Complete the following exercises from the Process Modelling Workbook available from Blackboard under Assignment Two: Workflow Modelling with DFDs section. These exercises aim to further develop your familiarity with the concepts and terms of workflow modelling using data flow diagrams for this assignment.
6.1 Data Flow Diagram Exercises
For the exercise below:
- Produce a System outline (refer to page 2) (20 Marks)
- Produce a Context Diagram. (30 Marks)
- Produce a Top Level Dataflow Diagram. (50 Marks)
6.2.5 Rodney Gas Billing System
Rodney has just begun to provide gas to a limited number of customers. It is expected that the number of customers will increase as further gas pipes are installed. Currently the billing is done manually, but it is planned to computerise the system in anticipation of increased volumes of users. You have been requested to investigate the system and prepare a system proposal.
This is what you have found out from your information gathering;
The meter reader visits the gas customers every six weeks in order to read their gas meter. When all readings have been logged for the period, the meter reader brings the log into head office where the accounts clerk copies the readings into a “Customer Gas Meter Readings” file which contains, for each customer, details of their previous readings.
To produce the bills for the customers, the accounts clerk subtracts the customer’s previous meter reading from their current reading, in order to find the total vol- ume of gas used for the period. This is multiplied by the gas charge rate which the clerk finds in a “Gas Charge Rates” file. If this is the first bill for the customer, a charge for installation may be added, and sometimes there are maintenance charges. These extra charges are supplied by the Maintenance Department. The gas charge rates are set annually by management. All charge amounts are added to any previous amounts owed which are found for the customer in the “Outstanding Bills” file. The current bill is posted to the customer.
Customers post their payments to the Rodney offices. The payments are banked and a “List of Deposits” is returned by the bank. This list is compared to the “Outstanding Bills” and paid bills are placed in the “Paid Invoices” file. Partial payments are recorded on the matching bill which remains in the “Outstanding Bills” file.
For the Rodney Gas Billing System
- Produce a System outline (as below refer to page 2 of Litchfield(2017)) (20 Marks)
System Outline
Title System Document Name Sheet
Input Processes
Files (Datastores)
Outputs
External Entities
Author Date
Figure 1.1: Sample system outline. A large collection of these will be created to meet the needs of a complex system.
- Produce a Context Diagram. (30 Marks)
- Produce a Top Level Dataflow Diagram. (50 Marks)