The challenge is a Java8 + Spring Boot project which uses HSQLDB as the database.
Most of merchants sell products online. For these merchants the necessary REST services are listed below. We kindly ask you to implement them.
- Product adding, removing or updating services.
- Product listing service which returns product name, description, remaining stock count and price.
- Payment service for the end user to buy their selected product.
- A product should not be sold for more than its stock.
- Customers paying for the same product at the same time should not buy the product if the stock is depleted. (i.e. if there are 2 stocks left and 3 customers pay at the same time, first 2 successful should buy the product and the 3rd one should fail with an appropriate message.)
- No front end is necessary.
- Test coverage for the implemented service should be above 80%. We expect both Integration and unit tests.
The bank responses are persisted to database.In class we have simulated 100 customers calling the payment service.
public void pay(BigDecimal price) {
//pay with bank
BankPaymentRequest request = new BankPaymentRequest();
request.setPrice(price);
BankPaymentResponse response = bankService.pay(request);
//insert records
Payment payment = new Payment();
payment.setBankResponse(response.getResultCode());
payment.setPrice(price);
paymentRepository.save(payment);
logger.info("Payment saved successfully!");
}In the simulation for some reason the bank response times take ~5 seconds. Due to this latency, a database connection problem is encountered after some time. class displays "Connection is not available, request timed out after 30005ms." error after some time.)
Find a way to persist bank responses to the database in this situation.
- DB connection pool should stay the same.
- BankService.java and PaymentServiceClients.java classes should not be changed.
- In case of an error, there should not be any dirty data in the database.