RTC: a real-time communication middleware on top of RTAI-Linux

Abstract

This paper describes RTC, a partially object-oriented middleware inspired on the ISO/OSI standard that implements a complete real-time communication platform on a cluster running under real-time Linux. Media Access Control (MAC) is implemented by means of a modified TDMA protocol, and at the application level a channel-oriented communication is provided. The RTC platform guarantees a bandwidth for each channel, which makes it attractive for multimedia applications, which currently is the main application considered. In addition, RTC supports non-real-time traffic using TCP/IP, for instance. The platform has two principal components: the communication protocols implemented as modules of the Linux/RTAI operating system and the user space API (Application Program Interface) implemented in a object-oriented manner and based on the LXRT feature of the RTAI. Furthermore, the non-real-time capabilities are supported by a software layer in the kernel of Linux. Currently, SCI is used as underlying communication network. SCI has been selected due to its low latency, low jitter and high bandwidth[6]. RTC, however has been designed to support other network technologies as well. Included in the paper are performance evaluation results that demonstrate the real-time properties of RTC.