gradual closeness to the planned final product shape.
ADVANTAGES | DISADVANTAGES |
---|---|
Some functions can be quickly developed at the beginning of the development lifecycle | Iterative model requires more resources than the waterfall model |
The paralleled development can be applied | Constant management is required |
The progress is easy measurable | Issues with architecture or design may occur because not all the requirements are foreseen during the short planning stage |
The shorter iteration is - the easier testing and debugging stages are | Bad choice for the small projects |
It is easier to control the risks as high-risk tasks are completed first | The process is difficult to manage |
Problems and risks defined within one iteration can be prevented in the next sprints | The risks may not be completely determined even at the final stage of the project |
Flexibility and readiness to the changes in the requirements | Risks analysis requires involvement of the highly-qualified specialists |
Use cases for the Iteration model:
- The requirements to the final product are strictly predefined
- Applied to the large-scale projects
- The main task is predefined, but the details may advance with the time
Spiral SDLC Model
Spiral model – is SDLC model, which combines architecture and prototyping by stages. It is a combination of the Iterative and Waterfall SDLC models with the significant accent on the risk analysis. The main issue of the spiral model – is defining the right moment to make a step into the next stage. The preliminary set time frames are recommended as the solution to this issue. The shift to the next stage is done according to the plan, even if the work on the previous stage isn’t done yet. The plan is introduced basing on the statistic data, received during the previous projects even from the personal developer’s experience.
ADVANTAGES | DISADVANTAGES |
---|---|
Lifecycle is divided into small parts, and if the risk concentration is higher, the phase can be finished earlier to address the treats | Can be quite expensive |
The development process is precisely documented yet scalable to the changes | The risk control demands involvement of the highly-skilled professionals |
The scalability allows to make changes and add new functionality even at the relatively late stages | Can be ineffective for the small projects |
The earlier working prototype is done - sooner users can point out the flaws | Big number of the intermediate stages requires excessive documentation |
Use cases for the Spiral model
- Customer isn’t sure about the requirements
- Major edits are expected during the development cycle
- The projects with mid or high-level risk, where it is important to prevent these risks
- The new product that should be released in a few stages to have enough of clients feedback
![Software development life cycle phases Software development life cycle phases](https://www.codekulture.com/wp-content/uploads/2017/04/Development-Life-Cycle2.png)
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V-shaped SDLC Model
V-shaped SDLC model is an expansion of classic waterfall model and it’s based on associated test stage for the every development stage. This is a very strict model and the next stage is started only after the previous phase. This is also called “Validation and verification” model. Every stage has the current process control, to make sure that the conversion to the next stage is possible.
ADVANTAGES | DISADVANTAGES |
---|---|
Every stage of V-shaped model has strict results so it’s easy to control | Lack of the flexibility |
Testing and verification take place in the early stages | Bad choice for the small projects |
Good for the small projects, where requirements are static and clear | Relatively big risks |
Use cases for the V-shaped model: 123 music old tamil songs.
- For the projects where an accurate product testing is required
- For the small and mid-sized projects, where requirements are strictly predefined
- The engineers of the required qualification, especially testers, are within easy reach.
Agile SDLC Model
In the agile methodology after every development iteration, the customer is able to see the result and understand if he is satisfied with it or he is not. This is one of the advantages of the agile software development life cycle model. One of its disadvantages is that with the absence of defined requirements it is difficult to estimate the resources and development cost. Extreme programming is one of the practical use of the agile model. The basis of such model consists of short weekly meetings – Sprints which are the part of the Scrum approach.
ADVANTAGES | DISADVANTAGES |
---|---|
Corrections of functional requirements are implemented into the development process to provide the competitiveness | Difficulties with measuring the final cost because of permanent changes |
Project is divided by short and transparent iterations | The team should be highly professional and client-oriented |
Risks are minimized thanks to the flexible change process | New requirements may conflict with the existing architecture |
Fast release of the first product version | With all the corrections and changes there is possibility that the project will exceed expected time |
Use cases for the Agile model:
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- The users’ needs change dynamically
- Less price for the changes implemented because of the many iterations
- Unlike the Waterfall model, it requires only initial planning to start the project
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Conclusion
If you are already experienced in the SDLC models and you have your own professional opinion on this – leave your comments in the section below. If you have questions on about picking up a correct model for your business – Contact Us, so we could assist you in this question or visit our page dedicated to Custom Software Development Servicesto learn more.
Software Development Lifecycle Models
During the years of the SDLC evolution, different models were developed from the basic cascade model to meet a huge variety of development requirements and expectations. There is no only one suitable model for all the projects, starting conditions and payment model. Even at the first sight, multi-purpose Agile cannot be used widely because of some customers’ unpreparedness to scale the budget. The SDLC models often cross in the solutions and particularly look similar.
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