April 19, 20231
April 19, 2023April 19, 2023 Azusa, CAAzusa, CA
Sheldon X. Liang Ph. D.
Software Engineering Software Engineering in CS in CS at at APUAPU
Azusa Pacific University, Azusa, CA 91702, Tel: (800) 825-5278 Department of Computer Science, http://www.apu.edu/clas/computerscience/
CS 470 Software Engineering ICS 470 Software Engineering I
April 19, 20232
Azusa Pacific University, Azusa, CA 91702, Tel: (800) 825-5278 Department of Computer Science, http://www.apu.edu/clas/computerscience/
Software Engineering Software Engineering in CS in CS at at APUAPU
CS 470 Classical AnalysisCS 470 Classical Analysis
April 19, 20233
Azusa Pacific University, Azusa, CA 91702, Tel: (800) 825-5278 Department of Computer Science, http://www.apu.edu/clas/computerscience/
Software Engineering Software Engineering in CS in CS at at APUAPU
CS 470 Classical AnalysisCS 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.
April 19, 20234
Azusa Pacific University, Azusa, CA 91702, Tel: (800) 825-5278 Department of Computer Science, http://www.apu.edu/clas/computerscience/
Software Engineering Software Engineering in CS in CS at at APUAPU
CS 470 Classical AnalysisCS 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.
April 19, 20235
Azusa Pacific University, Azusa, CA 91702, Tel: (800) 825-5278 Department of Computer Science, http://www.apu.edu/clas/computerscience/
Software Engineering Software Engineering in CS in CS at at APUAPU
CS 470 Classical AnalysisCS 470 Classical Analysis
April 19, 20236
Azusa Pacific University, Azusa, CA 91702, Tel: (800) 825-5278 Department of Computer Science, http://www.apu.edu/clas/computerscience/
Software Engineering Software Engineering in CS in CS at at APUAPU
CS 470 Classical AnalysisCS 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
April 19, 20237
Azusa Pacific University, Azusa, CA 91702, Tel: (800) 825-5278 Department of Computer Science, http://www.apu.edu/clas/computerscience/
Software Engineering Software Engineering in CS in CS at at APUAPU
CS 470 Classical AnalysisCS 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
April 19, 20238
Azusa Pacific University, Azusa, CA 91702, Tel: (800) 825-5278 Department of Computer Science, http://www.apu.edu/clas/computerscience/
Software Engineering Software Engineering in CS in CS at at APUAPU
CS 470 Classical AnalysisCS 470 Classical Analysis
Methods of Analysis
• Demarco(1979) – Data Flow Diagram
– Data Dictionary
– Structured English
– Decision Tables
– Decision Trees
April 19, 20239
Azusa Pacific University, Azusa, CA 91702, Tel: (800) 825-5278 Department of Computer Science, http://www.apu.edu/clas/computerscience/
Software Engineering Software Engineering in CS in CS at at APUAPU
CS 470 Classical AnalysisCS 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?
April 19, 202310
Azusa Pacific University, Azusa, CA 91702, Tel: (800) 825-5278 Department of Computer Science, http://www.apu.edu/clas/computerscience/
Software Engineering Software Engineering in CS in CS at at APUAPU
CS 470 Classical AnalysisCS 470 Classical Analysis
• The data flow diagram (DFD) shows the logical data flow – “What happens, not how it happens”
• First refinement– Infinite number of possible interpretations
Step 1. Draw the DFD
April 19, 202311
Azusa Pacific University, Azusa, CA 91702, Tel: (800) 825-5278 Department of Computer Science, http://www.apu.edu/clas/computerscience/
Software Engineering Software Engineering in CS in CS at at APUAPU
CS 470 Classical AnalysisCS 470 Classical Analysis
• Second refinement– PENDING ORDERS is scanned daily
Step 1. Draw the DFD
April 19, 202312
Azusa Pacific University, Azusa, CA 91702, Tel: (800) 825-5278 Department of Computer Science, http://www.apu.edu/clas/computerscience/
Software Engineering Software Engineering in CS in CS at at APUAPU
CS 470 Classical AnalysisCS 470 Classical AnalysisStep 1. Draw the DFD
• Portion of third refinement
April 19, 202313
Azusa Pacific University, Azusa, CA 91702, Tel: (800) 825-5278 Department of Computer Science, http://www.apu.edu/clas/computerscience/
Software Engineering Software Engineering in CS in CS at at APUAPU
CS 470 Classical AnalysisCS 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
April 19, 202314
Azusa Pacific University, Azusa, CA 91702, Tel: (800) 825-5278 Department of Computer Science, http://www.apu.edu/clas/computerscience/
Software Engineering Software Engineering in CS in CS at at APUAPU
CS 470 Classical AnalysisCS 470 Classical AnalysisStep 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
April 19, 202315
Azusa Pacific University, Azusa, CA 91702, Tel: (800) 825-5278 Department of Computer Science, http://www.apu.edu/clas/computerscience/
Software Engineering Software Engineering in CS in CS at at APUAPU
CS 470 Classical AnalysisCS 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
April 19, 202316
Azusa Pacific University, Azusa, CA 91702, Tel: (800) 825-5278 Department of Computer Science, http://www.apu.edu/clas/computerscience/
Software Engineering Software Engineering in CS in CS at at APUAPU
CS 470 Classical AnalysisCS 470 Classical Analysis
Take a look at my research
Thank you very much!
Questions?
April 19, 202317
Azusa Pacific University, Azusa, CA 91702, Tel: (800) 825-5278 Department of Computer Science, http://www.apu.edu/clas/computerscience/
Software Engineering Software Engineering in CS in CS at at APUAPU
CS 470 Classical AnalysisCS 470 Classical Analysis
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