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ros-sharp Service call

I created sample ros service to add 2 numbers. I put the code on git

I can test service with:

rosservice call /add_numbers [1,2]

and get response 

sum: 3.0

what is OK,

But don't know how to do the same call with ros-sharp over rosbridge.

I try the only sample from here and it work OK but only for GetParamRequest

// Service Call:
rosSocket.CallService<rosapi.GetParamRequest, rosapi.GetParamResponse>("/rosapi/get_param", ServiceCallHandler, new rosapi.GetParamRequest("/rosdistro", "default"));

How to change this line to call my add_numbers???

Asked by jernejp on 2019-08-01 14:38:51 UTC

Comments

Answers

Hello @jernejp,

I'm not an expert on ROS#, but I found an example in their repository using a console socket:

Launching a node, consuming a topic and calling a service

https://github.com/siemens/ros-sharp/blob/711396cf78578cc95aca49d2f6443ed406440376/Libraries/RosBridgeClientTest/RosSocketConsoleExample.cs

Line 58: service is called

https://github.com/siemens/ros-sharp/blob/711396cf78578cc95aca49d2f6443ed406440376/Libraries/RosBridgeClientTest/RosSocketConsoleExample.cs#L58

rosSocket.CallService<rosapi.GetParamRequest, rosapi.GetParamResponse>("/rosapi/get_param", ServiceCallHandler, new rosapi.GetParamRequest("/rosdistro", "default"));

Line 78: handling service response

https://github.com/siemens/ros-sharp/blob/711396cf78578cc95aca49d2f6443ed406440376/Libraries/RosBridgeClientTest/RosSocketConsoleExample.cs#L78

private static void ServiceCallHandler(rosapi.GetParamResponse message)
{
        Console.WriteLine("ROS distro: " + message.value);
}

I hope it can help you.

Asked by marcoarruda on 2019-08-02 11:10:00 UTC

Comments

IIUC, the code you show tests whether the JsonConvert.SerializeObject(..) function correctly transforms ServiceCall instances to json fragments. It does not show how to invoke a service call.

as far as I know, ROS services are asynchronous

services are not asynchronous. They are synchronous. Actions can be both.

Asked by gvdhoorn on 2019-08-02 11:39:20 UTC

Thanks for the observation! As I said, not an expert on ROS#, but thought it could give a clue. Let me fix the wrong guesses on the answer :) The confusion about services.. we handle the response on a callback, like a subscriber, but indeed they are synchronous. Thanks

Asked by marcoarruda on 2019-08-02 12:45:33 UTC

This still seems incorrect:

Then, you must have a response string json = JsonConvert.SerializeObject(comm);

json is not the response, it's the json-ified version of the request ..

Edit: thanks for the edit. This seems like something the OP could use.

Asked by gvdhoorn on 2019-08-02 12:51:26 UTC