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 underlyingrcl_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 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: str¶
- 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 underlyingrcl_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. IfNone
, then the nodes default callback group is used.qos_profile (
QoSProfile
) – The quality of service profile to apply to the subscription.raw (
bool
) – IfTrue
, then received messages will be stored in raw binary representation.
- destroy()¶
- property handle¶
- property topic_name¶