process models

With the final blog post of the semester for Software Process Management, I wanted to review the process models we went over (waterfall and agile approaches), and perhaps take a look at some more models that we didn’t go over in class.

The waterfall approach as we went over it in the semester essentially that everything is planned at the start of the development process. This means that the plan is rigid during the course of the process. With the agile approach, the plan is highly flexible and able to change during the course of the process. Each increment of development, usually a few weeks, is followed by a plan for the following few weeks, and the cycles continues, with each aspect of the plan being adjustable as needed.

The agile approach is great for large projects and very versatile, but what other process models are there? In a blog post written by Omar Elgabry, he lays out two models that sort of make up the agile process model (incremental and iterative), as well as two other models, the spiral model and the prototype model.

Both the incremental and iterative models are based on increments of development, but the increment is the difference between them and the agile model. With the incremental approach, a complete feature is completed with each increment. With the iterative model, each increment is a small portion of all features. Compare with agile, in which each increment is a small functional portion of each feature.

The prototyping process isn’t a whole process by itself, it’s rather a tool in the form of a process to test the feasibility of a project. It’s in the name, a prototype is quickly built according to a customer’s requirements, and is helpful when the resource cost of a full project isn’t clear. The customer is usually in the loop for the development of the prototype. Once this prototyping phase is complete, the development team can opt for another process model to move forward.

The spiral model is used for cases where there is high risk associated with the project, typically large projects. The model is rarely used, but is good for testing feasibility. Essentially, each loop in a visual spiral is a phase of the project, and each phase is made up of an objective setting phase, a risk analysis phase, a development phase, and a planning phase where it is determined if the development should continue into another phase.

While I appreciate the spiral model for it’s uniqueness, I can definitely see why most teams use the agile model. It’s essentially a direct improvement from the incremental and iterative models in terms of versatility, and if you need a prototype, you can still build one using that process. Still, it’s interesting to know that we are still trying to find more ways to streamline our development to be more efficient, and I’m sure someday even agile will be taken over by another model.