1. System Analysis System Analysis - Mr. Ahmad Al-Ghoul System Analysis and Design

2. Avicenna System Analysis and Design System Analysis2 Learning Objectives Discuss and draw the Lower-Level Diagrams Discuss and draw the Lower-Level Diagrams Explain how to level and balance a set of data flow diagrams Explain how to level and balance a set of data flow diagrams Explain when to stop leveling Explain when to stop leveling Explain how to validate the DFDs Explain how to validate the DFDs Distinguish between logical and physical DFDs Distinguish between logical and physical DFDs

3. Avicenna System Analysis and Design System Analysis3 Creating a Set of DFDs Draw the Lower-Level Diagrams Draw the Lower-Level Diagrams Business processes are too complex to be shown on a single DFD Business processes are too complex to be shown on a single DFD Must use leveling and balancing techniques Must use leveling and balancing techniqueslevelingbalancinglevelingbalancing leveling is the process of representing the system in a hierarchy of DFD diagrams leveling is the process of representing the system in a hierarchy of DFD diagrams leveling Uses a series of increasingly detailed DFDs to describe an information system Uses a series of increasingly detailed DFDs to describe an information system leveling also is called Exploding, partitioning, or decomposing leveling also is called Exploding, partitioning, or decomposingExplodingpartitioningdecomposingExplodingpartitioningdecomposing Child diagrams show a portion of the parent diagram in greater detail Child diagrams show a portion of the parent diagram in greater detail

4. Avicenna System Analysis and Design System Analysis4 Creating a Set of DFDs Draw the Lower-Level Diagrams Draw the Lower-Level Diagrams Data flow diagrams are built in layers Data flow diagrams are built in layers The top level is the Context level The top level is the Context level Each process may explode to a lower level Each process may explode to a lower level The lower level diagram number is the same as the parent process number The lower level diagram number is the same as the parent process number Each process on diagram zero may be exploded to create a child diagram Each process on diagram zero may be exploded to create a child diagram Each process on a lower-level diagram may be exploded to create another child diagram Each process on a lower-level diagram may be exploded to create another child diagram These diagrams found below Diagram 0 are given the same number as the parent process These diagrams found below Diagram 0 are given the same number as the parent process

5. Avicenna System Analysis and Design System Analysis5 Creating a Set of DFDs Draw the Lower-Level Diagrams Draw the Lower-Level Diagrams Each process is numbered with the parent diagram number, a period, and a unique child diagram number Each process is numbered with the parent diagram number, a period, and a unique child diagram number If the parent process has data flow connecting to a data store, the child diagram may include the data store as well If the parent process has data flow connecting to a data store, the child diagram may include the data store as well A lower-level diagram may contain data stores not shown on the parent process A lower-level diagram may contain data stores not shown on the parent process

6. Avicenna System Analysis and Design System Analysis6 Creating a Set of DFDs Level 1 DFD for process1, shows details of the FILL ORDER process in the order system. Level 1 DFD for process1, shows details of the FILL ORDER process in the order system. The FILL ORDER consists of three processes, VERIFY ORDER, PREPARE REJECT NOTICE, and ASSEMBLE ORDER The FILL ORDER consists of three processes, VERIFY ORDER, PREPARE REJECT NOTICE, and ASSEMBLE ORDER Two data stores CUSTOMERS and PRODUCTS Two data stores CUSTOMERS and PRODUCTS Depending on the processing logic Depending on the processing logic A CUSTOMER submit an ORDER, the VERIFY ORDER requires PRODUCT DETAIL from PRODUCTS data store and CREDIT STTUS from CUSTOMERS data store, apply either REJECTED NOTICE to PREPARE REJECT NOTICE process or ACCEPTED ORDER to ASSEMBLE ORDER process as output A CUSTOMER submit an ORDER, the VERIFY ORDER requires PRODUCT DETAIL from PRODUCTS data store and CREDIT STTUS from CUSTOMERS data store, apply either REJECTED NOTICE to PREPARE REJECT NOTICE process or ACCEPTED ORDER to ASSEMBLE ORDER process as output If the order rejected, PREPARE REJECT NOTICE sends ORDER REJECTED NOTICE to the CUSTOMER entity and CREDIT HISTORY to the CUSTOMERS data store If the order rejected, PREPARE REJECT NOTICE sends ORDER REJECTED NOTICE to the CUSTOMER entity and CREDIT HISTORY to the CUSTOMERS data store If the order accepted, ASSEMPLE ORDER process requires PICKING DETAIL from PRODUCTS data store, apply both PICKING LIST to WAREHOUSE entity and INVENTORY CHANGE to PRODUCTS data store, as outputs If the order accepted, ASSEMPLE ORDER process requires PICKING DETAIL from PRODUCTS data store, apply both PICKING LIST to WAREHOUSE entity and INVENTORY CHANGE to PRODUCTS data store, as outputs [1]

7. Avicenna System Analysis and Design System Analysis7 Creating a Set of DFDs Level 1 DFD for process 3, shows details of the APPLY PAYMENT process in the order system. Level 1 DFD for process 3, shows details of the APPLY PAYMENT process in the order system. The APPLY PAYMENT consists of four processes, POST PAYMENT, DEPOSIT PAYMENT, PREPARE ACCOUNTING ENTERY, and PAY COMMISSION The APPLY PAYMENT consists of four processes, POST PAYMENT, DEPOSIT PAYMENT, PREPARE ACCOUNTING ENTERY, and PAY COMMISSION Two data stores ACCOUNTS RECEIVABLE and DAILY PAYMENTS Two data stores ACCOUNTS RECEIVABLE and DAILY PAYMENTS Depending on the processing logic Depending on the processing logic A CUSTOMER submit a PAYMENT, the POST PAYMENT process requires INVOICE DETAIL from ACCOUNTS RECEIVABLE data store, apply both CUSTMER PAYMENT to the DAILY PAYMENT data store and PAYMENT DETAIL to the ACCOUNTS RECEIVABLE data store as outputs A CUSTOMER submit a PAYMENT, the POST PAYMENT process requires INVOICE DETAIL from ACCOUNTS RECEIVABLE data store, apply both CUSTMER PAYMENT to the DAILY PAYMENT data store and PAYMENT DETAIL to the ACCOUNTS RECEIVABLE data store as outputs DEPOSIT PAYMENT requires DAILY PAYMENT from DAILY PAYMENTS data store, apply BANK DEPOSIT to the BANK entity as output DEPOSIT PAYMENT requires DAILY PAYMENT from DAILY PAYMENTS data store, apply BANK DEPOSIT to the BANK entity as output PREPARE ACCOUNTING ENTERY requires ACCOUNTING PAYMENT from DAILY PAYMENTS data store, apply CASH RECEIPT ENTERY as output to the ACCOUNTING entity PREPARE ACCOUNTING ENTERY requires ACCOUNTING PAYMENT from DAILY PAYMENTS data store, apply CASH RECEIPT ENTERY as output to the ACCOUNTING entity PAY COMMISSION requires COMMISSION EARNED from POST PAYMENT process, apply COMMISSION as output to the SALES REP entity PAY COMMISSION requires COMMISSION EARNED from POST PAYMENT process, apply COMMISSION as output to the SALES REP entity [1]

8. Avicenna System Analysis and Design System Analysis8 Creating a Set of DFDs  when to stop leveling : leveling  if a process has a single input data flow or a single output data flow then it should be apparent that there is little point in leveling it any further.  when a process can be accurately described by a single active verb with a singular object, this also indicates that the level has been carried out to a sufficiently low level. When you believe that there is a separate process for each choice on all lowest-level menu options, ask yourself if anything useful will be gained by further leveling of a process. Would any more detail influence your decisions? If the answer is no, then there is little point in taking the leveling further. When you believe that there is a separate process for each choice on all lowest-level menu options, ask yourself if anything useful will be gained by further leveling of a process. Would any more detail influence your decisions? If the answer is no, then there is little point in taking the leveling further.

9. Avicenna System Analysis and Design System Analysis9 Data Flow Diagrams Balancing Balancing involves insuring that information presented at one level of a DFD is accurately represented in the next level of a DFD. involves insuring that information presented at one level of a DFD is accurately represented in the next level of a DFD. DFD level 0 must have the same inputs and outputs as context diagram DFD level 0 must have the same inputs and outputs as context diagram Process 1.0, which appears in a level 0 diagram, must have the same inputs and outputs when decomposed into a level 1 diagram, the same thing for the other processes in level o Process 1.0, which appears in a level 0 diagram, must have the same inputs and outputs when decomposed into a level 1 diagram, the same thing for the other processes in level o

10. Avicenna System Analysis and Design System Analysis10 Data Flow Diagrams Validating the DFD Validating the DFD Syntax errors Syntax errors Assure correct DFD structure Assure correct DFD structure Semantics errors Semantics errors Assure accuracy of DFD relative to actual and desired business processes Assure accuracy of DFD relative to actual and desired business processes User walkthroughs User walkthroughs Examine lowest level DFDs to ensure consistent decomposition Examine lowest level DFDs to ensure consistent decomposition Examine names carefully to ensure consistent use of terms Examine names carefully to ensure consistent use of terms

11. Avicenna System Analysis and Design System Analysis11 Logical Versus Physical DFD s While structured analysis tools are used to develop a logical model for a new information system, such tools also can be used to develop physical models of an information system While structured analysis tools are used to develop a logical model for a new information system, such tools also can be used to develop physical models of an information system Logical data flow diagrams show how the business operates Logical data flow diagrams show how the business operates They have processes that would exist regardless of the type of system implemented They have processes that would exist regardless of the type of system implemented Physical data flow diagrams show how the system operates or how the new system will be implemented Physical data flow diagrams show how the system operates or how the new system will be implemented Physical data flow diagrams include Physical data flow diagrams include Clarifying which processes are manual and which are automated Clarifying which processes are manual and which are automated Describing processes in greater detail Describing processes in greater detail Sequencing processes in the order they must be executed Sequencing processes in the order they must be executed

12. Avicenna System Analysis and Design System Analysis12 Sequence Summary Lower level DFDs show additional detail of the information system through the leveling technique of numbering and partitioning Lower level DFDs show additional detail of the information system through the leveling technique of numbering and partitioning Leveling continues until you reach the the functional primitive processes, which are not decomposed further Leveling continues until you reach the the functional primitive processes, which are not decomposed further All diagrams must be balanced to ensure their consistency and accuracy All diagrams must be balanced to ensure their consistency and accuracy

13. Avicenna System Analysis and Design System Analysis13 Sequence Summary In this Sequence we have In this Sequence we have Explained how to draw level 1 and the Lower-Level Diagrams Explained how to draw level 1 and the Lower-Level Diagrams Defined the terms leveling and balancing Defined the terms leveling and balancing Explained how to level and balance a set of data flow diagrams Explained how to level and balance a set of data flow diagrams Explained when to stop leveling Explained when to stop leveling Explained how to validate the DFDs Explained how to validate the DFDs Distinguish between logical and physical DFDs Distinguish between logical and physical DFDs

14. Avicenna System Analysis and Design System Analysis14 Reference [1] System Analysis and Design, Sixth Edition Authors: Gary B. Shelly, Thomas J. Cashman and Harry J. Rosenblatt, Authors: Gary B. Shelly, Thomas J. Cashman and Harry J. Rosenblatt, Publisher: SHELLY CASHMAN SEWIES. Publisher: SHELLY CASHMAN SEWIES. [2] system analysis and design, sixth edition Authors: Kenneth E. Kendall and Julie E. Kendall Authors: Kenneth E. Kendall and Julie E. Kendall Publisher: Prentice Hall Publisher: Prentice Hall [3] Modern Systems Analysis and Design Third Edition Authors: Jeffrey A. Hoffer, Joey F. George, Joseph S. Valacich Authors: Jeffrey A. Hoffer, Joey F. George, Joseph S. Valacich Publisher: prentice hall Publisher: prentice hall [4] System Analysis and Design, 3 rd Edition Authors: Dennis, Wixom, & Roth Authors: Dennis, Wixom, & Roth Publisher: John Wiley & sons Publisher: John Wiley & sons