CLASSIC DESIGN DATA FLOW DIAGRAM Before UML to be created (the current paradigm of diagrams to turn programming code) used for computer flow charts to visually represent the data flow through systems for information processing. They were the cominezos of Diagrams in Computer Science. The flow charts describe what operations and in what sequence are required to solve a problem dado.Un flowchart or organizational chart is a representation that illustrates the sequence of operations to be performed to achieve the solution of a flow chart problema.El Data (DFD) is one of the most important tools used by systems analysts. The use of data flow diagrams as a modeling tool was popuralizado by De Marco (1978) and Gane and Sarson (1979), through its structured methodologies for systems analysis. They suggested that the data flow diagram is used as a first tool for analysts to model system components system. These components are the system processes the data used by these processes, external entity that interacts with the system and information flows of the system.
Now describe each of the four parties that form a DFD a) – The processes are what makes the system. Each process has one or more data inputs and produces one or more data outputs. Are represented by circles. b) – A file or data warehouse is a repository of data. Processes can enter or retrieve them.
Each data store is represented by a thin line and has a unique name. c) – External entities outside the system, but they provide or use data from it. They are entities over which the designer has no control. d) – And the most important are the data flows that model the movement of information in the system and are represented by lines connecting the components. The flow direction is indicated by an arrow, and the line with the name of the data flow. It must be recognized that the classical charts and was a bit DFD abstract, and thank goodness for the good of the designers that evolved in a more clear and concise so you do not give errors when translated to a programming language. As a preview to the next type of diagrams tell you what are called Entity-Relationship Model and is what is being used now to design applications, also known as ER diagrams, and was a key concept when it comes to appear 'Classes' and' objects' but all I'll leave this breakthrough for a next installment.