How to implement CM based on DDS protocol

[yuzu-ogura]

It seems implement CM based on DDS protocol is more difficult than someip.

[langroodi]

I am not personally experienced with DDS, so I may not precisely can compare it with SOME/IP. Even though DDS is known as a data-centeric pub/sub protocol, but technically speaking both protocols support RPC, Fire-Forget, and Pub/Sub communication patterns. So, you should not face architectural challenges in your application layer while migrating to DDS from communication pattern perspective.

Besides that, same as SOME/IP there are open-source implementations of DDS namely Fast-DDS or Cyclone DDS. So, there will even less challenges from application lifetime perspective while migrating to DDS from SOME/IP.

However, from following perspectives, there are more requirement to be considered while using DDS over SOME/IP:

• Transport layer: DDS next to TCP/IP can support other IPC mechanisms including Shared Memory. This brings more flexibility in choosing the communication medium while it can complicate the configuration of the communication layer adapter.
• QoS: Due to the fact that DDS has a more broad application than to be only specified to the automotive industry, it has more quality of service policies like where you can use UDP over TCP for communication compare to SOME/IP. So, you may need to keep more points in your mind while architecturally designing your system.
• Security: Due to the previously mentioned reason, DDS has more fine-grained security considerations. It won't be like SOME/IP to combine it with TLS and you end up with a relatively secure way of communication. The DDS protocol specifies these security practices which may lead to more work, but it can provide you more customized version of security that fits your use-case better.

[yuzu-ogura]

Thank you for your advice. I would like to look for an open source CM implement based on DDS protocol, but I've not found up to now. If it is not too difficult, I'd like to try to implement it.

[langroodi]

No problem. As mentioned before, there are open-source DDS implementations. But as far as I know (same as you), I could not find any open source usage of DDS within the AUTOSAR domain in general.

To judge that whether it is difficult to implement or not, you can take a look into the AUTOSAR SWS Communication Management document next to an open source DDS implementation document such as FastDDS. To my knowledge, AUTOSAR same as SOME/IP supports Event, RPC, and Service Discovery for DDS too. Besides that, it also covers QoS within DDS.

So, you may end up with a little more work than SOME/IP. Personally, I expect DDS within AUTOSAR context not be complex if you are familiar with communication patterns. It is only a matter of time, how much effort you want to spend on it, and to what extend of maturity you want to support it. Good luck with your journey there.