Topics

Publisher

class rclpy.publisher.Publisher(publisher_handle, msg_type, topic, qos_profile, event_callbacks, callback_group)

Create a container for a ROS publisher.

Warning

Users should not create a publisher with this constuctor, instead they should call Node.create_publisher().

A publisher is used as a primary means of communication in a ROS system by publishing messages on a ROS topic.

Parameters

  • publisher_handle (Handle) – Capsule pointing to the underlying rcl_publisher_t object.

  • msg_type (~MsgType) – The type of ROS messages the publisher will publish.

  • topic (str) – The name of the topic the publisher will publish to.

  • qos_profile (QoSProfile) – The quality of service profile to apply to the publisher.

assert_liveliness()

Manually assert that this Publisher is alive.

If the QoS Liveliness policy is set to RMW_QOS_POLICY_LIVELINESS_MANUAL_BY_TOPIC, the application must call this at least as often as QoSProfile.liveliness_lease_duration.

Return type

None

destroy()
get_subscription_count()

Get the amount of subscribers that this publisher has.

Return type

int

property handle
publish(msg)

Send a message to the topic for the publisher.

Parameters

msg (Union[~MsgType, bytes]) – The ROS message to publish.

Raises

TypeError if the type of the passed message isn’t an instance of the provided type when the publisher was constructed.

Return type

None

property topic_name
Return type

str

Subscription

class rclpy.subscription.Subscription(subscription_handle, msg_type, topic, callback, callback_group, qos_profile, raw, event_callbacks)

Create a container for a ROS subscription.

Warning

Users should not create a subscription with this constructor, instead they should call Node.create_subscription().

Parameters

  • subscription_handle (Handle) – Handle wrapping the underlying rcl_subscription_t object.

  • msg_type (~MsgType) – The type of ROS messages the subscription will subscribe to.

  • topic (str) – The name of the topic the subscription will subscribe to.

  • callback (Callable) – A user-defined callback function that is called when a message is received by the subscription.

  • callback_group (CallbackGroup) – The callback group for the subscription. If None, then the nodes default callback group is used.

  • qos_profile (QoSProfile) – The quality of service profile to apply to the subscription.

  • raw (bool) – If True, then received messages will be stored in raw binary representation.

destroy()
property handle
property topic_name