TRANSFORM ANALYSIS

1. TRANSFORM ANALYSIS Heuristics and Rules

2. DFD with Transform Flow Characteristics input-driven center of transformation output-driven

3. Structured Analysis and DesignInformation Flow Analysis 1 - specify the flow of information in your system => DFD 2 - identify typical structural patterns in the DFD => analysed & annotated DFD 3 - use a proven heuristic to map DFD into SC => first SC 4 - refine and check your Structure Chart => final SC

4. Structured Analysis and DesignTransform Analysis 1 - specify the flow of information in your system 2 - a) confirm transform flow characteristics b) identify the center of transformation ===> annotated DFD 3 - transform your DFD into a first Structure Chart using IPO structure as design heuristic 4 - refine and check your Structure Chart ===> complete SC

5. Transform Analysis - Step 1 • the DFD should exist as a result of systems requirements engineering and systems analysis • check completeness of the DFD, data dictionary, and process dictionary • refine the DFD (decompose, etc.) if that is necessary

6. printer user invoice prepare invoice print invoice invoice_prt registration reg+ reg-profile read & check reg. prices registration db conf_msg reg_info reg+ write conf. error_msg accept reg. conf. user

7. registration reg+ read registration reg_i check registration reg+ error_reason error-handler registration error_msg

8. Transform Analysis - Step 2 • Step 2a: • check the list of properties for transform flow characteristics • be aware that this is a guideline only • Step 2b: • find and mark the center of transformation in the DFD

9. Transform Analysis - Step 2b • locate the center of transformation • follow input-driven flows into the center until the data is in an internal format, correct and complete ===> mark position • trace back output-driven flows to the center until the data is complete and ready for presentation, but not yet in external format ===> mark position • connect all markings: center of transformation

10. center of transformation printer user invoice prepare invoice print invoice registration invoice_prt reg+ reg-profile read & check reg. prices registration db conf_msg reg_info reg+ write conf. error_msg accept reg. conf. user

11. registration reg+ read registration reg_i check registration reg+ error_reason error-handler registration error_msg

12. Transform Analysis - Step 3IPO mapping heuristic i1 o1 o2 ct1 i2 ct2 o3 sys I-ctrl P-crtl O-ctrl i1 i2 ct1 ct2 o1 o2 o3

13. The IPO Mapping & Design Heuristic • establish a top level main controller (system) • always introduce: • Input-driven flow controller • transform flow controller (Processing) • Output-driven flow controller • translate DFD processes into SC modules and hang them from the correct controller • allocate subprocesses => submodules

14. reg. sys. comp reg. prod. output read & check read reg. error hdlg. reg. prep. inv. print inv. write conf. check reg. acc. reg. crt db prt crt

15. Transform Analysis - Step 4 • add data (and control) flows • further decompose (factor) were necessary • user interface handling modules • error-handling modules • add initialisation & termination modules • check quality of design: • cohesion • coupling • reconfirm mapping with DFD

16. See ourStructure Chart Example(Section 3c)for a completespecification ofdata and control flows.

17. End of Section 3e coming up: software design quality