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opc-uamilo

Issue connecting to remote OPCUA server

I am new to opcua. I have tried the example from https://dentrassi.de/2017/09/14/creating-opc-ua-solutions-eclipse-milo/ and managed to connect to a local OPCUA server but not a remote one.

Error shown below:

Exception in thread "main" java.util.concurrent.ExecutionException: java.nio.channels.UnresolvedAddressException
    at java.util.concurrent.CompletableFuture.reportGet(Unknown Source)
    at java.util.concurrent.CompletableFuture.get(Unknown Source)
    at com.programcreek.helloworld.test2.main(test2.java:101)
Caused by: java.nio.channels.UnresolvedAddressException
    at sun.nio.ch.Net.checkAddress(Unknown Source)
    at sun.nio.ch.SocketChannelImpl.connect(Unknown Source)
    at io.netty.channel.socket.nio.NioSocketChannel.doConnect(NioSocketChannel.java:209)
    at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.connect(AbstractNioChannel.java:207)
    at io.netty.channel.DefaultChannelPipeline$HeadContext.connect(DefaultChannelPipeline.java:1279)
    at io.netty.channel.AbstractChannelHandlerContext.invokeConnect(AbstractChannelHandlerContext.java:453)
    at io.netty.channel.AbstractChannelHandlerContext.connect(AbstractChannelHandlerContext.java:439)
    at io.netty.channel.ChannelDuplexHandler.connect(ChannelDuplexHandler.java:50)
    at io.netty.channel.AbstractChannelHandlerContext.invokeConnect(AbstractChannelHandlerContext.java:453)
    at io.netty.channel.AbstractChannelHandlerContext.connect(AbstractChannelHandlerContext.java:439)
    at io.netty.channel.AbstractChannelHandlerContext.connect(AbstractChannelHandlerContext.java:421)
    at io.netty.channel.DefaultChannelPipeline.connect(DefaultChannelPipeline.java:1024)
    at io.netty.channel.AbstractChannel.connect(AbstractChannel.java:203)
    at io.netty.bootstrap.Bootstrap$2.run(Bootstrap.java:167)
    at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:358)
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:374)
    at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:112)
    at java.lang.Thread.run(Unknown Source)
Solution

  • The UnresolvedAddressException means either the URL you’re using to call GetEndpoints or the URL inside the endpoint you’ve chosen to connect to has a host name that your machine can’t resolve.

    If the URL in the endpoints doesn’t match the one you used for the original call and correctly configuring the server in question is not an option you can use the EndpointUtil to replace the hostname in an EndpointDescription with another one, in this case the original hostname you used for discovery.