Incremental process model | Rapid application development model (RAD)

Software Engineering Models : Successive version model is another name for incremental process model.

After that, a simple working system with only a few basic functions is constructed and handed to the customer. Then, until the desired system is released, numerous more iterations/versions are implemented and handed to the customer.

Incremental Model

A, B, C are modules of Software Product that are incrementally developed and delivered.

Life cycle activities Incremental process model –

Software requirements are initially broken down into multiple modules that can be built and supplied in stages. At any given time, the plan is only for the next increment, not for any long-term goals. As a result, customizing the version to meet the needs of the customer is much easier. The Development Team begins by developing the system’s fundamental features (which do not require services from other features).

Once the fundamental elements are complete of Incremental process model, they are improved to include new functions in subsequent editions, increasing the level of capability. An iterative waterfall methodology of development is typically used to create each incremental version.

As each new version  of the Incremental process model programme is built and deployed, the customer’s feedback is collected, and these are then included into the next edition. Each new version of the software adds more features to the previous versions.

Incremental Model activity

Following the gathering and specification of needs, the requirements are divided into multiple different versions, starting with version-1 and progressing to the next version, which is then built and deployed at the customer site. It has now been installed at the client site following the last update Incremental process model (version n).


Types of Incremental model –

  1. Staged Delivery Model –

Only one portion of the project is built at a time.

Staged Delivery Model

  1. Parallel Development Model:

Different subsystems are developed at the same time in a parallel development model. If enough resources are available, it can reduce the calendar time required for development, i.e. TTM (Time to Market).

Parallel Development Model

When should you use this –

  • Funding schedule, risk, programme complexity, or the necessity for early benefit realisation are all factors to consider.
  • When the requirements are known ahead of time.
  • When a project’s development schedule is protracted.
  • Projects involving cutting-edge technology.

Advantages –

  • Reduced Errors (The customer uses the main components from the start of the phase, and these are thoroughly tested) Tasks are broken down using divide and conquer.
  • Reduces the cost of the initial delivery.
  • Resource Deployment in Small Steps

Disadvantages –

  • It necessitates careful planning and design.
  • The total cost is not reduced.
  • Module interfaces must be well defined.

 Rapid application development model (RAD)


The Rapid Application Development Model was first proposed by IBM in 1980’s. The use of powerful development tools and techniques is a key feature of this model.

This model can be used to construct a software project if the project can be split down into discrete modules and each module can be allocated to its own team. Finally, these modules can be joined to create the final product.

As indicated in the picture, the development of each module incorporates the several essential processes of the waterfall model, including analysing, designing, coding, and testing.

Another notable feature of this model is the short time limit for delivery (time-box), which is typically 60-90 days.

Rapid Application Model

The projects also include the usage of strong development tools such as JAVA, C++, Visual BASIC, XML, and others.

There are four basic phases in this model:

1.Requirements Planning –

Software Engineering Models It includes brainstorming, task analysis, form analysis, user scenarios, FAST (Facilitated Application Development Technique), and other requirements elicitation approaches. It also includes the whole structured plan that describes the key data, the methods for obtaining it, and the subsequent processing of the data to produce the final refined model.

2.User Description –

This phase entails Software Engineering Models gathering user feedback and constructing a prototype with development tools. To put it another way, it entails a re-examination and validation of the information gathered in the initial phase. In this phase, the dataset attributes are also identified and clarified.

3.Construction –

The prototype is fine-tuned and delivered at this phase. It entails converting process and data models into a final working product using strong automated tools. This phase also includes all necessary modifications and additions.

4.Cutover –

All interactions between the individual modules built by different teams must be thoroughly tested. Testing is made easier by the use of powerfully automated tools and subparts. After that, the user does acceptability testing.

Building a quick prototype, presenting it to the customer, and receiving feedback are all part of the process. The SRS document is created and the design is completed after the customer’s approval and Software Engineering Models.

Advantages –

  • The use of reusable components helps to shorten the project’s cycle time.
  • Customer feedback is available during the early stages of the project.
  • Cost savings because fewer developers are required.
  • The use of strong development tools results in higher-quality goods in a shorter amount of time.
  • The project’s growth and development can be tracked at different phases.
  • Because of the small iteration time spans, it is easier to handle changing needs.

Disadvantages –

  • High-skilled experts are required to employ powerful and efficient tools.
  • The lack of reusable components might contribute to project failure.
  • To complete the project on time, the team leader must collaborate closely with the developers and clients.
  • This model can’t be used for systems that can’t be modularized properly.
  • Throughout the life cycle, customers must be involved.
  • It is not intended for small-scale projects because the expense of adopting automated tools and processes in such circumstances may exceed the project’s total budget.

Applications –

  1. This paradigm is appropriate for a system with well-defined requirements and a quick development period.
  2. It’s also appropriate for projects where requirements can be modularized and reusable components can be developed.
  3. When current system components can be used to construct a new system with few changes, the model can be used.
  4. This model is only applicable if the teams are made up of domain experts. This is due to the fact that necessary knowledge and the capacity to employ powerful approaches are required.
  5. When the budget allows for the use of automated tools and procedures, this approach should be adopted.

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