Incremental model of software development life cycle is the standard model to develop application software products. It is a method of software development in which designed, implemented and tested phase is upgraded and/or incremented (a little more is added each time) until the required product done. This method involves both development and maintenance phases. The under development product is defined as completed when it satisfies all of its functional requirements. This model combines the elements of the waterfall model with the iterative philosophy of prototype model.

Design phases | Advantages | Disadvantages | Pros & Cons | Applications

In this model life cycle involves multiple development and testing cycles take place, likewise “multi waterfall” cycles. These developments and testing cycles are divided up into smaller iterations. These iterations can be easy to managed to go through a set of sequential phases including design, implementation and testing phases. A working version of the software is produced during the first iteration, so working software is created early in the development process during this software life cycle. Each subsequent release enhance by the functionality with addition of function to the previous release of the product. The process continues till the complete system is achieved.

In other words the working behaviour of this software development life cycle is to decomposed the product into a number of components and each component are designed and built separately (termed as builds). After successfully completed the functionality of each component this product is delivered to the client. This allows partial utilisation of product and avoids a long development time required to an actual product.


Design phase of SDLC incremental model:

SDLC Incremental modeling approach is an attractive approach for complex and large functionality software project development. In this system modeling approach the developer dividing the functionality into different categories. By applying multiple linear sequential phases similar to waterfall model enhance the functional categories of the system with each successive release of the products until all functional categories are covered. The ultimate goal of this model is to provide a system with overall functionality.

Design phase of SDLC Incremental model
Design phase of SDLC Incremental model

Following phases in the figure below representing the different phases of SDLC incremental model:

  • Requirement phase:

In this phase of incremental model the basic requirements are identifying by the product analysis expertise. This phase involves to understanding the system functional requirement by requirement analysis team. After completely understanding the user demand team members ready a product requirement tools documents and categorized the functionality of the system. On the bases of functional categorization the analyst decided how to accomplish the task completely in step by step modulation of the actual product. This requirement phase plays an important role in the development of product under incremental model of software life cycle.

  • Design and Development phase:

In this phase of incremental model of SDLC the design of the system functionality and the development process is done successfully. Incremental model use design and development phase each time when the new functionality and/or new version of the product have to be developed.

  • Testing phase:

The testing phase of the incremental model checks the behavior of each existing function in the system under development as well as the additional functionality. Several testing methods are used under this phase to check the behavior of the each categorized function and system respond.

  • Implementation phase:

Implementation phase of incremental model enable the coding phase of the under developed system. This phase includes the final coding of the system that design in the design and development phase and tested the functionality under testing phase. After completion of this phase the product working is enhanced and upgraded up to final system product.


Advantages and disadvantages of incremental model:

Every software development model has own advantages and disadvantages that decide the working area of the model. Here we are listing all the advantage and disadvantages of incremental model:

Advantages of incremental model:

Incremental model are able to generates working software quickly and early during the software life cycle. It also gives a hike in the SDLC model to create complex and rich functionality software system. This model gives a large initial capital outlay with the subsequent long wait avoided. This model of development also helps ease the traumatic effect of introducing completely new system all at once.


Disadvantages of incremental model:

This model has vey fewer drawbacks because this was designed under the consideration to overcome the drawback of waterfall model of SDLC. Incremental modelling approach required good planning and design expertise team members. It requires a complete task and full functional requirement with the product in the requirement analysis phase that take high amount of time. The total cost of this system is higher than waterfall model of software development life cycle.


Pros and Cons of incremental model:

There are many pros and cons of incremental model. In the following list we are trying to cover all pros and cons of incremental model, follow us;

Pros of incremental modelCons of incremental model
More flexible in working and addition of new functionalityNeeds good planning and design.
less costly to change scope and requirementsNeeds a clear and complete definition of the whole system before start design
Easier to test and debug during a smaller iterationFunctionality divination takes more time
High customer interaction with review and feedback to each buildTotal cost is higher than waterfall model.
Generates working software quickly and early during the software life cycle
Lowers initial delivery cost
Easier to manage risk because risky pieces are identified
Handling functionality during iteration process


Application of Waterfall Model:

There is various software development models in SDLC approach available and used by all software development companies. Each software development application has different requirements based on internal and external factors of the system. There have some situations where the use of incremental model is more suitable and handle the problem very smartly:

  • Incremental model flexibly used when the requirements of the complete system are clearly defined and understood.
  • Major requirements must be defined; however, some details can evolve with time.
  • There is a need to get a product to the market early.
  • Resources with needed skill set are not available
  • There are some high risk features and goals.
  • A new technology is being used




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