ISO/IEC 26551:2012

INTERNATIONAL ISO/IEC
STANDARD 26551
First edition
2012-12-01


Software and systems engineering —
Tools and methods for product line
requirements engineering
Ingénierie du logiciel et des systèmes — Outils et méthodes pour
l'ingénierie d'exigences pour gammes de produits




Reference number
ISO/IEC 26551:2012(E)
©
ISO/IEC 2012

---------------------- Page: 1 ----------------------
ISO/IEC 26551:2012(E)

COPYRIGHT PROTECTED DOCUMENT


©  ISO/IEC 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56  CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland

ii © ISO/IEC 2012 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/IEC 26551:2012(E)
Contents Page
Foreword . v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Reference model for product line requirements engineering . 3
5 Product Line Scoping . 7
5.1 Product scoping . 7
5.1.1 Structure information to be used for scoping . 8
5.1.2 Identify products . 8
5.1.3 Analyze common and variable features . 9
5.1.4 Define a product portfolio. 9
5.2 Domain scoping . 10
5.2.1 Identify functional domains . 10
5.2.2 Map features to functional domains . 10
5.2.3 Define domain scope . 11
5.3 Asset scoping . 11
5.3.1 Gather historical data from existing single products . 12
5.3.2 Estimate additional effort required to adapt potential assets . 12
5.3.3 Estimate expected development effort for new products in the product portfolio definition . 13
5.3.4 Estimate economic benefits from reusing proposed assets . 13
5.3.5 Derive asset proposals from economic evaluation results . 13
6 Domain Requirements Engineering . 14
6.1 Domain requirements elicitation . 14
6.1.1 Draw a context diagram . 15
6.1.2 Gather domain information . 15
6.1.3 Identify initial domain requirements . 16
6.1.4 Review the elicited initial domain requirements . 16
6.2 Domain requirements analysis . 17
6.2.1 Classify and balance initial domain requirements . 17
6.2.2 Analyze commonalities and variabilities . 18
6.2.3 Model domain requirements . 18
6.2.4 Create prototypes and analyze feasibility. 19
6.2.5 Develop conceptual test cases and scenarios for acceptance testing . 19
6.2.6 Review the analyzed domain requirements . 19
6.3 Domain requirements specification . 20
6.3.1 Identify sources of domain requirements . 20
6.3.2 Establish traceability . 21
6.3.3 Document domain requirements . 21
6.3.4 Review the domain requirements specification . 22
6.4 Domain requirements verification and validation . 22
6.4.1 Verify domain requirements . 23
6.4.2 Validate domain requirements . 23
6.4.3 Validate conceptual test cases and scenarios for acceptance testing . 23
6.4.4 Baseline domain requirements . 24
6.4.5 Initiate change management process . 24
6.5 Domain requirements management . 24
6.5.1 Manage domain requirements change . 25
6.5.2 Manage traceability . 26
© ISO/IEC 2012 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO/IEC 26551:2012(E)
6.5.3 Manage versions of domain requirements .26
6.5.4 Record and report status .26
6.5.5 Manage process improvement .27
6.5.6 Manage feedback .27
7 Variability Management in Requirements Engineering .27
7.1 Variability in textual requirements .28
7.1.1 Define requirements variability in textual requirements .28
7.1.2 Document requirements variability in textual requirements .28
7.2 Variability in requirements models .29
7.2.1 Define requirements variability in model .29
7.2.2 Document requirements variability in requirements model .30
7.3 Traceability between requirements variability and variability model .30
7.3.1 Define explicit links between requirements variability and variability model .30
8 Asset Management in Requirements Engineering .31
8.1 Domain requirements artifacts as domain assets .31
8.1.1 Identify domain requirements artifacts managed as domain assets .32
8.1.2 Define configuration and annotation .32
8.2 Application requirements artifacts as application assets .32
8.2.1 Identify application requirements artifacts managed as application assets .33
8.2.2 Define configuration and annotation for application requirements assets .33
9 Application Requirements Engineering .34
9.1 Application requirements elicitation.34
9.1.1 Draw a context diagram for an application .35
9.1.2 Identify the requirements gaps between domain and application requirements .35
9.1.3 Bind the best matching variants .36
9.1.4 Select domain assets .36
9.1.5 Review the elicited application requirements .36
9.2 Application requirements analysis .37
9.2.1 Classify and balance application specific initial requirements .38
9.2.2 Analyze commonalities and variabilities .38
9.2.3 Model application specific requirements .38
9.2.4 Create prototypes and analyze feasibility .39
9.2.5 Develop conceptual test cases and scenarios for acceptance testing .39
9.2.6 Review the analyzed application requirements .40
9.3 Application requirements specification .40
9.3.1 Identify sources of application specific requirements .41
9.3.2 Establish traceabilities for application specific requirements .41
9.3.3 Document application specific requirements .41
9.3.4 Document the rationale for variability decision .42
9.3.5 Review the application requirements specification .42
9.4 Application requirements verification and validation .42
9.4.1 Verify application specific requirements .43
9.4.2 Validate application specific requirements .43
9.4.3 Validate conceptual test cases and scenarios for acceptance testing .43
9.4.4 Baseline application specific requirements .44
9.4.5 Initiate application change management process .44
9.5 Application requirements management .44
9.5.1 Manage application specific requirements change .45
9.5.2 Manage application specific traceability .46
9.5.3 Manage versions of application specific requirements artifacts .46
9.5.4 Record and report status of application requirements management .46
9.5.5 Manage application specific process improvement .47
Annex A (informative) Comparison of requirements engineering tasks between single product
and product line .48
Annex B (informative) A Construct for Process, Method, Tool, and Aspect .51
Bibliography .52

iv © ISO/IEC 2012 – All rights reserved

---------------------- Page: 4 ----------------------
ISO/IEC 26551:2012(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO also take part in the work. ISO collaborates closely with the International
Electrotechnical Commission (IEC) on all matters of electro-technical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for
voting. Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO/IEC 26551 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 7, Software and systems engineering.
© ISO/IEC 2012 – All rights reserved v

---------------------- Page: 5 ----------------------
ISO/IEC 26551:2012(E)
Introduction
The major purpose of this International Standard is to deal with the capabilities of tools and methods of
software and systems product line (SSPL) requirements engineering. This International Standard defines how
the tools and methods can support for the software and systems product line-specific requirements
engineering processes.
Decision for the initial boundaries of domain is conducted in advance by defining a product line scope before
initiating domain requirements engineering processes. Domain requirements engineering will be carried out in
a comprehensive manner because common and variable requirements and captured variabilities have
consequential impacts on member products in a product line. The outcomes of domain requirements
engineering processes are transferred into the requirements of a family of products at the application
requirements engineering processes. Therefore requirements engineering tools and methods should consider
both engineering processes namely domain requirements engineering and application requirements
engineering.
Product line requirements engineering can be differentiated from a single product requirement engineering
because of the following aspects:
 There are two core processes in requirements engineering: domain requirements engineering and
application requirements engineering. The major aims of the domain requirements engineering processes
are to analyze commonality and variability for a family of products, and to prepare necessary variability
information for variability modelling. The major aims of the application requirements engineering
processes are to define application specific requirements and bind variability defined in domain
requirements engineering processes.
 It is essential to analyse the costs and benefits estimation of a product line and thereby an organization
can make a go/no-go decision. Moreover, the costs and benefits estimation plays a pivotal role as an
indicator for assessing the effectiveness and efficiency of a product line.
This International Standard can be used in the following modes:
 By the users of this International Standard – to benefit people who develop, operate, and manage
requirements engineering for software and systems product lines.
 By a product line organization – to provide guidance in the evaluation and selection for tools and methods
for product line requirements engineering.
 By providers of tools and methods – to provide guidance in implementing or developing tools and
methods by providing a comprehensive set of the capabilities of tools and methods for product line
requirements engineering.
ISO/IEC 26550 (ISO/IEC 26550, Software and systems engineering — Reference model for product line
engineering and management) addresses both engineering and management processes and covers the key
characteristics of product line development. ISO/IEC 26550 provides an overview of the consecutive
international standards (i.e., ISO/IEC 26551 through ISO/IEC 26556) as well as the structure of the model:
 Processes and capabilities of methods and tools for product line scoping, domain requirements
engineering, and application requirements engineering are provided as ISO/IEC 26551, Software and
systems engineering — Tools and methods for product line requirements engineering.
 Processes and capabilities of methods and tools for domain design and application design are provided
as ISO/IEC 26552, Software and systems engineering — Tools and methods for product line architecture
design.
vi © ISO/IEC 2012 – All rights reserved

---------------------- Page: 6 ----------------------
ISO/IEC 26551:2012(E)
 Processes and capabilities of methods and tools for domain realization and application realization are
provided as ISO/IEC 26553, Software and systems engineering — Tools and methods for product line
realization.
 Processes and capabilities of methods and tools for domain verification and validation and application
verification and validation are provided as ISO/IEC 26554, Software and systems engineering — Tools
and methods for product line verification and validation.
 Processes and capabilities of methods and tools for technical management are provided as
ISO/IEC 26555, Software and systems engineering — Tools and methods for product line technical
management.
 Processes and capabilities of methods and tools for organizational management are provided as
ISO/IEC 26556, Software and systems engineering — Tools and methods for product line organizational
management.

© ISO/IEC 2012 – All rights reserved vii

---------------------- Page: 7 ----------------------
INTERNATIONAL STANDARD ISO/IEC 26551:2012(E)

Software and systems engineering — Tools and methods for
product line requirements engineering
1 Scope
This International Standard deals with the tools and methods of requirements engineering for software and
systems product line. The scope of this International Standard is as follows:
 provide the terms and definitions specific to requirements engineering for software and systems
product lines.
 define process groups and their processes performed during product line requirements engineering.
Those processes are described in terms of purpose, inputs, tasks, and outcomes.
 define method capabilities to support the defined tasks of each process.
 define tool capabilities to automate/semi-automate tasks or defined method capabilities.
This International Standard does not concern processes and capabilities of requirements tools and methods
for a single system but rather deals with those for a family of products.
NOTE This International Standard is not suitable for handling physical artifacts. In the Systems arena, the word
"Product" must be understood as System-level artefacts, such as requirement documents, architectural data, validation
plans, Behavioral Models, etc. In any case, the word "Product" must not be understood as physical items such as
electronic boards, mechanical parts or qualified human operators. In the case of the Software components of a Systems,
this International Standard can apply twice: once to handle the System-Level Product Line and a second time to handle
the Software Part Product Line, if any. The Product Line processes are recursive within the different levels of Products.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO/IEC 26550, Software and systems engineering ― Reference model for product line engineering and
management
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 26550 and the following apply
following terms and definitions apply.
3.1
application assets in requirements
application specific artifacts produced during application requirements engineering such as application
requirements specifications and application requirements models
3.2
application requirements elicitation
identifies stakeholders relevant to an application, elicits application specific requirements, and binds the
appropriate variants
© ISO/IEC 2012 – All rights reserved 1

---------------------- Page: 8 ----------------------
ISO/IEC 26551:2012(E)
3.3
application requirements analysis
ensures that all application specific requirements are understood, and scrutinizes incorrect and inconsistent
application requirements through modeling. And application requirements that cannot be satisfied through the
domain requirements are then analyzed and negotiated
3.4
application requirements specification
documents the application specific requirements and integrates it with the domain requirements specification
whose variants are bound
3.5
application requirements verification and validation
confirms that the application specific requirements are consistent and feasible, and ensures that the bound
variants satisfy the specific product’s requirements
3.6
application requirements management
manages traceability and changes on application requirements
3.7
asset proposal
includes major assets (functional areas and high-level common and variable features of all applications) that
will be included in a product line with their quantified costs and benefits, and estimation results
3.8
application specific requirements
requirements specific to an application or requirements not covered in domain requirements
3.9
domain assets in requirements
reusable artifacts produced during domain requirements engineering such as asset proposals, domain
requirements specifications and domain requirements models
3.10
domain requirements elicitation
identifies initial requirements from domain stakeholders for a product line
3.11
domain requirements analysis
models domain requirements so as to analyze and scrutinize commonality/variability of a product line in
requirements
3.12
domain requirements specification
documents domain requirements for a product line based on domain analysis results
3.13
domain requirements verification and validation
confirms that domain requirements are corrective, consistent, and complete
3.14
domain requirements management
manages traceability and changes with respect to domain requirements and their relevant domain/application
artifacts
3.15
functional domain
categorized functions that are generally used together
2 © ISO/IEC 2012 – All rights reserved

---------------------- Page: 9 ----------------------
ISO/IEC 26551:2012(E)
3.16
production plan
description of how domain assets are to be used to develop member products in a product line
3.17
requirements traceability
covers traceabilities in domain and application requirements respectively, and those between them
3.18
variability in requirements
deals with both external and internal variability in requirements engineering phase. Also variability modeling
and traceability with domain requirements artifacts are addressed
4 Reference model for product line requirements engineering
The methods and tools for product line requirements engineering should support systematic management and
interaction of the domain and application requirements engineering processes. They also need to be
adequately integrated with the subsequent processes of product line engineering lifecycle processes in order
to enable traceability between all requirements artifacts and the related design, realization, and testing
artifacts. In the rest of this document, product line requirements engineering practices, methods, and tools are
described in accordance with a framework focusing on product line requirements engineering (Figure 1).
Product line scoping leads and controls all work on a product line by creating and maintaining the product line
scope through ongoing interactions with the domain and application requirements engineering.
Domain requirements engineering serves to:
 decompose features defined in Product Line Scoping into initial requirements and elicit additional
requirements and derived requirements from stakeholders and domain experts;
 analyze domain requirements with the variabilities of those;
 model and simulate the static and behavioral constructs of domain requirements;
 document domain requirements specifications that can be bound by specific member products of a
product line.
The complexity of variability grows higher in accordance with the complexity of a product line. Separating
variability from domain requirements engineering mitigates this problem. Defining variability in requirements
independently leads to a clear understanding of the necessary capabilities of tools and methods, and thus
helps in selecting tools that support product line requirements engineering.
Application requirements engineering serves to:
 identify gaps between domain features and application specific features
 reuse domain requirements from the asset repository and elicit application specific requirements;
 define application variability model by binding domain variability model and adding application specific
variability;
 analyze and document application specific requirements;
 provide feedback to product line scoping and domain requirements engineering for the evolution of a
product line.
© ISO/IEC 2012 – All rights reserved 3

---------------------- Page: 10 ----------------------
ISO/IEC 26551:2012(E)
The reference model for product line requireme
...