2 The Design of the TAO Real-time ORB Endsystem 2 . 1 Real-time Support in TAO

There is increasing demand to extend Object Request Broker (ORB) middleware to support applications with stringent quality of service (QoS) requirements. However, conventional ORBs do not define standard features for specifying or enforcing end-to-end QoS for applications with deterministic realtime 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 illustrates how integrating a real-time ORB with a real-time I/O subsystem can reduce latency bounds on end-to-end communication between high-priority clients without unduly penalizing low-priority and best-effort clients.