Commercial off-the-shelf (COTS) middleware is now widely used to develop distributed real-time and embedded (DRE) systems. DRE systems are themselves increasingly combined to form "systems of systems" that have diverse quality of service (QoS) requirements. Earlier generations of COTS middleware, such as Object Request Brokers (ORBs) based on the CORBA 2.x standard, do not facilitate the separation of QoS policies from application functionality, which makes it hard to configure and validate complex DRE applications. The new generation of component middleware, such as the CORBA component model (CCM) based on the CORBA 3.0 standard, addresses the limitations of earlier generation middleware by establishing standards for implementing, packaging, assembling, and deploying component implementations. There has been little systematic empirical study of the performance characteristics of component middleware implementations in the context of DRE systems. This paper therefore provides three contributions to the study of CCM for DRE systems. First, we describe the challenges involved in benchmarking different CORBA component model (CCM) implementations. Second, we describe key criteria for comparing different CCM implementations using key black-box and white-box metrics. Third, we describe the design of our CCMPerf benchmarking suite to illustrate test categories that evaluate aspects of CCM implementation to determine their suitability for the DRE domain. We demonstrate CCMPerf by using it to collect metrics from a CCM implementation designed for DRE applications.

QoS-enabled component middleware solutions can help reduce the programming complexity of configuring real-time aspects, such as priorities and rates of invocation. However, few empirical studies have been conducted to guide distributed real-time and embedded (DRE) system developers in choosing among alternative configuration mechanisms and performance optimization techniques in practice. This paper makes three contributions to research on QoS-enabled component middleware for DRE systems in the context of the component-integrated ACE ORB (CIAO). First, it describes the design of CIAO's static component configuration mechanisms, which enhance configurability by avoiding features that are not supported by key real-time platforms, while reducing run-time overhead and footprint. Second, it compares the performance of dynamic and static configuration mechanisms in CIAO to help guide the selection of suitable configuration mechanisms based on specific requirements of each DRE system. Third, it presents an empirical comparison of CIAO's static configuration mechanisms to the static configuration mechanisms in Boeing's PRISM avionics component middleware solution.

Although existing CORBA specifications, such as Real-time CORBA and CORBA Messaging, address many end-to-end quality of service (QoS) properties, they do not define strategies for configuring these properties into applications flexibly, transparently, and adaptively. Therefore, application developers must make these configuration decisions manually and explicitly which is tedious, error-prone, and often suboptimal. Although the recently adopted CORBA Component Model (CCM) does define a standard configuration framework for packaging and deploying software components, conventional CCM implementations focus on functionality rather than adaptive quality of service, which makes them unsuitable for next generation applications with demanding QoS requirements. The paper presents three contributions to the study of middleware for QoS-enabled component based applications. It outlines reflective middleware techniques designed to adaptively: (1) select optimal communication mechanisms; (2) manage QoS properties of CORBA components in their containers; and (3) (re)configure selected component executors dynamically. Based on our ongoing research on CORBA and the CCM, we believe the application of reflective techniques to component middleware will provide a dynamically adaptive and (re)configurable framework for COTS software that is well-suited for the QoS demands of next generation applications.