Ambiguity and SpecificityAmbiguity and Specificity

Sriram Mohan/ Steve ChenowethChapters 23, 24 - Requirements Text

1

ProblemProblem

Specification must be easy to understand and must be clear.◦ Balancing the two might be difficult

◦ Must be easy enough for the client to understand

◦ Must be unambiguous for the developers

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Light Box ExerciseLight Box Exercise

After On pushed but before Off pushed system is termed “power on”.

After Off pushed but before On pushed system is termed “power off”.

Since most recent On press if count has been pressed an Odd/Even number of times, Odd/Even shall be lit.

If either light burns out, the other shall flash every 1 second.

3

Count

On Off

Even Odd

Power

4

Off

On

Off

On

Duty Cycle B

Duty Cycle A

0 1 2 3 4 5 6

Techniques for DisambiguationTechniques for Disambiguation

How do we detect it?◦ Memorization technique

◦ Emphasis technique or Keyword Technique How do we avoid it?

◦ Use natural language if possible

◦ Use pictures and diagrams to illustrate intent

◦ Communicate – When in doubt ask?

◦ Augment with technical specs

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Technical Methods for Specifying RequirementsTechnical Methods for Specifying Requirements

Finite State Machines

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Technical Methods for Specifying RequirementsTechnical Methods for Specifying Requirements

Decision Tables and Decision Trees

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Technical Methods for Specifying RequirementsTechnical Methods for Specifying Requirements

Entity Relationship Diagrams◦ You will get extra credit for Milestone 3 if you develop an ER

diagram.

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Technical Methods for Specifying RequirementsTechnical Methods for Specifying Requirements

Pseudo code◦ What is it?

◦ We will use it for our design phase in 371. For each function(s) that results from an use case, you

must provide the following information◦ Name

◦ Arguments

◦ Return Type

◦ Pseudo code You must also develop an architecture diagram.

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System Architecture DiagramSystem Architecture Diagram

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Bloomington Ford Database

Ford Main Module

Authentication Module

DB Connector Module

Exception

Handler Module

Utilities Generator Module

Blue Log Module

White Log Module

Find Module

Reports Module

Maintenance Module

Help Module