Commercial off-the-shelf (COTS) middleware increasingly offers not only functional support for standard interfaces, but also the ability to optimize their resource consumption patterns. For example, a COTS real-time object request broker (ORB) may permit users to configure its server-side thread pooling policies. On one hand, this flexibility makes it possible to use standard functional interfaces in applications where they were not applicable previously. On the other hand, the nonstandard nature of the optimization mechanisms – i.e., the "knobs and dials" – acts against the very product-independence that standardized COTS interfaces are intended to provide. This paper provides two contributions to the study of mechanisms for reducing the life-cycle costs of distributed real-time and embedded (DRE) systems. First, we present a mechanism–called a Quality Connector–that enables applications to specify the qualities of service that they require from their infrastructure...
Joseph K. Cross, Douglas C. Schmidt