Annotation-Based Configuration

@EnableIntegration 1
@IntegrationComponentScan 2
@Configuration
public static class Config {

    @Value(${some.port})
    private int port;

    @MessagingGateway(defaultRequestChannel="toTcp") 3
    public interface Gateway {

        String viaTcp(String in);

    }

    @Bean
    @ServiceActivator(inputChannel="toTcp") 4
    public MessageHandler tcpOutGate(AbstractClientConnectionFactory connectionFactory) {
        TcpOutboundGateway gate = new TcpOutboundGateway();
        gate.setConnectionFactory(connectionFactory);
        gate.setOutputChannelName("resultToString");
        return gate;
    }

    @Bean 5
    public TcpInboundGateway tcpInGate(AbstractServerConnectionFactory connectionFactory)  {
        TcpInboundGateway inGate = new TcpInboundGateway();
        inGate.setConnectionFactory(connectionFactory);
        inGate.setRequestChannel(fromTcp());
        return inGate;
    }

    @Bean
    public MessageChannel fromTcp() {
        return new DirectChannel();
    }

    @MessageEndpoint
    public static class Echo { 6

        @Transformer(inputChannel="fromTcp", outputChannel="toEcho")
        public String convert(byte[] bytes) {
            return new String(bytes);
        }

        @ServiceActivator(inputChannel="toEcho")
        public String upCase(String in) {
            return in.toUpperCase();
        }

        @Transformer(inputChannel="resultToString")
        public String convertResult(byte[] bytes) {
            return new String(bytes);
        }

    }

    @Bean
    public AbstractClientConnectionFactory clientCF() { 7
        return new TcpNetClientConnectionFactory("localhost", this.port);
    }

    @Bean
    public AbstractServerConnectionFactory serverCF() { 8
        return new TcpNetServerConnectionFactory(this.port);
    }

}