基于发布/订阅模型的中间件实时拓展

Real-time Expansion of Middleware Based on Publish/Subscribe Model

基于发布/订阅模型的卫星数据模型中间件不具备实时性。为此,给出一种对其进行实时拓展的服务软件总体框架。提出将任务的中间件优先级映射到本地节点优先级的线性均匀分布动态映射算法。引入超周期思想,在静态优先级可抢占调度算法下,对优先级任意的硬实时周期和非周期混合任务进行可调度性分析。采用恢复块技术对其进行冗余备份以解决服务软件单点故障。分析结果表明,该框架基本可以满足实时系统的要求。

An overall framework is put forward to expand the real-time ability of the middleware Satellite Data Model（SDM） based on publish/ subscribe model.A linear and dynamic method is presented to map middleware priority to native operating system.It analyzes the schedulability test of scheduling hard real-time period and sporadic tasks under static priority preemptive scheduling algorithm whose priority is assigned freely.To improve its fault-tolerance capability,the software by Recovery Block（RB） technique is done back up so that it can avoid the breakdown of any part one.Compared with the preceding system,this service framework possibly meets the needs of distributed real-time applications.