Problems setting a ROS Service

Hello everyone,

I'm trying to implement a service in Unity but I found some problems (some already solved). First of all I started this project some months ago so I'm still using version 0.4.0 of ROS TCP Connector and URDF Importer.

First bug I found was while Generating ROS Service messages. I have my messages and services in a package called haru-unity. Normal messages are inside a folder /msg and services in a folder /srv. When I build msg the button changes to 'Rebuild msg' and the generated C# classes appear in a folder of name HaruUnity and they use

Code (CSharp):

1. namespace RosMessageTypes.HaruUnity

. I have no problems with these generated classes. But when I try to build a service, first when clicking 'Build srv' button it never changes to 'Rebuild srv'. But it generates C# classes in a folder Haru-unity, and they use:

Code (CSharp):

1. namespace RosMessageTypes.Haru-unity

With this I get a bunch of errors in the console when compiling including

Code (CSharp):

1. error CS0116: A namespace cannot directly contain members such as fields or methods

So I have to change those classes by hand for removing the hyphen. Is this bug due to version 0.4.0 of the packages?

Second problem I found (already solved) was following the tutorial https://github.com/Unity-Technologi...torials/ros_unity_integration/service_call.md as in my version of ROS TCP Connector, ImplementService<> takes just one argument. I found it changes with a new release of the version 0.6.0 a week ago. So this one is solved but was a bit confusing while following the tutorial.

The last problem I had (also solved) was while declaring the service in my custom server endpoint. I was using something like this:

Code (CSharp):

1. topicsDict = {}
2.  
3.  
4. # Subscriber example
5. topicsDict['ball_color'] = RosSubscriber('ball/color', UnityColor, tcp_server)
6.      
7.  
8. # Publisher example
9. topicsDict['ball_pose'] = RosPublisher('ball/pose', Pose, queue_size=1)
10.        
11.  
12. # Service example
13. topicsDict['video_srv'] = RosService('play_video_service', PlayVideoService)
14.  
15. #Start TCP using topics from dictionary
16. tcp_server.start(
17.     topicsDict
18. )

Finally i found I have to use the following instead:

Code (CSharp):

1. topicsDict['video_srv'] = UnityService('play_video_service', PlayVideoService, tcp_server)

When I started following these Unity Robotics tutorials many months ago I saw that it was necessary to declare your publishers/subscribers/services and its topics in a dictionary that tcp_server.start() takes. But I don't see any of this in the current tutorials https://github.com/Unity-Technologies/Unity-Robotics-Hub/tree/main/tutorials/ros_unity_integration . I don't see any mention in current tutorials on how to include your publishers/subscribers/services in a custom server endpoint. Is it not necessary anymore? Where can I find an example of how to create a custom server endpoint?

My last question, should I update ROS TCP Connector and URDF Importer? I see these have changed but I'm worried about the integrity of my project. I'm new working with Unity and would like to know how is the better way of updating these packages in my project.

Thank you.

 

Hello Laurie,

Thank you for you answers. I was trying to use a service implemented in Unity. The thing is when I started there was only a tutorial about a service called out from unity, that used RosService class, and I didn't know how to declare a Unity Service in my custom server endpoint. That's what I was trying to point out in my question. I don't see any tutorial on how to use the classes from ros-tcp-endpoint for declaring publishers, subscribers and both type of services in a custom server endpoint. I think even old tutorial versions don't say anything about UnityService class.

Now, thanks to your answer I understand that with new packages it's not necessary anymore to create a custom server endpoint. But I don't see in what released version it stopped being necessary https://github.com/Unity-Technologies/ROS-TCP-Connector/releases .

I understand these packages are still quite experimental, I will try to update them. Should I just remove them from my Package Manager and then install them again? Can I update them directly from Package Manager? I see that option with other Unity packages (such as Visual Studio Code Editor) but seems they don't search for newer versions automatically.

Thank you.

 

Thank you Laurie. In my project we actually use underscores for package project name, declared in the CMakeList. For example in my example it is haru_unity. But we use dashes for package folder names, so it is haru-unity. That convention was already used before I arrived to the project 4 years ago and I was told to follow it. And we generate deb files using dashes too. But I think you follow this same convention in package ROS-TCP-Endpoint https://github.com/Unity-Technologies/ROS-TCP-Endpoint , right? You use dashes for the folder and underscore for the project name

 

I have updated the packages to their last versions and after changing messages names and some namespaces, all things seem to work well with the default server endpoint. Thank you for your help.

I have a last question somehow related to services. Are you planning to add ROS actions too?