Waterfall vs. Agile Methodology
Most software development projects apply either the Waterfall or Agile methodology. A development methodology is the procidure used by an engineering team in order to create a desired product. The Waterfall methodology represents the traditional approach, where the development process is conducted in a linear series of events. On its way toward the conclusion the progress flows continously through the phases of a project (analysis, design, development, testing, release) like a waterfall. The entire project is planned in advance. Agile is a more recently developed software development methodology, where the linear approach is replaced by an incremental, iterative one. Instead of planning the whole project in advance, Agile enables the adaption of requirements during the whole project. This artice provides an introduction of each methodology, a comparison and examples of use, in order to facilitate the decision whether Agile or Waterfall is more suitable for the next project.
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Waterfall Methodology
The lifcycle model which is today known as traditional or Waterfall model was first described by Royce in 1970.[1] It is called Waterfall model because of its sequential and down-flow characteristic where the phases analysis, design, implementation, testing and release are processed consecutively downwards.[2] Each phase of the Waterfall model is processed in order without any overlapping and within a specified time period. Once a phase is completed there is no going back to a privious phase as it will be frozen.[3]
Analysis
In this phase all the requirements and customer needs of the desired system or product are gatherd and recorded in detail in a specification document.[2] This document will be used as input in the design and implementation phase. The requirements of the product should be clear before moving to the next phase as changes in requirement can not be adapted later in the process.[3]
Design
The outcome of the design phase are a specified hardware and a virtual overview of the desired system or software.[3]
Implementation
The actual development of the system starts in the implementation phase. The system is therefor divided in small sub units which are tested by the developers before forwarding them to the testing phase. A quality gate checklist helps to control if there is a deviation from the requirements, planned time-line and product scope.[4]
Testing
In this phase the sub units are integrated to one working system which is tested regarding quality and functional aspects. The collected measures of performance are used for the decision whether the system is ready for the relase. In order to ensure that the outcome of the project meets the customers' requirements the tested system is reviewed according to a checklist. [4]
Release
The product gets prepared for beeing released into the market or delivered to the customer (including installation instructions of the system for customers and user-guides). There is another quality gate in order to check if the final product meets the customer and quality requirements and wheter it is delivered in time. [4]
Maintenance
After releasing the product in the customer environment there can occur problems in the products performance. Hence, the company must provide maintenace in order to solve this issues.[4]
Pros
- All requirements are clearly documented before the development of the product starts
- Each phase is finished in a specified period of time before moving to the next phase
- Waterfall is simple to implement as it is a linear model
- The amount of resources needed for implementing the waterfall methodology is minimal
- Each phase follows appropriate documentation in order to ensure the quality development [3]
Cons
- you cannot return to a privious phase. If the design phase fails the project might become very complicated in the implementation phase.
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Agile Methodology
Pros
Cons
Comparison of the Waterfall and the Agile Methodology
Example of Use
The following example demonstrates the different approaches of each methodology. The project goal is the development of a customer adress book.
Waterfall Model
Product Requirements
First, the Product Manager has to create a document of requirements:
• Enable user to create new contacts
• Enable user to see his contacts
• Enable user to import contacts from other applications
• Enable user to email his contacts from the adress book
• Enable user to add pictures to represent his contacts
The created document will comprise detailed requirements, user scenarios and potential layouts
Analysis
Design
Implementation
Testing
Release
Agile Model
Product Requirements
The product manager creates a document of requirements:
• Enable user to create new contacts
• Enable user to see his contacts
• Enable user to import contacts from other applications
• Enable user to email his contacts from the adress book
• Enable user to add pictures to represent his contacts
Iteration Nr.1
Iteration Nr.2
Iteration Nr.3
Release
Conclusion
References
- ↑ Sommerville I., "Software process models," ACM Computing Surveys (CSUR), vol. 28, pp. 269-271, 1996
- ↑ 2.0 2.1 Dubey A.; Jain A.; Mantri A., "Comparative Study: Waterfall v/s Agile Model", International Journal of Engineering Sciences & Research Technology (IJESRT), 2015
- ↑ 3.0 3.1 3.2 3.3 Balaji S.; Dr. Sundararajan Murugaiyan M., "Waterfall vs V-Model vs Agile: A Comparative Study on SDLC", International Journal of Information Technology and Business Management (JITBM), 2012
- ↑ 4.0 4.1 4.2 4.3 Bomarius F. et al., "Product-Focused Software Process Improvement", 10th International Confernce, Springer, 2009
