Team Skill 6 - Building The Right System

Part 2: Traceability, Change and Quality(Chapters 27-29 of the requirements text)

CSSE 371 Software Requirements and Specification Don Bagert, Rose-Hulman Institute of Technology

October 11, 2005

Thanks to Mark Ardis and Steve Chenoweth for some of the slides included.

Traceability in the US food supply, from http://www.ers.usda.gov/Briefing/Traceability/overview.htm

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Outline

• Tracing Requirements

• Managing Requirements

• Assessing Requirements Quality

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Tracing Requirements

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Traceability: Primary Questions

• Why is tracing important?

• What mechanisms are used for tracing?

Why we care – remember this triangle?

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Traceability: The Problem

• How do you know, if you’re at one of these later stages, that you have a requirements fault?

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In general, how to trace…

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With use cases, for instance…

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Managing Requirements

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Managing Change: Primary Questions

• How do you capture change requests?

• How do you respond to these (individually & overall)?

• How does this tie-in with tracing requirements?

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A Process for Managing Change – 1/3

Step 1: Recognize that change is inevitable, and plan for it

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A Process for Managing Change – 2/3

• Step 2: Baseline the requirements– This means they are signed-off on, and– From then on, they fall under change control – see

below

• Step 3: Establish a single channel to control change– No ad hoc additions– No ad hoc fixes, either

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A Process for Managing Change – 3/3

In this big picture, you especially need to know what “release management” is!

Figure on middle right from http://www.debian.org/vote/2002/platforms/raphael

Step 4: Use a Change Control System to Capture ChangesStep 5: Manage Change Hierarchically

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Assessing Requirements Quality

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Quality Issues

• Products vs. Processes

• Review Methods

• Checklists

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Products vs. Processes

• Organizations that produce high-quality products invest in high-quality processes.

• Product quality can be measured through testing.

• How can we measure process quality?

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Review Methods

• Informal– Ask a peer to read and give comments

• Formal– Ask a peer to prepare for review– Record and report results of review

• Active– Interrogate reviewer

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Checklists

• Look for anticipated defects

• Some defects apply to almost all artifacts– Does the artifact exist?

• Some defects are artifact-specific– Have you identified all stakeholders?

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Problem Statement Checklist

1. Has a problem statement been drafted?

2. Is it written in an easy-to-understand way?

3. Does the team understand it?

4. Has it been circulated for agreement to the key stakeholders, including management?

5. Do the team members have agreement that this is the problem they are trying to solve?

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Supplementary Specification Checklist (1/2)

1. Have you established an appropriate template?

2. Are all non-functional requirements included in the supplementary specification?

3. Have requirements for usability, reliability, performance and supportability been captured?

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Supplementary Specification Checklist (2/2)

4. Have design constraints been identified?

5. Have supplementary requirements been linked to use cases where appropriate?