IEC SRD 62559-4:2020

IEC SRD 62559-4 ®
Edition 1.0 2020-03
SYSTEMS
REFERENCE DELIVERABLE
colour
inside
Use case methodology –
Part 4: Best practices in use case development for IEC standardization
processes and some examples for application outside standardization

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IEC SRD 62559-4 ®
Edition 1.0 2020-03
SYSTEMS
REFERENCE DELIVERABLE
colour
inside
Use case methodology –
Part 4: Best practices in use case development for IEC standardization

processes and some examples for application outside standardization

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.020 ISBN 978-2-8322-7939-7

– 2 – IEC SRD 62559-4:2020  IEC 2020
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
0.1 General . 6
0.2 Objectives of this document . 6
1 Scope . 8
2 Normative references . 8
3 Terms, definitions and abbreviated terms . 8
3.1 Terms and definitions . 8
3.2 Abbreviated terms . 9
4 Overview of the methodology . 9
4.1 Concept of systems engineering . 9
4.2 Systems engineering methodology for use case development . 9
4.2.1 General . 9
4.2.2 Overview of the phased approach . 11
4.2.3 Phase 1: Methodology for executives . 11
4.2.4 Phase 2: Modelling user requirements with use cases . 13
4.2.5 Phase 3: Methodology for project engineers: developing detailed user
requirements . 22
4.3 Use of Unified Modelling Language (UML) . 25
4.3.1 General . 25
4.3.2 Use case diagram . 26
4.3.3 Scenario flow chart . 26
4.3.4 Activity diagram . 27
4.3.5 Sequence diagram . 30
4.3.6 Data class diagram . 30
4.4 Determining the quality of a use case . 30
4.4.1 General . 30
4.4.2 Considerations for use case management and collaborative working . 31
4.4.3 Version numbering . 32
4.4.4 Management of use case overarching topics like actors, information
objects or requirements . 32
4.4.5 Actor hierarchy und multiple instances of an actor . 33
4.5 Coordination of parallel system use case supporting the same business use
case . 34
4.5.1 General . 34
4.5.2 Decomposition of coordinated high-level use case into sets of low-level
use cases, maximizing the use of already existing elements of
standards (e.g. implantation example use case) . 35
4.5.3 Perform gap analysis to identify necessary standardization work . 35
4.5.4 Components as the linking element between use cases, reference
architectures model and standards . 36
4.6 Outlook to support cooperation of different contributing domains by
identifying cross standardization groups use cases . 36
Bibliography . 38

Figure 1 – Project definition process . 10
Figure 2 – Internal and external stakeholders for the ATM example . 13

Figure 3 – Use case workshop process . 15
Figure 4 – Graphically drafted business use case for the ATM example . 16
Figure 5 – Graphically drafted system use case for the ATM example . 17
Figure 6 – Sequence diagram showing the appropriate boundaries of exchange in the
step-by-step analysis . 20
Figure 7 – Sequence diagram showing an inappropriate level of detail of information
exchange . 21
Figure 8 – Flow diagram for alternate (error) scenarios . 22
Figure 9 – Base plane of the SGAM showing its requisite domains and zones . 25
Figure 10 – Example use case diagram showing actors, assumptions, objectives and
preconditions. . 26
Figure 11 – Example use case diagram scenario flow . 27
Figure 12 – Example activity diagram using Unified Modelling Language showing the
interaction of ATM operator bank, contractual bank, and a customer. 28
Figure 13 – Example activity diagram with object flow . 29
Figure 14 – Example for use case modelling down to data flow modelling . 29
Figure 15 – Example UML data class diagram showing the elements of a use case . 30
Figure 16 – Use case lifecycle process . 31
Figure 17 – Management of use case overarching topics . 33
Figure 18 – Translation of a technical architecture into an actor hierarchy . 33
Figure 19 – Mapping business processes with standards and components. 35
Figure 20 – Components as the linking element between use cases, reference
architecture models and standards . 36
Figure 21 – Actor naming in cross-domain use cases . 37

Table 1 – Use case scenario description according to IEC 62559-2 . 18
Table 2 – Use case information object description according to IEC 62559-2 . 19
Table 3 – Use case requirement description according to IEC 62559-2 . 19
Table 4 – Examples of poorly-formed requirements and requisite improvement. 24

– 4 – IEC SRD 62559-4:2020  IEC 2020
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
USE CASE METHODOLOGY –
Part 4: Best practices in use case development for IEC standardization
processes and some examples for application outside standardization

FOREWORD
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