Applications are designed according using a system development life cycle, which passes through several phases including requirements gathering, design, implementation, testing, and maintenance. We describe the application design process by designing an information system for Riordan Manufacturing, Inc., an industry in the field of plastic injection moulding. The first step of design is to identify the processes and the entities. Processes represent the operations performed by the system. Entities represent all the information sources of the system. We represent the entities and the processes in the data flow diagrams, DFD. While designing the DFD’s we increase the level of detail with each level. At each level the process divides into sub-processes until indivisible sub-processes are reached. Here is an example.
Data Flow Diagram 0:
Here we represent the information system at Riordon Manufacturing Inc. The information system comprises of :
Employees are the people working for Riordan Inc. Their job is to make innovative plastic designs of international acclaim, help in the production of the finished plastic products from these designs,etc. They include the Chemical Engineers, Labour, etc.
The Clients or the customers are the people who give orders to purchase the finished products developed in the industry.
Manager is also an employee at Riordan Inc. but his job is more important as he has to manage the whole Information System. He has to look into the Sales and the Accounting and also talk with the Clients. He also listens to the problems of the employees and the complaints from the Clients and takes the corrective measures.
Visitors are the group of people who visit the industry's website to gather information about the company and its products but are not interested in placing the orders right now.
Data Flow Diagram 1
Here the Information System shown in the Data Flow Diagram 0 is divides into the following modules:
The production module at Riordan Inc. is linked with the Sales and the Accounting modules. The amount of production is directly linked to the sales, if the sales in a particular financial year are high then the production is stepped up, on the other hand if the sales are low then the production is slowed down.
Production module is also directly linked to the Accounting module as the cost of production and the raw materials purchased by the company for the production are directly a part of the Accounting process.
The sales module is linked with the Clients and the Manager. The Clients place the order for the products which leads to sales and the Manager manages the whole sales process.
The accounting process is linked to the Sales and the Production modules as they directly affect the Accounting at Riordon Inc. Employees and the Clients have also been linked to the module as employees take their salary from the company bank accounts and the Clients deposit the cheques in the bank accounts.
In the DFD it has been shown that the employee controls the production system. The production system sends the details to the stock (inventory database). The sales module takes the updates from the stock inventory to check whether the products being ordered by the customer are actually available or not. If they are not then the product request is rejected otherwise accepted.
The accounting process subtracts the salary of the employees from the accounts of the company. It also adds the earnings from the Clients and other sources like the government funds,etc. to the accounts database.
Manager finalises the sales decisions and supervises the accounting process.
Data Flow Diagram 2
Each module has been divided into the various...