Applying Model-Integrated Computing to Provision Middleware and Application Quality of Service

Commercial of-the-shelf (COTS) distribution middleware is gaining acceptance in the distributed real-time and embedded (DRE) community as (1) the cost and time required to develop and verify DRE applications precludes developers from implementing DRE applications from scratch and (2) implementations of standard COTS middleware specifications, such as CORBA, mature. Although standard COTS specifications define the interfaces and policies to provision DRE application resources end-to-end, they do not yet provide sufficient abstractions to separate quality of service (QoS) policy configurations and adaptations from application functionality. DRE application developers must therefore configure QoS policies and program adaptation mechanisms in an ad hoc way. This tight-coupling tends to scatter the code that ensures end-toend QoS throughout many parts of DRE applications, making it hard to configure, validate, modify, and evolve complex DRE applications consistently. This paper provides three contributions to the study of the development of QoS-enabled DRE applications. First, we illustrate how standard component-based middleware can be enhanced to flexibly compose static QoS provisioning policies with application logic. Second, we describe how standard component-based middleware can be integrated with adaptive middleware capabilities to flexibly compose dynamic QoS provisioning and adaptation into DRE applications. Third, we illustrate how the Model-Integrated Computing paradigm can be applied to simplify the development of DRE applications and to help generate and validate static and dynamic QoS provisioning for both middleware and applications. Our qualitative and quantitative results show that (1) static and dynamic QoS provisioning improves the performance and helps ensure the end-to-end QoS of DRE systems and (2) decoupling the QoS provisioning logic from the application logic simplifies the maintenance and and evolution of DRE systems.