[ros-users] [Discourse.ros.org] [Next Generation ROS] Design By Contract

Asmodehn ros.discourse at gmail.com
Mon Sep 11 02:08:47 UTC 2017

[quote="fkromer, post:21, topic:2405"]
ROS is a multi process system on the robot/(multi-)processor level itself. I guess you mean multi device system instead of multiprocess system

Actually I do mean multiprocess. But I do not mean "We cannot make it work/do what we want" or even "We cannot make it do what we want all the time". I mean "We cannot be sure that it will never do [things](https://www.engadget.com/2017/07/17/dc-security-robot-throws-itself-into-pool/) that weren't intended".
And I know for a fact that there are more robots out in the world, doing unexpected dangerous thing, because they weren't programmed with total safety in mind, than most people know about. All it takes is an unchecked integer to wrap around, and disaster strikes in the real world. Make it distributed, and the disaster likeliness increases exponentially.

So sure we can build robots, and distributed systems, but, when it come to a robot that can poke the eye of a child because it looks like it's a button to press, it's different than a harmless backend database cluster in the basement, so you better be sure of what you're programming... and for distributed systems (multiprocess) the theory is quite new, so most language/frameworks won't help you there.

[quote="fkromer, post:21, topic:2405"]
Isnt it the time to ease the development of such systems (and single robots) by providing better framework capabilities?

Definitely yes, but instead of adding potentially heavy features, without being sure they will be used and maintained, I would first focus on doing like https://jepsen.io/, that is, provide tools that show people working in robotics, what and where the problems are in the system they build. Actually probably doing the same as what works for security hackers : tell people their system is broken/unsafe, nobody cares. Make anyone (including their customer) able to [break it](https://usbkill.com/), and then they react... and some might listen.

[quote="fkromer, post:22, topic:2405"]
Instead of waiting for more capabilities in ROS2 it is probably more valuable to add more capabilities to the current ROS1 framework.

I personally fully agree with this statement, but I _think_ most people are focusing on ROS2 these days, which means even less maintenance resource for ROS1, so we need to be careful that what we add is really worth it.

[quote="fkromer, post:22, topic:2405"]
Currently the set of reusable test nodes is limited. What about adding more generic test nodes

I would also agree there. You can always send a PR to add the tests node you miss to rostest, and discuss it with the maintainers :-)
And you can also write a package for the specific nodes you need. I started doing that for my own needs in https://github.com/pyros-dev/pyros-test.
But these days I am thinking we need something more like a ROS [Simian Army](https://github.com/Netflix/SimianArmy) : 

- some package that randomly kill and restart nodes, probably based on launch files...
- some package that randomly sends messages around, like a ros-[hypothesis](http://hypothesis.readthedocs.io/) that would generate any valid message based on a ROS definition, to test your nodes against. I have already implemented most of this one, as part of other projects, but I still need to make it a package on its own, whenever I get the time and motivation...
- probably a few more...

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