Architectural tactics for scalability

Scalability is the ability to handle increased workload by repeatedly applying a cost-effective strategy for extending a systems capacity. Architectural tactics have been proposed as a way to systematically organize design decisions to provide quality attributes (QA), and many have been published for performance, availability, security and so on. Scalability-related tactics have usually been included in catalogs of performance and availability tactics, or for specific contexts like big data, but proper understanding of their aspects and trade-offs requires a specific catalog. This article surveys scalability tactics proposed in the literature; compares and homologates them into a smaller set; proposed to consider “workload” as their stimulus; and organizes them into a taxonomy addressing (workload) detection, reaction, and prediction. This proposal is a first step towards giving scalability first-class status as an addressable quality attribute.