ISOM221+Lecture+6+-+Process+Modeling+I

ISOM221+Lecture+6+-+Process+Modeling+I - ISOM221...

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ISOM221 Information Systems Analysis and Design Lecture 6: Process Modeling I 1 Agenda Understand the key definitions of DFD DFD elements Process Decomposition Relationship among Levels of DFD 2
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Key Definitions Process Model A formal way of representing how a business system operates Illustrates the activities that are performed and Illustrates the activities that are performed and how data moves among them Data Flow Diagramming (DFD) A common technique for creating process models 3 Key Definitions Logical process models describe processes without suggesting how they are conducted Physical process models provide information that is needed to build the system (i.e., how that is needed to build the system (i.e., how the system is physically and technically implemented) We focus on logical process models 4
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Reading a DFD (Supermarket Checkout) 5 Naming and Drawing DFD Elements Process Data flow Data store External entity 6
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Elements of a DFD Process An activity or function performed for a specific business reason Manual or computerized Data flow A single piece of data or a logical collection of data Always starts or ends at a process 7 Elements of a DFD (cont.) Data Store A collection of data that is stored in some way Data flowing out is retrieved from the data store Data flowing in updates or is added to the data store External entity A person, organization, or system that is external to the system but interacts with it People who execute a process are part of the process and are not regarded as external entities (e.g., data-entry clerks, order takers) People who use the information from the system to perform other processes or who decide what information goes into the system are regarded as external entities 8
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Using a DFD to Define Business Processes Business processes are too complex to be shown on a single DFD Decomposition is the process of representing
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This note was uploaded on 12/22/2010 for the course ISOM ISOM221 taught by Professor Sheunhhee during the Spring '09 term at HKUST.

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ISOM221+Lecture+6+-+Process+Modeling+I - ISOM221...

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