Spring 集成 Tcp 连接单用VS setSoKeepAlive

Question

I was using

TcpNetClientConnectionFactory cf = new TcpNetClientConnectionFactory(host, port);

for TcpOutboundGateway, normally TcpOutboundGateway is working req/reply order but in my case I extend TcpOutboundGateway to receive arbitrary messages with MessageChannel. This is why ı thought that i should use

cf.setLeaveOpen(true)

to keep connection open.

Although i started to use that option, after long time when i called tcp server again i have received Exception like

org.springframework.integration.MessageTimeoutException: Timed out waiting for response

but i did not understand why i am taking this error because i set "true" to keep connection open in my connection factory.

THEN

I did some google and it was supposed to use CachingClientConnectionFactory, I understand that it is by default single-use=true and not supposed to change it false, but then i assume that connection will be open and close in my each request response transaction so is it obstacle to receive arbitrary data from server without any request from client?

OR

How should i keep open connection between client and server? should i use

cf.setSoKeepAlive(true)?

to keep connection open? Are

cf.setSoKeepAlive(true) and cf.setLeaveOpen(true)

same with each other?

EDIT

Also when i use cf.setSoKeepAlive(true), after 1 hour i got same exception too.

Full code:

private MessageChannel createNewSubflow(Message<?> message) {
    String host = (String) message.getHeaders().get("host");
    Integer port = (Integer) message.getHeaders().get("port");

    boolean hasThisConnectionIrregularChannel = message.getHeaders().containsKey("irregularMessageChannelName");


    Assert.state(host != null && port != null, "host and/or port header missing");
    String flowRegisterKey;

    if (hasThisConnectionIrregularChannel) {
        flowRegisterKey = host + port + ".extended";
    } else {
        flowRegisterKey = host + port;
    }

    TcpNetClientConnectionFactory cf = new TcpNetClientConnectionFactory(host, port);

    CachingClientConnectionFactory ccf = new CachingClientConnectionFactory(cf, 20);
    ccf.setSoKeepAlive(true);

    ByteArrayCrLfSerializer byteArrayCrLfSerializer = new ByteArrayCrLfSerializer();
    byteArrayCrLfSerializer.setMaxMessageSize(1048576);

    ccf.setSerializer(byteArrayCrLfSerializer);
    ccf.setDeserializer(byteArrayCrLfSerializer);

    TcpOutboundGateway tcpOutboundGateway;
    if (hasThisConnectionIrregularChannel) {
        String unsolicitedMessageChannelName = (String) message.getHeaders().get("irregularMessageChannelName");
        DirectChannel directChannel = getBeanFactory().getBean(unsolicitedMessageChannelName, DirectChannel.class);
        tcpOutboundGateway = new ExtendedTcpOutboundGateway(directChannel);
    } else {
        tcpOutboundGateway = new TcpOutboundGateway();
    }
    tcpOutboundGateway.setRemoteTimeout(20000);

    tcpOutboundGateway.setConnectionFactory(ccf);

    IntegrationFlow flow = f -> f.handle(tcpOutboundGateway);

    IntegrationFlowContext.IntegrationFlowRegistration flowRegistration =
        this.flowContext.registration(flow)
            .addBean(ccf)
            .id(flowRegisterKey + ".flow")
            .register();

    MessageChannel inputChannel = flowRegistration.getInputChannel();

    this.subFlows.put(flowRegisterKey, inputChannel);
    return inputChannel;
}

Answer 1

Why are you using the CachingClientConnectionFactory ? It is not needed when you keep the connection open; it is intended to be used when you want to maintain multiple open connections.

Timed out waiting for response

Means the socket was open just fine (from the client's perspective) when you sent the request; we just didn't get a reply. This could mean that some network component (router) silently closed the socket due to inactivity. Keep-alives should help with that but it depends on your operating system and how often the TCP stack is configured to send keep alives.