Approaches to System Development Chapter 3

Methodologies, Models, Tools and Techniques A system development methodology –provides guidelines to follow for completing every activity in the systems development life cycle. A model is a representation of some important aspect of the real world some models used in system development --Flowchart, DFD, ERD, Structure charts Use case diagrams, class diagrams, seq. diagrams some models used to manage the development process --PERT charts, Gantt chart organ. Hierarchy chart --Financial analysis models –NPV, ROI

Tools A tool is software support that helps create models or other components required in the project. -smart editors, C-S help, debugging tools CASE (Computer-Aided System Engineering) Tools -- Help the analyst create the important system models.

Techniques A technique is a collection of guidelines that help an analyst complete a system development activity. Some Techniques OO analysis Data Modeling Relational database design Structured analysis and design Software-testing

Two approaches to System Development Structured system development Information Engineering (IE) is a popular variation to structured development Structured Analysis and Design Technique (SADT) – developed in the 1060’s was the first attempt to provide guidelines to improve the quality of software. Top down programming– divides more complex programs into a hierarchy of program modules. Structure design – Structure Charts- Structured analysis- Data flow diagrams (DFD) – Entity-Relationship Diagram (ERD)

The Object Oriented Approach OO approach – view an information system as a collection of interacting objects that work together to accomplish tasks Object – a component in the computer system that can respond to messages. OO design –defining all of the types of objects necessary to communicate with people and devices in the system and refining the definition of each type of object so it can be implemented with a specific language or environment OO Programming –Writing statements in a programming language to define what each type of object does, including the messages that objects send and receive.