In the CreditCardGateway class, , we implement the Void credit card operation which checks whether the credit card data is authorized and if a possibility of fraud exists. If the transaction is accepted, then we forward the request of the backend system.

public TransactionResponse Void(String token, BigDecimal amount) {
  if ( isAuthorised(token) && isFraud(token) ) {
    BackEndSystem.getInstance().voidOp(UUID.fromString(token), amount);
    return new TransactionResponse("Success.", 20002, token);  
  } else {
    return new TransactionResponse("Authorization invalid or fraud suspect.", 9997, null);     
  }
}

As a result of the transaction, we send the operation data back to the client.

We can see the following two methods in the previous code snippet:

These two methods have a private scope in the CreditCardGateway class and likewise are not exposed as a web service operation.

Furthermore, the BackEndSystem.getInstance().voidOp call implements the a to the public method of a backend system, which is not exposed as a web service operation either.

We can see that with JavaBean, we can freely decide what public methods will become available and are exposed as web service operations.