The Prototyping Approach

1. The Prototyping Approach Techniques for prototype application

2. Type I (Procedure) High volume Low transaction cost Well structured Measurable Process & efficiency Data Clerical Type II (Goal) Low volume High trans. value Poorly structured Hard to measure Goal & effectiveness Concepts Mgrs, professionals Types of Information Systems Sprague & Watson, DSS for Management, Prentice Hall, 1996

3. IS Development Approaches • Systems Development Life Cycle • Information Center (DSS) • Object and Component

4. Type ILarge Systems • Intercommunications among applications • Formal methodologies • CASE technologies • Purchased products • Outsourcing

5. Type ISDLC • Type I systems • Large and Costly • Cost justified • Formal stages of evaluation • Stages carefully reviewed and formally approved • Data, Process, Communications

6. Type IIInformation Center (DSS) • Type II systems • Relatively small and inexpensive • Value justified • Prototyping and evolutionary design • Data, Dialog, Model

7. Prototyping “It is easier to tell what you don’t like about an existing system than to describe what you would like in an imaginary one” A.M. Jenkins, 1983

9. Life Cycle Prespecification possible Changes expensive Good project communication Static model OK Rigorous approach useful Iteration unacceptable Prototype Prespecification difficult Quick tools work Communications gap Animated model needed Rigor after requirements Iteration accepted Choice

10. The Prototyping Process Identify Initial Requirements Use and Evaluate Develop System Iterate Document and Install

11. Prototyping Life Cycle • Determine suitability for prototyping • Identify basic needs • Develop working model • Demonstrate and solicit refinements • Revise and redemonstrate • Clean up and document

12. Assumptions • All requirements cannot be specified • Quick build tools are available • Communications gap between builders and users • Active models are required • Rigorous approaches are appropriate once requirements are known • Iteration is valuable

13. Use Prototyping If • Life cycle too slow • Scope of project manageable 30 screens Small team: 1-2 users/designers 50 attributes • User not sure of specifications • User satisfaction very important • Reporting or DSS • Irregular or infrequent use

14. Do Not Use Prototyping If • Don’t understand tools • Data not well managed • Software not well managed • Professional staff not available • Technology response not adequate • User not willing to invest time

15. Factors Favoring Prototyping • Structure: interactive, on-line (OLAP) • Logic: structured but not algorithmic DSS applications are often data-report types • User: competent and active participant • Time Constraint: not a crash project • Management: willing to work with method • Size: not overly large or complex

16. Factors Favoring Prototyping • Problem: imprecise specifications, poorly defined communications, interactive model needed Why not use prototyping

17. Roles • User Responsible for business solutions • Intermediary Run system for user • Builder Write code for application • Technical Supports the development Support tools • Toolsmith Build basic tool modules (often work for software houses)

18. Requirements for Successful Prototyping: User • Initiate the process • Seeks IS assistance • Competent in business area • Willing to spend time with system

19. Requirements for Successful Prototyping: Builder • Assigned to Prototyping • Competent with tools • Knows organizational data resources

20. Requirements for Successful Prototyping: Technology • Roles identified • 4GL Tools established • Data is managed • Technology response adequate

21. Builders Added Value(Professional Design) • Date and time stamps • Control totals • Audit trails • Common interface feel • Additional functions • Testing

22. Prototyping Principles 1. Most applications arise from a small set of basic systems 1. Batch edit/update 7. On-line application 2. Batch reporting interface 3. Batch data update 8. On-line report 4. Batch interface 5. On-line update/query 6. On-line ad hoc query

23. Add Modify Display Delete Locate Browse Activate Copy Connect Stop Prototyping Principles 2. Most systems use a common set of data processing functions

24. Prototyping Principles 3. Most editing derives from a small set of models. • Tunnel edits • Cross field edits • Cross record edits

25. Prototyping Principles 4. Most reports are based on a four step process. • Select data from the database • Sort by specification • Format and edit for printing • Print

26. Audit trails Control totals Menu and command modes Help facility Standard screen formats Date/time stamping Ergonomics Prototyping Principles 5. There are a standard set of value added design structures that should be added

27. Prototyping Tactics • Normalize data to 3NF • Use component engineering Use existing components Assemble from existing parts Reuse pieces Create pieces so that they can be reused • Cut and paste • Keep a set of examples

28. Prototyping Tactics • Use active data dictionaries • Automate documentation • Keep teams small • Integrated software workbench tools • Specify objectives not procedures • Provide end-user report writing tools • Use professional prototypers • Have systems developers work with prototypers

29. Project Management • Initial Model: 2-6 weeks Must be fast enough to maintain interest • Revisions: immediate - 2 weeks • Chargeback: use charges to avoid frivolous changes • Approval: determine the group who approves iterations • Sign off: formal acceptance

30. AdditionalImplementation Requirements • Operational documentation and procedures • Data size and operational impact analysis • Test plan • Training procedures

31. Tactic • Evolution • Throwaway • Life Cycle component

32. References • Bernard H. Boar, Application Prototyping, Wiley, 1984. • Ralph Sprague & Eric Carlson, Building Effective Decision Support Systems, Prentice Hall, 1984.