UDP server with spring-integration

Question

I wonder if it is possible to create a UDP server with spring-integration framework that is able to accept requests and return responses.

For TCP there are TCP gateways which allow request/response processing but I don't see similar thing for UDP.

It is easy to setup UDP listener and receive packets but then I don't see how to return a response as I can only route it to a predefined output channel.

Also I don't see sender's IP and port as the transformer doesn't receive the DatagramPacket object but only the data.

Here is my configuration:

<int:channel id="ChannelIn" />

<ip:udp-inbound-channel-adapter id="ChannelReceiver"
    channel="ChannelIn"
    port="5555"
    multicast="false"
    check-length="false" 
    pool-size="10"
    />

<int:transformer
    ref="datagramToPacketTransformer"
    input-channel="ChannelIn"
    output-channel="ChannelSA" 
    method="toPacket"/>

<int:channel id="ChannelSA" />

<int:service-activator id="ChannelActivator" 
    input-channel="ChannelSA"
    ref="PacketHandler"
    method="process"
/>

Answer 1

I have found n way to deal with UDP. Below is my configuration

<int-ip:udp-inbound-channel-adapter id="ChannelReceiver"
                                    channel="serverBytes2StringChannel"
                                    port="9000"
                                    multicast="false"
                                    check-length="false" 
                                    pool-size="10"
                                    lookup-host="false"
/>

<int:transformer id="serverBytes2String"
                 input-channel="serverBytes2StringChannel"
                 output-channel="udpSA" 
                 expression="new String(payload)"

/>

<int:service-activator input-channel="udpSA" 
                       ref="deviceService" 
                       method="udpMessage"/>

And deviceService bean has this code:

 public Message udpMessage(Message message) {
        String response = "KO";
        try {
            response = process(message);
        } catch (Throwable th) {
            //do something
        }
        Message msg = MessageBuilder.withPayload(response.getBytes()).copyHeaders(message.getHeaders()).build();
        sendReply(msg);
        return null;
    }
    private void sendReply(Message message) {
        try {
            int port = (Integer) message.getHeaders().get("ip_port");
            String ip = (String) message.getHeaders().get("ip_address");
            InetAddress IPAddress = InetAddress.getByName(ip);

            byte[] sentence = (byte[]) message.getPayload();
            byte[] sendData = new byte[sentence.length];
            byte[] receiveData = new byte[1024];
            sendData = sentence;
            DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, port);
            DatagramSocket clientSocket = new DatagramSocket();
            clientSocket.send(sendPacket);
            clientSocket.close();
        } catch (Exception ex) {
            throw new RuntimeException("KO");
        }
    }

And this is working perfectly on my personal computer however when I deploy this code on Amazon AWS it is not working. I found that even though program is listening on UDP 9000 port, but no communication received at server side. This could be an issue with AWS setup though I have allowed all UDP port for that AWS instance.

Any hints on how to make this work on Amazon AWS?

Answer 2

I opened a new feature JIRA nearly two years ago

https://jira.springsource.org/browse/INT-1809

but it received no votes, or watchers, so I closed it.

Feel free to add a comment to it and we can re-open it.

The sender's ip is in the message header, but not his port...

            message = MessageBuilder.withPayload(payload)
                    .setHeader(IpHeaders.HOSTNAME, hostName)
                    .setHeader(IpHeaders.IP_ADDRESS, hostAddress)
                    .build();

If you want to open a new JIRA for that, it's a small enough change to get into the 2.2. release that will come out shortly (but the gateways will not make 2.2).

https://jira.springsource.org/browse/INT