Information system development traditional approach requirement

Matakuliah : M0054 Information System Development Tahun : 2012 Topic The Traditional Approach Requirement Rules Read active Bina Nusantara assignments only On time! ask questions Requirements On time! Bina Nusantara PERMISSION TO LEAVE PROHIBITED BEHAVIOUR Traditional Approach Requirement Points to discuss : • Traditional vs Object Oriented Approaches • Requirements for the Traditional and OO Approaches • Data Flow Diagram Bina Nusantara Traditional vs Object-Oriented Approaches Figure 6-1 Systems Analysis and Design in a Changing World, 5th Requirements for the Traditional and OO Approaches Figure 6-2 Systems Analysis and Design in a Changing World, 5th Data Flow Diagrams (DFDs) • Graphical system model that shows all main requirements for an IS in one diagram – Inputs/outputs – Processes – Data storage • Easy to read and understand with minimal training Systems Analysis and Design in a Changing World, 5th Data Flow Diagram Symbols Figure 6-3 Systems Analysis and Design in a Changing World, 5th DFD Fragment Showing Use Case Look Up Item Availability from the RMO Figure 6-4 Systems Analysis and Design in a Changing World, 5th DFD Integrates Event Table and ERD Figure 6-5 Systems Analysis and Design in a Changing World, 5th 10 RMO Subsystems and Use Cases/Activities from Event Table Figure 6-10 Systems Analysis and Design in a Changing World, 5th 19 Context Diagram for RMO Order-Entry Subsystem Figure 6-11 Systems Analysis and Design in a Changing World, 5th 20 Five Separate DFD Fragments for RMO Order-Entry Subsystem Figure 6-12 Systems Analysis and Design in a Changing World, 5th 21 Decomposing DFD Fragments • Most DFD fragments can be further described using structured English • Sometimes DFD fragments need to be diagrammed in more detail • Decomposed into subprocesses in a detailed DFD • DFD numbering scheme – Hierarchical decomposition • DFD Fragment is decomposed into Diagram • Diagram has processes 2.1, 2.2, 2.3, 2.4 Systems Analysis and Design in a Changing World, 5th 22 Detailed DFD for Create new order DFD Fragment Figure 6-14 Systems Analysis and Design in a Changing World, 5th 23 Physical and Logical DFDs • Logical model – Assumes implementation in perfect technology – Does not tell how system is implemented • Physical model – Describes assumptions about implementation technology – Developed in last stages of analysis or in early design Systems Analysis and Design in a Changing World, 5th 24 Physical DFD for Schedulin g Courses Figure 6-15 Systems Analysis and Design in a Changing World, 5th 25 Evaluating DFD Quality • • • • Readable Internally consistent and balanced Accurately represents system requirements Reduces information overload – rule of +/- – Single DFD should not have more than +/-2 processes – No more than +/- data flows should enter or leave a process or data store in a single DFD • Minimizes required number of interfaces Systems Analysis and Design in a Changing World, 5th 26 Data Flow Consistency Problems • Differences in data flow content between a process and its process decomposition • Data outflows without corresponding inflows • Data inflows without corresponding outflows • Results in unbalanced DFDs Systems Analysis and Design in a Changing World, 5th 27 Consistency Rules • All data that flows into a process must – Flow out of the process, or – Be used to generate data that flows out of the process • All data that flows out of a process must – Have flowed into the process, or – Have been generated from data that flowed into the process Systems Analysis and Design in a Changing World, 5th 28 Unnecessary Data Input: Black Hole Figure 6-16 Systems Analysis and Design in a Changing World, 5th 29 Process with Impossible Data Output: a Miracle Figure 6-17 Systems Analysis and Design in a Changing World, 5th 30 Process with Unnecessary Data Input Figure 6-18 Systems Analysis and Design in a Changing World, 5th 31 Process with Impossible Data Output Figure 6-19 Systems Analysis and Design in a Changing World, 5th 32 Documentation of DFD Components • Lowest-level processes need to be described in detail • Data flow contents need to be described • Data stores need to be described in terms of data elements • Each data element needs to be described • Various options for process definition exist Systems Analysis and Design in a Changing World, 5th 33 ... questions Requirements On time! Bina Nusantara PERMISSION TO LEAVE PROHIBITED BEHAVIOUR Traditional Approach Requirement Points to discuss : • Traditional vs Object Oriented Approaches • Requirements... Requirements for the Traditional and OO Approaches • Data Flow Diagram Bina Nusantara Traditional vs Object-Oriented Approaches Figure 6-1 Systems Analysis and Design in a Changing World, 5th Requirements... Requirements for the Traditional and OO Approaches Figure 6-2 Systems Analysis and Design in a Changing World, 5th Data Flow Diagrams (DFDs) • Graphical system model that shows all main requirements