Edicts: implementing features with flexible binding times

ManuscriptIn a software product line, the binding time of a feature is the time at which one decides to include or exclude a feature from a product. Typical binding site implementations are intended to support a single binding time only, e.g., compile time or run time. Sometimes, however, a product line must support features with variable binding times. For instance, a product line may need to include both embedded system configurations, in which features are selected and optimized early, and desktop configurations, in which client programs choose features on demand. We present a new technique for implementing the binding sites of features that require flexible binding times. Our technique combines design patterns and aspect-oriented programming: a pattern encapsulates the variation point, and targeted aspects-called edicts-set the binding times of the pattern participants. We describe our approach and demonstrate its usefulness by creating a middleware product line capable of serving the desktop and embedded domains. Our product line is based on JacORB, a middleware platform with many dynamically configurable features. By using edicts to select features at compile time, we create a version of JacORB more suited to resource-constrained environments. By configuring four JacORB subsystems via edicts, we achieve a 32.2% reduction in code size. Our examples show that our technique effectively modularizes binding-time concerns, supporting both compile-time optimization and run-time flexibility as needed

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

Product-line architectures (PLA)s are an emerging paradigm for developing software families for distributed real-time and embedded (DRE) systems by customizing reusable artifacts, rather than handcrafting software from scratch. To reduce the effort of developing software PLAs and product variants for DRE systems, developers are attempting to leverage 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