Class RelayNodelet

Inheritance Relationships

Base Type

  • public cras::Nodelet

Class Documentation

class RelayNodelet : public cras::Nodelet

Nodelet for relaying messages on a different topic.

ROS parameters:

  • ~in_queue_size (uint, default 10): Queue size for the subscriber.

  • ~out_queue_size (uint, default $in_queue_size): Queue size for the publisher.

  • ~lazy (bool, default False): Whether to shut down the subscriber when the publisher has no subscribers. The ~input topic will be subscribed in the beginning, and will unsubscribe automatically after the first message is received (this is needed to determine the full type of the topic to publish).

  • ~tcp_no_delay (bool, default False): If True, the TCP_NODELAY flag is set for the subscriber. This should decrease the latency of small messages, but might give suboptimal transmission speed for large messages.

Subscribed topics:

  • ~input (any type): The input messages. If lazy is true, it will only be subscribed when ~output has some subscribers.

Published topics:

  • ~output (same type as ~input): The relayed output messages.

Command-line arguments: This nodelet (or node) can also be called in a way backwards compatible with topic_tools/relay. This means you can pass CLI arguments specifying the topics to subscribe/publish.

  • rosrun cras_topic_tools relay TOPIC_IN [TOPIC_OUT]

    • TOPIC_IN: The topic to subscribe. It is resolved against parent namespace of the node(let) (as opposed to the ~input topic which is resolved against the private node(let) namespace).

    • TOPIC_OUT: The topic to publish. It is resolved against parent namespace of the node(let) (as opposed to the ~output topic which is resolved against the private node(let) namespace). If not specified, output topic will be ${TOPIC_IN}_relay.

Protected Functions

void onInit() override
virtual void processMessage(const ::ros::MessageEvent<const ::topic_tools::ShapeShifter> &event, ::ros::Publisher &pub)

Republish the received message.

Parameters:

  • event – [in] The event with the incoming message.

  • pub – [in] The publisher to use for publishing the output messages.

Protected Attributes

::std::unique_ptr<::cras::GenericLazyPubSub> pubSub

The lazy pair of subscriber and publisher.