The water fall model is a popular version of the system development lifecycle model for software engineering.
It is often considered the classic approach to the system development life cycle.
In order to design a good system, traditionally, the development have used the waterfall model.
This model describes a development method that is linear and sequential.
Waterfall development has distinct goals for each phase of development.
System Development Model; We have 2 models for system development 1. Waterfall model (or) Linear sequential model 2. Spiral model Waterfall Model; Information needs specifications Analysis System design Mission & Goal Process design Testing Implementation Maintenance Water fall model
Once an application is in the testing stage, it is very difficult to go back and change.
Something that was not well though out in the concept stage.
The RAD Model Rapid application development is an incremental S/W development process model that emphasizes an extremely short development cycle. The RAD model is a “high-speed ” adaptation of the linear sequential model in which rapid development is achieved by using component-based construction. If the requirement are well understood & project scope is constrained, the RAD process enables a development team to create a “ fully functional system ” within very short time period. The RAD approach encompasses the following phases; Business modeling The information flow among businesses function is molded in a way that answers the following questions: 1. What information drives the business processes/ 2. What information is generated? 3. Who generates it? 4. where does the information go? 5. Who process it
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 characterizes (called attributes) of the each object are identified & the relationships b/w these objects 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 description are created for adding, modifying, deleting, or retrieving a data object. Application Generation; RAD assumes the use of the 4 th generation techniques. Rather than creating S/W using conventional 3 rd generation programming languages the RAD process works to reuse existing program components or create reusable components. In all cases, automated tools are used to facilitate construction of the S/W.
The developer interviews the user and develops an initial system using a DBMS
The user works with the proto type and suggest changes
Process will repeats until the user or developer is satisfied
Steps in system development by proto type : System development initiated Investigate and analyze problem sufficiently to develop workable solution Develop prototype Put proto type into operation Refine and modify proto type Complete component of system
Give data to the system without explaining the process that creates that data
Take data from the system without explaining what it does with that data
Establish what flows are sent to and from the
system from the external entities
Draw the context diagram
Structured systems Analysis & Design [SSAD ] Symbols; Flow of data process of Storage of Entity Transforming Data Data Example ; Customer Process Customer order Order acceptance Product data Customer data Customer order Order acceptance
Systems analysis plays a central role in the development of the MIS
MIS lies in the information needs of the various personnel in the org across all levels of the mgt
The MIS development process largely relies on the SAD as a source of the scientific development
The modern MIS largely depends on how these technologies are blended with the main systems
The SA begins with the O/P design
The SA with its structural analysis ensures an appropriate coverage of the sub-systems
MIS methodology may be the conventional design of data, DB & file approach
MIS may call for an open system design
Systematic approach in development helps in achieving the objectives of the MIS
BUSINESS PROCESS REENGINEERING [BPR] BPR is a methodology for introducing a fundamental change in specific business process & usually supported by an IS. Business Process; A business process is a collection of activities that --- takes one or more kinds of I/P --- create an O/P of value to the customers BPR combines a strategy of promoting business innovation with a strategy of making major improvements to business processes, so that a company can Become a much stronger & more successful competitor in the marketplace. Restructuring & transforming a business process by a fundamental rethinking & redesign to achieve dramatic improvements in the cost, quality, & speed. Example ; Order Mgt Proposal Commitment Configuration Credit checking delivery Billing Collections
The architect ‘s primary function as liaison between the client’s abstract design requirements and contractor detailed building plan may be compare to analyst’s role as liaison between the users logical design requirements in details and physical system design.
The analyst plays the role of a psychologist in the way he/she reaches people, interprets their thoughts, assesses their behavior and draws conclusions from these interactions.