Data Flow Diagram
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Data Flow Diagram (DFD) is the part of the SSADM method (Structured Systems Analysis and Design Methodology), intended for analysis and information systems projection. Data Flow Diagrams are intended for graphical representation of data flows in the information system and for analysis of data processing during the structural projection. By means of data flow diagrams, it is possible to show visually the work of the information system and the results of this work. Data Flow Diagram visualizes processes, data depositories, and external entities in information systems and data flow connecting these elements. Data Flow Diagram consists of the following components:
This variant of presentation of Data Flow Diagram objects got the name of Yourdon – de Marco notation.
Objects of Data Flow Diagrams are interpreted in the following way:
Every diagram object should have a name. Each data flow is denoted with an indication of transferred data and with the possibility of an indication of the format of these data. Data Flow Diagram should not involve more than 10 objects, excluding arrows, representing data flows. In the case of a more complicated system, the totality of several objects (as a rule, processes) is united and represented on the diagram in the form of one object. This complicated compound object is presented in the form of a separate flow diagram. Each component has a number, at this, diagrams illustrating compound objects are numerated starting from the number of an object which they describe. For example components of the diagram of the description of an object with number 5 will be enumerated 5.1, 5.2, etc. Generally, Process Flow Diagram depicts just the major equipment without details. For clearness, there is a possibility to duplicate notations of used data depositories and external entities. Processes can’t be duplicated. For example, if one the same data depository is used in several different processes it is better to duplicate it on the diagram but not to create several intricate data flow arrows from one object to several processes. This concerns external entities as well. Duplicates of data depositories are marked with the double line from the left side, external entities duplicates - with the asterisk. Data flow on the diagram can ramify and merge which implies branching or confluence of data in the information system. |
Example 1. Data Flow Diagram
Thus the information system is represented by a planner in the form of the high-level DFD in which objects are worked out in detail by diagrams of the lower level with the preset level of detailed elaboration. There is also another way of looking at which all events in the system are described at once and each event is represented in the form of process transforming data flows, further these sub runs are grouped for getting diagrams of the higher level.
Example 2. Data Flow Diagram in ConceptDraw DIAGRAM
The following features make ConceptDraw DIAGRAM extended with Data Flow Diagrams Solution the best Data Flow Diagram software:
- You don't need to be an artist to draw professional-looking diagrams in a few minutes.
- Large quantity of ready-to-use vector objects makes your drawing diagrams quick and easy.
- A great number of predesigned templates and samples give you a good start for your own workflow diagram or process flow diagram.
- ConceptDraw DIAGRAM provides you the possibility to use the grid, rules, and guides. You can easily rotate, group, align, arrange the objects, use different fonts and colors to make your organizational workflow diagram exceptionally looking.
- All ConceptDraw DIAGRAM documents are vector graphic files and are available for reviewing, modifying, and converting to a variety of formats: image, HTML, PDF file, MS PowerPoint Presentation, Adobe Flash, MS Visio.
- Using ConceptDraw STORE you can navigate through ConceptDraw Solution Park, managing downloads and updates. You can access libraries, templates, and samples directly from the ConceptDraw STORE.
- If you have any questions, our free of charge support is always ready to come to your aid.
TEN RELATED HOW TO's:
Data Flow Diagrams →
There are a lot of structured analysis and design technique methodologies used to describe systems and data sources. To visualize data structures, data flow diagrams can be used for various purposes in the area of software engineering. Nowadays these diagrams are also used in the area of business analysis and information system analysis. This data flow diagram depicts an account processing system of a typical account department of a small manufacturing enterprise. It shows the data transmission through the order processing to shipping verification. This data flow diagram was created according to standard of Yourdon and Coad notation. The vector graphic objects of Yourdon/Coad notation symbols was delivered by ConceptDraw Data Flow Diagrams solution. The current DFD can be employed as an example of a business process model, representing the set of business events and interactions commonly engaged in a accounts receivable process.
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Data Flow Diagram (DFD) →
In software engineering, it is important to understand how the system would cooperate with external sources, like data sources. To give this information a visual representation, data flow diagrams (DFD) were used for years. The entire system is usually divided into smaller ones, and all of them process data flows in appropriate ways. The visualizing business processes which engages the data transfer, is commonly preformed using DFDs (data flow diagrams). DFD is used to show the data flow processing and transformation. This DFD represents the electronic system of a customer purchase. It was created using Gane/Sarson notation. Data flow diagrams helps you to sort through and clarify transferring process making it available for analysis, and representation. ConceptDraw DFD solution introduces the vector library, containing the full set of icons from DFD notations.
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A waterfall model describes software development process as a sequence of phases that flow downwards. SSADM is one of the implementations of waterfall method. It’s easier to learn about structured systems analysis and design method (SSADM) with ConceptDraw DIAGRAM because this software has appropriate tools for creating data flow diagrams. You can use all the three main techniques of SSADM method with special tools and predesigned templates. This data flow diagram illustrates the Structured Systems Analysis and Design Method. This method method considers analysis, projecting and documenting of information systems. Data flow models are the most important elements of SSADM and data flow diagrams are usually used for their description. It includes the analysis and description of a system as well as visualization of possible issues.
DFD Library System →
The diagrams with highest level in the hierarchy define the main processes or subsystems with external and internal data sources. To detail them, DFD Library is used to build a system of lower level diagrams. This decomposition continues hereinafter it is meaningless. This data flow diagram of a system of a library management is a context-level DFD. The data flow diagram of this type depicts the large system as a solid process, and does not input any explanation of its content. It is an ordinary practice - creation of a context-level data flow diagram when starting system development. This DFD was made using ConceptDraw solution designed especially for data flow diagrams development. One can find out Data Flow Diagrams Solution in a Solution Park of ConceptDraw and can use in as addition to the common Conceptdraw DIAGRAM diagramming tools.
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