System Design Tools
System Flow Chart
System flow chart is a diagrammatic representation to explain how a system work, the diagrammatic representation is easier to understand that a lengthy text. System flow chart is one of the major tools of the system analyst to show an overview of the processing in a complete system. It is more advantage than program flow chart program flow chart only describes the flow of data. Showing the sequence of operation symbols
Data Flow Diagram (DFD)
Data flow diagram is the tool that describes the flow of data through a system and works or processing performed by that system. It shows the flow of data from external entities into the system how the data moves form one process to enter and its logical storage. It is a good practice to draw context diagram. All symbols used in context diagram are also valid in DFD.
Entity- Relation Diagram
Entity Relation diagram shows in terms of the entities and relationship described by the data. IT can be a set of person, place, objects, events or even concepts.
- One to one – a driver – drive a car
- One to many- a teacher teaches many students at a time
- Many to many – many readers read many books.
- Many to one – many students reading a school.
Context Diagram is a diagram that represents the actors outside a system that interact. With the system. It is useful in system design to represent external factor’s interacting with the system itself so that system requirement and constraints can be studied very easily. It is used to document the scope for a system.
A decision table allows us to identify the exact course of actions for given conditions. A decision table provides unambiguous decisions. Leading to a good program design. It is a precise way to model a complicated logic. It is consist of three parts Conditions, Actions, and Rules
Decision tree also does more or less the same job as decision table, except that it follows the tree structure and each node of the denote conditions It is popular because it is simple to understand and interpret It is used is displaying branching algorithm operational research decision analysis conditional probability etc.
UML (Unified Modeling Language)
UML is a slandered language for specifying visualizing, constructing and a documenting the software system, as well as for business modeling the UML is a very important part of developing object oriented software and the software development process which is independent of particular programming language and developing process.
In software and systems engineering, a use case is a list of actions or event steps, typically defining the interactions between a role (known in the Unified Modeling Language as an actor) and a system, to achieve a goal. The actor can be a human, an external system, or time.