ping

Instructions

Implementation Reference

• src/qgis_mcp/qgis_mcp_server.py:146-151 (handler)

  MCP tool 'ping' handler: Forwards the ping request to the QGIS socket server via the client and returns the formatted JSON response.

  @mcp.tool()
  def ping(ctx: Context) -> str:
      """Simple ping command to check server connectivity"""
      qgis = get_qgis_connection()
      result = qgis.send_command("ping")
      return json.dumps(result, indent=2)

• qgis_mcp_plugin/qgis_mcp_plugin.py:171-173 (handler)

  Low-level ping handler in the QGIS plugin server that responds with a simple pong message.

  def ping(self, **kwargs):
      """Simple ping command"""
      return {"pong": True}

• qgis_mcp_plugin/qgis_mcp_plugin.py:133-149 (registration)

  Registration of the 'ping' handler (and other commands) in the QGIS plugin's command dispatcher dictionary.

  handlers = {
      "ping": self.ping,
      "get_qgis_info": self.get_qgis_info,
      "load_project": self.load_project,
      "get_project_info": self.get_project_info,
      "execute_code": self.execute_code,
      "add_vector_layer": self.add_vector_layer,
      "add_raster_layer": self.add_raster_layer,
      "get_layers": self.get_layers,
      "remove_layer": self.remove_layer,
      "zoom_to_layer": self.zoom_to_layer,
      "get_layer_features": self.get_layer_features,
      "execute_processing": self.execute_processing,
      "save_project": self.save_project,
      "render_map": self.render_map,
      "create_new_project": self.create_new_project,
  }

• src/qgis_mcp/qgis_mcp_server.py:79-108 (helper)

  Helper function to manage persistent connection to QGIS server, used by ping tool; includes connection health check.

  def get_qgis_connection():
      """Get or create a persistent Qgis connection"""
      global _qgis_connection
      
      # If we have an existing connection, check if it's still valid
      if _qgis_connection is not None:
          # Test if the connection is still alive with a simple ping
          try:
              # Just try to send a small message to check if the socket is still connected
              _qgis_connection.sock.sendall(b'')
              return _qgis_connection
          except Exception as e:
              # Connection is dead, close it and create a new one
              logger.warning(f"Existing connection is no longer valid: {str(e)}")
              try:
                  _qgis_connection.disconnect()
              except Exception:
                  pass
              _qgis_connection = None
      
      # Create a new connection if needed
      if _qgis_connection is None:
          _qgis_connection = QgisMCPServer(host="localhost", port=9876)
          if not _qgis_connection.connect():
              logger.error("Failed to connect to Qgis")
              _qgis_connection = None
              raise Exception("Could not connect to Qgis. Make sure the Qgis plugin is running.")
          logger.info("Created new persistent connection to Qgis")
      
      return _qgis_connection