Airport Integration Flow

@Configuration
@EnableIntegration
public class ExampleConfiguration { 
    
    @Bean
    IntegrationFlow inboundFlow(
      ErrorManager errorManager,
      SeatSelector seatSelector,
      Prioritizer priority
    ) {
        return IntegrationFlows
                .from(Http.inboundGateway("/example/bookmyflight"))
                .enrichHeaders(headerEnricherSpec -> headerEnricherSpec.header("original_request", request)
                                               .header("priority", priority.for(request))) 
                .channel(channel -> channel.priority())
                .transform(//build credit card charge request with info from flight booking request)
                .enrich(e -> e.requestChannel("paymentChannel")
                                 .header("paymentInfo", this.paymentInfo)
                .handle((payload, headers) -> seatSelector.selectSeat(payload))
                .publishSubscribeChannel(Executors.newCachedThreadPool(), s -> s
                    .subscribe(subflow -> subflow
                            .<String>handle((payload, headers) -> "You have successfully booked your seat.")
                    .subscribe(subflow -> subflow
                            .enrichHeaders(headerEnricherSpec -> headerEnricherSpec.header("mail_to", payload.getEmailAddress()))
                            .handle(Mail.outboundAdapter("smtp.gmail.com")
                            .credentials(ExampleCiConfig.AUTHENTICATION_EMAIL, ExampleCiConfig.AUTHENTICATION_PASSWORD)
                            .javaMailProperties(mailProperties()))
                            .channel(channel -> channel.queue("outboundEmail"))))
                .get();
    }
    
    @Bean
    public Prioritizer prioritizer() {
         return new Prioritizer() {
            public int for(Object request) {
              //Figures out from the request whether the customer came from the airline's website or from a 
              //comparison website, and assigns a higher priority to the first type of customer
            }
         }.get();
    }
    
    @Bean
    public ErrorManager errorManager() {
         return new ErrorManager() {
             public Object handleError(int statusCode, Object payload) {
                  //Handle different HTTP status codes and, if call successful, return payload
             }
         }
    }
    
   @Bean
    public SeatSelector seatSelector() {
         return new SeatSelector() {
             public Object selectSeat(Object payload) {
                 //make call to some external seat selection service
             }
         }
    }
    
    Properties mailProperties() {
        Properties properties = new Properties();
        properties.put("mail.smtp.ssl.enable", true);
        return properties;
    }
    
}