An Architectural Approach to Software Cost Modeling

The value of a software system results from the interactions between its functionality and quality attributes (such as performance, reliability and security) and the market-place. Quality is a direct consequence of architectural design decisions. Traditional product cost models have focussed on the short term development cost of the product. We argue that if one wants to build realistic cost models, the quality of the product and the time-period for which the product is going to be in the market must be taken into account for analysis. One needs to consider the costs of technical tradeoffs encountered by the system’s architect while designing the system to understand how to maximize the system’s benefits. For long-lived products the long range costs of the system with its inherent uncertainties must be incorporated into these models. We believe that an architectural approach to cost-modeling will be able to capture these concerns so that the software architect can reason about the risks in the system and the cost of mitigating them.