Two evolutionary model in the software process model is:
1. Incremental Model
1. Elemet-combine elements of nature with Iterations Waterfall / iteration.
2. Element-element in the Waterfall done with the results of a product with certain specifications, and the process starts from the first phase to end and produce a product with a more complete specifications from the previous. So on until all specifications to meet the needs defined by the user.
3. Products are usually the first increment core product (core products), which are products that meet basic needs. These products are used by the user or a detailed review or checks. The results of a review of the provision for development in the next increment. This is done continuously until the complete product is produced.
4. This model is suitable if the number of team members and developers / builders PL is not enough.
5. Able to accommodate changes in flexibility.
6. Products produced in the first increment is not a prototype, but the products that can work with basic specifications.
2. Spiral Model
1.Determining Objectives / Target
Each cycle begins with the identification spiral target of the cycle, and the collection of alternatives to achieve the target, and determine the constraints.
2.Risk Assessment
The next level is to evaluate alternative alternative-based targets and constraints. Here, including identifying the uncertainties and risks (as well as benchmarking, simulation and prototyping).
3.Development and Validation
The next level is determined based on risk has not been handled. Spiral model, which is determined by the possible risk to accommodate the needs of each merger orientation, prototypes, and other simulations.
4. Planning
The project review and plan the next phase of the helix.
while the waterfall methodology offers a software structure for the orderly development, the demand to reduce time-to-market make a series of steps that should not. The next evolutionary step from the waterfall is where the various steps for a phased delivery of some or handoffs. But the evolution of the water fall is a spiral, taking advantage of the fact that development projects work best when they get better, and repeated, where the team is able to start small and the benefits of trial and error enlightened along the way.
The spiral methodology reflects the relationship with the rapid prototyping tasks, increased parallel, and concurrency in the design and building activities. The spiral method should still be Planned methodically, with tasks and Deliverables IDENTIFIED for each step in the spiral. The spiral method still must be methodically planned, with tasks and deliverables identified for each step in the spiral.