rosgraph_msgs Log message type.

[mlautman]

I am working on a port of rqt_console with @dirk-thomas which uses the rosgraph_msgs/Log message. I see that rosgraph_msg/Log hasn't been ported to ros2 yet and I was wondering if I should implement the Log msg or if there was a specific reason for not porting Log in rosgraph_msgs. As this is more of a design decision, I am happy to move the conversation to discourse if you believe that this should be a more general discussion.

[tfoote]

I don't believe that there's any reason that it hasn't been ported except that it hasn't been needed yet.

I would suggest coordinating with @nburek

He's working on several PRs right now to start publishing console outputs:
ros2/rclcpp#582
ros2/rcl#327
ros2/rcutils#127

[nburek]

Hey Mike,

I am currently working on adding support for logging to a "rosout" topic and as part of that have ported over the Log message from rosgraph_msg. The message I'm working with looks mostly the same except that I've adjusted the level constants to match the enum values from the rcl code and I've removed the list of topics in the message as it didn't make sense to me that you would want that list with every log message.

I was also looking at moving the message from "rosgraph_msg" into "common_interfaces/diagnostic_msgs" as logs seemed better grouped as a diagnostics tool than a rosgraph tool.

I'll start working on getting a pull request created for my Log message port (it may take a couple of days to go through my company's open source approval process before I can officially make the pull request).

I've updated the discourse topic discussing ROS2 logging with this information: https://discourse.ros.org/t/ros2-logging/6469

[dirk-thomas]

Since the message should be used by rcl please add the Log message to rcl_interfaces package. That one is a dependency of rcl already. Putting the message in common_interfaces would add another dependency to rcl and require common_interfaces to be released before rcl which isn't desired.

[nburek]

Ok, makes sense. I'll add it to rcl_interfaces instead.

[tfoote]

For consistency I'd suggest keeping the same package + name too.

[dirk-thomas]

For consistency I'd suggest keeping the same package + name too.

Imo rosgraph_msgs doesn't make any sense for the Log message. So I don't think keeping that package name is a good idea.

[nburek]

Pull request for the Log msg file: #53

[brawner]

@mlautman @nburek This issue can be closed with #53 merged, yah?