DFD-Basics

DFD-Basics - DFD Basics Yong Choi BPA CSUB Creating Data...

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DFD Basics Yong Choi BPA CSUB
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Creating Data Flow Diagrams Steps: 1. Create a list of activities 2. Construct Context Level DFD (identifies external entities and processes) 3. Construct Level 0 DFD (identifies manageable sub process ) 4. Construct Level 1- n DFD (identifies actual data flows and data stores ) 5. Check against rules of DFD
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How to find each one… External Entities (EE) people/organizations/things that supply information to or use information from the system Processes (P) actions/doing words/verbs Data Flows (DF) movement/exchange of information/data between external entities to processes, and processes to processes Data Stores (DS) store/record information/data
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Apply logical sequence of the system. . A student (EE) sends in an application form (DF) containing their personal details, and their desired course The university checks (P) that the course is available. If the course is available the student is enrolled (P) in the course, and the university confirms (P) the enrolment by sending a confirmation letter (DF) that they are registered for the course to the student. Or if the course is unavailable the student is sent a rejection letter (DF).
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DFD Naming Guidelines External Entity Noun Data Flow Names of data Process verb phrase a system name a subsystem name Data Store Noun
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Level 0 Tips Generally move from top to bottom, left to right Minimize crossed lines Iterate as needed The DFD is often drawn many times before it is finished, even with very experienced systems analysts
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This note was uploaded on 02/10/2011 for the course MBA mba taught by Professor Mba during the Spring '11 term at IIT Bombay.

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DFD-Basics - DFD Basics Yong Choi BPA CSUB Creating Data...

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