Facing exception while performing browse operation

[bibhudatta-sahu]

Hello Everyone,

    When we starts browse operation, it continues without error for few minutes after that we are facing below exception.

[2022-04-19 13:02:15,189] – [milo-netty-event-loop-0] – [ERROR] – o.e.m.o.s.c.t.u.UascClientMessageHandler : [remote=EmPilot1APM/10.8.4.59:56000] Exception caught: Connection reset by peer
java.io.IOException: Connection reset by peer
at sun.nio.ch.FileDispatcherImpl.read0(Native Method)
at sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:39)
at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:223)
at sun.nio.ch.IOUtil.read(IOUtil.java:192)
at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:379)
at io.netty.buffer.PooledByteBuf.setBytes(PooledByteBuf.java:258)
at io.netty.buffer.AbstractByteBuf.writeBytes(AbstractByteBuf.java:1132)
at io.netty.channel.socket.nio.NioSocketChannel.doReadBytes(NioSocketChannel.java:350)
at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:151)
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:722)
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:658)
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:584)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:496)
at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:986)
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
at java.lang.Thread.run(Thread.java:748)

[2022-04-19 13:02:15,198] – [milo-shared-thread-pool-61] – [WARN] – o.e.milo.opcua.sdk.client.SessionFsm : [5] Keep Alive failureCount=2 exceeds failuresAllowed=1

[2022-04-19 13:02:16,213] – [epmtuscpltadintv2.azure-devices.net-d963bb0b-d685-4785-8b3e-df3487172799-36503549-Cxncdf6e2f2-45d8-45ee-9c3f-46b68d175e1e-azure-iot-sdk-IotHubReceiveTask] – [ERROR] – : Browsing nodeId=NodeId{ns=4, id=qihg:kjhhumidity.cntdeadband} failed: UaException: status=Bad_ConnectionRejected, message=io.netty.channel.AbstractChannel$AnnotatedConnectException: Connection refused: Machine1/12.9.5.60:23000
java.util.concurrent.ExecutionException: UaException: status=Bad_ConnectionRejected, message=io.netty.channel.AbstractChannel$AnnotatedConnectException: Connection refused: Machine1/12.9.5.60:23000

Can anyone please provide any reason why this is happening and how to handle this exception.

Thanks,
Bibhudatta

[kevinherron]

I think you might be overwhelming the server you are connected to with your (recursive?) browse.

[ERROR] – o.e.m.o.s.c.t.u.UascClientMessageHandler : [remote=EmPilot1APM/10.8.4.59:56000] Exception caught: Connection reset by peer

The server closed the connection.

[WARN] – o.e.milo.opcua.sdk.client.SessionFsm : [5] Keep Alive failureCount=2 exceeds failuresAllowed=1

The server isn't responding to the "keep alive" reads targeting the server State. Possibly because it's overwhelmed?

[ERROR] – : Browsing nodeId=NodeId{ns=4, id=qihg:kjhhumidity.cntdeadband} failed: UaException: status=Bad_ConnectionRejected, message=io.netty.channel.AbstractChannel$AnnotatedConnectException: Connection refused: Machine1/12.9.5.60:23000
java.util.concurrent.ExecutionException: UaException: status=Bad_ConnectionRejected, message=io.netty.channel.AbstractChannel$AnnotatedConnectException: Connection refused: Machine1/12.9.5.60:23000

Looks like at this point the client is reconnecting and getting a connection refused error. Maybe the server is offline now? Not sure.

[bibhudatta-sahu]

Thank you Kevin!! Yes, we are following recursive method call to browse address space. It looks like the server is not responding during browse call. Can you please suggest, is there anything in client side we need to do while performing browse operation so that we can avoid this issue.

[kevinherron]

You might need to pause periodically or something. A blind recursive browse is a bit of a dangerous move - you don't know how big the server address space is or how long it will take, and there is rarely a case you actually need to know the full address space contents instead of e.g. allowing a user to browse it dynamically when needed.