Data Flow Diagram Level 0 | Analisis dan Desain Sistem

Summary

This video delves into the creation of Data Flow Diagrams (DFD) Level 0, focusing on its role in providing a more detailed view than the context diagram. It explains the importance of entities, data flows, processes, and data stores, and how to break down a system into manageable components. The video also covers process numbering, the significance of data storage, and how to structure the diagram effectively. Examples from a grading system and order system are used to illustrate these concepts, helping viewers understand how to represent complex systems visually.

Takeaways

• 😀 The video discusses Data Flow Diagrams (DFD), focusing on DFD Level 0 and its distinction from a context diagram.
• 😀 DFD Level 0 is a more detailed version of the context diagram and shows internal processes, data flow, and data storage.
• 😀 Unlike the context diagram, DFD Level 0 contains multiple processes, each with its own data flow and data store.
• 😀 Entities from the context diagram must be included in DFD Level 0, along with the data flows to and from these entities.
• 😀 When expanding from the context diagram to DFD Level 0, all connections and data flows must be retained, ensuring nothing is omitted.
• 😀 DFD Level 0 uses process numbering (1, 2, 3, etc.), in contrast to the context diagram where there is usually only one process numbered '0'.
• 😀 Data stores in DFD Level 0 are numbered and named starting with 'D', followed by a number (e.g., D1, D2).
• 😀 The number of processes in DFD Level 0 is determined by the functional requirements list (e.g., 1.1, 1.2 for sub-processes).
• 😀 Process numbering in DFD Level 0 does not indicate the execution order of the processes; the focus is on data flow direction, not sequence.
• 😀 When creating DFD Level 0, it’s important to ensure all data flows are correctly represented, even if they come from different processes in the system.

Q & A

What is the main focus of the video discussed in the script?

The main focus of the video is about analyzing and designing system data flow diagrams (DFD), specifically focusing on Level 0 DFD, explaining how it differs from a context diagram, and how to develop and visualize the system processes and data flows.

How does DFD Level 0 differ from a context diagram?

DFD Level 0 provides a more detailed breakdown than the context diagram. While the context diagram shows a single process with external entities and data flows, DFD Level 0 introduces multiple internal processes, data flows, and data stores within the system.

What is the key principle to remember when expanding from a context diagram to a DFD Level 0?

When expanding from a context diagram to a DFD Level 0, it is essential to maintain all the connections, external entities, and data flows as they appear in the context diagram, ensuring nothing is omitted and that the data flows are consistent.

How should processes be numbered in a DFD Level 0?

In DFD Level 0, processes are numbered starting from 1, 2, 3, and so on. In contrast, the context diagram typically has only one process, numbered 0.

What is the purpose of creating a list of functional requirements when designing a DFD Level 0?

Creating a list of functional requirements helps in organizing and defining the necessary processes for the DFD Level 0, making it easier to identify how each process interacts with others and to assign proper data flows and stores.

Can processes in a DFD Level 0 be executed sequentially?

No, processes in a DFD Level 0 are not required to be executed in a sequential order. Unlike flowcharts, which represent sequential tasks, DFDs show the flow of data without implying a specific order of execution.

What does a data store represent in a DFD Level 0?

A data store in a DFD Level 0 represents a collection of data within the system that can be accessed or updated by the processes. Data stores are marked with a 'D' followed by a number, such as D1, D2, etc.

How are data flows handled if they go in both directions with the same name?

If data flows go in both directions with the same name, an arrow with a 'forked' head can be used to represent the bidirectional flow in the DFD, ensuring clarity in how data is transmitted in and out of the system.

What should you focus on when reading a DFD Level 0 diagram?

When reading a DFD Level 0 diagram, focus on the direction and integrity of the data flows. Ensure that all data entering or exiting the system is correctly linked to the appropriate processes and entities, and check that no flows are missing.

Why is it important to correctly place external entities in relation to processes in DFD Level 0?

Correctly placing external entities in relation to processes is important because it visually clarifies which processes interact with which entities. It helps in identifying the sources and destinations of data, making the system’s structure easier to understand.