A RESTful API server described to handle client/terminal request as below:

1. When client sends POST request as the following command does:
   curl -X POST -d ‘json={"cardType":"Visa","TransactionType":"Credit"}’ http://localhost:8888/terminals
   Server service should take the following actions:

• Assign a terminal ID, and store the input data entry into the in-memory array.
• If above succeeds, return the terminal ID, e.g. {16}, to client.
• If there is no available terminal ID to assign, return {}, which means the system is running on the maximum capacity designed.
• Returning empty to client means abnormal error happens on server side.
  NOTE - Input data in JSON format:
  {
  “cardType”: [
  “Visa”,
  “MasterCard”,
  "EFTPOS”
  ],
  “TransactionType”: [
  “Cheque”,
  “Savings”,
  “Credit”
  ]

2. When the client sends GET request as the following command does:
   curl -X GET http://localhost:8888/terminals/
   Server service should take the following actions:

• If succeed, return the output data entry to Client in JSON format, e.g. {"terminalID":15,"transactions":{"cardType":"Visa","TransactionType":"Credit"}}
• If no Data Entry exists, just return {} to client.
• Returning empty to client means abnormal error happens on server side.
  NOTE - Output data in JSON format:
  {
  "terminalID": 1,
  "transactions": [
  {
  "cardType": "Visa",
  "TransactionType": "Credit"
  },
  {
  "cardType": "EFTPOS",
  "TransactionType": "Savings"
  }
  ]
  }

3. When client sends GET request as the following command does:
   curl -X GET http://localhost:8888/terminals/
   Server service should take the following actions:

• If succeed, return the terminal ID list to client, e.g. {2 24 35 48 80}.
• If there is no terminal ID in use, return {} to client.
• Returning empty to client means abnormal error happens on server side.

Current Development Environment (Nov 20,2018):

Linux Version: ubuntu 16.04.01
libmicrohttpd version: 0.9.44 (re-run "sudo apt install libmicrohttpd-dev" can see it)
cJSON Libarary - clone & complied from https://github.com/DaveGamble/cJSON on Nov 20, 2018.

Dependent packages:

libmicrohttpd - sudo apt install libmicrohttpd-dev
curl - sudo apt install curl
cJSON - complied and install cJSON
cmock - download cmock from https://github.com/ThrowTheSwitch/CMock

Source list:

db_api.c
global.h
Makefile
README.md
req_handler.c
req_handler.h
term_svr.c
term_svr.h
to_do_func.c
to_do_func.h
test/UTfuncs_ut.c
test/system_test.scr

make commands:

Run make command in current directory.
make BLD : create final executable "term_api".
make UT: create executable "UTfuncs" under test directory for unit testing.
make clean_all: clean up generated sources(by cmock) and all binaries in current directory and test directory.

Logging:

ERR.log (in directory term_api being invoked) - Any code failure (non-zero return value) will put a message with recording the function name and code line.

Unit testing:

Unit testing was done with cmock/unity and run under test directory.

ubuntu->cd test
ubuntu->ls
ERR.log system_test.scr UTfuncs_runner.c UTfuncs_ut.c
System_test.log UTfuncs UTfuncs_runner_test.o UTfuncs_ut_test.o
ubuntu->UTfuncs
./test/UTfuncs_ut.c:32:test_query_term_info1:PASS
./test/UTfuncs_ut.c:54:test_query_term_info2:PASS
./test/UTfuncs_ut.c:72:test_query_term_info3:PASS
./test/UTfuncs_ut.c:88:test_query_term_info4:PASS
./test/UTfuncs_ut.c:114:test_parse_json1:PASS
./test/UTfuncs_ut.c:136:test_parse_json2:PASS
./test/UTfuncs_ut.c:157:test_parse_json3:PASS
./test/UTfuncs_ut.c:170:test_parse_json4:PASS
./test/UTfuncs_ut.c:184:test_parse_json5:PASS
./test/UTfuncs_ut.c:198:test_parse_json6:PASS
./test/UTfuncs_ut.c:212:test_init_db:PASS
./test/UTfuncs_ut.c:231:test_insert_db1:PASS
./test/UTfuncs_ut.c:258:test_insert_db2:PASS
./test/UTfuncs_ut.c:282:test_find_spare_id1:PASS
./test/UTfuncs_ut.c:301:test_find_spare_id2:PASS
./test/UTfuncs_ut.c:320:test_svr_process_req1:PASS
./test/UTfuncs_ut.c:342:test_svr_process_req2:PASS
./test/UTfuncs_ut.c:367:test_svr_process_req3:PASS
./test/UTfuncs_ut.c:387:test_svr_process_req4:PASS
./test/UTfuncs_ut.c:406:test_svr_process_req5:PASS
./test/UTfuncs_ut.c:424:test_query_db1:PASS
./test/UTfuncs_ut.c:446:test_query_db2:PASS
./test/UTfuncs_ut.c:459:test_query_db3:PASS
./test/UTfuncs_ut.c:474:test_query_term_list1:PASS
./test/UTfuncs_ut.c:505:test_query_term_list2:PASS
./test/UTfuncs_ut.c:525:test_struct2json:PASS

~-----------------------
26 Tests 0 Failures 0 Ignored
OK

System testing (Acceptance testing):

In a terminal window, invoke server product.
ubuntu->cd test
ubuntu->../term_api

In another terminal window, run automate system testing script under test directory and verify the result.
ubuntu->cd test
ubuntu->system_test.scr
Testcase1:[In initial empty DB, query assigned terminal IDs, receive {}]:PASS
Testcase2:[Send Visa input data to server, get expected ID]:PASS
Testcase3:[Query an assigned Visa terminal ID, get expected output data]:PASS
Testcase4:[Send EFTPOS input data to server, get expected ID]:PASS
Testcase5:[Query an assigned EFTPOS terminal ID, get expected output data]:PASS
Testcase6:[Send MasterCard input data to server, get expected ID]:PASS
Testcase7:[Query an assigned MasterCard terminal ID, get expected output data]:PASS
Testcase8:[Send typo json data "BADTransactionType" to server, receive nothing]:PASS
Testcase9:[Send typo json data "cardBADType" to server, receive nothing]:PASS
Testcase10:[Query all assigned terminal IDs, get expected ID list]:PASS
Testcase11:[Query a non-assigned terminal ID, receive {}]:PASS
Testcase12:[Query an out-of-range terminal ID, receive nothing]:PASS
Testcase13:[When running out of terminal ID slot, send json input data to server and receive {}]:PASS

~--------------------------------
13 Tests: 13 Successes 0 Failures
OK
NOTE: Please see ./System_test.log for test details.