gRPC service generation

Learn how to generate and fill your own gRPC services.

1: Create a client
2: Create a server

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

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. To complete the server implementation you have to fill the generated *ServiceImpl.cpp. Have a look at the linked content beneath for a tutorial how it would be done for a SeatService leveraging https://raw.githubusercontent.com/eclipse-kuksa/kuksa-incubation/0.4.0/seat_service/proto/sdv/edge/comfort/seats/v1/seats.proto .

To run the example you need to start the velocitas app for the server first and then the second velocitas app for the client.

1 - Create a client

Learn how to create a client for a service definition.

App configuration

{
  "type": "grpc-interface",
  "config": {
      "src": "https://raw.githubusercontent.com/eclipse-kuksa/kuksa-incubation/0.4.0/seat_service/proto/sdv/edge/comfort/seats/v1/seats.proto",
      // "required" indicates you are trying to write a client for the service
      "required": {
        "methods": [
          "Move", "CurrentPosition"
        ]
      },
  }
}

Project configuration

You need to specify devenv-devcontainer-setup >= v2.4.2 in your project configuration. Therefore your .veloitas.json should look similair to this example:

{
  "packages": {
    "devenv-devcontainer-setup": "v2.4.2"
  },
  "components": [
    {
      "id": "grpc-interface-support", 
    }
  ],
}

To do that you can run velocitas component add grpc-interface-support when your package is above or equal to v2.4.2

Example code

To create a client we use the generated SeatsServiceClientFactory.h and seats.grpc.pb.h. These define request and response types and the operations that are available. An example implementation for the SeatService follows:

main.cpp

#include <sdk/middleware/Middleware.h>
#include <services/seats/SeatsServiceClientFactory.h>
#include <services/seats/seats.grpc.pb.h>

#include <iostream>

using namespace velocitas;

int main(int argc, char** argv) {
    auto serviceClient = SeatsServiceClientFactory::create(Middleware::getInstance());

    ::grpc::ClientContext                        context;
    ::sdv::edge::comfort::seats::v1::MoveRequest request;
    ::sdv::edge::comfort::seats::v1::MoveReply   response;

    ::sdv::edge::comfort::seats::v1::Seat seat;

    ::sdv::edge::comfort::seats::v1::SeatLocation seat_location;
    seat_location.set_row(1);
    seat_location.set_index(1);

    ::sdv::edge::comfort::seats::v1::Position seat_position;
    // we only set base here to keep the example simple
    // extend here if yu want to set lumbar etc.
    seat_position.set_base(1000);

    seat.set_allocated_location(&seat_location);
    seat.set_allocated_position(&seat_position);

    request.set_allocated_seat(&seat);

    auto status = serviceClient->Move(&context, request, &response);

    std::cout << "gRPC Server returned code: " << status.error_code() << std::endl;
    std::cout << "gRPC error message: " << status.error_message().c_str() << std::endl;

    if (status.error_code() == ::grpc::StatusCode::UNIMPLEMENTED) {
        return 1;
    } else {
        ::grpc::ClientContext                                   context;
        ::sdv::edge::comfort::seats::v1::CurrentPositionRequest request;
        ::sdv::edge::comfort::seats::v1::CurrentPositionReply   response;

        request.set_row(1);
        request.set_index(1);

        auto status_curr_pos = seatService->CurrentPosition(&context, request, &response);
        std::cout << "current Position:" << response.seat().position().base() << std::endl;
        std::cout << "gRPC Server returned code: " << status_curr_pos.error_code() << std::endl;
        std::cout << "gRPC error message: " << status_curr_pos.error_message().c_str() << std::endl;
        return 0;
    }
}

2 - Create a server

Learn how to create a server for a service definition.

App configuration

{
  "type": "grpc-interface",
  "config": {
      "src": "https://raw.githubusercontent.com/eclipse-kuksa/kuksa-incubation/0.4.0/seat_service/proto/sdv/edge/comfort/seats/v1/seats.proto",
      // "provided" indicates you want to implement the server business logic for the service
      "provided": { }
  }
}

Project configuration

You need to specify devenv-devcontainer-setup >= v2.4.2 in your project configuration. Therefore your .veloitas.json should look similair to this example:

{
  "packages": {
    "devenv-devcontainer-setup": "v2.4.2"
  },
  "components": [
    {
      "id": "grpc-interface-support", 
    }
  ],
}

To do that you can run velocitas component add grpc-interface-support when your package is above or equal to v2.4.2

To create a server that is providing the gRPC service we are leveraging the generated SeatsServiceImpl.h and SeatsServiceServerFactory.h. The SeatsServiceImpl.cpp needs to be filled with the actual implementation of the service. A quick example for a SeatService is described in the following:

main.cpp

#include <sdk/middleware/Middleware.h>
#include <services/seats/SeatsServiceServerFactory.h>
#include "SeatsServiceImpl.h"

#include <memory>

using namespace velocitas;

int main(int argc, char** argv) {
    auto seatsImpl = std::make_shared<SeatsService>();

    velocitas::VehicleModelContext::getInstance().setVdbc(
        velocitas::IVehicleDataBrokerClient::createInstance("vehicledatabroker"));
    auto seatServer =
        SeatsServiceServerFactory::create(Middleware::getInstance(), seatsImpl);

    seatServer->Wait();
    return 0;
}

SeatsServiceImpl.cpp

#include "SeatsServiceImpl.h"
#include <sdk/VehicleApp.h>
#include <sdk/VehicleModelContext.h>
#include <sdk/vdb/IVehicleDataBrokerClient.h>
#include <vehicle/Vehicle.hpp>
#include <grpc/grpc.h>
#include <services/seats/seats.grpc.pb.h>

namespace velocitas {

::grpc::Status SeatsService::Move(::grpc::ServerContext*                              context,
                                  const ::sdv::edge::comfort::seats::v1::MoveRequest* request,
                                  ::sdv::edge::comfort::seats::v1::MoveReply*         response) {
    (void)context;
    (void)response;
    vehicle::Vehicle Vehicle;

    auto seat     = request->seat();
    auto location = seat.location();
    auto row      = location.row();
    auto pos      = location.index();

    // you would need to extend this to add support for lumbar etc.
    // Vehicle.Cabin.Seat.Row(row).Pos(pos).Position.set(seat->position()->xxxxxx())->await();
    auto status = Vehicle.Cabin.Seat.Row1.DriverSide.Position.set(seat.position().base())->await();
    if (status.ok()) {
        return ::grpc::Status(::grpc::StatusCode::OK, "");
    } else {
        return ::grpc::Status(::grpc::StatusCode::CANCELLED, status.errorMessage());
    }
}

::grpc::Status
SeatsService::MoveComponent(::grpc::ServerContext*                                       context,
                            const ::sdv::edge::comfort::seats::v1::MoveComponentRequest* request,
                            ::sdv::edge::comfort::seats::v1::MoveComponentReply*         response) {
    (void)context;
    (void)request;
    (void)response;
    return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, "");
}

::grpc::Status SeatsService::CurrentPosition(
    ::grpc::ServerContext*                                         context,
    const ::sdv::edge::comfort::seats::v1::CurrentPositionRequest* request,
    ::sdv::edge::comfort::seats::v1::CurrentPositionReply*         response) {
    (void)context;
    (void)request;
    vehicle::Vehicle Vehicle;

    auto             seat          = response->mutable_seat();
    auto             seat_position = seat->mutable_position();

    auto seatPos = Vehicle.Cabin.Seat.Row1.DriverSide.Position.get()->await().value();

    // we only set base here to keep the example simple
    // extend here if yu want to set lumbar etc.
    seat_position->set_base(seatPos);
    return ::grpc::Status(::grpc::StatusCode::OK, "");
}

} // namespace velocitas