OOPSLA 2008–Economics-Driven Architecting

As a student volunteer I had to take the responsibility of a tutorial session which turned out to be the CBAM tutorial presented by Rick Kazman and Ipek Ozkaya. CBAM is a quantitative approach to architecture design decision making. CBAM augments ATAM by adding costs and benefits as attributes to be traded off. As an advantage of CBAM, Rick and Ipek mentioned that stakeholders like CBAM as it helps them reach consensus through a rational process.

Having had read the SAIP two years before, I was familiar with CBAM. However, this tutorial refreshed me on the subject of architecture analysis techniques.  Specially, the hands-on approach they took by having the participants use CBAM on an example of city information system was quite effective. They began by introducing several concepts such as quality attribute, value, utility, … . Then, they went through the steps of CBAM on the NASA ECS project.

My comment on CBAM is that this technique looks reasonable once you have reliable data about response measures and effects of architectural strategies on response levels. However, as Rick and Ipek were pointing out throughout the tutorial, uncertainty should be considered in decision making as well. They explained how uncertainty is taken into account in the following iterations of CBAM. But, that looked quite simplistic and insufficient. Uncertainty was not considered as  a central element of architectural decision making. Nevertheless, I think CBAM has already gone too far in trying to quantify costs and benefits and coming up with values for uncertainties requires guidelines, formulas, estimates, voting, … which will make the CBAM quite complicated.