This level 2 diagram must balance with its “parent” process box - the data-flows to and from the process on the level 1 diagram will all become data-flows across the system boundary on the level 2 diagram. Make the process box on the level 1 diagram the system boundary on the level 2 diagram that decomposes it. How do you create a level 2 data flow diagram? It can be used to plan or record the specific makeup of a system. We can think of a level 1 DFD as an “exploded view” of the context diagram.Ī level 2 data flow diagram (DFD) offers a more detailed look at the processes that make up an information system than a level 1 DFD does. While a conceptual or logical Entity Relationship Diagram will focus on the high-level business concepts, a Data Dictionary will provide more detail about each attribute of a business concept.Įssentially, a data dictionary provides a tool that enables you to communicate business stakeholder requirements in such a way that your technical team can more easily design a relational database or data structure to meet those requirements.Ī level 1 DFD notates each of the main sub-processes that together form the complete system. Usually, DFD Level-0 is created with Data Dictionary during the project initial stage.Ī Data Dictionary, also called a Data Definition Matrix, provides detailed information about the business data, such as standard definitions of data elements, their meanings, and allowable values. It's a basic overview of the whole system or process being analyzed or modeled. Here are some examples of data stores: membership forms, database tables, etc.Ī data flow represents the flow of information, with its direction represented by an arrowhead that shows at the end(s) of flow connector.ĭFD Level 0 is also called a Context Diagram, shows a data system as a whole and emphasizes the way it interacts with external entities. A process can be decomposed to a finer level of details, for representing how data is being processed within the process.Ī data store represents the storage of persistent data required and/or produced by the process. For this reason, people used to draw external entities on the edge of a diagram.Ī process is a business activity or function where the manipulation and transformation of data take place. It is external to the system we study, in terms of the business process. It is where certain data comes from or goes to. External EntityĪn external entity can represent a human, system or subsystem. Now we'd like to briefly introduce to you a few diagram notations which you'll see in the tutorial below.
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