Latched topic ros. Returns whether or not this topic is latched.


Latched topic ros. foo [0], it will just sit there blocking. It looks as if this is actually a problem with gazebo_ros_control (or a related package), not ros_comm. toby on 2018-09-11: I have an additional question: if you start a node and publish to a latched topic but then kill the node which did the original publishing, will the data still be available for future subscribers? Thanks! Sep 22, 2018 · 0 Scenario: a node A publishes "hello" to a latched topic /x with queue size 1 then a node B publishes "world" to the same latched topic /x with queue size 1 Because of the latched topics, I assume a late subscriber will receive both "hello" and then "world", correct? But is the order guaranteed, will he always receive "hello", then "world" ? Nov 11, 2022 · Description ROS 1 supported a --repeat-latched feature (ros/ros_comm#1850) to repeat latched topics at the start of each bag split. The service may eventually be phased out. Jan 13, 2021 · I need to figure out if a topic is latched on the subscriber side in cpp. $ rostopic type /topic_name | rosmsg show Roadmap rostopic is a stable command-line tool within the ROS core toolchain. ros::Publisher is reference counted internally -- this means that copying them is very fast, and does not create a "new" version of the ros::Publisher. We have the ability to get and set parameters (and get notified when they change), we have the ability to publish transient_local (latched) topics, etc. Definition at line 132 of file publisher. The consequence of this change is that it will constrain us to one interactive marker server per topic. Definition at line 115 of file publisher. I am trying to publish several ros messages but for every publish that I make I get the &quot;publishing and latching message for 3. Is that possible and if yes any hints how? Originally posted by Nov 19, 2021 · There isn't exactly a way to see history of messages across a topic. h. Steps to reproduce # Latched topic publisher, in the background rostopic pub -l /foo std_msgs/Bool Oct 10, 2015 · When migrating a bag with latched topics, those topics will no longer be latched. One of my node just parses a file and stream reference trajectories as Path/Markers topics. Is ther Definition at line 112 of file publisher. Originally posted by clyde on ROS Answers with karma: 1247 on 2018-10-14 Post score: 8 Comment by clyde on 2018-10-15: I just tested this w/ a Python listener with the same QoS. Publisher pub = rospy. Of To achieve a “latched” topic that is visible to late subscribers, both the publisher and subscriber must agree to use ‘Transient Local’. Note that the map data may be retrieved via either latched topic (meaning that it is sent once to each new subscriber), or via service. Note that if there are multiple publishers on the same topic, instantiated in the same node, then only the last published message from Nov 15, 2019 · With ROS 2, we have a bunch of tools that make solving the problem of a dynamic robot_description possible. Jul 23, 2019 · I’ve started porting interactive_markers to ROS 2 and taken this as an opportunity to revisit the design. Therefore I would li Nov 29, 2021 · As a premise I must say I am very inexperienced with ROS. Oct 20, 2014 · Comment by dornhege on 2017-02-15: There is no time limit. 0 seconds& Feb 22, 2018 · how do we map ROS 1's latched topics (ros1_bridge, rosbag v2 playback, and ported nodes) to ROS 2? is the constraint that history settings/depth control durabilities scope ok? Who is affected This is blocking decisions about how to map latched topics over the bridge, with notable examples like /tf_static (ros2/geometry2#12) and /map (ros2/rmw#111). Jul 24, 2024 · 一 参数latch分析 ros wiki上面的介绍为: ~latch (bool, default: True for a static map, false if no initial map is given) ~latch(bool,默认值:对于静态地图为True,如果没有给出初始地图则为false) Whether topics are published latched or only once per change. Still no luck: if the publisher runs first, then the subscriber gets the message. In ROS 1, it is possible . Mar 1, 2023 · How does latch work with queue_size? Acoording to the ROS wiki, when a connection is latched, a reference to the last message published is saved and sent to any future subscribers that connect. Finally, just have a service call that asks for the state of that component Any thoughts? Originally posted by stevemacenski on ROS Answers with karma: 8272 on 2018-03-10 Post score: 2 I'm using FastRTPS. $ rostopic type /topic_name This is useful for piping to other commands, like rosmsg, e. When a connection is latched, the last message published is saved and automatically sent to any future subscribers that connect. Returns whether or not this topic is latched. As far as I can tell, rosbag2 does not have this feature. Definition at line 145 of file publisher. Compatibility of deadline QoS policies: Another option is to have the state be a latched topic but I'm unsure if this is actually any better performancewise. Definition at line 160 of file publisher. Is there anyway to force rosbag to record latched topics in each bag? Mar 1, 2022 · Class Publisher source code object --+ | Topic --+ | Publisher Class for registering as a publisher of a ROS topic. map (nav_msgs/OccupancyGrid) Receive the map via this latched Mar 22, 2012 · I've noticed that if I start up a node, create a latched publisher, and then publish a single message (let's say on the topic foo), if I then go into rosh and do topics. Published Topics map_metadata (nav_msgs/MapMetaData) Receive the map metadata via this latched topic. Hello, I have some constant data published as MarkerArray topics so it can be seen in rviz. Here are a few different ways I’ve though about to make the robot_description Hi there, I have the following problem. Definition at line 157 of file publisher. Self-contained files also simplify post-processing workflows. Comment by buckley. It can be used via an optional argument to rospy. The expected behavior would be for every advertiser to publish its o Returns the topic that this Publisher will publish on. To reproduce the problem: Jan 19, 2010 · In rosplay, to actually mirror the appearance of multiple nodes, I need to create multiple latched publishers on the same topic. For ROS users, rosbag record has a --repeat-latched flag that is on by default and helps with this. This is needed to implement a feature in rosbag-snapshot. Definition at line 148 of file publisher. g. Apr 14, 2025 · 文章浏览阅读767次,点赞10次,收藏26次。点云的地图的发送逻辑中,我发现每次使用rostopic echo 时只会打印一次,然后就不会再打印了。并且rviz中也是始终都会显示的,这里面其实就是用到了latched持久话机制,可以接受这最后一次发布的消息。我们通过一个具体的项目来学习和认识这个过程。_latch Nov 25, 2015 · I'm trying to record TF data across split bags. Thanks. For maximum performance when building a map (with frequent updates), set to false. (rosbag record --split --duration=5s /tf /tf_static) The /tf_static topic is only recorded in the first bag. Definition at line 95 of file publisher. Once all copies of a ros::Publisher are destructed the topic will be shutdown. However, you can make a publisher latching. Publisher('topic_name', topic_type, queue_size=10, latch=True) Hi there, my question is simple: is there support for latched publishers? My use case is simple: I would like to advertise a topic from the unity side, which will only publish msgs when a new subscriber from the ROS side is listening. If the publisher runs second, the subscriber never gets rostopic type type <topic-name> Display topic type of a topic. Definition at line 147 of file publisher. cpp. This means that when it publishes a message it will continue to be seen by subscribers until a new message replaces it. When set to true Oct 2, 2023 · Description When using rosbag record with splits and --repeat-latched, the latched messages in the subsequent bags are not marked as latched (and also lose the callerId). Definition at line 150 of file publisher. When a connection is latched, the last message published is saved and automatically sent to any future Sep 28, 2013 · The problem is that the gazebo_ros_control Gazebo plug-in will not receive (or will ignore) a message on one of its "command" topics if the message is published too soon after the latched publisher is created. Instead of streaming constant data, I thought it would be much more optimal to use latched topics to publ Sep 2, 2020 · From the wiki : latch [optional] Enables "latching" on a connection. One of the proposed changes is to use a ROS service, instead of a latched topic, to communicate the full state between an interactive marker server and client. This caused issue when I tried to replay a rosbag from the middle using -s. Jan 16, 2025 · 锁存话题(latched topics) ROS中的消息是短暂的。如果一条消息发布的时候我们还没有订阅这个话题,那么我们将错过它。如果发布者的发布频率很高的话,这没有什么影响,因为下一条消息马上就会到来 然而,有些情況下频繁发布消息是很坏的主意。 举个例子, map_server 节点在 map 话题上播地图(nav Introduction to Nodes and Topics ROS is a distributed operating system Meaning it controls potentially (and typically) multiple computers One of them is in the robot itself Almost always there is at least one more which is more powerful It could be your laptop or your web workspace which runs on our rover cluster The computers have to be on the same network Jan 16, 2024 · This includes latched topics like ROS’s /tf_static – they should be published at the start of each file so that the rest of the file can be interpreted and visualized correctly. According to rosh's documentation, this makes sense, but is there a way to get a latched topic at all in rosh? Jul 24, 2024 · 在ros发布数据的advertise函数参数里面最后一个参数"latch",默认为false,一直没有注意,今天在分析其他问题时在ros wiki[ Publishers and Subscribers ]上偶然注意到了这个参数, 说明如下: latch [optional] Enables "latching" on a connection. Definition at line 98 of file publisher. This is useful for slow-changing to static data like a map. These trajectories are almost never updated. tnonp0 zy ee wjj qj7l uj6s x1vrm qhsu4 moo uxp3tw