ROS 2 over email: rmw_email, an RMW implementation

[christophebedard]

@AndyZe

Is it realtime safe?

Unsurprisingly, it’s really not

@gavanderhoorn

But in all seriousness: this is a great ‘toy’ example of an RMW implementation.

Should this become a tutorial?

Edit: I would love to be able to answer questions about RMW implementations by directing people to a “ROS2-over-email example” tutorial.

This did cross my mind, especially since I read @methylDragon’s RMW deep dive before writing the RMW implementation, so I also think an actual RMW implementation tutorial/example would be great. I’ll think about it and see how this could be done.

@sloretz

I’m curious about your thoughts on the void * abstraction when working with C++ types like std::vector<T> in the introspection typesupport. What changes could be made to that interface to make working with it easier?

That’s a good question. Perhaps the introspection layer could simply provide some tools to more easily interpret those type-erased pointers? I haven’t really looked into how the other (more serious) implementations do their serialization, so maybe this exists, but yeah it would be great if it were provided by the type support introspection library directly.

@AndyZe

This might have legitimate uses, too. Like getting an email about the status of your robot every morning, or sending automatic updates to non-technical people.

You could definitely skip rmw_email_cpp and use the email middleware directly from a node that does that!

@Katherine_Scott

I am sure that this was fun and informative to write. Any plans to use other transport layers like carrier pigeons, USB drives on airplanes, or SMS messages?

It was indeed a ton of fun! And yeah, writing a 2nd/3rd/Nth implementation should be easy (and everyone’s giving some great ideas), so that means I have to do it right?