Nodelets are a type of ROS node that are designed to run multiple nodes in a single process, with each node running as a thread. The threaded nodes can communicate with each other efficiently without overloading the network having, zero copy transport between two nodes. These threaded nodes can communicate with external nodes too.

As we did using pluginlib, in nodelets also, we can dynamically load each class as a plugin, which has a separate namespace. Each loaded class can act as separate nodes, which are on a single process called nodelet.

Nodelets are used when the volume of data transferred between nodes are very high, for example, in transferring data from 3D sensors or cameras.

Next, we look at how to create a nodelet.