Resource conscious development of middleware for control environments: a case of CORBA-based middleware for the CAN bus systems

摘要

While it is imperative to exploit middleware technologies in developing software for distributed embedded control systems, it is also necessary to tailor them to meet the stringent resource constraints and performance requirements of embedded control systems. In this paper, we propose a CORBA-based middleware for Controller Area Network (CAN) bus systems. Our design goals are to reduce the memory footprint and remote method invocation overhead of the middleware and make it support group communication that is often needed in embedded control systems. To achieve these, we develop a transport protocol on the CAN and a group communication scheme based on the publisher/subscriber model by realizing subject-based addressing that utilizes the message filtering mechanism of the CAN. We also customize the method invocation and message passing protocol of CORBA so that CORBA method invocations are efficiently serviced on a low-bandwidth network such as the CAN. This customization includes packed data encoding and variable-length integer encoding for compact representation of IDL data types. We have implemented our CORBA-based middleware using GNU ORBit. We report on the memory footprint and method invocation latency of our implementation.