The Design and Performance of an I/O Subsystem for Real-time ORB Endsystem Middleware

There is increasing demand to extend Object Request Bro- ker (ORB) middleware to support applications with stringent quality of service (QoS) requirements. However, conventional ORBs do not define standard features for specifying or enforc- ing end-to-end QoS for applications with deterministic real- time requirements. This paper provides two contributions to the study of real-time ORB middleware. First, it describes the design of a real-time I/O (RIO) subsystem optimized for ORB endsystems that support real-time applications running on "off-the-shelf" hardware and software. Second, it illus- trates how integrating a real-time ORB with a real-time I/O subsystem can reduce latency bounds on end-to-end communi- cation between high-priority clients without unduly penalizing low-priority and best-effort clients.