What is Requirements Management?

Transcription

1 Jeremy Dick Version 1 05 November 2004 This document contains proprietary information that belongs to Telelogic AB. Using any of the information contained herein or copying or imaging all or part of this document by any means is strictly forbidden without express written consent of Telelogic AB. Telelogic, TAU and DOORS are registered trademarks, SYNERGY is a trademark of Telelogic AB

2 Table of Contents and their management... 4 What are the benefits?... 5 Who is doing requirements management?... 5 The key concepts... 5 The right tool for the right job... 9 The future of requirements management Conclusion About Telelogic of 13

3 Introduction A decade ago, few engineers would have recognized Management as a discipline in its own right. Companies did not hire Managers, nor did the title appear on resumes or CVs. management tools were in their infancy - the earliest versions of Telelogic DOORS appeared in Today, organizations hire requirements managers to exercise a recognized discipline. There are annual international conferences devoted to the subject; for instance, the IEEE Engineering conference has been run in Germany, California and Japan over the last few years. There now exists a choice of requirements management tools, and analysts identify the market for such software as worth millions of dollars per year. Most major engineering companies, and many in the commercial sector, now have requirements management functions. Factors that have brought about this evolution include: Complexity. Projects have become more ambitious. Software is more pervasive and can be arbitrarily complex. Globalization. Companies have become more global through acquisitions, mergers and partnerships. The need to communicate and to create products that satisfy the requisites, regulations and standards of multiple markets increases complexity. Competition. There is pressure to deliver better products to market more quickly and cheaply. Reuse of off-the-shelf components adds complexity to procurement and management. Compliance. An ever-stringent culture of compliance is developing in all industries. Companies are obliged to provide evidence that they comply with regulations such as those mandated by the FDA and Sarbanes-Oxley. management is a discipline essential to addressing these new demands. 3 of 13

4 and their management are concerned with anything that affects the quality of a product or service, including performance, design and manufacture and may address function, safety and legality. Usually expressed as textual statements, requirements may also be tables, diagrams or mathematical expressions. Complex products are typically defined by thousands of requirements. management is the discipline of gathering, expressing, organizing, tracing, analyzing, reviewing, agreeing, changing and validating requirement statements and managing the documents that contain them with the purpose of defining and delivering the right product or service. management processes span the entire development lifecycle - from inception when requirements are gathered and defined, to the end of development when final ing is carried out with respect to the initial requirements. In every management decision, a project manager has to find a balance between delivering the right product quality within cost and on time. These three axes are not independent: generally, if a project takes longer, it costs more. Cost and schedule can be reduced by delivering lower quality. This is illustrated in Figure 1 as the classic management triangle. Figure 1. The Management Triangle 4 of 13

5 What are the benefits? The benefits of effective requirements management include: Greater confidence that objectives are being met. Organizing and tracing requirements engenders greater reflection on the design process and makes the design rationale more explicit. Ability to manage change through impact analysis. tracing allows the potential impact of changes to be assessed more rapidly. Improved customer / supplier relations through better definition and understanding of contracts, a large part of which are requirements. Ability to track progress / status particularly in the formative stages of a project. When all that the project team is doing is writing documents, it is sometimes hard to measure progress. Effective requirements management puts measurable processes in place. Ability to save costs through cost / benefit analysis. Again, requirements tracing is a way of documenting the relationship between benefits (as expressed by the requirements) and cost (as expressed by the design). Who is doing requirements management? management is wide-spread. Here is a sample of companies using Telelogic DOORS : Aero-Defense: Boeing, Lockheed Martin, Rolls Royce, Westland Helicopters, BAE Systems, Thales, Astrium, Airbus, AeroInternational Telecoms: Motorola, Nokia, Ericsson, Alcatel, Vodafone Rail: Network Rail (UK), Alstom, Bombardier, Dutch Railways Electronics: Philips, Siemens, Sony Automotive: PSA, Daimler-Chrysler, Ford Finance: Citibank, Lloyds TSB, Deutsche Bank, Equity, Capital One Defense: MoD (UK), DoD (US), MoD (Australia), United Emirates Government: Department for Transport (UK) The key concepts Figure 2 shows the classic systems engineering V-Model. To manage complexity, development is undertaken in levels, with requirements playing a role at each level. Fundamental to the V-Model are the relationships between layers of requirements - 5 of 13

6 satisfaction - and the relationship between requirements and s - validation or verification. Traceability, a key concept in requirements management, is concerned with how these relationships are documented and managed. Statement of need Operational use Customer System validating the product verifying the system Acceptance System Subsystem qualifying the subsystems Subsystem Component qualifying components Component Figure 2. in the V-Model Traceability enables the traversal of related requirements, for instance, from the original customer requirements through system requirements, and into design and implementation. Many of the concerns of requirements management exist to enable traceability. It is through this discipline that we hope to understand and document: how requirements are satisfied; how requirements are ed; the impact of changing requirements; the impact of failure. Figure 3 shows a typical example of requirements tracing. Reading from right to left, individual statements of requirement in the Software Specification document are traced back to individual statements in the System Reqs document, which are in turn traced to individual statements in the Customer Reqs document. The sets of links can be characterized as a relationship; that is, the links specify which requirements in 6 of 13

7 one document satisfy those in the document to the left. Note that the relationship exists between individual requirement statements. Customer Reqs System Reqs Software Specification Figure 3. Example of requirements tracing The ability to establish such tracing depends on a number of other aspects of requirements management: Before beginning a project, the planned project documentation should be identified and organized into appropriate development layers. The number and the type of the layers depends on the nature of the product being developed. Requirement statements are organized into documents in the development layers. The requirements managers are expected to identify requirements appropriate for each layer and to know how best to express them for those layers. typically get more detailed and technical as you travel down the V-Model from customer to component requirements. Requirement statements are atomic, that is, each statement (or paragraph) is expected to contain at most one requirement. If two requirements are contained in a single statement, then the proper granularity of tracing cannot be achieved. Once established, tracing can be used to carry out impact analysis. Suppose a customer requirement was subject to change, then the satisfaction links could be used to identify the related system requirements, and, in turn, the related software requirements that would be subject to change as a result. This is illustrated in Figure 4. 7 of 13

8 Customer Reqs System Reqs Software Specification Figure 4. Example of impact analysis Figure 5 shows impact analysis in the V-Model, in which the effect of changing a customer requirement extends downwards through the satisfaction relationships as well as across the validation relationships to the s. Statement of need Operational use Customer System validating the product verifying the system Acceptance System Subsystem qualifying the subsystems Subsystem Component qualifying components Component Figure 5. Traceability in the V-Model 8 of 13

9 Figure 6 shows an example of a development process used by an actual customer where two kinds of traceability relationships are managed: and validates. Impact analysis can now also take into account the that may need to be redefined and rerun as the result of a change in the requirements. Figure 6. Using several tools to support a development process Note that, in this example, Telelogic DOORS is used for requirements management and traceability in conjunction with tools appropriate to the related disciplines, like ing. The right tool for the right job Word processing and document management tools are insufficient for requirements management because they do not give effective statement to statement tracing. In addition to document creation, editing, versioning, retrieval and publishing, requirements management needs the ability to manage the life and status of individual statements and to create, control and analyze traceability to statements in other documents. management tools such as Telelogic DOORS allow: Documents to be managed, versioned, published; Statements within documents to be identified, classified and controlled; Statements within documents to be traced to one another; Traceability relationships to be analyzed for impact analysis; Complex traceability reports to be generated. 9 of 13

10 Figure 7 shows an example traceability report in Telelogic DOORS. The underlying document structure is a cascade of four documents leading from User down to Test Cases. The screen shot shows how traceability links can be used in Telelogic DOORS to draw related information together into a single report. Figure 7. Example traceability report in Telelogic DOORS Figure 8 shows another example in Telelogic DOORS of a traceability view, which uses an explorer window to allow the user to traverse a tree of linked requirements. 10 of 13

11 Figure 8. Example traceability view The future of requirements management While requirements management is a relatively young discipline, it s here to stay, and its concepts will continue to develop and mature. In the future, we can expect the concept of information traceability to become more widely used, not just in engineering sectors, but in many other domains, such as corporate governance and legislative compliance. Tools will improve as well, and, before long, information traceability tools will be a part of everyone s desktop. 11 of 13

12 Conclusion management, a discipline that spans the entire development lifecycle, is concerned with the gathering, expressing, organizing, tracing, analyzing, reviewing, agreeing, changing and validating requirement statements and managing the documents that contain them with the purpose of defining and delivering the right product or service. Effective requirements management provides projects with: Greater confidence that objectives are being met. Organizing and tracing requirements engenders greater reflection on the design process and makes the design rationale more explicit. Ability to manage change through impact analysis. tracing allows the potential impact of changes to be assessed more rapidly. Improved customer / supplier relations through better definition and understanding of contracts, a large part of which are requirements. Ability to track progress / status particularly in the formative stages of project. When all that the project team is doing is writing documents, it is sometimes hard to measure progress. Effective requirements management puts measurable processes in place. Ability to save costs through cost / benefit analysis. Again, requirements tracing is a way of documenting the relationship between benefits (as expressed by the requirements) and cost (as expressed by the design). While requirements management is a relatively young discipline, it s here to stay, and its concepts will continue to develop and mature. 12 of 13

13 About Telelogic Telelogic is the leading global provider of solutions for advanced systems and software development. Telelogic's best-in-class software tools automate and support best practices throughout the application development lifecycle, so nothing is lost, overlooked, or misunderstood. By optimizing each phase of development, Telelogic tools improve visibility and collaboration, enabling customers to deliver better software and systems faster. Telelogic's requirements-driven solutions span a project s entire lifecycle, from initial analysis and planning through development, ing and tracking. They include: Telelogic DOORS - an integrated family of tools that empowers an organization through a structured requirements management process, enabling more effective communication and collaboration. Telelogic TAU - an integrated family of analysis, modeling, design and ing tools that provides a unique visual development environment for complex, demanding systems and software. Telelogic SYNERGY - an integrated tool family for change and configuration management, which provides lifecycle control for a company's software development assets. Telelogic's Professional Services Team offers a combination of training, consulting and support that makes the introduction and ongoing use of our tools as smooth as possible, while maximizing your return on investment and empowering you to become extremely competitive. Headquartered in Malmö, Sweden with U.S. headquarters in Irvine, California, Telelogic has operations in 17 countries worldwide. Customers include Alcatel, BAE SYSTEMS, BMW, Boeing, DaimlerChrysler, Deutsche Bank, Ericsson, General Motors, Lockheed Martin, Motorola, NEC, Nokia, Philips, Siemens, Thales and Vodafone. For more information, please visit 13 of 13