Issue with DataTypeTreeBuilder.build(client) causing ClosedChannelException on HTTPS endpoint (Milo SDK 0.6.15)

[ravi-kothapally]

Hi, I'm using Milo SDK version 0.6.15, and I'm facing an issue when trying to build the DataTypeTree. Below is a minimal reproducible snippet:

final String s = "ns=5;s=Double";
DataValue dataValue = client.readValue(
        0.0,
        TimestampsToReturn.Neither,
        NodeId.parse(s)
).get();

DataTypeTree dataTypeTree = DataTypeTreeBuilder.build(client); // <-- Causes issue

final StatusCode statusCode = client.writeValue(
        NodeId.parse(s),
        DataValue.valueOnly(dataValue.getValue())
).get();

The moment I add this line:

DataTypeTree dataTypeTree = DataTypeTreeBuilder.build(client);

My write operation fails with the following exception only when using an HTTPS endpoint (no security policy and with username/password) with Prosys Simulation Server:

21:41:46.705 [main] ERROR o.e.m.e.client.ClientExampleRunner - Error running client example: java.nio.channels.ClosedChannelException
java.util.concurrent.ExecutionException: java.nio.channels.ClosedChannelException
	at java.base/java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:395)
	at java.base/java.util.concurrent.CompletableFuture.get(CompletableFuture.java:2005)
	at org.eclipse.milo.examples.client.UnifiedAutomationReadCustomDataTypeExample.extractedProsysSimpleTyep(UnifiedAutomationReadCustomDataTypeExample.java:250)
	at org.eclipse.milo.examples.client.UnifiedAutomationReadCustomDataTypeExample.run(UnifiedAutomationReadCustomDataTypeExample.java:69)
	at org.eclipse.milo.examples.client.ClientExampleRunner.run(ClientExampleRunner.java:155)
	at org.eclipse.milo.examples.client.UnifiedAutomationReadCustomDataTypeExample.main(UnifiedAutomationReadCustomDataTypeExample.java:50)
Caused by: java.nio.channels.ClosedChannelException: null
	at io.netty.handler.ssl.SslHandler.channelInactive(SslHandler.java:1154)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:303)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:281)
	at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:274)
	at io.netty.channel.DefaultChannelPipeline$HeadContext.channelInactive(DefaultChannelPipeline.java:1402)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:301)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:281)
	at io.netty.channel.DefaultChannelPipeline.fireChannelInactive(DefaultChannelPipeline.java:900)
	at io.netty.channel.AbstractChannel$AbstractUnsafe$7.run(AbstractChannel.java:811)
	at io.netty.util.concurrent.AbstractEventExecutor.runTask(AbstractEventExecutor.java:173)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:166)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:469)
	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:566)
	at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:994)
	at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
	at java.base/java.lang.Thread.run(Thread.java:829)
	Suppressed: io.netty.handler.ssl.StacklessSSLHandshakeException: Connection closed while SSL/TLS handshake was in progress
		at io.netty.handler.ssl.SslHandler.channelInactive(Unknown Source)

Observations:

• Works fine with the Milo Local Sample Server
• Fails with Prosys Simulation Server on https:
• The connection and read succeed, only the write fails after the DataTypeTreeBuilder.build(...) line.
• No exception is thrown at the build line itself — only later during write.

Why is the ClosedChannelException triggered when I use DataTypeTreeBuilder.build(client)?

• Is this a known issue with Prosys or Milo over HTTPS ?
• Is there a recommended workaround or safe way to build the DataTypeTree without affecting the channel?

Any help or guidance is appreciated!

[kevinherron]

The HTTPS transport is untested/unsupported. I'm not even sure it's fully functional. It's also HTTPS + Binary encoding, and AFAIK the Prosys Server is HTTP + XML Encoding.

[kevinherron]

and AFAIK the Prosys Server is HTTP + XML Encoding.

Doesn't seem to be true any more, but many years ago when I did what little work on the HTTPS transport exists I was unable to find a server that supported the HTTPS + Binary combination.

[ravi-kothapally]

Yeah it has HTTPS + Binary now