Hello,
Thank you for your quick reply Sir!
Yes, that is the web service I have to use I think, if the system does deal with REST services.
However the problem I am facing is because I do not understand how web services do work, I think.
I read the Studio 1311 documentation and if I am not wrong, in this case, to use the REST service offered by SAP ByDesign in another system I have to:
* create a communication scenario
* create a communication system
* and create a communication arrrangement
However, it seems to me, that the documentation for the Studio is only meant to consume external web services IN ByDesign FROM other systems and not FROM ByDesign TO another system.
1- So, does the configuration has to be on the ByDesign side?
2- Does it have to be on the in-house system side and only need the URL from the REST ByDesign webservice?
3- Or both?
Finally, when I try to extract the parameters from this URL in ByDesign in the New Rest Service functionality, it tells me that no parameters are found; even if the URL does work and does send some query results in my browser.
Sorry if it seems trivial, but this is not for me. 
Thank you for your attention.
Best regards.
Jacques-Antoine