A soft real-time TMO platform-WTMOS-and implementation techniques

Abstract

The TMO (Time-triggered Message-triggered Object) model is a real time object model pursuing the timeliness guaranteed 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. We present the functions and the design techniques of a middleware platform to support execution of TMOs on the Windows environment, named WTMOS (Windows TMO System). The WTMOS platform does not support the concept of design time guarantee. But, as 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 TMOs. It also offers used defined deadline exception handlers to compensate for 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 typical soft real time applications such as multimedia services and virtual reality services.