Difference between DDS and RTPS Protocol

[Nitind7]

What's difference between DDS and RTPS protocols? Which one is good option when need to implement inter process communication?

[JesusPoderoso]

Hi @Nitind7, you may be interested in what is DDS? section of the Fast DDS documentation. In summary, the RTPS protocol supports DDS applications. Both DDS and RTPS share the same publication-subscription-topic structure, and allow configuration of their endpoints (QoS and attributes, respectively).
If the communication from the user application to the final transport is represented in layers, the Fast DDS architecture is structured with the RTPS domain as the inner layer and the DDS domain as the outer layer.

Which one is good option when need to implement inter process communication?

For inter-process communication, the best delivery mechanism is data-sharing, but there are several constraints that need to be met to use it. If not possible, then the shared-memory transport is the following option.
In both cases, mind that serialization can be avoided (reducing the number of copies) using loans. This thread may be of interest to you.