Not to add further confusion, but another possibility could be to write C#
wrappers for the partially-complete ROS-C library:

http://wiki.ros.org/rosc

Looks like no significant changes since last year, but you could get in
touch with the devs and ask about contributing to it.


On 20 July 2014 16:17, Zsolt Szabo <szabo.zsolt@nik.uni-obuda.hu> wrote:

> Dear ROS Community,
>
> First of all, let me say hello. I am Zsolt Szabo from Obuda University
> (Budapest, Hungary). Our department has recently bought a Turtlebot2 robot
> (and another department from the uni has a Nao, if I am correct) - both is
> running ROS.
>
> However, students in our faculty mainly learn C# (with a little (very
> little) java). Of course, you can say that they should use rosjava, or
> learn a proper programming language instead. However, it is not for us to
> question their choice. The fact is that most of the students know only C#
> and I plan to make it possible for them to work with ROS using C#, somehow.
>
> I checked the official roscs, but it is very old and uses heavily some cpp
> middleware. Also, the code is funny on some places. So instead I started
> messing around, and managed to create a lightweight (~2K) cpp middleware
> that allowes sending fixed-size text messages between c# ROS nodes.
> However, sending complex (struct) messages, this poses a problem.
>
> Without a middleware, I do not think that it is possible, as the mono
> documentation says <quote>This makes it nearly impossible to directly
> invoke functions that are not C ABI compatible, such as C++ library
> functions that are not extern "C".</quote>
>
> Another solution I tried is re-implementing the big ROS api itself, but to
> be honest I did not put too much effort into this one. I checked the Master
> API ( http://wiki.ros.org/ROS/Master_API ), I managed to execute the
> getSystemState via XMLRPC, but I got stuck at the registerSubscriber call,
> because the ROS documentation says "the subscriber will also receive
> notifications of new publishers via the publisherUpdate API" , and I found
> absolutely ZERO documentation about the publisherUpdate API ...
>
> So to access ROS from c#, I think we have the following three
> possibilities; these pose three nice questions:
>
> 1) try to use and modify the old roscs ==> QUESTION: any
> details/documentation about the current roscs implementation? Does anyone
> have any clue about the code structure and about the reason behind the
> quarks in the .cs code (e.g. MessageField.cs freaks me out A LOT)
>
> 2) implement a new roscs with this lightweight cpp middleware using
> converters or something similar to support more complex messages. ==>
> QUESTION: do you think this is doable? Right now, to pass non-text
> messages, I managed to give the absolute pointer of the data from the cpp
> middleware to the c# code. But I do not think that a cpp code and a c# code
> sharing the same pointer is a wise idea...
>
> 3) implement a new roscs without a cpp middleware (just like rosjava),
> with XMLRPC + TCPROS support. ==> QUESTION: do you think this is doable /
> worthwhile? QUESTION: can anyone point me to the proper protocol
> specifications? the ones I found at the ROS wiki seem kinda stripped down
> and short.
>
> Sorry for the long mail, and thank you all for your help and suggestions.
>
> Yours,
> Zsolt Szabo
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