DS301(带书签)应用层和通信概要

　　The Application Layer comprises a concept to configure and communicate real-time-data as well as the mechanisms for synchronization between devices. The functionality the application layer offers to an application is logically divided over different service objects in the application layer. A service object offers a specific functionality and all the related services. These services are described in the Service Specification of that service object. Applications interact by invoking services of a service object in the application layer. To realize these services， this object exchanges data via the CAN Network with （a） peer service object（s） via a protocol. This protocol is described in the Protocol Specification of that service object. Service Primitives： Service primitives are the means by which the application and the application layer interact. There are four different primitives： • a request is issued by the application to the application layer to request a service • an indication is issued by the application layer to the application to report an internal event detected by the application layer or indicate that a service is requested

　　a response is issued by the application to the application layer to respond to a previous received indication • a confirmation is issued by the application layer to the application to report the result of a previously issued request.