title: Additional ROS components
description: Self-assess your comprehension on additional **ROS components, i.e., ROS services, actions, parameters, and tools**. Read carefully each question. Once answered, you will receive feedback. Good luck!
questions:

 - type: "multiple-answer"
   points: 1
   question: ROS services are characterized by (select all that apply)
   items:
    - choice: bi-directional one-to-one communication.
      comment: Correct!
      correct: true
    - choice: one-way one-to-one communication.
      comment: Think about ROS services as a Remote Procedure Call.
      correct: false
    - choice: bi-directional many-to-one communication.
      comment: Think about ROS services as a Remote Procedure Call.
      correct: false
    - choice: one-way many-to-one communication.
      comment: Think about ROS services as a Remote Procedure Call.
      correct: false
    - choice: synchronous, i.e., the client waits until it gets the response back.
      comment: Correct!
      correct: true
    - choice: asynchronous, i.e., the client doesn't wait for a response back.
      comment: The client would wait for the reply.
      correct: false

 - type: "multiple-answer"
   points: 1
   question: ROS actions (select all that apply)
   items:
    - choice: are asynchronous
      comment: Correct!
      correct: true
    - choice: provide mechanisms to get feedback on execution
      comment: Correct!
      correct: true
    - choice: provide ways to cancel the execution
      comment: Correct!
      correct: true
    - choice: are synchronous
      comment: Think about how ROS services are, and identify then the characteristics that differentiate ROS actions from ROS services.
      correct: false
    - choice: do not provide ways to get feedback
      comment: Think about how ROS services are, and identify then the characteristics that differentiate ROS actions from ROS services.
      correct: false
    - choice: do not provide ways to cancel the execution
      comment: Think about how ROS services are, and identify then the characteristics that differentiate ROS actions from ROS services.
      correct: false

 - type: "multiple-choice"
   points: 1
   question: "ROS parameter server stores parameters locally."
   items:
    - choice: True.
      correct: false
    - choice: False.
      correct: true

 - type: "matching"
   points: 1
   question: "Match the tools with their function."
   items_a:
    - tf2
    - rviz
    - rosbag
    - rqt_console
   items_b:
    - provides support for transformation system
    - visualizes messages
    - record/play ROS messages
    - displays logs
   distractors:
    - simulates a robot
    - checks the syntax of the ROS node
    - modifies parameters