As we've already discussed, aiml_server is responsible for loading and saving the AIML and AIM brain files. It is subscribed to the /chatter topic, which is the input of the AIML interpreter and publishes the /response topic, which is the response from the AIML interpreter. This is the main code snippet of aiml_server.py:

 
    def load_aiml(xml_file): 
 
      data_path = rospy.get_param("aiml_path") 
      print data_path 
      os.chdir(data_path) 
 
      if os.path.isfile("standard.brn"): 
        mybot.bootstrap(brainFile = "standard.brn") 
 
      else: 
        mybot.bootstrap(learnFiles = xml_file, commands = "load aiml 
    b") 
        mybot.saveBrain("standard.brn") 
 
    def callback(data): 
 
      input = data.data 
      response = mybot.respond(input) 
      rospy.loginfo("I heard:: %s",data.data) 
      rospy.loginfo("I spoke:: %s",response) 
      response_publisher.publish(response) 
 
    def listener(): 
 
      rospy.loginfo("Starting ROS AIML Server") 
      rospy.Subscriber("chatter", String, callback) 
 
      # spin() simply keeps python from exiting until this node is 
    stopped 
      rospy.spin() 
 
    if __name__ == '__main__': 
 
      load_aiml('startup.xml') 
      listener() 

This ROS node is doing the same thing as the code that we used to load and save the AIML files. That code is converted into a ROS node that can accept input and send the response through a topic.