Thanks.
I think which of the two roads I should choose...
Or, I create a one "universal" web-service
that call the "universal" stored procedure
that will parse many different POST-requests and
call the stored procedure corresponding to the request.
Either I create hundreds of enabled web-services for each stored procedure (which is equivalent to “I am not sure that they did not pull me into a hundred little bearlings ...” (c) Baloo).

One approach is to create CREATE SERVICE and CREATE PROCEDURE in pairs, using the same name for each, and storing them in the same *.sql file.

In a simpler world, the syntax would be combined... but the world is not simple, and sometimes services have aliases like "root".

IMO "universal" services and procedures will make your life more difficult, similar to a "universal code table" folks sometimes use instead of creating a hundred separate tables... both performance and especially maintenance suffers because of the unnecessary complexity AND the inevitable compromises when the "universal" structure doesn't accomodate special cases without blunt hacks.