quality model for requirements eng. copyright, 2002 © jerzy r. nawrocki...

Quality Model for RQuality Model for Requirements Eng.equirements Eng.

Copyright, 2002 © Jerzy R. Nawrocki

Jerzy.Nawrocki@put.poznan.pl

www.cs.put.poznan.pl/jnawrocki/mse/quality/

Quality ManagementQuality Management

Auxiliary MaterialAuxiliary Material

Quality ManagementQuality Management

Auxiliary MaterialAuxiliary Material

J. Nawrocki, Quality Model for Req.

Plan of the lecturePlan of the lecturePlan of the lecturePlan of the lecture

Overview of RE guidelinesScoringMaturity levels for REBasic guidelinesIntermediate guidelinesAdvanced guidelines

J. Nawrocki, Quality Model for Req.

Overview of RE guidelinesOverview of RE guidelinesOverview of RE guidelinesOverview of RE guidelines

The requirements document

Requirements elicitation

Reqs analysis & negotiation

Describing requirements

System modelling

Requirements validation

Requirements management

RE for critical systems

Basic Interm Adv

8

6

54

3

4

4

2

36

-

6

21

3

3

3

3

21

-

1

1-

-

1

2

4

9

J. Nawrocki, Quality Model for Req.

ScoringScoringScoringScoring

3 - standardised: documented standard followed and checked as part of the quality management process;

2 - normal use: widely followed but not mandatory;

1 - discretionary use: used at discretion of project manager;

0 - never: never or very rarely used;

3

0

J. Nawrocki, Quality Model for Req.

Maturity levels for REMaturity levels for REMaturity levels for REMaturity levels for RE

Defined

> 85 Basic & > 40 Interm & Adv

Defined

> 85 Basic & > 40 Interm & AdvRepeatable

> 55 Basic & < 40 Interm & Adv

Repeatable

> 55 Basic & < 40 Interm & AdvInitial

< 55 Basic

Initial

< 55 Basic

J. Nawrocki, Quality Model for Req.

Legend for RE quidelinesLegend for RE quidelinesLegend for RE quidelinesLegend for RE quidelines

• Responsibility of Project Managers• Responsibility of SDS Senior Responsibility of SDS Senior

Managers or Quality AssurersManagers or Quality Assurers• At a discretion of Project

Managers

J. Nawrocki, Quality Model for Req.

Basic guidelinesBasic guidelinesBasic guidelinesBasic guidelines

Requirements document

• Define a standard document structureDefine a standard document structure• Explain how to use the document• Include a summary of the requirements• Make a business case for the system• Define specialised terms• Lay out the document for readability• Help readers find information• Make the document easy to change

J. Nawrocki, Quality Model for Req.

Basic guidelinesBasic guidelinesBasic guidelinesBasic guidelines

Requirements elicitation

• Assess system feasibility• Be sensitive to organisational &

political considerations• Identify and consult stakeholders• Record requirement sources• Define operating environment• Use business concerns to drive

requirements elicitation

Give me a crocodile!

J. Nawrocki, Quality Model for Req.

Basic guidelinesBasic guidelinesBasic guidelinesBasic guidelines

Analysis and negotiation

• Define system boundaries• Use checklists for requirements Use checklists for requirements

analysisanalysis• Provide software to support Provide software to support

negotiationsnegotiations• Plan for conflicts and conflict

resolution• Prioritise requirements

J. Nawrocki, Quality Model for Req.

Basic guidelinesBasic guidelinesBasic guidelinesBasic guidelines

Describing requirements

• Define standard templates for Define standard templates for describing requirementsdescribing requirements

• Use language simply & concisely• Use diagrams appropriately• Supplement natural language with

other descriptions of requirements

J. Nawrocki, Quality Model for Req.

Basic guidelinesBasic guidelinesBasic guidelinesBasic guidelines

System modelling

• Develop complementary system models

• Model the system’s environment• Model the system architecture

J. Nawrocki, Quality Model for Req.

Basic guidelinesBasic guidelinesBasic guidelinesBasic guidelines

Requirements validation

• Check that the requirements Check that the requirements document meets your standarddocument meets your standard

• Organise formal requirements Organise formal requirements inspectionsinspections

• Use multidisciplinary teams to Use multidisciplinary teams to review requirementsreview requirements

• Define validation checklistsDefine validation checklists

J. Nawrocki, Quality Model for Req.

Basic guidelinesBasic guidelinesBasic guidelinesBasic guidelines

Requirements management

• Uniquely identify each requirement

• Define policies for requirements Define policies for requirements managementmanagement

• Define traceability policiesDefine traceability policies• Maintain a traceability manual

J. Nawrocki, Quality Model for Req.

Basic guidelinesBasic guidelinesBasic guidelinesBasic guidelines

RE for critical systems

• Create safety requirements Create safety requirements checklistschecklists

• Involve external reviewers in the Involve external reviewers in the validation processvalidation process

J. Nawrocki, Quality Model for Req.

Intermediate guidelinesIntermediate guidelinesIntermediate guidelinesIntermediate guidelines

Requirements elicitation

• Look for domain constraints• Record requirements rationale• Collect requirements from

multiple viewpoints• Prototype poorly understood

requirements• Use scenarios• Define operational processes

Give me a crocodile!

J. Nawrocki, Quality Model for Req.

Intermediate guidelinesIntermediate guidelinesIntermediate guidelinesIntermediate guidelines

Analysis and negotiation

• Classify requirements using using a multidimensional approach

• Use interaction matrices to find conflicts and overlaps

J. Nawrocki, Quality Model for Req.

Intermediate guidelinesIntermediate guidelinesIntermediate guidelinesIntermediate guidelines

Describing requirements

• Specify requirements quantitatively

J. Nawrocki, Quality Model for Req.

Intermediate guidelinesIntermediate guidelinesIntermediate guidelinesIntermediate guidelines

System modelling

• Use structured methods for system modelling

• Use a data dictionary• Document the links between

stakeholder requirements and system models

J. Nawrocki, Quality Model for Req.

Intermediate guidelinesIntermediate guidelinesIntermediate guidelinesIntermediate guidelines

Requirements validation

• Use prototyping to animate requirements

• Write a draft user manual• Propose requirements test

cases

J. Nawrocki, Quality Model for Req.

Intermediate guidelinesIntermediate guidelinesIntermediate guidelinesIntermediate guidelines

Requirements management

• Use a database to manage requirements

• Define change management policies

• Identify global system requirements

J. Nawrocki, Quality Model for Req.

Intermediate guidelinesIntermediate guidelinesIntermediate guidelinesIntermediate guidelines

RE for critical systems

• Identify and analyse hazards• Derive safety requirements from

hazard analysis• Cross-check operational and

functional requirements against safety requirements

J. Nawrocki, Quality Model for Req.

Advanced guidelinesAdvanced guidelinesAdvanced guidelinesAdvanced guidelines

Requirements elicitation

• Reuse requirements

Give me a crocodile!

J. Nawrocki, Quality Model for Req.

Advanced guidelinesAdvanced guidelinesAdvanced guidelinesAdvanced guidelines

Analysis and negotiation

• Assess requirements risks

J. Nawrocki, Quality Model for Req.

Advanced guidelinesAdvanced guidelinesAdvanced guidelinesAdvanced guidelines

Requirements validation

• Paraphrase system models

J. Nawrocki, Quality Model for Req.

Advanced guidelinesAdvanced guidelinesAdvanced guidelinesAdvanced guidelines

Requirements management

• Identify volatile requirements• Record rejected requirements

J. Nawrocki, Quality Model for Req.

Advanced guidelinesAdvanced guidelinesAdvanced guidelinesAdvanced guidelines

RE for critical systems

• Specify systems using formal specification

• Collect incident experience• Learn from incident experience• Establish an organisational

safety culture

J. Nawrocki, Quality Model for Req.

Further readingsFurther readingsFurther readingsFurther readings

• I. Sommerville, P. Sawyer, Requirements Engineering, John Wiley & Sons, Chichester, 1997.

J. Nawrocki, Quality Model for Req.

Quality assessmentQuality assessmentQuality assessmentQuality assessment

1. What is your general impression? (1 - 6)

2. Was it too slow or too fast?

3. What important did you learn during the lecture?

4. What to improve and how?