13 years, 7 months ago

Brownfield Requirements Engineering

Some partial and selective notes from the RESG meeting on Brownfield Requirements Engineering, held at BCS headquarters on October 12th 2010. By Richard Veryard.

Chairman’s Introduction

Ian Alexander opened the meeting by pointing out the gulf between the demands of real engineering projects (95% brownfield) and the body of knowledge about requirements engineering offered by academics and authors (95% greenfield), and sketching some of the characteristic features of brownfield requirements. The importance of this topic is demonstrated by an excellent turnout for this meeting.

Brownfield Systems Engineering

Ian Gallagher of Altran Praxis presented some experience from several large systems projects, both military and civilian. The typical scenario is a major upgrade of existing systems to improve performance and deal with obsolescence; the upgrade may therefore include different types of requirement

  • doing new things
  • doing old things in new ways
  • migrating away from ageing technologies, proprietary systems or restricted technologies (e.g. those subject to export licenses)

The upgrade may be regarded as a single large increment (from AS-IS to TO-BE) but is often managed as a series of smaller increments.

With greenfield engineering, the requirements of the engineering project are pretty much the same as the requirements of the TO-BE system, but brownfield engineering introduces a critical choice: whether to write total requirements for the TO-BE system or to write requirements for the project (or separate increments) based on the difference(s) between AS-IS and TO-BE. IanG expressed a strong preference for the former, but acknowledged that this isn’t always acceptable to key stakeholders, especially if the effort would be perceived as excessive. But in any case it’s obviously important to be clear what kind of requirements we are talking about.

Beyond the scope of the TO-BE system, there may be a larger system-of-systems context, in which other equally large systems are the subject of equally large brownfield engineering activity. This raises questions of the interoperability of the increments, and the coordination between autonomous brownfield engineering projects, which is another important issue for brownfield requirements engineering.

A key issue is the pressure to reuse and repurpose existing assets. There are three possible reasons for this.

  1. Rational economics – genuine cost-saving based on lifetime exploitation of assets
  2. Irrational inertia – desire to justify past investment decisions, resistance to change
  3. Commercial – vested interests from key stakeholders (such as contractors) to maintain proprietary dependencies

Requirements such as migrating towards more “open” architectures are therefore not only relevant for an immediate brownfield project but also have important implications for the economics of future brownfield projects.

Managing Brownfield Financial Software

Phil Cantor of Smartstream then talked about his past and present experience managing and maintaining software products in the financial sector. (Most of his examples came from previous companies he had worked for.) The requirements of such products don’t come exclusively (or even primarily) from the “users” but from a body of knowledge that the package vendor is expected to master. Phil gave the example of an obscure piece of financial calculation that is now only required in the Philippines: users elsewhere in the world may not know about this, but a package that doesn’t cater for this requirement will be unacceptable to a global bank.

The package vendor then has to balance a wishlist of enhancement requests and bug reports from hundreds of user organizations, with the practical constraints of maintaining – and hopefully improving the quality of – an existing body of software.

For me, one of the most interesting issues raised by Phil was when he talked about the platform and its requirements. There is an internal platform supporting the user-facing components of the product suite, containing common services and suchlike, and the requirements for this platform cannot be derived purely from the requirements of the package as a whole. Furthermore, the package as a whole serves as a platform for the business processes of the user organizations (Phil’s customers), so the same question arises at that level as well. However, this is not particularly a brownfield issue.

Phil also mentioned the challenges of training. From a sociotechnical perspective this is a major brownfield issue, since the performance of the TO-BE system will be affected by the user habits and expectations (e.g. knowing where to find things) carried forward from the AS-IS system. Training is a solution (and often not a very good one) to some set of sociotechnical requirements, and there may be better ways of conveying a new set of habits and expectations to the users and technical staff, but clearly we need to have an understanding of these requirements as well.


Lots of further issues came up in the discussion, and I didn’t manage to capture half of them. Someone raised the question of scale – what do you do with a brownfield situation with a complex network of interdependent pieces of hardware and software, with the need for upgrades constrained by small budgets and massive complexity. This led to the question of timing – how do you decide whether to upgrade something now or to defer the upgrade until next year. (Nobody actually mentioned the concept of technical debt, but that is clearly relevant here.)

Finally, my memory and notes can be supplemented by a few choice tweets.

@rmonhem much debate over how much to document requirements with significant re-use of existing applications

@rmonhem most difficult challenges have often been posed by cultural, commercial and legal factors.

@jiludvik Bit too much focus on techniques documenting and signing off detailed reqs. This is not specific for brownfield projects!

@jiludvik Phil Cantor’s pres has been very entertaining and spot on for brownfield req’s eng. I can certainly relate to many challenges he mentioned