A Soft Real-Time TMO Platform - WTMOS - and its Implementation Techniques

The TMO (Time-triggered Message-triggered Object) model is a real-time object model pursuing the timelinessguaranteed computing paradigm. A TMO contains two types of methods: time-triggered method activated by its internal clock and message-triggered method activated by a request from a client. In this paper, we present the functions and the design techniques of a middleware platform to support execution of TMO's on the Windows environment, named WTMOS (Windows TMO System). The WTMOS platform does not support the concept of design-time-guarantee. But, as a middleware platform, it supports soft real-time system by trying to meet the goal of on-time activation and finishing within deadlines imposed on time-triggered and message-triggered methods in TMO's. It also offers used-defined deadline exception handlers to compensate the lack of timeliness guaranteed design. Besides the above functions, the activation sources of message-triggered methods on WTMOS are expanded so that it can be activated not only by distributed IPC messages but also by Windows system messages. As a result, message-triggered methods now can play the roll of Windows message callback functions naturally. This is to add window management facilities and interfaces of Win32 API to the TMO model. Therefore, the TMO model and WTMOS together can be regarded as a powerful development environment for 1 This work has been done as a part of the project entiled “ Integrated Object-Oriented Development Environment for Distributed Real-Time Systems” funded by KOSEF of KOREA (Project no. 96-01-0107-01-3). typical soft real-time applications such as multimedia services and virtual reality services.