The Place Order process also passes the Transaction details to the Stock Exchange Center, which is an entity out of the system scope. The result is that he will receive the Withdrawn amount and the Updated account balance will be stored in the Account data store.įinally, both the Customer and Broker can initiate the Place Order process, which results in the Transaction details being stored in the Transaction data store. The process Check Transaction receives Transaction details from the Transaction data store and pass it on to Customer.Ī Customer can Deposit Cash by providing the Deposit amount and the result is the Updated account balance being stored in the Account data store. If this information is important and worth mentioning, consider to model it with diagrams like BPMN Business Process Diagram or UML Activity Diagram. Note that Data Flow Diagram does not answer in what way and in what order the information is being used throughout a system. Strictly speaking, the diagram only tells us the Open Account process receives customer details and produce customer and account details, with no order specified. It is our common sense that lead us to interpret the diagram in the way that we understand it naturally. Although we said that the attempt to store customer and account details happens after the details are being provided by the Customer Service Assistant, the Data Flow Diagram implies no such thing. The result is the Customer details being stored in Customer data store and Account details being stored in Account data store. Although there is no design guidelines that governs the positioning of shapes in a Data Flow Diagram, we tend to put the processes in the middle and data stores and external entities on the sides to make it easier to comprehend.īased on the diagram, we know that a Customer Service Assistant provides customer details to the Open Account process. The securities trading platform Data Flow Diagram example contains five processes, three external entities and three data stores. Read through the diagram, and then we will introduce some of the key concepts based on this diagram. break down) of the securities trading platform process shown in the context DFD. The figure below shows the level 1 DFD, which is the decomposition (i.e. It contains one and only one process and does not show any data store. In between the process and the external entities, there are data flow (connectors) that indicate the existence of information exchange between the entities and the system.Ĭontext DFD is the entrance of a data flow model. In this example, CS Assistant, Customer and Broker are the entities who will interact with the system. It also shows the participants who will interact with the system, called the external entities. It contains a process (shape) that represents the system to model, in this case, the " securities trading platform". The figure below shows a context Data Flow Diagram that is drawn for a security trading platform. The Securities Trading Platform Example Context DFD
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