Today, we are tackling Requirements traceability. What exactly does this mean? How do you create traceable links between requirements and design or engineering artifacts corresponding to requirements? Where does that discipline fit into the vast field of requirements engineering? A great number of questions here, but don't worry, they'll find a proper answer. We will then delve into the many benefits of requirements traceability, as well as the obstacles still standing in the way of its implementation. Last but not least, we'll share with you some best practices for the successful implementation of traceability processes, starting with leveraging modern tools and technology. Let’s get started!
TABLE OF CONTENTS
1. What is Requirements Traceability?
2. Traceability and Requirements Management
3. Tracing Requirements Forward and Backward
4. The Benefits of Requirements Traceability
5. The Most Common Challenges to Traceability’s Implementation
6. Best practices for a successful implementation of Requirements traceability
7. SodiusWillert’s Requirements Traceability Tools
What is Requirements Traceability?
In a research paper from 1994, Orlena Gotel and Anthony Finkelstein wrote that Requirements traceability could be defined as the “ability to describe and follow the life of a requirement in both a forward and backward direction”.
This approach may have been formulated more than 30 years ago, but the recurring necessity to track and document the lineage and relations of requirements and artifacts throughout the development process is still as relevant as ever. It seems now impossible to ignore how much product complexity, and interdependencies of software, electronics, and hardware components built into a product have exponentially risen over the past three decades.
Today, many more disciplines are usually involved in the requirements engineering process, each with its very own needs and perspectives on the system under development and its growing amount of point decisions. Involving relevant stakeholders and team members in a requirements engineering process and gathering, documenting, and keeping track of all those decisions without losing visibility, comprehension, and consistency are requirements management's toughest battles.
For this reason, this definition of requirements traceability has a greater resonance today than it did 30 years ago. Requirements engineering is much broader and more complex than one might think, so we thought it wise to remind the place and role of requirements traceability within this vast and still too underestimated discipline.
Fig. 1 - Specialists from various disciplines involved in the requirements engineering process
(Source, Renate Stücka for SodiusWillert German blog)
Traceability and Requirements Management
Requirements Traceability is one of the five activities involved in Requirements Management, along with tracking and controlling changes, version control, communication, and monitoring and reporting (Fig.2).
As for requirement management, it is one of the five requirements engineering processes (Fig.3).
Fig. 2 - Requirements Traceability, a crucial sub-discipline of Requirements Management
Fig. 3 - Requirement Management, a key component of the Requirement Engineering Process
(Source: geeksforgeeks)
Requirements Management can be defined as a fundamental sub-discipline of requirements engineering processes that oversee capturing, analyzing, documenting, tracking, prioritizing, agreeing on the requirement, and controlling communication with stakeholders.
This step is essential, as it considers the changing nature of requirements throughout the software development lifecycle. It will ensure that requirements are as modifiable as possible and that changes in the requirements are properly integrated at all stages of lifecycle development.
Tracing Requirements Forward and Backward
As the 1994 definition indicates, there are two ways of tracing the paths of requirements throughout the project’s lifecycle. Taken together as bidirectional traceability, these two approaches provide an extensive framework for examining the completeness, correctness, and quality of a system.
Forward Traceability
It refers to the ability to trace a requirement from its origin through its implementation and testing. By “origin” we understand the initial source, or more precisely, the first time the requirement and its associated need were mentioned. These can include contributions from stakeholders, a business need, a requirement stemming from an industry standard, a market analysis, a customer request, and so on. Forward traceability guarantees that all requirements are correctly taken into account in the development process. It also ensures that the final product incorporates all the functionalities defined at the outset of the project.
Let's take a concrete example from an automotive system: if a braking system is required to engage after a certain delay, forward traceability will consist of following this requirement throughout the system's design, from the coding of the control software to the test procedures, to ensure that the braking system meets the specified criteria.
Backward Traceability
It refers to the ability to elements of implementation, such as design artifacts, code, or test cases, to their associated requirements. The objective here is to ensure that no part of implementation is unnecessary and that all implemented components are justified by a requirement. In this way, any superfluous elements can be eliminated early on in the development process, as they would not add anything pertinent to the quality of the final product but rather waste valuable time and money.
Back to our braking system requirement example. Backward traceability involves checking that each piece of code and test case linked to the braking system can be traced back to the original requirement. The aim is to ensure that every feature implemented is necessary and justified.
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The Benefits of Requirements Traceability
The value of requirements traceability has grown steadily over the years, particularly in industries such as automotive, aerospace, and healthcare, where safety and compliance are paramount.
So, let's take a look at the key benefits of implementing a requirements traceability workflow
Facilitate Compliance Demonstration and Risk Management
In industries ruled by standards regulations (ISO 26262, ASPICE, DO-178C, IEC 62304, etc. to name just a few) Requirements traceability is a mandatory process for organizations to demonstrate compliance. When preparing for an audit, being able to prove traceability for each requirement is necessary to demonstrate that a project has complied with its obligations, backed up by tangible and traceable proof. By applying rigorous and systematic requirements traceability processes throughout the development lifecycle, teams' stakeholders can easily identify potential risks associated with omitted or poorly implemented requirements.
Improve Quality Assurance
Requirements Traceability is said to be the keystone of Quality Assurance processes. And with good reason: it ensures that software and systems meet requirements and maintain high standards of safety and performance. Requirements Traceability enables defects and errors to be detected and prevented early in the lifecycle by carefully reviewing and validating implementation against documented requirements. This helps to reduce the effort and costs that may be incurred later in the cycle.
With a well-thought-out requirements traceability process, each requirement has corresponding test cases. This is what enables you to confirm that the final product is delivered with the level of performance, quality, and safety required upstream.
Streamline Change Management
Changes and modifications are an integral part of the requirements management process. These can occur due to market dynamics, a new insight that needs to be considered, feedback from stakeholders, requests from the customer, or regulatory changes - the reasons are almost endless.
With an efficient requirements traceability process in place, teams can quickly pinpoint and understand how changes to a requirement affect other components of a system. This is called Impact analysis. It enables you to make informed decisions about the implementation of these changes.
Maintaining full and traceable documentation also facilitates change management. Your teams can ensure that all design elements, test cases, and requirements are updated as required.
Better collaboration and team alignment
Traceability also serves as a shared reference frame for all parties involved, enabling a common and unified understanding of requirements and their status. Trace relationships between related engineering assets make this alignment possible and considerably improve collaboration between various disciplines (such as systems engineering, software development, V&V teams, etc.) that would operate in silos without this capability.
A compass for continuous improvement: lessons learned & process optimization
Traceability documentation is a valuable source for keeping a record of a project’s successes and pitfalls. It refers to the detailed record that tracks the entire lifecycle of a product or system. This knowledge will help shape and refine any future methodologies and approaches. By analyzing the requirements traceability process itself, teams and companies can more easily pinpoint inefficiencies and optimize their approach to requirements management in future projects.
The Most Common Challenges to Traceability’s Implementation
In a recent publication on why organizations don’t trace (or don't trace enough), it emerged that cost issues were the main obstacle to the adoption of more mature practices. In fact, traceability is mainly carried out manually, and automated traceability tools were still relatively scarce.
The ROI of implementing requirements traceability processes
The cost requirements traceability can entail in a budget is often argued as being way too high compared with the savings expected. While this can be true for small projects, the costs of waiving requirements traceability are rising exponentially in mid to large-size projects and when developing complex products for regulated markets.
Requirements traceability ensures that bugs are either avoided or detected soon after having been injected AND it provides organizations with the documentation needed to successfully pass audits and compliance tests. The “shift left” effect – avoid bugs or fix bugs as early as possible creates enormous savings in error correction costs, and the availability of always up-to-date and complete documentation for audit and certification procedures reduces workload and the risk for repeated audits and endless reworks.
So, should we anticipate a well-thought-out budget or invest less but be overwhelmed by hidden, unexpected costs and a flood of errors that can cost more than money, reputation, and ability to serve a relevant target market?
The Persistence of Manual Traceability Practices
Right after the cost issue, the persistence of manual traceability practices is proving to be another key obstacle to a full and sophisticated implementation.
In fact, the most widely adopted requirements tools remain the general document software such as Microsoft Word and Excel, especially for the manual creation and management of Requirements Traceability Matrices (RTMs). The reasons, which are very understandable, are still the same over the years: costs, availability, and familiarity.
A Requirements Traceability Matrix is defined as a “table form illustrating logical links between functional requirements and systems artifacts”. Since traceability matrices are typically elaborated using a spreadsheet or a word processor, the requirements remain unconnected and independent of the artifacts from which the RTM captures the information. So, traceable links have to be manually established.
Fig. 4 - An example of a Requirements Traceability Matrix (RTM) supported by a spreadsheet
However, these manual methods can be labor-intensive and tedious to create and maintain, especially as software systems grow in size and complexity and as the number of traceability links rises exponentially. They are also prone to human errors, misinterpretation, and inconsistencies. The kinds of issues you detect much later in the lifecycle, and which are much more difficult to correct.
Therefore, change management and impact analysis become increasingly challenging to analyze and comprehend as the project progresses. If any changes are made to the elements captured in the RTM, the relevant parts of the traceability data must be updated manually. This, again, requires a considerable amount of time and meticulous line-checking.
Other major difficulties
The recent study we've mentioned above clearly identifies the two main obstacles to requirements traceability implementation: the cost issue and the manual traceability processes that persist. Nevertheless, it's interesting to note that although costs seem to be the main inhibitor to traceability, participants who responded to this survey don't think these costs outweigh the benefits of implementing such an approach. The lack of time, resources, and staff also seems to be a real barrier, as well as an unclear distribution of roles and responsibilities in the implementation of an approach as rigorous as traceability requirements.
Fig. 5 - Major obstacles to implementing Traceability
(Source: Ruiz, M., Hu, J.Y. & Dalpiaz, F. Why don’t we trace? A study on the barriers to software traceability in practice. Requirements Eng 28, 619–637 (2023). https://doi.org/10.1007/s00766-023-00408-9)
6 Best practices for a successful implementation of Requirements traceability
Now let’s dive into the key practices and strategies for achieving robust and successful requirements traceability. In this section, we’ll explore ways to streamline your processes and approaches, enhance collaboration, and leverage technologies and tools currently available and already proven on the market by a large number of organizations.
1. Connect stakeholders with requirements
Ensure that all stakeholders and contributors are associated with the requirements they are involved with. Each Requirement must be linked to the specific teams and fields it covers so that decisions regarding scope, modifications, or design can be taken in agreement with all contributors that need to be involved with this requirement and without costly delays.
2. Automate bidirectional traceability
We strongly recommend selecting a solution that automates bidirectional traceability. It enables requirements to be tracked both forward and backward and considerably reduces the risk of human error, and the time spent manually creating or maintaining these traceable links. This automated procedure is a guarantee that all requirements are properly met and easily verifiable.
3. Maintain clear and comprehensive documentation
It's also essential to keep a detailed record of all requirements, the changes that have taken place, the reasons and stakeholders involved in these changes, and the traceable links between them. Documentation is not only crucial for compliance audits but also for future projects and references.
4. Conduct formal reviews and audits of your traceability practices
Here is another habit that should be implemented on a regular basis. This not only ensures compliance with all notable regulations, internal controls, and policies but also enables you to identify any weaknesses and gaps in your methodologies. It lets you make the necessary adjustments to rectify them.
5. Train and support your team
This is paramount when we know that the lack of resources and guidance is another major obstacle to establishing requirements traceability. Provide regular training sessions on how to get to grips with tools, technologies, and methodologies. Remember to reiterate and demonstrate with tangible proof the benefits of Requirements traceability, especially if you're faced with a few reluctances.
6. Harness the power of modern technology
We've already mentioned the automation of bidirectional traceability. But it might also be worth considering requirements for traceability solutions that enable real-time collaboration, integration of data and artifacts from different environments, or a solution that enables the visualization and the coverage of trace relationships.
Conclusion and Recommendations
Creating traceability isn’t a smooth ride, but using requirements traceability will be! You can achieve it with the right tools and the right processes. If you are developing systems and software in highly regulated industries, then implementing a requirements traceability process is mandatory. At SodiusWillert, we take enabling traceability very seriously. That’s why we specialize in developing solutions that enable engineering data interoperability as well as requirements traceability. Our goal is to make engineering data available to systems and software development teams across all disciplines to accelerate development projects.
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