Traditional CMMI or waterfall development model

The waterfall model is a model which was developed for software development; that is to create software. It is called as such because the model develops systematically from one phase to other in a downward fashion, like a waterfall.

The most probable phases through which it progresses downwards are
•           Definition Study/Analysis
•           Basic Design
•           Technical Design/Detailed Design
•           Construction
•           Testing
•           Integration
•           Management and
•           Maintenance.

Waterfall Model
Before the advent of this method, the software development in the computer companies suffered from a haphazard integrated software network like cluttered knitting. However with this method they hoped to bring clarity in their projects.

About the Phases
As said earlier the waterfall model has been structured on multiple phases especially to help out the software construction companies to develop an organized system of construction. By following this method, the project will be divided into many stages thus easing out the whole process. For example you start with Phase I and according to this model, one only progresses to the next Phase once the previous one has been completed. This way one moves progressively to the final stage and once that point is reached, you cannot turn back; similar to the water in a waterfall.

Brief Description of the Phases of Waterfall Model
•           Definition Study / Analysis: During this phase research is being conducted which includes brainstorming about the software, what it is going to be and what purpose is it going to fulfill.
•           Basic Design: If the first phase gets successfully completed and a well thought out plan for the software development has been laid then the next step involves formulating the basic design of the software on paper.
•           Technical Design / Detail Design:  After the basic design gets approved, then a more elaborated technical design can be planned. Here the functions of each of the part are decided and the engineering units are placed for example modules, programs etc.
•           Construction / Implementation: In this phase the source code of the programs is written.
•           Testing: At this phase, the whole design and its construction is put under a test to check its functionality. If there are any errors then they will surface at this point of the process.
•           Integration: in the phase of Integration, the company puts it in use after the system has been successfully tested.
•           Management and Maintenance: Maintenance and management is needed to ensure that the system will continue to perform as desired.

Through the above mentioned steps it is clearly shown that the Waterfall model was meant to function in a systematic way that takes the production of the software from the basic step going downwards towards detailing just like a Waterfall which begins at the top of the cliff and goes downwards but not backwards.

Advantages of the Waterfall Model
•           The project requires the fulfillment of one phase, before proceeding to the next. Therefore if there is a fault in this software it will be detected during one of the initial phases and will be sealed off for correction.
•           A lot of emphasis is laid on paperwork in this method as compared to the newer methods. When new workers enter the project, it is easier for them to carry on the work from where it had been left. The newer methods don’t document their developmental process which makes it difficult for a newer member of the team to understand what step is going to follow next. The Waterfall Model is a straight forward method and lets one know easily what stage is in progress.
•           The Waterfall method is also well known amongst the software developers therefore it is easy to use. It is easier to develop various software through this method in short span of time.

Disadvantages of the Waterfall Model
•           Many software projects are dependent upon external factors; out of which the client for which the software is being designed is the biggest factor. It happens a lot of times, that the client changes the requirement of the project, thereby influencing an alteration in the normal plan of construction and hence the functionality as well. The Waterfall Model doesn’t work well in a situation like this as it assumes no alteration to occur once the process has started according to plan.
•           The other negative aspect of this model is that a huge amount of time is also wasted. For example if we study any software development process, we know that Phase II cannot be executed until Phase I has been successfully completed; so while the designers are still designing the software, time of the builders is completely wasted.
•           Another disadvantage of this method is that the testing period comes quite late in the developmental process; whereas in various other developmental programs the designs would be tested a lot sooner to find the flaw at a time when a lot of time and money has not been wasted.
•           Elaborate documentation during the Waterfall method has its advantages, but it is not without the disadvantages as well. It takes a lot of effort and time, which is why it is not suitable for smaller projects.