Invoke a REST API (JSON) in PLSQL - json

Question

I want to invoke a restful API (JSON) in plsql. The JSON Payload is as follows:
{
"data": {
"content": "encrypted content", "signature": "JKQWJK34K32JJEK2JQWJ5678",
"dataDescription": {
"codeType": "0",
"encryptCode": "1",
"zipCode": "0"
}
},
"globalInfo": {
"appId": "AP01",
"version": "1.1.20191201",
"dataExchangeId": "9230489223014123",
"interfaceCode": "T101",
"requestCode": "TP",
"requestTime": "2019-06-11 17:07:07",
"responseCode": "TA",
"userName": "admin",
"deviceMAC": "FFFFFFFFFFFF",
"deviceNo": "00022000634",
"tin": "1009830865",
5
"brn": "",
"taxpayerID": "1",
"longitude": "116.397128",
"latitude": "39.916527",
"extendField": {
"responseDateFormat": "dd/MM/yyyy",
"responseTimeFormat": "dd/MM/yyyy HH:mm:ss"
}
},
"returnStateInfo": {
"returnCode": "",
"returnMessage": ""
}
}
The Interface Codes (interfaceCode: T101) are defined, and for each method there is an interface Code, I just want to know how do i invoke a interface Method?

Answer 1

You can do it with UTL_HTTP package.
declare
v_req utl_http.req;
v_res utl_http.resp;
v_buffer varchar2(4000);
v_body varchar2(4000) := '{"field":"value"}'; -- Your JSON
begin
-- Set connection.
v_req := utl_http.begin_request('http://your.api/operation', 'POST');
utl_http.set_authentication(v_req, 'your_username','your_password');
utl_http.set_header(v_req, 'content-type', 'application/json');
utl_http.set_header(v_req, 'Content-Length', length(v_body));
-- Invoke REST API.
utl_http.write_text(v_req, v_body);
-- Get response.
v_res := utl_http.get_response(v_req);
begin
loop
utl_http.read_line(v_res, v_buffer);
-- Do something with buffer.
dbms_output.put_line(v_buffer);
end loop;
utl_http.end_response(v_res);
exception
when utl_http.end_of_body then
utl_http.end_response(v_res);
end;
end;
But if your database has got APEX installed, then you can try APEX_WEB_SERVICE package (much simpler).
declare
v_response clob;
v_buffer varchar2(32767);
v_buffer_size number := 32000;
v_offset number := 1;
begin
-- Set connection and invoke REST API.
v_response := apex_web_service.make_rest_request(
p_url => 'http://your.api/operation',
p_http_method => 'POST',
p_username => 'your_username',
p_password => 'your_password',
p_body => '{"field":"value"}' -- Your JSON.
);
-- Get response.
begin
loop
dbms_lob.read(v_response, v_buffer_size, v_offset, v_buffer);
-- Do something with buffer.
DBMS_OUTPUT.PUT_LINE(v_buffer);
v_offset := v_offset + v_buffer_size;
end loop;
exception
when no_data_found then
null;
end;
end;
If you get an ACL exception, then you have to create ACL to open TCP port to connect with REST API.
BEGIN
DBMS_NETWORK_ACL_ADMIN.create_acl (
acl => 'acl.xml',
description => 'Connecting with REST API',
principal => 'YOUR_DATABASE_SCHEMA',
is_grant => TRUE,
privilege => 'connect',
start_date => SYSTIMESTAMP,
end_date => NULL
);
DBMS_NETWORK_ACL_ADMIN.assign_acl (
acl => 'acl.xml',
host => 'localhost', -- Or hostname of REST API server (e.g. "example.com").
lower_port => 80, -- For HTTPS put 443.
upper_port => NULL
);
COMMIT;
end;
I assume your REST API is protected by basic authentication scheme (user and password). To keep this example simple i used HTTP. If you have to connect via HTTPS, then you have to change TCP port in ACL and configure Oracle Wallet for your Oracle database instance.