What is the waterfall model? - Definition and guidance (2023)

What is the waterfall model?

The waterfall model is a linear, sequential approach to theSoftware development lifecycle(SDLC), which is popular in software development and product development.

The waterfall model uses a logical sequence of SDLC steps for a project, similar to the direction water flows over the edge of a cliff. It establishes clear endpoints or goals for each phase of development. These endpoints or destinations cannot be revisited once completed.

dr Winston W. Royce of the Lockheed Software Technology Center introduced the concept in an article published in 1970 about his experiences developing software for satellites. However, Royce did not use the termwaterfall; Instead, he pointed to the downstream value of documentation.

The waterfall model continues to be used in industrial design applications. It is often referred to as the first software development methodology. The model is also used more generally as a high-level project management method for complicated, multi-faceted projects.

Who Uses the Waterfall Model?

project teams andproject managerUse the waterfall model to achieve goals based on your organization's needs. The model is used in many different project management contexts, such as design, manufacturing, IT, and software development.

With the waterfall method, each step depends on the output of the previous step. The way these projects develop is linear.

For example, building typically follows these three general steps:

1. The physical design of a building is created before construction begins.
2. The foundation is poured before the skeleton of a building is erected.
3. The skeleton of the building is completed before the walls are erected.

On an assembly line, the steps in building a product are followed sequentially in a controlled order until the finished result is created.

The waterfall model does not contain any projectsend useror client as well as other development methods. Users are consulted in the initial stages of collecting and definingRequirements, Involvement of the customerReturn messagethereafter. By leaving the customer out of the main part of the waterfall process, the development team moves quickly through the phases of a project.

This methodology is suitable for teams and projects that want to develop a project according to fixed or unchanging requirements established at the beginning of the project. Waterfall projects have a high degree of process definition with little or no output variability. Waterfall is also a good choice when the project is limited by cost or time.

Projects based on the waterfall model are well defined, predictable and have specific documentation. They also have the following properties:

• fixed requirements;
• abundant resources;
• an established schedule;
• well understood technology; And
• unlikely that significant changes will be required.

In software development, when an application needs to work on the first try and there is a risk of losing customers, waterfall is a suitable method as it aims to achieve this goal. Compare that toAgile project managementand development methodology. Agile methods use continuous iteration, an iterative approach in which software is designed, developed, and tested in repeated cycles that build on each other.

Phases of the waterfall model

When used for a software development process, the waterfall method has seven stages:

1. Requirements. Possible requirements, deadlines and guidelines for the project are analyzed and recorded in a formal requirements document, also called afunctional specification. This development phase defines and plans the project without mentioning specific processes.
2. Analyse.The system specifications are analyzed to generate product models andbusiness logicto lead production. The financial and technical resources are also checked for feasibility.
3. Design.A design specification document is created to outline the technical design requirements such as: B. the programming language,Hardware, data sources, architecture and services.
4. coding and implementation.TheSource codeis developed using the models, logic and requirements specifications identified in the previous phases. Typically, the system is coded into smaller components or units prior to assembly.
5. To test.That's ifquality control,Unit,SystemAndBetaTests identify problems that need to be solved. This can e.g. B. cause a forced repetition of the coding stageDebugging. If the system passes integration and testing, the waterfall continues.
6. operation and use.The product or application is considered fully functional and is deployed in a live environment.
7. Maintenance.Corrective, adaptive and perfect maintenance will be carried out indefinitely to improve, update and expand the product and its functionality. This could include a releasePatchUpdates and new versions.

Before moving on to the next phase in the waterfall process, there is usually a review and approval to ensure all defined goals have been met. For example, developers would ensure that each unit of technology is properly integrated in the implementation phase before moving on to the testing phase.

Advantages of the waterfall model

Nowadays, the agile methodology is oftenused on the spotof the waterfall model. However, the waterfall approach has advantages such as: B. the following:

• allows large or rotating teams to move towards a common goal defined in the requirements phase;
• forces structured, disciplined organization;
• makes it easier to understand, follow and organize tasks;
• facilitates departmental division and management control based on schedule or deadlines;
• strengthenedgood programming habitsdefine and then code before implementing the design;
• enables early system design and specification changes to be easily implemented; And
• clearly defines milestones and deadlines.

Disadvantages of the waterfall model

Disadvantages of the waterfall model typically focus on the risk associated with a lack of overhaul and flexibility. Specific issues include the following:

• Design is not adaptable; When an error is found, the whole process often has to start over.
• The method does not include any user or customer feedback in the middle of the process and makes changes based on the results.
• The waterfall model delays testing until the end of the development lifecycle.
• It does not take error correction into account.
• The methodology does not handle change requests,ScopeAdjustments and updates good.
• Waterfall prevents processes from overlapping for concurrent work on different stages, reducing overall efficiency.
• No working product is available until the later stages of the project lifecycle.
• Waterfall is not ideal for complex, high-risk ongoing projects.

Software and tools for waterfall models

Gantt-Diagramare a common management tool for waterfall projects. These charts allow for easy visualization of successive phases, allowing project managers to assign dependencies and subtasks to each phase of the process. They provide a clear overview of timelines and deadlines for each phase.

Some project management software products that include Gantt charts include the following:

• Asana,
• And,
• Microsoft Excel,
• Microsoft Project,
• Microsoft-SharePoint,
• project manager,
• Smartsheet und
• Write.

project management softwareoften includes other tools to help waterfall-based teams get their jobs done. Some important features that should be present in a project management software are as follows:

• work in groups,
• Notes,
• testing and development and
• data analysisand visualization.

Alternatives to the waterfall

In addition to agile software development methods, alternatives to the waterfall process include:

• joint application development,
• rapid application development,
• sync and stabilize, and
• Spiralmodell.

Software development teams today often use Agile and DevOps methodologies instead of the waterfall method. Learnhow the three approaches compare.