Multicast Transmission in DDS Based on the Client-Server Discovery Model 2024-01-2392

The functions of modern intelligent connected vehicles are becoming increasingly complex and diverse, and software plays an important role in these advanced features. In order to decouple the software and the hardware and improve the portability and reusability of code, Service-Oriented Architecture (SOA) has been introduced into the automotive industry. Data Distribution Service (DDS) is a widely used communication middleware which provides APIs for service-oriented Remote Procedure Call (RPC) and Service-Oriented Communications (SOC). By using DDS, application developers can flexibly define the data format according to their needs and transfer them more conveniently by publishing and subscribing to the corresponding topic. However, current open source DDS protocols all use unicast communication during the transmission of user data. When there are multiple data readers subscribing to the same topic, the data writer needs to send a unicast message to each data reader individually. Obviously, this unicast transmission method not only brings queuing delay to the later readers, but also reduces the transmission efficiency of DDS. This paper proposes a multicast transmission method based on the client-server discovery mechanism, where the discovery server allocates a multicast address and a listening port to a specific topic. In this way, the data writer only needs to send one multicast message and then all data readers will receive this data message. To compare the performance of the unicast and the multicast transmission mechanisms, we designed multicast working conditions to test their performance in terms of latency and sending efficiency. Experimental results show that the multicast transmission method can eliminate the extra delay generated by the original unicast method, and can significantly improve the transmission efficiency of DDS.