[ros-users] [Discourse.ros.org] [Next Generation ROS] Rosbag Backward Compatibility

ROS Discourse ros.discourse at gmail.com
Wed Nov 2 10:09:31 UTC 2016

Phew, been a while ;-)

What I can say about my own work on the format @gbiggs mentions is that it was motivated not completely, but significantly, by internal politics. At my old lab, we had a different middleware developed internally, and it was not acceptable (politically) to use ROS. I thought that maybe others had the same problem, but exchanging data would be very useful, so we tried to create something which didn't have "ROS" in the name, but was conceptually quite close, so ROS could eventually migrate. There was not a lot of interest either in the ROS camp, nor in the other camp, though, so this went nowhere, unfortunately.

Otherwise I probably wouldn't have felt the need to change anything fundamentally ;-)

 * The use of textual data-type definitions in rosbag2 was the most problematic thing, and we discussed about that quite a bit.
 * I recall I found some of the arbitrarily sized meta-data structures to be a bit annoying to parse.
 * Other than that, yes, the format is non-standard, but it's not overly complicated. To my knowledge, there are no generic data-writing libraries out there, because it appears that almost everybody his or her own format. This is a bit annoying, but it also suggests that finding the right abstractions is not trivial.

My colleagues here also tell me that they some of the use cases of rosbag2 are problematic, e.g., when a rosbag is split, there is no information about this in the bag file. You have to infer either using external information, or a heuristic based on the file-name. We would prefer some information on this to be in the library.

Maybe I'll post some more later, if I remember anything more.

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