Copyright 2002 Prentice-Hall, Inc. Modern Systems Analysis and Design Chapter 8 Structuring System Requirements: Process Modeling 8.1

Process Modeling Modeling a system’s process Utilize information gathered during requirements determination and organized it into meaningful representation (DFD). Example: Hoosier Burger is a restaurant that uses an information system that takes customer orders, send them to the kitchen monitors goods sold and inventory, and generates reports to the management. 8.2

Process Modeling Context data flow diagram (DFD)  Scope of system 8.3

Figure 8-4 Context diagram of Hoosier Burger’s food ordering system 8.4

Four symbols are used in DFD process. data store source/sink (represent external entity) data flow Two different standard sets can be used  DeMarco and Yourdan  Gane and Sarson 8.5

DFD Elements

Data Flow Depicts data that are in motion and moving as a unit from one place to another in the system. Drawn as an arrow Select a meaningful noun to represent the data 8.7

Data Store Depicts data at rest May represent data in  File folder  Computer-based file  Notebook The name of the store as well as the number are recorded in between lines 8.8

Data Flow Diagramming Mechanics Process Depicts work or action performed on data so that they are transformed, stored or distributed Number of process as well as name are recorded 8.9

Source/Sink Depicts the origin and/or destination of the data Sometimes referred to as an external entity Drawn as a square symbols 8.10

Data Flow Diagramming Definition Context Diagram A data flow diagram (DFD) of the scope of an organizational system that shows the system boundaries, external entities that interact with the system and the major information flows between the entities and the system  Represents the whole system as one process (black box)  Has external entities  Has data flows  No data stores 8.11

A video shop (1) A customer can order a video tape, the video shop will deliver the video with a delivery note and an invoice. The system also can send a purchase order for the distributor and the distributor will send a delivery note after delivering.

A video shop (1) (context level) Process Orders Customer Distributor customer order Purchase order invoice Delivery note

example WEPAY specializes in processing payroll for small businesses. The company uses an application written for PC to process its customers’ payroll. Following is a description of the payroll system at WEPAY. Client companies send a time sheet report of their employees’ total hours for the pay period to WEPAY. The clerk at WEPAY uses the time sheet report to update the company’s employee payroll data file. Once the employee payroll data file has been updated, the payroll information is used to generate the payroll invoice and pay checks. Payment entries are also made to the general ledger by the clerk. The invoice, along with the pay checks, are then sent to the client company.

Employees at Perks Travel are evaluated by the Personnel Department periodically. Employees in each branch prepare and submit their dossiers to the branch manager. The manager reviews the dossiers and the employees’ previous performance as described in the branch personnel file and makes his/her recommendations (promotions, demotions, etc.) to the personnel department. The manager also gives the initial feedback to the employees. A personnel evaluation committee, headed by the manager of the Personnel Department, examines the recommendations of the branch managers and makes final evaluations. The central personnel file is then updated accordingly. The branch managers and the employees are informed of the final decisions. In the case of a promotion, the employee gets the feedback in the form of a new title, added responsibilities, raises in salary, etc…Salary adjustments are sent to the payroll department, where the payroll file is updated accordingly. When the branch manager receives the final evaluation, he/she updates the branch personnel file.