Context-Specific Middleware Specialization Techniques for Optimizing Software Product-line Architectures

摘要

Product-line architectures (PLAs) are an emerging paradigm for developing software families for distributed real-time and embedded (DRE) systems by customizing reusable artifacts, rather than hand-crafting software from scratch. To reduce the effort of developing software PLAs and product variants for DRE systems, developers are applying general-purpose - ideally standard - middleware platforms whose reusable services and mechanisms support a range of application quality of service (QoS) requirements, such as low latency and jitter. The generality and flexibility of standard middleware, however, often results in excessive time/space overhead for DRE systems, due to lack of optimizations tailored to meet the specific QoS requirements of different product variants in a PLA. This paper provides the following contributions to the study of middleware specialization techniques for PLA-based DRE systems. First, we identify key dimensions of generality in standard middleware stemming from framework implementations, deployment platforms, and middleware standards. Second, we illustrate how context-specific specialization techniques can be automated and used to tailor standard middleware to better meet the QoS needs of different PLA product variants. Third, we quantify the benefits of applying automated tools to specialize a standard Realtime CORBA middleware implementation. When applied together, these middleware specializations improved our application product variant throughput by ～65%, average- and worst-case end-to-end latency measures by ～43% and ～45%, respectively, and predictability by a factor of two over an already optimized middleware implementation, with little or no effect on portability, standard middleware APIs, or application software implementations, and interoperability.