Middle-out design: A proposed best-practice for GEOSS design

Overton, Jerry; Hall, Jon G. and Rapanotti, Lucia (2010). Middle-out design: A proposed best-practice for GEOSS design. Technical Report 2010/10; Department of Computing, The Open University.

DOI: https://doi.org/10.21954/ou.ro.000160a0

Abstract

The proposed scale of the Global Earth Observation Systems of Systems (GEOSS) [1] suggests that its design will have all the challenges of designing Ultra-Large-Scale (ULS) systems: competing requirements, continuous evolution, heterogeneous parts, and normal failures [2]. Evidence suggests that many `traditional' design methods have difficulty handlling the challenges of ULS systems: in particular, top-down design is unlikely to converge on a viable solution and bottom-up design is unlikely to result in a useful system. To successfully work at the scale of the GEOSS, we need alternative design approaches that will allow us to converge onto a viable solution to our problem while at the same time address our ULS-specific design issues. In this position paper, we describe the method of middle-out design, which we propose as a practical design method for ultra large scale systems and a best practice for GEOSS design. In essence, middle-out design proceeds starting from a new model of systems design we call the problem view. The problem view is an addition to Kruchten's 4+1 model, and allows us to transform ULS problems inot simpler, more tractable problems that can be handled using traditional design and development methods.