Spring integration TCP/IP close connection problem - spring-integration

Question

I use spring integration as a Full Duplex communication system's gateway module.
that flow is client app <--> spring-integration-ip-module (siid) <--> server app
The problem is when client app closed, ssid can't closed connection with server app side?
here is my code
// siid connet to client
#Bean
public TcpNetServerConnectionFactory server(){
TcpNetServerConnectionFactory server=new TcpNetServerConnectionFactory(1234);
server.setMapper(new TcpSerMapper()); // use 'mapper' attribute in XML
MySerializer mySeri=new MySerializer();
server.setDeserializer(mySeri);
server.setSerializer(mySeri);
return server;
}
// inboundGateway, inChannel as reqeustChannel
#Bean
public TcpInboundGateway inGate(){
TcpInboundGateway inGate=new TcpInboundGateway();
inGate.setConnectionFactory(server());
inGate.setRequestChannelName("inChannel");
inGate.setReplyChannelName("outputChannel");
return inGate;
}
// serviceActivator to get inChannel's payload msg and send though a gateway.
#ServiceActivator(inputChannel = "inChannel")
public byte[]doClientForward(Message<?> msg){
byte[]msgPayload=(byte[])(msg.getPayload());
byte[]sendResult=null;
ToTCP toTcp=(ToTCP)contextBean.get("toTcpBean"); // ToTCP is a gateway
sendResult=toTcp.sends((msgPayload),"localhost",7779);
QueueChannel outputChannel=(QueueChannel)contextBean.get("outputChannel");
return sendResult;
}
public static class DynamicSerSeri extends AbstractPooledBufferByteArraySerializer {
protected byte[] doDeserialize(InputStream inputStream, byte[] buffer) throws IOException {
byte[] bytes = this.copyBuffer(inputStream, buffer);
return bytes;
}
public void serialize(byte[] object, OutputStream outputStream) throws IOException {
outputStream.write(object);
}
public byte[] copyBuffer(InputStream inputStream, byte[] buffer) throws IOException {
int n = 0;
int bite = 0;
try {
while (true) {
bite = inputStream.read(); // blocked here
this.setMaxMessageSize(inputStream.available() + 1);
buffer = new byte[inputStream.available() + 1];
if (bite < 0 && n == 0) {
throw new SoftEndOfStreamException("Stream closed between payloads");
}
checkClosure(bite);
buffer[n++] = (byte) bite;
if (bite == -1) {
break;
}
if (n == this.maxMessageSize) {
break;
}
}
return buffer;
} catch (SoftEndOfStreamException e) {
throw e; // I was stuck here. when client closed, cf can't receive this exception and send close singnal to server side
} catch (IOException e) {
publishEvent(e, buffer, n);
throw e;
} catch (RuntimeException e) {
publishEvent(e, buffer, n);
throw e;
}
}
}
#MessagingGateway()
public interface ToTCP {
#Gateway(requestChannel = "toTcp.input", replyChannel = "outputChannel")
public byte[] sends(byte[] data, #Header("host") String host, #Header("port") int port);
}
#Bean
public IntegrationFlow toTcp() {
return f -> f.route(new ClientTcpRouter());
}
// I am not sure I understand IntegrationFlowContext,but it works
public static class ClientTcpRouter extends AbstractMessageRouter {
#Autowired
private IntegrationFlowContext flowContext;
#Override
protected synchronized Collection<MessageChannel> determineTargetChannels(Message<?> message) {
// connection to server side.
TcpNetClientConnectionFactory cf = new TcpNetClientConnectionFactory(host, port); //?? this connection factory does's closed when inGate's connection factory throw SoftEndOfStreamException
TcpOutboundGateway handler = new TcpOutboundGateway();
handler.setConnectionFactory(cf);
cf.setDeserializer(new DynamicSerSeri());
cf.setSerializer(new DynamicSerSeri());
IntegrationFlow flow = f -> f.handle(handler);
IntegrationFlowContext.IntegrationFlowRegistration flowRegistration =
this.flowContext.registration(flow)
.addBean(cf)
.id(hostPort + ".flow")
.register();
MessageChannel inputChannel = flowRegistration.getInputChannel();
this.subFlows.put(hostPort, inputChannel);
return inputChannel;
}
}
TcpInboundGateway get the connection from client into the inputChannel, and I use a serviceActivator to get inputChannel's payload and send to server side by a TcpOutboundGateway which has a connection factory with server side.
when the client closed the connection with spring-integration-ip-module, TcpInboundGateway can get the exception in SoftEndOfStreamException, but I don't known how to closed TcpOutboundGateway's connection to the server side.

Answer 1

Use an ApplicationListener bean or #EventListener method to listen for TCP Events.
When you first open an outbound connection, you will get a TcpConnectionOpenEvent. It is published on (and will be receive on) the calling thread by default. You can associate the outbound connection id with the inbound.
Listen for TcpConnectionCloseEvent from the inbound connection factory; you can then close the outbound connection using its connectionId.
outboundFactory.closeConnection(connectionId);
EDIT
Since you are using a TcpNetServerConnectionFactory, you can use a ThreadAffinityClientConnectionFactory which will automatically associate the outgoing connection with the incoming connection.
When you get the event for the incoming connection close, it will be on the same thread, so you can simply call releaseConnection() on that thread and the outgoing connection will close.
Here is an example
#SpringBootApplication
public class So55207274Application {
public static void main(String[] args) {
SpringApplication.run(So55207274Application.class, args);
}
#Bean
public IntegrationFlow flow() {
return IntegrationFlows.from(Tcp.inboundGateway(server()))
.log()
.handle(Tcp.outboundGateway(threadBoundClient()))
.get();
}
#Bean
public TcpNetServerConnectionFactory server() {
return new TcpNetServerConnectionFactory(1234);
}
#Bean
public ThreadAffinityClientConnectionFactory threadBoundClient() {
return new ThreadAffinityClientConnectionFactory(client());
}
public TcpNetClientConnectionFactory client() {
TcpNetClientConnectionFactory client = new TcpNetClientConnectionFactory("localhost", 1235);
client.setSingleUse(true);
return client;
}
#EventListener
public void listen(TcpConnectionCloseEvent event) {
if (event.getConnectionFactoryName().equals("server")) {
try {
threadBoundClient().releaseConnection();
}
catch (Exception e) {
e.printStackTrace();
}
}
System.out.println(event);
}
// Test server
#Bean
public IntegrationFlow test() {
return IntegrationFlows.from(Tcp.inboundGateway(Tcp.netServer(1235)))
.transform(Transformers.objectToString())
.<String, String>transform(p -> p.toUpperCase())
.get();
}
}