Research And Practice Of Distributed Real-time Event Service

For many distributed applications, such as control and command in automobiles, ships, airplanes and battlefields, a lots of events occurred cannot be anticipated. These occurrences are usually parts of the system's behavior. System is not affected by some events but could be halted or crashed by others. However, these events are very hard to be managed because they are difficult to be predicted in the distributed system sometimes. It is very expensive to monitor some events of low-probability, so that it is significant to create a mechanism for processing these burst events of different importance. This aim can be reached through using distributed event service.The Distributed Real-time Event Service (DRES) provides a flexible mechanism for real-time, asynchronous and group communication between event suppliers and consumers. DRES discussed in the paper is studied and developed based on OMG's CosEvent. DERS is then extended to meet real-time performance requirements and the functions of event filtering, scheduling, dispatching and combining are implemented.DRES is characterized by two points, real-time performance and distributed performance. The first is exhibited by the real-time characteristic of event itself and each event is arranged strictly according to its priority when it is transferred. Distributed performance is exhibited by the fact that event service can be deployed on different computer network nodes, by which resources for network transmitting are reduced, so the performance of distributed event service is improved in some fields.Deficiency of specification is analyzed in this paper based on introduction of CORBA, real-time CORBA and event service. Concept and framework of distributed event service is put forward and then DRES is implemented. Tests and experiments show that the event service is conformed to the requirement of distributed real-time applications.