How to solve if `RotatingServerAdvice` is not fetching file for multiple times?

Question

I am using IntegrationFlow as Sftp Inbound DSL Configuration where I am using CustomTriggerAdvice to handle manual trigger. Please see below code snippet for reference.

I am also using RotatingServerAdvice for handling multiple path in same host.

But when I start the Sftp Inbound it fetch file for the first time from every path but it does not work for second time and onward. Sftp Inbound Starts but does not fetch file from paths. I couldn't figure out the problem. Is there anything that I am missing?

SftpConfiguration

public IntegrationFlow fileFlow() {
    SftpInboundChannelAdapterSpec spec = Sftp
            .inboundAdapter(dSF())
            .preserveTimestamp(true)
            .remoteDirectory(".")
            .autoCreateLocalDirectory(true)
            .deleteRemoteFiles(false)
            .localDirectory(new File(getDestinationLocation()));

    return IntegrationFlows
            .from(spec, e -> e.id(BEAN_ID)
                    .autoStartup(false)
                    .poller(Pollers
                            .fixedDelay(5000)
                            .advice(
                                    customRotatingServerAdvice(dSF()),
                                    customTriggerAdvice()
                            )
                    )
            )
            .channel(sftpReceiverChannel())
            .handle(sftpInboundMessageHandler())
            .get();
}

private MessageChannel sftpReceiverChannel() {
    return MessageChannels.direct().get();
}

... ... ...

@Bean
public RotatingServerAdvice customRotatingServerAdvice(
      DelegatingSessionFactory<LsEntry> dSF
) {
    List<String> pathList = getSourcePathList();
    for (String path : pathList) {
        keyDirectories.add(new RotationPolicy.KeyDirectory(KEY, path));
    }

    return new RotatingServerAdvice(
            dSF,
            keyDirectories
    );
}

@Bean
public CustomTriggerAdvice customTriggerAdvice() {
    return new CustomTriggerAdvice(customControlChannel(),BEAN_ID);
}


@Bean
public IntegrationFlow customControlBus() {
    return IntegrationFlows.from(customControlChannel())
            .controlBus()
            .get();
}


@Bean
public MessageChannel customControlChannel() {
    return MessageChannels.direct().get();
}

CustomTriggerAdvice

public class CustomTriggerAdvice extends AbstractMessageSourceAdvice {
    private final MessageChannel controlChannel;
    private final String BEAN_ID;

    public CustomTriggerAdvice(MessageChannel controlChannel, String beanID) {
        this.controlChannel = controlChannel;
        this.BEAN_ID = beanID;
    }

    @Override
    public boolean beforeReceive(MessageSource<?> source) {
        return true;
    }

    @Override
    public Message<?> afterReceive(Message<?> result, MessageSource<?> source) {
        if (result == null) {
            controlChannel.send(new GenericMessage<>("@" + BEAN_ID + ".stop()"));
        } 
        return result;
    }
}

Starting Sftp Inbound using MessageChannel

@Qualifier("customControlChannel") MessageChannel controlChannel;


public void startSftpInbound(){
       controlChannel.send(new GenericMessage<>("@" + beanID + ".start()"));
}

Answer 1

I need the system to start on demand and fetch file completing one cycle. If it is not stopped after that, it will continue polling and won't stop and my system will fall into an infinite loop. Is there any way to get that when the RotatingServerAdvice is completing polling from all servers at least one? Does it throw any event or something like that ?

You probably misunderstood the logic with the afterReceive(@Nullable Message<?> result, MessageSource<?> source) contract. You can't stop a channel adapter for your requirements when one of the servers has returned nothing to poll. This way you don't give a chance for another server to poll on the next polling cycle.

I think your idea is to iterate over all the servers only once and then stop. Probably independently of the result from any of them. It looks like the best way to stop for you it is to use a RotatingServerAdvice with the fair = true to move to the next server every time. The stop might be performed from the custom afterReceive() independently of the result when you see that the RotationPolicy.getCurrent() is equal to a last one in the list. So, this way you iterate over all of them and stop moving the first one for the next poling cycle.