DEEL BACKEND TASK

what was done:

• project architecture quick refac (MVC) ✓
• implementation of seven tasks ✓
• added unit tests (jest) ✓
• added concurrence benchmark tests (apache ab) ✓

what can we improve:

• migrate the project to Typescript;
• migrate two raw queires to usei Model interfaces;
• use increment function to update balance;
• currency standardization;

tests	collection	code challenge ref
		challenge

quick explanation:

.
├── scripts
│   └── seedDb.js //to hydrated the db 
├── src
│   ├── config //config rules
│   ├── middleware //the middlewares
│   ├── model //model rules
│   ├── router //router rules
│   ├── server.js //entry point
│   └── service //service rules
└── test //jest files
    └── apache //to run apache ab

to run

npm run start

to feed the data base

npm run seed

to test

npm run test
or
npm run fill-db-run-test

apache ab

chmod +x ./test/apache/ab.sh && ./test/apache/ab.sh

addition of 10 to the balance per request (ab -n 10 -c 10 )

Before:

Many things happening...

After:

Results without the improvements: 10.732 seconds 🙁

This is ApacheBench, Version 2.3 <$Revision: 1901567 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking 127.0.0.1 (be patient).....done

Server Software:
Server Hostname:        127.0.0.1
Server Port:            3001

Document Path:          /balances/deposit/2
Document Length:        62 bytes

Concurrency Level:      10
Time taken for tests:   10.732 seconds
Complete requests:      10
Failed requests:        8
   (Connect: 0, Receive: 0, Length: 8, Exceptions: 0)
Non-2xx responses:      7
Keep-Alive requests:    2
Total transferred:      1329 bytes
Total body sent:        1950
HTML transferred:       124 bytes
Requests per second:    0.93 [#/sec] (mean)
Time per request:       10732.318 [ms] (mean)
Time per request:       1073.232 [ms] (mean, across all concurrent requests)
Transfer rate:          0.12 [Kbytes/sec] received
                        0.18 kb/s sent
                        0.30 kb/s total

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.1      0       0
Processing:    57 6112 4275.4   9442   10675
Waiting:       56 5668 4619.1   9442   10675
Total:         57 6112 4275.4   9442   10675

Percentage of the requests served within a certain time (ms)
  50%   9442
  66%   9450
  75%   9473
  80%  10113
  90%  10675
  95%  10675
  98%  10675
  99%  10675
 100%  10675 (longest request)

I know, I know, the time could be better. 😬
I thought of a few reasons for this but my knowledge of Sequelize those a total of 4 hours.
Things I know can improve this result:

• pool connections;
• improve retry strategy;

Another thing that can also be improved is the entity relationship and the rest layer routing.

Results with the improvements: 0.878 seconds 🔥

This is ApacheBench, Version 2.3 <$Revision: 1901567 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking 127.0.0.1 (be patient).....done


Server Software:        
Server Hostname:        127.0.0.1
Server Port:            3001

Document Path:          /balances/deposit/2
Document Length:        62 bytes

Concurrency Level:      10
Time taken for tests:   0.878 seconds
Complete requests:      10
Failed requests:        8
   (Connect: 0, Receive: 0, Length: 8, Exceptions: 0)
Non-2xx responses:      8
Keep-Alive requests:    2
Total transferred:      1434 bytes
Total body sent:        1950
HTML transferred:       124 bytes
Requests per second:    11.40 [#/sec] (mean)
Time per request:       877.575 [ms] (mean)
Time per request:       87.758 [ms] (mean, across all concurrent requests)
Transfer rate:          1.60 [Kbytes/sec] received
                        2.17 kb/s sent
                        3.77 kb/s total

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.1      0       0
Processing:    72  530 179.4    553     805
Waiting:       72  529 179.4    553     805
Total:         72  530 179.4    553     805

Percentage of the requests served within a certain time (ms)
  50%    553
  66%    554
  75%    554
  80%    554
  90%    805
  95%    805
  98%    805
  99%    805
 100%    805 (longest request)