RobofleetUnrealClient

Client-side code for Robofleet in the form of an Unreal Engine module. It is nominally a stripped down clone of robofleet_client, with ROS dependencies and message scheduling removed.

Code Overview

This Module, other Robofleet clients, and the Robofleet server makes used of flatbuffers and a common library to facilitate common functions. These shared components are detailed here.

flatbuffers and generated schemas

The flatbuffers library is a way to serialize and package data across platforms. The 'blueprint' for how to encode and decode these structures is defined in the flatbuffer schema, which is specified in robofleet_client_lib/include/schema_generated.h.

robofleet_client_lib

This is a shared library that all existing robofleet clients use, in varying degrees. It includes it's own decode and encode functions that can be defined and used cross-platform. Additionally, it defines a number of C++ structs in message_structs.h that are useful once a flatbuffer object is received and decoded.

robofleet_client

While not used directly in this Module, it's notable to mention that if you're using robofleet with robots, they will likely be using this as their client. Therefore, you should be aware that new functionality may need to be added here for your robot to publish new data.

Adding new functionality (new messages)

When adding new message support to the Robofleet system, these are the general steps that need to be carried out:

• add the new definition to the schema_generated.h file in robofleet_client_lib
• add a relevant C++ struct with the same fields in message_structs.h in robofleet_client_lib
• add definitions to the encode.hpp and decode.hpp for the new message type in robofleet_client_lib
• add support for the message type in encode_ros.hpp and decode_ros.hpp in robofleet_client IF your robot needs to publish those messages to robofleet

At this point, unless there are any logic issues with the added support, new messages should be able to be sent by a robot, through robofleet, and received by the client library used by RobofleetUnrealClient. The only thing to do now is to integrate that data within the Module itself.

This will require subscribing to the new message topic, e.g. in RobofleetClientBase.cpp:

	RegisterRobotSubscription("my_topic_name_here", "*");

and then catch incoming messages in the function void URobofleetBase::DecodeMsg() so you can handle the decoding process correctly for that data. Once the data is decoded and made available under the RobotMap data field, it can be accessed on-demand.

When everything is tested, you'll need to create a pull request for each of the three libraries you modified to add support.

An example of adding message support to robofleet_client_lib can be seen here. An example of adding message support to robofleet_client can be seen here.