Behavioral Model

Data Flow Diagram Entity Relationship Diagram

Data DictionaryProcess Specifications State-transition diagrams

Data Flow DiagramA Graphic tool used to describe and analyse the movement of data flowing into the system , between processes and in and out of data stores

Data Flow DiagramExploding the Context DiagramGoing from higher level to lower is called exploding a data flow diagram

Developing the First Level Physical Data Flow Diagram for our Payroll Monitoring System

Types of Data Flow DiagramsThe physical DFD is a model of the current system and is used to ensure that the current system has been clearly understood. Physical DFDs show actual devices , departments and people involved in the current system Logical DFDs are the models of the proposed system. They should clearly show the requirements on which the new system should be built. Later during design activity this is taken as the basis for drawing the system structure charts

First Level DFD The New Employee Data from the filled appointment form is entered into the respective departments employee register by the administration clerk Administration clerk makes changes in the employee register wherever required The months transaction list is written out after the following gather the following details Months attendance details are obtained from the attendance register Day-wise O.T data obtained from the O.T register Advance salary details obtained from the advance salary vouchers obtained from the accounts departments

First Level DFD Now using this transaction list and the details from the employee register the payroll of each employee is calculated. The payroll statement of the month is prepared using the calculated figures

The payroll statement forms the basis for typing out the payslips and the bank statement and salary statement The payslips are handed over to the employees of the respective departments and the bank statement is sent to the banks

First Level DFD

Second Level Data Flow DiagramThe Second Level DFD for obtaining months transaction process for payroll calculation Administration clerk gets the attendance register from the respective department and calculates the days absent of each employee He also gets the day-wise O.T register and totals the O.T hours of each employee The accounts departments supplies the admin clerk with the advance salary taken details through vouchers Having got this he makes out a months transaction list containing days absent ( if any ) , total O.T hours and advance salary taken for each employee

Second Level DFDFor Calculation process of the payroll system

That the administration clerk checks the employee register and by passes all exit cases For each non-exit case he checks the transaction list for any transactions of that particular employee He then uses the data present in the employee register and the transaction list to calculate the payroll for the month

Deriving the Logical ViewA Logical DFD is derived from the Physical version by doing the following

Showing the actual data needed in a process , not documents that contain them eg : show new emp.dat rather than appointment form Remove routing information , that is , show the flow between procedures not between people , offices or locations Remove tools and devices such as folders files etc Consolidate redundant data stores Remove unnecessary processes , such as those that do not change the data or data flows

General rules for drawing Data Flow Diagrams

Validation of Data Flow Diagrams