AIS Ch 4

Data flow diagrams (DFD)

portray a business process activities, stores of data, and flows of data among those elements.

System flowcharts

present a comprehensive picture of the management, operations, information systems, and process controls embodied in business processes.

Systems flowchart:

A graphical representation of a business process, including information processes as well as the related operations processes.Depict the sequence of activities performed as the business events flow through the process.Gives a complete picture of a system by combining the physical and logical aspects.

Data flow diagram:

A graphical representation of a system.Depicts the systems components; the data flows among the components; and the sources, destinations, and storage of data.Uses a limited number of symbols.Includes Context Diagram, Physical Data Flow Diagram, and Logical Data Flow Diagram.

Internal entity

An entity within the system that transforms data. Includes, for example, accounting clerks (persons), departments (places), and computers (things)

Physical data flow diagram (DFD)

Graphical representation of a system showing the system's internal and external entities, and the flows of data into and out of these entities.Specifies where, how, and by whom a system's processes are accomplished.Does not specify what is being accomplished.

Logical data flow diagram (DFD):

Graphical representation of a system showing the system's processes (as bubbles), data stores, and the flows of data into and out of the processes and data stores.Specifies what activities the system is performing, without specifying how, where, or by whom activities are accomplished.

External entities

Those entities (i.e., persons, places, or things) outside the system that send data to, or receive data from, the system.

Context diagram:

Top-level, or least a detailed, diagram of a system depicting the system and all its activities as a single bubble and showing the data flows into and out of the system and into and out of the external entities.

FLOWCHART VS DATA FLOW

• The main difference between flow chart and data flow diagram is that flow chart presents steps to complete a process where as data flow diagram presents the flow of data.• Flow chart does not have any input from or output to external source whereas data flow diagram describes the path of data from external source to internal store or vice versa.• The timing and sequence of the process is aptly shown by a flow chart where as the processing of data is taking place in a particular order or several processes are taking simultaneously is not described by a data flow diagram.• Data flow diagrams define the functionality of a system where as flow diagram shows how to make a system function.• Flow charts are used in designing a process but data flow diagram are used to describe the path of data that will complete that process.