a b s t r a c tDistributed real-time and embedded (DRE) systems have become critical in domains such as avionics (e.g., flight mission computers), telecommunications (e.g., wireless phone services), tele-medicine (e.g., robotic surgery), and defense applications (e.g., total ship computing environments). These types of system are increasingly interconnected via wireless and wireline networks to form systems of systems. A challenging requirement for these DRE systems involves supporting a diverse set of quality of service (QoS) properties, such as predictable latency/jitter, throughput guarantees, scalability, 24x7 availability, dependability, and security that must be satisfied simultaneously in real-time. Although increasing portions of DRE systems are based on QoS-enabled commercial-off-the-shelf (COTS) hardware and software components, the complexity of managing long lifecycles (often ∼15-30 years) remains a key challenge for DRE developers and system integrators.For example, substantial time and effort is spent retrofitting DRE applications when the underlying COTS technology infrastructure changes.This paper provides two contributions that help improve the development, validation, and integration of DRE systems throughout their lifecycles. First, we illustrate the challenges in creating and deploying QoS-enabled component middleware-based DRE applications and describe our approach to resolving these challenges based on a new software paradigm called Model Driven Middleware (MDM), which combines modelbased software development techniques with QoS-enabled component middleware to address key challenges faced by developers of DRE systems -particularly composition, integration, and assured QoS for end-to-end operations. Second, we describe the structure and functionality of CoSMIC (Component Synthesis using Model Integrated Computing), which is an MDM toolsuite that addresses key DRE application and middleware lifecycle challenges, including partitioning the components to use distributed resources effectively, validating software configurations, assuring multiple simultaneous QoS properties in realtime, and safeguarding against rapidly changing technology.

This paper presents two contributions to the study of component deployment for distributed real-time and embedded (DRE) systems. First, it uses an inventory tracking systems (ITS) as a case study to elicit challenges involved in deploying DRE systems to account for their quality of service requirements. Second, it describes how we designed and implemented the Deployment And Configuration Engine (DAnCE), which is QoS-enabled middleware that addresses the challenges that arose in the context of our ITS case study. Our experience shows that DAnCE provides an effective platform for deploying DRE system components using a standard runtime environment and metadata.

Quality of service (QoS)-

Quality of service QoS-enabled component middleware can help reduce the complexity of deploying and con guring QoS aspects, such as priorities and rates of invocation. Few empirical studies have been conducted, however, to guide developers of distributed r e al-time and embedded DRE systems in choosing among alternative designs and performance optimizations. Moreover, few empirical studies have been conducted to examine the performance and exibility trade-o s between standardsbased and domain-speci c DRE middleware solutions. This paper makes three key contributions to research on QoS-enabled component middleware for DRE systems. First, it describes optimizations applied to an implementation of the OMG's Deployment and Con guration D&C of Components speci cation that enable performance trade-o s between QoS aspects of DRE systems. Second, it compares the performance of several dynamic and static con guration mechanisms to help guide the selection of suitable con guration mechanisms based on speci c DRE system requirements. Third, it compares the performance of our static standards-based approach to an avionics domain-speci c approach. Our results show that these optimizations 1 provide developers improved c ontrol over key trade-o s between exibility and performance at di erent stages of the DRE system lifecycle, 2 enhance trustworthiness of component-based DRE systems by supporting greater customization of how they are c on gured t o m e et speci c requirements of each application, and 3 o er greater exibility at a reasonable performance cost, compared to a domain-speci c approach.