docstr: Controller for federated XGBoost.
  
  Args:
      port: the port for the gRPC server to listen on.
      world_size: the number of sites.
      server_key_path: the path to the server key file.
      server_cert_path: the path to the server certificate file.
      client_cert_path: the path to the client certificate file.
docstr_tok: ["Controller","for","federated","XGBoost",".","Args",":","port",":","the","port","for","the","gRPC","server","to","listen","on",".","world_size",":","the","number","of","sites",".","server_key_path",":","the","path","to","the","server","key","file",".","server_cert_path",":","the","path","to","the","server","certificate","file",".","client_cert_path",":","the","path","to","the","client","certificate","file","."]
code: def __init__(
      self,
      port: int,
      world_size: int,
      server_key_path: str,
      server_cert_path: str,
      client_cert_path: str,
  ):
      """Controller for federated XGBoost.
  
      Args:
          port: the port for the gRPC server to listen on.
          world_size: the number of sites.
          server_key_path: the path to the server key file.
          server_cert_path: the path to the server certificate file.
          client_cert_path: the path to the client certificate file.
      """
      super().__init__()
      self._port = port
      self._world_size = world_size
      self._server_key_path = server_key_path
      self._server_cert_path = server_cert_path
      self._client_cert_path = client_cert_path
      self._server = None
  
file_path: xgboost/demo/nvflare/vertical/custom/controller.py
imports: import multiprocessing
  from nvflare.apis.client import Client
  from nvflare.apis.fl_context import FLContext
  from nvflare.apis.impl.controller import Controller, Task
  from nvflare.apis.shareable import Shareable
  from nvflare.apis.signal import Signal
  from trainer import SupportedTasks
  import xgboost.federated
label_desc: Use image node_id 1 to create a new XGBoostController object from inherited base classes: Controller with example: obj = XGBoostController(port, world_size, server_key_path, server_cert_path, client_cert_path)