7COM1014 | Comparative Modelling of a System | Systems Modelling

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A system is to be developed for a small bank. The bank employs cashiers for transactions, but customers can withdraw money from an Automated teller machine (ATM).

Any prospective client may have an account opened with the bank; at this point, they will be assigned a unique account number and given a folder for their personal details along with details of the services provided by the bank.

Based on the information given below you are asked to construct an Entity Relationship (ER) Diagram (15 marks), Context (Level 0) Data Flow Diagram (10 marks) and a Level 1 Data Flow Diagram (25 marks) for the system.

The marks will be weighted by 4/5 to arrive at a total of 40.

Information for Process- and Data Modelling

Customers send customer details and requests to open an account or make changes in existing accounts (details, closing accounts, transactions, et cetera). These issues are dealt with by bank staff. Bank staff use the bank system to check, create, amend and delete accounts as well as to check and amend customer details.

The bank staff are informed back about the state of the processes inside the banking system that deal with handling customer details and with handling accounts.

The banking system processes and stores the customer details and account requests. The data base is queried in case customer details are needed for handling accounts. Transactions, such as depositing or withdrawing money, are dealt with on the basis of account requests, information about customer identity, and the state of the accounts retrieved from a database.

Customers are informed about transactions and the state of their account by the banking system.

Things to do

1. The bank wishes to keep accurate records of ATMs, bank staff, customers and their accounts which includes regular checks on the balance of every account.

Set up an ER Diagram (ERD) which allows the bank to store and query these records. The entities should be named, but - apart from names of valid keys - declaring attributes is optional.

2. Set up a Context Data Flow Diagram (DFD) (Level 0) for the system.

Draw the ERD and the Level 0 DFD using any method or material you like (by hand, in Power Point, Microsoft Visio, MySQL Workbench et cetera) but copy and paste the diagrams into a WORD document with a title of the following format: “Surname SRN CW Exercise 1 2” (e.g. “Johnson 1234 CW Exercise 1 2”). Submit the document to Canvas before 29 April, 23:00.

3. Set up a Level 1 DFD for the system.

This should be done by completing the Excel Spreadsheet “CW Systems Modelling Exercise”. How to do this is described in the following pages. After completion submit the spreadsheet with a title of the following format: “Surname SRN CW Exercise 3” (e.g. “Johnson 1234 CW Exercise 3”). Submit the document to Canvas before 29 April, 23:00.

Instructions for completing the spreadsheet CW Systems Modelling Exercise

Open the spreadsheet CW Systems Modelling Exercise.

The spreadsheet contains a DIAGRAM and three TABLES (TABLE 1, 2 and 3) (Fig. 1). The DIAGRAM contains empty ellipses and boxes, which are the (yet undefined) elements of a DFD.

DO NOT TAMPER WITH THE LAYOUT OF THE SPREAD SHEET! Do not enter additional ellipses or boxes. The position and size of the slots for tables and diagram should remain intact for automated marking.

Your task for this course work is the completion of the diagram and the tables; if done correctly, the result is an accurate Level 1 DFD of the system. To achieve this you should:

1.  Classify and label the elements.
2.  Insert data flows.
3. Define the data flows.
4. Specify the links between elements by defined data flows in a connection matrix.

1. Classifying Elements In TABLE 1 classify the Type of Element by writing its name in the cell next to the corresponding letters (A to H). Also, add an appropriate Label. You are free to choose any name, as long as it makes sense.

2. Inserting data flows Insert arrows or elbow arrow connectors representing data flows to link elements.

Figure 2

Do this by clicking the Insert label on the ribbon and then selecting Shapes. Click on the connector of your choice (an Arrow for straight connections, or else an Elbow Arrow, see Fig. 2), hover the mouse over the element from which you want a data flow to leave until the connection points of an attachment marker  show up, and click. The connector will now be attached. Next, click the end-point of the connector and drag it to an attachment-marker of the element to which it should be linked (Fig. 3). Use the yellow adjustment handle to change the shape of the connector if needed.  Choose and shape the connectors so that no data flow in the diagram intersects with any other.

Figure 3

Do not insert more than 16 data flows in the diagram

Defining data flows Click on the Text Box icon (under the Insert tab, see Fig.4) and insert a text box along an arrow representing a data flow in the diagram. The text box is going to function as a tag and for this you should write an identification number in the text box. These identification numbers (1 – 6) are listed in TABLE 2.


Figure 4

To define the data flows, the identification numbers should match to corresponding labels. This done in TABLE 2 by writing appropriate labels next to the listed identification numbers.
Note that the identification numbers in TABLE 2 are coloured. Colour the data flows with the colour of the corresponding identification numbers tagged to them. Do this by clicking on a data flow connector with the right-hand mouse button. From the option box that appears, click on the Shape Outline icon to select a colour (Fig. 5).