Process analysis and design, , wixom, and M. Roth © 2015 John Wiley & Sons. All Rights 1Learning Objectivesq Explain the rules and style guidelines for data flow diagramsq Describe the process used to create data flow diagramsq Create data flow diagrams © 2015 John Wiley & Sons. All Rights 2Key Definitionsq Process model. o A formal way of representing how a business process. operates. o Illustrate activities that are performed and how data moves. between them. o Logical process models describe processes without. suggesting how they are conducted o Physical process models include process implementation. Data flow diagramming. o A popular technique for creating process models. © 2015 John Wiley & Sons. All Rights 3Data Flow do dfds tell us?. © 2015 John Wiley & Sons. All Rights 4Reading . © 2015 John Wiley & Sons. All Rights 5DFD Elements q Process. o An activity or function performed for a specific. business reason. o Can be manual or computerized. o Includes the following:. • A number. • A name (verb phrase). • A description. • At least one output data flow. • At least one input data flow. © 2015 John Wiley & Sons. All Rights 6DFD Elements, con’t. q Process, con’t o Logical process models omit any processes. that simply move or route data and leave the. data unchanged o You do include logical processes that:. • Perform computations (., calculate grade point. average). • Make decisions (., determine availability of ordered. products). • Sort, filter or otherwise summarize data (., identify. overdue invoices). • Organize data into useful information (., generate a. report or answer a question). • Trigger other processes (., turn on the furnace or. instruct a robot). • 2015 John Wiley & Sons. All Rights update or delete a 7. © Use stored data (create, read,DFD Elements, con’t. q Data flow. o A single piece of data or a logical collection of. data. o Data Flow names describe the content of the. data flow but not how it is implemented. o Always starts or ends at a process. o Includes the following:. • A name (noun). • Description. • One or more connections to a process. © 2015 John Wiley & Sons. All Rights 8DFD Elements, con’t. q Data flow, con’t o A data flow is data in motion • an input of data to a process, or the output of data (or. information) from a process • the creation, deletion, or update of data in a file or. database (called a data store on the DFD) • A data flow is depicted as a solid-line with arrow • Control flows (non-data flows) trigger processes, such. as ‘time to run the weekly payroll’. • The control flow is depicted as a dashed-line with arrow © 2015 John Wiley & Sons. All Rights 9DFD Elements, con’t. q Data Store. o Most information systems capture data for later. use o A data store is a collection of data that is. stored in some way. o Include the following:. • A number. • A name (noun). • Description. • One or more input data flows (somewhere in process. model). • One or more output data flows (somewhere in process. model). © 2015
