Data Flow Diagrams & Structured Analysis for Systems

Anah Objective Structured Analysis

Consider a system, fully or partially, so you can know all the tasks that are performed as part of daily activities, the information flows between them and how the data are stored to support management of them.

Purpose and scope

Its purpose is to support understanding of large complex systems through:

• Modeling components and constructing a model of the system
• Structured analysis components, including graphic symbols, data dictionary, descriptions of processes and procedures, and rules
• Data Flow Diagrams: a technique representing information flows and transformations that are applied to the data when moving from input to output of a system under study

What the technique allows

This technique allows:

• Analysis of a system to determine whether the data have been defined and which processes are involved in it
• Greater understanding of the interrelationships of systems and technical subsystems
• Communication of current system knowledge to users through data flow diagrams
• Providing the basis for the initial technical specification of a system

Components of a Data Flow Chart

Entity: Represents external entities with which the system under study interacts, either receiving information to support their management or by sending product information for management.

Process: Shows a part of the system that transforms inputs into outputs; i.e., the functional components of the system. The process is usually named with a verb-object phrase.

Components of a Data Flow Diagram

Flow: Used to describe the movement of packets of information from one part of the system to another. Represents data in motion.

Warehouse: Physical or logical location where data is stored.

Levels of Data Flow Diagram

Context Diagram: The objective is to delineate the border between the system under study and the outside world by defining the information flows into and out of the system to its environment.

System Diagram: The first decomposition of the context diagram. It represents the main processes that take place in the system under study.