Recently I had to get an ORDS remote procedure call to work on a CentOS / Apex 4.2 / ORDS 2.0.10 server. I had a hard time finding the right documentation for that old ORDS version, so I thought I'd share how I got it to work finally.

Source:
https://apextips.blogspot.com/2014/11/exposing-procedures-for-url-access-with.html

More info:
https://docs.oracle.com/cd/E37099_01/doc.20/e25066/config_file.htm#AELIG7162
https://matthiashoys.wordpress.com/2013/02/22/http-404403-executing-apex-procedure-from-url-with-oracle-11g-xe/
http://daust.blogspot.com/2006/04/xe-calling-stored-procedures.html
https://stackoverflow.com/questions/40507352/permission-denied-to-procedure

As database schema tedstruik: create or replace procedure output_name(p_name in varchar2) as begin htp.p('Hello ' || p_name || '. You have successfully exposed your procedure using RESTful services.' ); end output_name; grant execute on tedstruik.output_name to apex_public_user;
As database schema sys: create or replace noneditionable function apex_040200.wwv_flow_epg_include_mod_local( procedure_name in varchar2) return boolean is begin -- return false; -- remove this statement when you modify this function -- -- Administrator note: the procedure_name input parameter may be in the format: -- -- procedure -- schema.procedure -- package.procedure -- schema.package.procedure -- -- If the expected input parameter is a procedure name only, the IN list code shown below -- can be modified to itemize the expected procedure names. Otherwise you must parse the -- procedure_name parameter and replace the simple code below with code that will evaluate -- all of the cases listed above. -- if lower(procedure_name) in ( 'tedstruik.output_name') then return TRUE; else return FALSE; end if; end wwv_flow_epg_include_mod_local;
As OS user oracle: vi defaults.xml [add/edit these lines] <entry key="security.validationFunctionType">plsql</entry> <entry key="security.requestValidationFunction">wwv_flow_epg_include_modules.authorize</entry>
As OS user root: service tomcat status
In a browser:
Test using a URL like this: http://localhost:8090/ords/tedstruik.output_name?p_name=bob
Result: “Hello bob. You have successfully exposed your procedure using RESTful services.”

Note: sometimes Tomcat is slow to pick up changes, it seems. Wait a bit and/or restart Tomcat again if you get 503/404/403 errors.