You've bought the plot of land for your dream home. You have your list of requirements - 4 bedrooms, 3 bathrooms, spacious kitchen, 2 living rooms, 2 garages, landscaped gardens, etc. Would you be happy to simply hand that list to the builders and let them start work? Unlikely, I think. Typically, you call in an architect, who can take your quantitative requirements and qualitative desires and produce a blueprint, the architectural design that incorporates your wishes where feasible and adds creative flourish based on the architect's knowledge of house design. The blueprint enables you and the builders to have a much clearer picture of the desired end result than that original list of requirements. And it affords you the opportunity to influence the architecture, and for the builders to question and look at feasibility & cost options, before the foundations are dug and the first bricks are laid.
The same applies in product development. Systems engineers who are responsible for the holistic product specification and design don't just use textual requirements lists to capture the problem domain and describe the proposed solution. They analyze the requirements, identifying integrated scenarios, and often depict those using modeling languages such as UML or SysML. These modeled scenarios are easier to discuss and review with all stakeholders, and as the systems engineer evolves the proposed architecture (also in the same modeling language) they can run the scenarios against the architecture in model simulations to find inconsistencies or gaps in the requirements and flaws in the design, long before any software is coded, circuit boards are soldered or metal is welded.
So what value are our textual requirements lists - should we throw them away in favor of models? Well, not everything can be expressed in the model and not everyone involved in a development effort maybe using models. Going back to the house building analogy, there are contracts, numerous standards and regulations to be adhered to, and simply details that would make the blueprints unreadable. The various contractors (and I know from recent experience that sub-contracting is the name of the game in house building these days!) involved in the building process need to ensure that they can meet the contractual and regulatory demands while delivering against the architecture. Again this is the same in product development, except in many cases, particularly safety-critical systems, traceability and demonstration of conformance to requirements and compliance to standards & regulations are demanded. This requires the ability to integrate requirements and modeling workflows, easily link requirements and design elements, and to report on that linked information.
The need and solutions for this capability are nothing new. Integrations between requirements management and modeling tools have existed for many years (I think I started using such an integration in the early 90's and I'm sure they preceded that time). But I know from first hand experience of using and indeed writing such integrations that they've not always been optimal in the way integration is performed and in the workflow that is supported. Typically it's meant synchronizing (i.e. copying) data between tools in order to create the traceability links in one of the tools. This brings up all sorts of issues like 'which tool is the master?', 'am I looking at the latest data?', 'what happens when information is deleted?', etc.
With Open Services for Lifecycle Collaboration (OSLC) we now have a much better way to link data across product development and operations tools, even when the tools maybe from different vendors, open source or in-house. OSLC has learnt from the principles of the World Wide Web and enables tool data to be shared and linked where it resides (called a ‘Linked Data’ approach). OSLC provides a common vocabulary for ‘resources’ in particular domains, i.e. what a requirement, test case, design element, change request, work item, etc. looks like, so that regardless of tool, technology or vendor, tools implementing OSLC specifications can share and link data.
With Rational DOORS 9.4 and Rational Rhapsody 8.0 with Design Manager 4.0, IBM is utilizing OSLC to provide a simplified workflow for linking requirements analysis and design. On September 20, Paul Urban (if you've been wondering about this blog post title, now you know the Paul I'm speaking of), Market Manager for IBM Rational Rhapsody, presented this simplified workflow and its benefits on a IEEE Spectrum webcast sponsored by IBM. You can watch and listen to the replay at your own leisure here. I hope you it enjoy it - please let Paul and I know what you think by leaving feedback on this blog post.