The DFD example here shows the level 1 DFD, which is the decomposition (i.e. break down) of the system shown in the Context DFD. The Data Flow Diagram example contains three processes, two external entities and three data stores. 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.

Based on the diagram, we know that the Perform Inspection process provides Bill to the Customer and store the Inspection result into the Inspection data store.

The DFD example here shows a context Data Flow Diagram drawn for a vehicle maintenance depot system. It contains a process (shape) that represents the system to model, in this case, the "vehicle maintenance depot system". It also shows the participants who will interact with the system, called the external entities. In this example, Customer and Mechanics are the entities who will interact with the system. 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.

The DFD example here shows the level 1 DFD, which is the decomposition (i.e. break down) of the Supermarket App process that is shown in the Context DFD. Read through the diagram and then we will introduce some of the key concepts based on this.

The Supermarket App Data Flow Diagram example contains five processes, one external entity and three data stores. Although there is no design guideline 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.

The data flow diagram example here shows a context Data Flow Diagram that is drawn for an Android supermarket app. It contains a process (shape) that represents the system to model, in this case, the "Supermarket App". It also shows the participants who will interact with the system, called the external entities.

In this example, there is only one external entity, which is the Customer. In between the process and the external entity, there is a bi-directional connector, which indicates the existence of information exchange between customer and the app, and the information flow is bi-directional.

The DFD example here shows the level 1 DFD, which is the decomposition (i.e. break down) of the CS System process shown in the Context DFD. Read through the diagram and then we will introduce some of the key concepts based on this diagram. The CS System Data Flow Diagram example contains four processes, two external entities and four data stores. 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.

Based on the diagram, we know that a Passenger can receive Transport details from the Inquiry Transport Details process, and the details are provided by the data stores Transport Details and Railway Live Statistic. While data stored in Transport Details are persistent data (indicated by the label "D"), data stored in Railway Live Statistic are transient data that are held for a short time (indicated by the label "T"). A callout shape is used to list out the kind of details that can be inquired by passenger.

The data flow diagram example here  shows a context Data Flow Diagram that is drawn for a railway company's Customer Service System. It contains a process (shape) that represents the system to model, in this case, the "Customer Service System". It also shows the participants who will interact with the system, called the external entities.

In this example, Customer Service Assistant and Passenger are the two entities who will interact with the system. 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.

The DFD example here shows the level 1 DFD, which is the decomposition (i.e. break down) of the securities trading platform process shown in the Context DFD. Read through the diagram, and then we will introduce some of the key concepts based on this diagram.

The securities trading platform Data Flow Diagram example contains five processes, three external entities and three data stores. 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.

The DFD example here shows a context Data Flow Diagram that is drawn for a security trading platform. It contains a process (shape) that represents the system to model, in this case, the "securities trading platform". It also shows the participants who will interact with the system, called the external entities.

In this example, CS Assistant, Customer and Broker are the entities who will interact with the system. 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.