Requirements Traceability: How to keep the linkage up to date? Mark Brörkens, Ömer Gürsoy itemis AG mark.broerkens@itemis.de, oemer.guersoy@itemis.de Copyright © 2012 by Mark Brörkens & Ömer Gürsoy. During the development of complex systems many different artifacts such as requirements specifications, architecture specifications, software units, test specifications or test cases need to be created and maintained. Due to the complexity of the systems it is no longer possible for single engineers to keep an overview over all these artifacts on all levels of detail. Typical questions are: • • • • Is it still possible to accept a late change request? What would be the impact? What is the overall level of completion of the system or a component? Which components are ready for testing? A failure occurs because the system is erroneous. What parts of the system should I check? In order to be able to answer these questions it is important do be able to follow the life of each requirement in both directions, i.e. from specification, via architecture to code and test and vice versa. Traceability is identified as a good practice for improving the quality within system and software development and is thus required by process standards such as SPICE[1], CMMI[2] and ISO 26262[3]. Methodological Guidelines Traceability is concerned with documenting the interrelationship between the artifacts during the overall system development. Typical activities that are supported by traceability include impact analysis, coverage analysis and calculation of implementation status. These analysis and calculations produce valuable results only if traces are created and maintained according to a solid methodology and the traces are continuously kept up to date. In recent projects it was identified that the best quality is achieved if the experts that create the development artifacts are additionally responsible for creating the trace relationships to the origin of each created artifact. When setting up a custom methodology for traceability the following aspects should be taken into consideration: • What elements need to be traced? • What trace linkage is needed? • Who is responsible for creating and maintaining trace relationships? • When and how to create and maintain traces? • How to ensure the quality of the trace information? Adding Traceability Support to Existing Tool Chains The biggest challenge for implementing traceability from requirements via architecture, design and implementation to code and documentation is the maintenance of the trace information. Although some tools already have some built-in support, these tools often do not cover the complete development life cycle and only have limited connectivity to traceable elements that are constructed in other tools. This results in high manual effort and poor quality of trace data. Within the VERDE [5] project a traceability framework for creating and managing trace relationships has been developed. This generic framework is based on Eclipse open source frameworks [4] and allows the creation and management of traces between arbitrary traceable elements. The basic idea is to store the trace data outside of the development artifacts and to provide adapters for each tool used in the development process. This allows adding traceability without the need for modifying the existing tool chain. In order to keep the trace data up to date the traceability framework developed in the VERDE project provides the following features: • Simple creation of traces by: o Evaluating the elements that are currently selected in the engineering tools. The trace framework evaluates the selection and creates the trace linkage on demand. o Querying the complete list of traceable elements from the engineering tools. Search and filter algorithms are supported in order to identify the correct traceable elements. • Automated update of trace data in case of modifications: o The Eclipse framework allows observing changes made in the Eclipse editors. Whenever, an element is modified or removed the tracing framework is informed about the change and updates the trace data on demand. For external tools, tool specific adapters that observe the modifications can be added. • Quality assurance: o For ensuring the quality of the trace data, reports and graphical visualization are available. • Role specific views and constraints: o Each engineering role in the development process is interested in the traceability of different artifacts. The tracing framework supports custom views on the trace data and on the traceable elements. This helps focusing on the relevant traces. Summary Traceability between artifacts within the system development is a very good technique for understanding complex systems. In addition to enabling tool supported impact analysis, coverage analysis or calculation of implementation status, the continuous creation, update and review of the trace relationships during the complete development process improves the overall consistency of the development artifacts and can improve the communication between the engineers that are working on different parts of the system. In order to keep the trace information consistent and up to date it is important to establish a methodology that clearly defines which elements should be traced, what linkage is allowed and who is responsible for creating the traces. Additionally, the tooling must make the creation and management of traceability as easy as possible. For implementing a tooling that supports the management and analysis of traces according to the specific process needs and existing tool chains, many components are already available in the Eclipse open source community [4]. References [1] HIS. “Automotive SPICE – Process Assessment Model”. http://www.automotivespice.com [2] Software Engineering Institute. “Capability Maturity Model Integration (CMMI)”. http://www.sei.cmu.edu/cmmi/ [3] ISO. “ISO 26262: Road vehicles - Functional safety”. [4] Eclipse Homepage. http://www.eclipse.org [5] ITEA Project VERDE. “Validation-driven design for component-based architectures”. http://www.itea-verde.org/ [6] Brörkens, M., Güroy, Ö. 2012. “Improving Agile Development Processes By Adding Traceability To Existing Tool Chains”, Kugler Maag Cie - Forum "Halten agile. Methoden, was sie versprechen?!" [7] Brörkens, M., Güroy, Ö. 2012. “Managing and understanding complex systems using traceability and open source software”, INCOSE International Symposium 2012. (not yet published) Biography Mark Brörkens is Software Architect, Project Manager and Product Manager at itemis AG. He has several years of experience in developing software in the automotive domain and was actively involved in standardization organizations such as AUTOSAR and HIS. His main focus is on domain specific languages and technologies, especially in the area of requirements managements and traceability. Ömer Gürsoy is Senior IT Consultant at itemis AG. He was operative as analyst, developer, architect, trainer and project leader in the domains enterprise systems, embedded systems and tool development. His special interests are system architectures and model driven software development. He offers professional services and in-depth knowledge.