gRPC service generation

This tutorial shows how to generate a basic gRPC service like a seat service. For this example the proto file at https://raw.githubusercontent.com/eclipse-kuksa/kuksa-incubation/0.4.0/seat_service/proto/sdv/edge/comfort/seats/v1/seats.proto is used.

All files included from services/seats are auto-generated and added to the app project as Conan dependency. For writing a complete gRPC service you need two velocitas apps/projects. One is implementing a client and the other one is for providing the server.

Networking

The examples shown in this tutorial are based on three components running:

• A client using the API defined in the proto file
• A server providing the API and communicating with Databroker to read or modify datapoints
• A Kuksa Databroker .

As a Velocitas developer you may use the Velocitas devenv-runtimes to deploy and run the Databroker instance, but it is also possible to connect to a Databroker running on localhost. The following setup was used for the examples:

• One Velocitas Devcontainer running the Client, based on the Vehicle App C++ Template .
• One Velocitas Devcontainer running the Server, based on the Vehicle App C++ Template .
• Databroker running on localhost.

For this to work the .devcontainer/devcontainer.json was changed. In the setup --network=host was added to allow the containers to use the host network. For the server forwardPorts": [ 5555 ] was additionally used to forward port 5555.

    "forwardPorts": [ 5555 ],
	"runArgs": [
		"--init",
		"--privileged",
		"--cap-add=SYS_PTRACE",
		"--network=host",
		"--security-opt",
		"seccomp=unconfined"
	],

Note that changes to .devcontainer/devcontainer.json may be overwritten when velocitas sync is performed.

Running the examples

To run the examples the following actions need to be performed in the shown order:

• Databroker needs to be started. If using a Databroker on host, make sure that it is compatible with the Velocitas version you are using. The catalog used must also be compatible with the signals used in the example.
• Set the current value of Vehicle.Cabin.Seat.Row1.DriverSide.Position to a valid value, for example 12, using a Databroker Client ( Kuksa Python Client or Databroker CLI ).
• Start the server.
• Start the client.
• Verify that no (unexpected) errors are reported.
• Use the Databroker Client to verify that the target value of Vehicle.Cabin.Seat.Row1.DriverSide.Position has been set to 75.