Dissecting some important ROS 2 layers
We have gone through the basics of DDS and explored its different features. In this section, we are going to explore the layers in ROS 2 that work on top of DDS. We can start with a detailed discussion of the RMW abstraction layer, which is one of the important layers connecting DDS to the ROS 2 framework.
RMW layer (ROS middleware abstraction interface)
Figure 1.8 shows a detailed architecture of the ROS 2 framework with all its layers.
Figure 1.8: ROS 2 detailed architecture (source: RTI | https://www.slideshare.net/slideshow/deep-dive-into-the-opc-ua-dds-gateway-specification/99648467)
We already discussed the DDS framework in Figure 1.2. We learned that DDS has an application layer or APIs that we can use to build our own apps. This is where ROS becomes relevant. The ROS 2 framework is built on top of the DDS API layer. If you take a look at Figure 1.8, you can see that after the DDS framework layer comes the ROS 2 framework...
