Spring boot 3 library and microservice uses it to reduce boilerplate code.

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Stack:

• Kotlin
• Spring Boot 3.2.2
• Spring Webflux.
• Native images support.

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lib project includes:

• Optional routes config (see com.illenko.payment.lib.api.Routes).
• Internal API model (com.illenko.payment.lib.api.request/response packages).
• Handlers (com.illenko.payment.lib.api.handler).
• Services interfaces (com.illenko.payment.lib.api.service)
• Enums, etc.

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paypal-integration project includes:

• Defines lib as dependency, see build.gradle.kts (implementation("com.illenko.payment:lib:$paymentLibVersion"))
• Implement only one of 2 services, defined in lib (com.illenko.payment.paypalintegration.service.CreditServiceImpl), it makes only /credit endpoint enabled, because of @ConditionalOnBean annotation used in lib.Routes.

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Please note, if you want to add any new endpoints with new request/response model and build your service in native image, additional info must be added to handler level, to add required info to native executable, see:

@Component
@RegisterReflectionForBinding(
    InternalCreditRequest::class,
    InternalCreditResponse::class,
)
class CreditHandler {
    //
}

This problem may just be specific for router-handler approach, but for @RestController's it must work without extra hints.

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Native image info:

• Size: 128.55 MB
• RAM on start: 33.04MiB
• RAM after benchmark: 101MiB

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Primitive /credit endpoint benchmark:

ab -n 10000 -c 100 -p credit_request.json -T application/json http://localhost:8080/credit

Server Hostname:        localhost
Server Port:            8080

Document Path:          /credit
Document Length:        71 bytes

Concurrency Level:      100
Time taken for tests:   8.518 seconds
Complete requests:      10000
Failed requests:        0
Total transferred:      1420000 bytes
Total body sent:        2430000
HTML transferred:       710000 bytes
Requests per second:    1174.05 [#/sec] (mean)
Time per request:       85.175 [ms] (mean)
Time per request:       0.852 [ms] (mean, across all concurrent requests)
Transfer rate:          162.81 [Kbytes/sec] received
                        278.61 kb/s sent
                        441.42 kb/s total

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.9      0      58
Processing:     2   84 345.0     29    3417
Waiting:        2   84 345.0     29    3417
Total:          2   85 345.0     29    3417

Percentage of the requests served within a certain time (ms)
  50%     29
  66%     36
  75%     41
  80%     45
  90%     59
  95%    319
  98%    638
  99%   3345
 100%   3417 (longest request)