To clarify what @Daniel_Stonier was talking about, it is serializing/deserializing from json to rosmsg and vice versa (since most REST apis use json messages), in order to interface ROS systems (a robot) with a potentially useful REST API (a server somewhere). Note the ROS system can be a client, but also a server, such as when someone writes a WebApp for a Robot UI, interfacing with ROS, using some "robot REST API" derived from existing ROS services. As a Reference, here is how one would specify a message for a REST API : http://swagger.io/specification/#simple-model-87 by default all fields are optional. required fields need to be specified explicitly. Same as current protobuf design from what i understood. An unset field has a different meaning than a field set to a default value automatically by the message type, without explicit user intent... --- [Visit Topic](https://discourse.ros.org/t/optional-fields-in-message/991/9) or reply to this email to respond. If you do not want to receive messages from ros-users please use the unsubscribe link below. If you use the one above, you will stop all of ros-users from receiving updates. ______________________________________________________________________________ ros-users mailing list ros-users@lists.ros.org http://lists.ros.org/mailman/listinfo/ros-users Unsubscribe: