ESS's Development Methodology covers the entire life cycle of an Information System, from the initial planning to the end of the System's useful life. This Methodology is a structured yet flexible approach to Information System delivery. ESS follows:                

	System Development Life Cycle (SDLC)
	Prototyping Model
	Rapid Application Development (RAD) Model

All these different software development models have their own advantages and disadvantages. Nevertheless, in the contemporary commercial software development world, the fusion of all these methodologies is incorporated.

	System/Information Engineering and Modeling
	Software Requirements Analysis
	Systems Analysis and Design
	Code Generation
	Testing
	Deployment
	Maintenance

System/Information Engineering and Modeling:

As software is always of a large system (or business), work begins by establishing requirements for all system elements and then allocating some subset of these requirements to software. This system view is essential when software must interface with other elements such as hardware, people and other resources. System is the basic and very critical requirement for the existence of software in any entity. So if the system is not in place, the system should be engineered and put in place. In some cases, to extract the maximum output, the system should be re-engineered and spruced up. Once the ideal system is engineered or tuned, the development team studies the software requirement for the system.

Software Requirement Analysis:

This is also known as feasibility study. In this phase, the development team visits the customer and studies their system. They investigate the need for possible software automation in the given system. By the end of the feasibility study, the team furnishes a document that holds the different specific recommendations for the candidate system. It also includes the personnel assignments, costs, project schedule, and target dates. The requirements gathering process is intensified and focussed specially on software. To understand the nature of the program(s) to be built, the system engineer ("analyst") must understand the information domain for the software, as well as required function, behavior, performance and interfacing. The essential purpose of this phase is to find the need and to define the problem that needs to be solved .

System Analysis and Design:

In this phase, the software development process, the software's overall structure and its nuances are defined. In terms of the client/server technology, the number of tiers needed for the package architecture, the database design, the data structure design etc are all defined in this phase. A software development model is created. Analysis and Design are very crucial in the whole development cycle. Any glitch in the design phase could be very expensive to solve in the later stage of the software development. Much care is taken during this phase. The logical system of the product is developed in this phase.

Code Generation:

The design must be translated into a machine-readable form. The code generation step performs this task. If the design is performed in a detailed manner, code generation can be accomplished without much complication. Programming tools like Compilers, Interpreters, Debuggers are used to generate the code. Different high level programming languages like C, C++, Pascal, Java are used for coding. With respect to the type of application, the right programming language is chosen. 

Testing:

Once the code is generated, the software program testing begins. Different testing methodologies are available to unravel the bugs that were committed during the previous phases. Different testing tools and methodologies are already available. Some companies build their own testing tools that are tailor made for their own development operations.

Maintenance:

Software will definitely undergo change once it is delivered to the customer. There are many reasons for the change. Change could happen because of some unexpected input values into the system. In addition, the changes in the system could directly affect the software operations. The software should be developed to accommodate changes that could happen during the post implementation period.

 
The RAD (Rapid Application Development) model is a high speed version of the waterfall model. The emphasis is on short development cycle. Short development cycle is achieved by using component-based construction. Used primarily for information systems applications, the RAD approach encompasses the following phases:

	Business Modeling
	Data Modeling
	Process Modeling
	Application Generation
	Testing and Turnover

Business Modeling The information flow among business functions is modeled in a way that answers the following questions:

 
Data Modeling: The information flow defined as part of the business modeling phase is refined into a set of data objects that are needed to support the business. The characteristic (called attributes) of each object is identified and the relationships between these objects are defined.

Process Modeling: The data objects defined in the data-modeling phase are transformed to achieve the information flow necessary to implement a business function. Processing the descriptions are created for adding, modifying, deleting, or retrieving a data object.

Application Generation: RAD assumes the use of the RAD tools like VB, VC++, Delphi etc rather than creating software using conventional third generation programming languages. The RAD works to reuse existing program components (when possible) or create reusable components (when necessary). In all cases, automated tools are used to facilitate construction of the software.

Testing and Turnover: Since the RAD process emphasizes reuse, many of the program components have already been tested. This minimizes the testing and development time.