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September 30, 2014

Software Engineering in CS at APU. CS 470 Software Engineering I. Sheldon X. Liang Ph. D. September 30, 2014. Azusa, CA. 1. September 30, 2014. Azusa Pacific University, Azusa, CA 91702, Tel: (800) 8 25-5278 Department of Computer Science, http://www.apu.edu/clas/computerscience/.

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September 30, 2014

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  1. Software Engineering in CS at APU CS 470 Software Engineering I Sheldon X. Liang Ph. D. September 30, 2014 Azusa, CA 1 September 30, 2014 Azusa Pacific University, Azusa, CA 91702,Tel: (800) 825-5278 Department of Computer Science,http://www.apu.edu/clas/computerscience/

  2. Software Engineering in CS at APU CS 470 Classical Analysis 2 September 30, 2014 Azusa Pacific University, Azusa, CA 91702,Tel: (800) 825-5278 Department of Computer Science,http://www.apu.edu/clas/computerscience/

  3. Software Engineering in CS at APU CS 470 Classical Analysis Systems Analysis: 1. What to do: the evaluation of an activity to identify its desired objectives and determine procedures for efficiently attaining them. 2. What needed: the methodical study of the data-processing needs of a business or department, together with recommendations for specific hardware and software installations. 3 September 30, 2014 Azusa Pacific University, Azusa, CA 91702,Tel: (800) 825-5278 Department of Computer Science,http://www.apu.edu/clas/computerscience/

  4. Software Engineering in CS at APU CS 470 Classical Analysis Role of the Analyst • The analyst is the liaison between the user and the development team. • His final product must be understandable to the users and the developers. • He doesn’t tell the developers how to create the product, just what it should do in a very exacting manner. 4 September 30, 2014 Azusa Pacific University, Azusa, CA 91702,Tel: (800) 825-5278 Department of Computer Science,http://www.apu.edu/clas/computerscience/

  5. Software Engineering in CS at APU CS 470 Classical Analysis 5 September 30, 2014 Azusa Pacific University, Azusa, CA 91702,Tel: (800) 825-5278 Department of Computer Science,http://www.apu.edu/clas/computerscience/

  6. Software Engineering in CS at APU CS 470 Classical Analysis The Goal of Analysis • The most important product of systems analysis – is the specification document.” - DeMarco • Informal enough for the client • The client is generally not a computer specialist • Formal enough for the developers • It is the sole source of information for drawing up the design 6 September 30, 2014 Azusa Pacific University, Azusa, CA 91702,Tel: (800) 825-5278 Department of Computer Science,http://www.apu.edu/clas/computerscience/

  7. Software Engineering in CS at APU CS 470 Classical Analysis Specification Document • The specification document is the final product of the systems analyst • It is a contract between the client and the developer • Specifies what the product must do and the constraints on the product 7 September 30, 2014 Azusa Pacific University, Azusa, CA 91702,Tel: (800) 825-5278 Department of Computer Science,http://www.apu.edu/clas/computerscience/

  8. Software Engineering in CS at APU CS 470 Classical Analysis Methods of Analysis • Demarco(1979) – Data Flow Diagram • Data Dictionary • Structured English • Decision Tables • Decision Trees 8 September 30, 2014 Azusa Pacific University, Azusa, CA 91702,Tel: (800) 825-5278 Department of Computer Science,http://www.apu.edu/clas/computerscience/

  9. Software Engineering in CS at APU CS 470 Classical Analysis Structured Systems Analysis • The analysts job: • What business functions should she computerize? • Accounts payable • Accounts receivable • Inventory • What equipment will they need? • How much are they willing to spend? 9 September 30, 2014 Azusa Pacific University, Azusa, CA 91702,Tel: (800) 825-5278 Department of Computer Science,http://www.apu.edu/clas/computerscience/

  10. Software Engineering in CS at APU CS 470 Classical Analysis Step 1. Draw the DFD • The data flow diagram (DFD) shows the logical data flow • “What happens, not how it happens” • First refinement • Infinite number of possible interpretations 10 September 30, 2014 Azusa Pacific University, Azusa, CA 91702,Tel: (800) 825-5278 Department of Computer Science,http://www.apu.edu/clas/computerscience/

  11. Software Engineering in CS at APU CS 470 Classical Analysis Step 1. Draw the DFD • Second refinement • PENDING ORDERS is scanned daily 11 September 30, 2014 Azusa Pacific University, Azusa, CA 91702,Tel: (800) 825-5278 Department of Computer Science,http://www.apu.edu/clas/computerscience/

  12. Software Engineering in CS at APU CS 470 Classical Analysis Step 1. Draw the DFD • Portion of third refinement 12 September 30, 2014 Azusa Pacific University, Azusa, CA 91702,Tel: (800) 825-5278 Department of Computer Science,http://www.apu.edu/clas/computerscience/

  13. Software Engineering in CS at APU CS 470 Classical Analysis Step 2. Decide What Parts to Computerize and How • It depends on how much client is prepared to spend • Large volumes, tight controls • Batch • Small volumes, in-house microcomputer • Online • Cost/benefit analysis 13 September 30, 2014 Azusa Pacific University, Azusa, CA 91702,Tel: (800) 825-5278 Department of Computer Science,http://www.apu.edu/clas/computerscience/

  14. Software Engineering in CS at APU CS 470 Classical Analysis Step 3. Determine the Details of the Data Flows • Determine the data items for each data flow • Refine each flow stepwise • We need a data dictionary for larger products 14 September 30, 2014 Azusa Pacific University, Azusa, CA 91702,Tel: (800) 825-5278 Department of Computer Science,http://www.apu.edu/clas/computerscience/

  15. Software Engineering in CS at APU CS 470 Classical Analysis Structured Systems Analysis • Response times cannot be determined • The number of I/O channels can only be guessed • CPU size and timing can only be guessed • Nevertheless, no other method provides these data for arbitrary products Overall • The method of Gane and Sarsen/De Marco/ Yourdon has resulted in major improvements in the software industry 15 September 30, 2014 Azusa Pacific University, Azusa, CA 91702,Tel: (800) 825-5278 Department of Computer Science,http://www.apu.edu/clas/computerscience/

  16. Software Engineering in CS at APU CS 470 Classical Analysis Take a look at my research 16 September 30, 2014 Azusa Pacific University, Azusa, CA 91702,Tel: (800) 825-5278 Department of Computer Science,http://www.apu.edu/clas/computerscience/

  17. Software Engineering in CS at APU CS 470 Classical Analysis Thank you very much! Questions? 17 September 30, 2014 Azusa Pacific University, Azusa, CA 91702,Tel: (800) 825-5278 Department of Computer Science,http://www.apu.edu/clas/computerscience/

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