The challenge of assessing and controlling complexity in a large portfolio of software systems

Controlling IT complexity in a large organization's portfolio of constantly evolving software systems is crucial in a business world with tighter economic constraints and an increased focus on business agility. Unfortunately, there are no commonly accepted metrics for software complexity, and the few metrics that exist have not been validated as good predictors of the impact on cost in a given context. Telenor Norway has therefore developed its own method to help assess the cost of IT complexity from a broad perspective. For all the systems affected by a given project, the architects and experts of each system subjectively estimate the change in the annual cost of developing and maintaining it as a result of the change in complexity brought about by that project. The method was subjectively evaluated and improved in six pilot studies. Following these experiences, it was decided to gradually introduce the method throughout the whole organization, in the belief that this would allow Telenor Norway to make better architectural decisions, and to achieve a reduced cost of ownership and an increased strategic flexibility. Work continues to improve the method.