Identifying Scalability Debt in Open Systems

Architectural technical debt can be generated by changes in the business and the environment of an organization. In this paper, we emphasize the change in scalability requirements due to new regulations. Scalability is the ability of a system to handle an increased workload. For complex systems that are abruptly exposed via open interfaces and hence a greater workload, the scalability requirements may quickly increase, leading to technical debt. We term this scalability debt. This paper describes scalability triage, a light-weight, novel technique for identifying scalability threats as a form of technical debt. We illustrate this technique with an open banking case from a large software organization. Open banking is partly caused by the new European PSD2 regulative that enforce banks to open interfaces to unknown third-party actors. Banking systems are well-established, mature systems. However, with the advent of open banking and PSD2, the workload may quickly rocket. This leads to tougher scalability requirements and accumulated architectural debt, despite previously sound architectural decisions. Using scalability triage, such risks may be identified fast. It will then be possible to prevent this form of technical debt with timely reengineering.