Implement POST /components/{component_id}/services/{service_name} endpoint to enable calling ROS 2 services on components

[mfaferek93]

Summary

Implement POST /components/{component_id}/services/{service_name} endpoint to enable calling ROS 2 services on components via the REST API. This endpoint allows external systems to invoke service operations (calibration, configuration, etc.) through the gateway, enabling remote service management capabilities.

The endpoint should:

• Accept JSON payloads with service type and request data
• Validate service type format
• Convert JSON to YAML for ROS 2 CLI
• Call services using ros2 service call
• Parse and return service response
• Handle synchronous service execution

---

Proposed solution (optional)

1. Create ServiceManager (include/ros2_medkit_gateway/service_manager.hpp + src/service_manager.cpp):

• Method: ServiceResponse call_service(const std::string& service_path, const std::string& srv_type, const nlohmann::json& request)
• Use existing ros2_cli_wrapper to execute ros2 service call
• Use existing output_parser to parse YAML response from CLI
• Return structured service response with success/failure status

2. Integrate with GatewayNode (src/gateway_node.cpp):

• Similar pattern to DataAccessManager integration

3. Add REST Handler (src/rest_server.cpp):

• Implement POST /components/{component_id}/services/{service_name} handler
• Extract component_id and service_name from URL path
• Parse JSON request body, validate required fields: type, request
• Validate service type format using existing validators
• Construct full service path from component namespace
• Call service_manager->call_service()
• Return service response

4. Request/Response Format:

  Request body (SetBool service):
  {
    "type": "std_srvs/srv/SetBool",
    "request": {"data": true}
  }

  Success response (200) - SetBool:
  {
    "success": true,
    "message": "Lights turned ON"
  }

  Request body (Trigger service):
  {
    "type": "std_srvs/srv/Trigger",
    "request": {}
  }

  Success response (200) - Trigger:
  {
    "success": true,
    "message": "Calibration completed successfully"
  }

  Error response (400):
  {
    "error": "Missing required field",
    "field": "type"
  }

  Error response (404):
  {
    "error": "Component not found",
    "component_id": "nonexistent"
  }

---

Additional context (optional)

Example Use Cases

Engine Calibration:

  # Trigger engine calibration
  curl -X POST http://localhost:8080/components/calibration/services/calibrate \
    -H "Content-Type: application/json" \
    -d '{"type":"std_srvs/srv/Trigger","request":{}}'

  # Response:
  # {"success": true, "message": "Calibration completed successfully"}