Software development models play crucial role in developing a software project. It has the ability to influence a project w.r.t efficiency, cost and time. That’s why a lot of brain storming goes while selecting the most suitable model for a project. In this post, we will try to understand what are these Software Development Models along with some popular examples such as Waterfall model, Iterative model, Spiral model, V model and agile model. We will also discuss their applications, advantages and disadvantages to give you a clear idea about each of them.
Software Development Models
Software Development Models are set of different processes or methods carefully chosen to develop a specific project considering its various requirements.
There are many software development models in Software Development Life Cycle (SDLC) which has been gradually developed to fulfill project specific requirements. One should choose the required SDLC model based on the project and business requirement.
These software development models are also called as “Software Development Process Models”.
Examples of Software Development Models
Some of the widely used Software Development Models are:
- Waterfall Model
- Iterative Model
- Spiral Model
- Agile Model
Waterfall Software Development Models
The waterfall model was the most common and earliest approach used in software development. As the name suggests, in this model the project flow is seen as flowing downwards just like a waterfall.
This means that the earlier phase must be completed before the next phase can begin, and no overlapping of the phases is allowed.
Fig. 1 – Waterfall Software Development Model
Where We Should Use Waterfall Software Development Models
Waterfall model is best suitable for:
- The projects which have clear documented requirements.
- The projects with no ambiguous requirements.
- The projects with no changes in the development time.
- It can be used for migration projects where only platform/language may change.
Advantages of Waterfall Software Development Models
The advantages of waterfall models are as follows:
- Easy to use and understand
- Verification check at every stage helps in resolving errors quickly
- Best suited for small and mid-sized projects
- Specific deliverables at every stage
Disadvantages of Waterfall Software Development Models
The disadvantages of waterfall model are as follows:
- Not suitable when requirements are not frozen
- Integration is done at the end, so early detection of challenges not possible
- Not suitable for complex and object-oriented projects
- Not good for long and ongoing projects
Iterative Software Development Models
This SDLC model does not need the full set of requirements to start with. The development process can start with the requirements to the functional part, which may be expanded later. At every iteration, the design modifications are made and new functional requirements are added.
In this model, the requirement is divided into various builds. At each iteration, the module goes through the design, testing and, implementation phases. Each release of the module adds functionality to the previous release. This process is continued until the complete requirement is met as per the customer needs.
Fig. 2 – Iterative Software Development Model
Where We Should Use Iterative Software Development Models
These models are suitable for the large systems which built in segments or phases. It is used widely in product-based companies. For example, ERP system which can start with the budget module as a first iteration and then inventory, logistics and so on.
Advantages of Iterative Software Development Models
The advantages of Iterative models are as follows:
- Smaller iteration helps in easy debugging and testing
- Problems identified in one build can be prevented in other builds
- Change requests can be handled easily
- Flexible model, scope can be changed in a cost-efficient manner
Disadvantages of Iterative Software Development Models
The disadvantages of Iterative models are as follows:
- Not suitable for small projects
- Risk as project end is not determined
- Constant management attention is required
- Design issues might occur as not all the requirements are known well before
Spiral Software Development Models
It is the combination of waterfall and iterative model used for large, expensive and complicated projects. In this model, the release is done in an incremental way.
The spiral model has four phases:
- Determine Objectives
- Identify and Resolve Risks
- Development & Testing
- Plan the next Iteration
Fig. 3 – Spiral Software Development Model
Where We Should Use Spiral Software Development Models
This model is mainly used in the software industry for medium to high- risk projects. In this, the budget is a constraint and customers are not sure of the requirements.
Advantages of Spiral Software Development Models
The advantages of Spiral models are as follows:
- Better Risk Management
- Clear Estimates as important issues are covered earlier
- Change requests can be accommodated
- Early user involvement
Disadvantages of Spiral Software Development Models
The disadvantages of Spiral models are as follows:
- Expensive for small projects
- In between stages add excessive documentation
- Indefinite time, Spiral might go on and on
- Need highly skilled resources for risk control
V Software Development Models
In this model, the execution of processes happens in a ‘V’ shaped manner. It is also called as Validation and verification (V&V) model.
It is an expansion of the commonly used waterfall model and there are Verification phases on one side and Validation phases on other side. It is joint by the coding phase.
Fig. 4 – ‘V’ Software Development Model
Where We Should Use V Software Development Models
Its usage is similar to the waterfall model. Requirements are written very well in advance and any change made in requirement is very expensive.
It is used in the medical field, as it is a very strict model.
Advantages of ‘V’ Software Development Models
The advantages of V models are as follows:
- Easy to understand and use
- Testing and verification are done early
- Requirements are very clearly defined
Disadvantages of ‘V’ Software Development Models
The disadvantages of V models are as follows:
- Not flexible to the changes, which makes it an expensive model
- Difficult to change a functionality, once the application is in testing phase
- Not suitable for object-oriented projects
Agile Software Development Models
This model is the combination of the iterative and incremental process models with focus on the customer satisfaction. In Agile model, the whole project is divided into small incremental builds.
Each iteration lasts from one to three weeks. In the end, the final build is displayed to the important stakeholders.
Fig. 5 – Agile Software Development Model
Where We Should Use Agile Software Development Models
The changes in this model are very dynamic i.e many iterations take place. It can be used in any of the projects, as when the customer needs to have functional requirements ready in less than three weeks and with not very clear requirements.
Advantages of Agile Software Development Models
The advantages of Agile models are as follows:
- Easy to manage as minimal planning is required
- Best for changing requirements
- Less risk involved
Disadvantages of Agile Software Development Models
The disadvantages of Agile models are as follows:
- High customer engagement and interaction required
- Lack of documentation may create problems
- New requirements may conflict with the existing system
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