Below is my environmental information

Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
PL/SQL Release 12.1.0.2.0 - Production


Below activity performed by DBA

grant execute on utl_http to schema_name
grant execute on dbms_lock to schema_name

BEGIN
DBMS_NETWORK_ACL_ADMIN.create_acl (
acl => 'scim_api_dev.xml',
description => 'A test of the API DEV - ACL functionality',
principal => 'schema_name',
is_grant => TRUE,
privilege => 'connect',
start_date => SYSTIMESTAMP,
end_date => NULL);
end;

DBMS_NETWORK_ACL_ADMIN.ADD_PRIVILEGE (acl => 'scim_api_dev.xml'
, principal => 'schema_name'
, is_grant => TRUE
, privilege => 'resolve');
begin
DBMS_NETWORK_ACL_ADMIN.assign_acl (
acl => 'scim_api_dev.xml',
host => ' https://hs-identity-api.example.com/scim/v1/dev/Users',
lower_port => 1,
upper_port => 50000);
end;
commit;

Below is the code snippet, but getting an error "ORA-29273: HTTP request failed ORA-12541: TNS:no listener ORA-06512:"

declare
req UTL_HTTP.REQ;
resp UTL_HTTP.RESP;
val VARCHAR2(2000);
str varchar2(1000);
begin
req := UTL_HTTP.BEGIN_REQUEST(' https://hs-identity-api.example.com/scim/v1/dev/Users' || '?' || 'filter=userName+Eq+%22madhan%22' || '&'||'attributes=id');
resp := UTL_HTTP.GET_RESPONSE(req);
LOOP
UTL_HTTP.READ_LINE(resp, val, TRUE);
DBMS_OUTPUT.PUT_LINE(val);
END LOOP;
UTL_HTTP.END_RESPONSE(resp);
EXCEPTION
WHEN UTL_HTTP.END_OF_BODY
THEN
UTL_HTTP.END_RESPONSE(resp);
END;

Please help me out.

1. It depends on your OS. Simple method is to see if you can access the site using browser while logged in to the server. Or using a command line tool like wget.
Testing on a laptop is useless. You need to be connected to the server.
-Yes. i am able to access complete url from browser.
2. I believe this refers to environment variables. You can't set these from PL/SQL.
If you're struggling, speak with your network admin.
- Had a meeting with network admin. They are able to see a call begin made to destination from PLSQL but there is a block in firewall and hence recommended to access the destination via Proxy settings from PLSQL.

When i used below command in PLSQL, receiving an error "ORA-29273: HTTP request failed
ORA-29024: Certificate validation failure"

Command
UTL_HTTP.SET_PROXY('webproxy.mycompany.com:8080','');

Would like to know if above command is correct - Please help.

Below is the code snippet.

declare
req UTL_HTTP.REQ;
resp UTL_HTTP.RESP;
val VARCHAR2(2000);
str varchar2(1000);
begin
UTL_HTTP.SET_PROXY('webproxy.mycompany.com:8080','');
req := UTL_HTTP.BEGIN_REQUEST(' https://hs-identity-api.company.com/' );
resp := UTL_HTTP.GET_RESPONSE(req);
LOOP
UTL_HTTP.READ_LINE(resp, val, TRUE);
DBMS_OUTPUT.PUT_LINE(val);
END LOOP;
UTL_HTTP.END_RESPONSE(resp);
EXCEPTION
WHEN UTL_HTTP.END_OF_BODY
THEN
UTL_HTTP.END_RESPONSE(resp);
END;

Team:

docs says we can have more than PK values are comma separated, but when tried it fails like this - kindly advice.

https://docs.oracle.com/en/database/oracle/oracle-rest-data-services/20.2/aelig/developing-REST-applications.html#GUID-D3A4C99B-3090-481B-846D-45FBA578B1D2

demo@XEPDB1> spool output.txt
demo@XEPDB1> $ curl -i -X GET http://localhost:8080/ords/xe/emp/7499
HTTP/1.1 200 OK
Date: Thu, 12 Nov 2020 03:42:02 GMT
Content-Type: application/json
ETag: "u1lQygTTgvOp7RL9UMBAMeCuO/4yLrgGf3UG9aev9NNN4RZA6lqaOakGXLLOI+aIkCzNwCa0QjE/wggaVFXI2g=="
Transfer-Encoding: chunked

{"empno":7499,"ename":"ALLEN","job":"SALESMAN","mgr":7698,"hiredate":"1981-02-19T18:30:00Z","sal":1600,"comm":300,"deptno":30,"links":[{"rel":"self","href":"http://localhost:8080/ords/xe/emp/7499"},{"rel":"edit","href":"http://localhost:8080/ords/xe/emp/7499"},{"rel":"describedby","href":"http://localhost:8080/ords/xe/metadata-catalog/emp/item"},{"rel":"collection","href":"http://localhost:8080/ords/xe/emp/"}]}
demo@XEPDB1>
demo@XEPDB1> $ curl -i -X GET http://localhost:8080/ords/xe/emp/7499,7369
HTTP/1.1 500 Server Error
Content-Type: text/html
Error-Reason: error="error"; error_description*=UTF-8''An%20unexpected%20error%20with%20the%20following%20message%20occurred%3a%20null
Content-Length: 16270

<!DOCTYPE html>
<html>
<style type="text/css" media="screen">
footer,header{display:block;}

Team:

when tried this url from browser, it works fine.
http://localhost:8080/ords/peeps/emp/?q={"deptno":{"$lte":10}}

However when invoked from curl command line, getting this error. Kindly help us to understand, what are we missing here.

C:\Users\admin>curl -i http://localhost:8080/ords/peeps/emp/?q={"deptno":{"$lte":10}}
curl: (3) nested brace in URL position 49:
http://localhost:8080/ords/peeps/emp/?q={deptno:{$lte:10}}
                                                ^

curl: (3) nested brace in URL position

Thanks, tried this but still doesn't work.

C:\Users\admin>curl -i -g http://localhost:8080/ords/peeps/emp/?q={"deptno":{"$lte":10}}
HTTP/1.1 400 Bad Request
Content-Type: text/html
Content-Length: 16131

<!DOCTYPE html>
<html>
<style type="text/css" media="screen">
footer,header{display:block;}