ORB middleware evolution for networked embedded systems

Standards-based COTS (common-off-the-shelf) middleware has been shown to be effective in meeting a range of functional and QoS (quality of service) requirements for distributed real-time and embedded (DRE) systems. Each standard makes limiting assumptions, often implicit, about the fundamental set of system capabilities and constraints typical of the domain to which the standard applies. When the characteristics of a particular class of systems violates a standard's assumptions, it may be appropriate to modify or extent the standard and its conforming implementations to better match the actual characteristics of that class of systems while still exploiting the capabilities of the standard. In this paper, we argue that key assumptions upon which even the more advanced middleware standards are based, e.g., Real-Time CORBA (RT-CORBA), are violated by an important class of DRE systems characterized by the following properties: (1) highly connected networks of (2) numerous memory-constrained endsystems, with (3) stringent timeliness requirements, and (4) support for adaptive reconfiguration of computation and communication elements and their associated timeliness requirements. We describe our recent work on nORB, a small footprint ORB middleware framework for the Boeing Open Experimental Platform (OEP) under the DARPA Nest program, to meet this entire set of requirements by adapting, unifying, and extending patterns and techniques from earlier related research on COTS middleware frameworks, such as UBI-core, ACE, Kokyu, and TAO.