Tutorial / Interpreting data flow diagrams

Question 1

Define the following terms relating to data flow diagrams and give examples: external entity, data store, and process.

Question 2

Discuss the nested hierarchy of data flow diagrams.

Questions 3-7 are based on the Level 1 DFD below for a railway reservation system.

Question 3

Prepare a Level 0 DFD (context diagram) for this system.

Question 4

List the external entities, data stores, and processes in the Level 1 DFD.

Question 5

Explain the flow of passenger reservation data from when a passenger enters their details until the reservation is stored. Include the processes and data stores involved.

Question 6

Describe the relationship between the 'create reservation' and 'check availability' processes. How does the system ensure a reservation is only made for available trains and seats?

Question 7

How does the 'reservation clerk' interact with the system? What processes can the clerk initiate, and what data flows result from their interaction?