使用 Eclipse Milo 连接到 OPC-UA 服务器，在 BadHostUnknown 上失败

Question

我是 OPC-UA 和 Eclipse Milo 的新手，我正在尝试构建一个可以连接到我们刚刚获得的机器的 OPC-UA 服务器的客户端。

我已经能够使用这个 python 教程系列在我的笔记本电脑上设置一个简单的 OPC-UA 服务器：https://www.youtube.com/watch?v=NbKeBfK3pfk。此外，我已经能够使用 Eclipse Milo 示例运行订阅示例成功地从该服务器读取一些值。

但是，我一直无法连接到我们刚收到的机器的 OPC-UA 服务器。我已使用 UaExpert 客户端成功连接到此服务器，但我们想使用 Eclipse Milo 构建我们自己的客户端。我可以看到在使用 UaExpert 连接到服务器时出现了一些警告，这些警告似乎提供了有关该问题的线索，但我在服务器客户端 communications/OPC-UA 方面的经验太少，希望得到一些帮助。我将解释当我使用 UaExpert 客户端时会发生什么，因为我一直在使用它来尝试诊断正在发生的事情。

我注意到，当我第一次启动 UaExpert 时，出现以下可能相关的错误：

Discovery FindServersOnNetwork on opc.tcp://localhost:4840 failed (BadTimeout), falling back to FindServers
Discovery FindServers on opc.tpc://localhost:4840 failed (BadTimeout)
Discovery GetEndpoints on opc.tcp://localhost:4840 failed

我是网络新手，所以不确定这到底是什么意思。

我将概述我在尝试让 Eclipse Milo 的 SubscriptionExample 与这台机器的服务器一起工作时所遵循的过程。首先，我将 getEndpointUrl() 方法更改为我们正在使用的设备的 IP 地址：return“opc.tcp://11.23.1.1:4840”。我可以从我的笔记本电脑上使用 ping 11.23.1.1 成功地 ping 设备。当我尝试使用此地址运行 SubscriptionExample 时，出现以下错误：

[NonceUtilSecureRandom] INFO  o.e.m.o.stack.core.util.NonceUtil - SecureRandom seeded in 0ms.
18:36:23.879 [main] ERROR o.e.m.e.client.ClientExampleRunner - Error running client example: java.net.UnknownHostException: br-automation
java.util.concurrent.ExecutionException: java.net.UnknownHostException: br-automation
    at java.util.concurrent.CompletableFuture.reportGet(Unknown Source)
    at java.util.concurrent.CompletableFuture.get(Unknown Source)
    at org.eclipse.milo.examples.client.SubscriptionExample.run(SubscriptionExample.java:50)
    at org.eclipse.milo.examples.client.ClientExampleRunner.run(ClientExampleRunner.java:120)
    at org.eclipse.milo.examples.client.SubscriptionExample.main(SubscriptionExample.java:42)
Caused by: java.net.UnknownHostException: br-automation
    at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
    at java.net.InetAddress.lookupAllHostAddr(Unknown Source)
    at java.net.InetAddress.getAddressesFromNameService(Unknown Source)
    at java.net.InetAddress.getAllByName0(Unknown Source)
    at java.net.InetAddress.getAllByName(Unknown Source)
    at java.net.InetAddress.getAllByName(Unknown Source)
    at java.net.InetAddress.getByName(Unknown Source)
    at io.netty.util.internal.SocketUtils.run(SocketUtils.java:148)
    at io.netty.util.internal.SocketUtils.run(SocketUtils.java:145)
    at java.security.AccessController.doPrivileged(Native Method)
    at io.netty.util.internal.SocketUtils.addressByName(SocketUtils.java:145)
    at io.netty.resolver.DefaultNameResolver.doResolve(DefaultNameResolver.java:43)
    at io.netty.resolver.SimpleNameResolver.resolve(SimpleNameResolver.java:63)
    at io.netty.resolver.SimpleNameResolver.resolve(SimpleNameResolver.java:55)
    at io.netty.resolver.InetSocketAddressResolver.doResolve(InetSocketAddressResolver.java:57)
    at io.netty.resolver.InetSocketAddressResolver.doResolve(InetSocketAddressResolver.java:32)
    at io.netty.resolver.AbstractAddressResolver.resolve(AbstractAddressResolver.java:108)
    at io.netty.bootstrap.Bootstrap.doResolveAndConnect0(Bootstrap.java:200)
    at io.netty.bootstrap.Bootstrap.access[=11=]0(Bootstrap.java:46)
    at io.netty.bootstrap.Bootstrap.operationComplete(Bootstrap.java:180)
    at io.netty.bootstrap.Bootstrap.operationComplete(Bootstrap.java:166)
    at io.netty.util.concurrent.DefaultPromise.notifyListener0(DefaultPromise.java:577)
    at io.netty.util.concurrent.DefaultPromise.notifyListenersNow(DefaultPromise.java:551)
    at io.netty.util.concurrent.DefaultPromise.notifyListeners(DefaultPromise.java:490)
    at io.netty.util.concurrent.DefaultPromise.setValue0(DefaultPromise.java:615)
    at io.netty.util.concurrent.DefaultPromise.setSuccess0(DefaultPromise.java:604)
    at io.netty.util.concurrent.DefaultPromise.trySuccess(DefaultPromise.java:104)
    at io.netty.channel.DefaultChannelPromise.trySuccess(DefaultChannelPromise.java:84)
    at io.netty.channel.AbstractChannel$AbstractUnsafe.safeSetSuccess(AbstractChannel.java:984)
    at io.netty.channel.AbstractChannel$AbstractUnsafe.register0(AbstractChannel.java:504)
    at io.netty.channel.AbstractChannel$AbstractUnsafe.access0(AbstractChannel.java:417)
    at io.netty.channel.AbstractChannel$AbstractUnsafe.run(AbstractChannel.java:474)
    at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
    at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:500)
    at io.netty.util.concurrent.SingleThreadEventExecutor.run(SingleThreadEventExecutor.java:989)
    at io.netty.util.internal.ThreadExecutorMap.run(ThreadExecutorMap.java:74)
    at java.lang.Thread.run(Unknown Source)
18:36:23.881 [ForkJoinPool.commonPool-worker-1] ERROR o.e.m.e.client.ClientExampleRunner - Error running example: java.net.UnknownHostException: br-automation
java.util.concurrent.ExecutionException: java.net.UnknownHostException: br-automation
    at java.util.concurrent.CompletableFuture.reportGet(Unknown Source)
    at java.util.concurrent.CompletableFuture.get(Unknown Source)
    at org.eclipse.milo.examples.client.SubscriptionExample.run(SubscriptionExample.java:50)
    at org.eclipse.milo.examples.client.ClientExampleRunner.run(ClientExampleRunner.java:120)
    at org.eclipse.milo.examples.client.SubscriptionExample.main(SubscriptionExample.java:42)
Caused by: java.net.UnknownHostException: br-automation
    at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
    at java.net.InetAddress.lookupAllHostAddr(Unknown Source)
    at java.net.InetAddress.getAddressesFromNameService(Unknown Source)
    at java.net.InetAddress.getAllByName0(Unknown Source)
    at java.net.InetAddress.getAllByName(Unknown Source)
    at java.net.InetAddress.getAllByName(Unknown Source)
    at java.net.InetAddress.getByName(Unknown Source)
    at io.netty.util.internal.SocketUtils.run(SocketUtils.java:148)
    at io.netty.util.internal.SocketUtils.run(SocketUtils.java:145)
    at java.security.AccessController.doPrivileged(Native Method)
    at io.netty.util.internal.SocketUtils.addressByName(SocketUtils.java:145)
    at io.netty.resolver.DefaultNameResolver.doResolve(DefaultNameResolver.java:43)
    at io.netty.resolver.SimpleNameResolver.resolve(SimpleNameResolver.java:63)
    at io.netty.resolver.SimpleNameResolver.resolve(SimpleNameResolver.java:55)
    at io.netty.resolver.InetSocketAddressResolver.doResolve(InetSocketAddressResolver.java:57)
    at io.netty.resolver.InetSocketAddressResolver.doResolve(InetSocketAddressResolver.java:32)
    at io.netty.resolver.AbstractAddressResolver.resolve(AbstractAddressResolver.java:108)
    at io.netty.bootstrap.Bootstrap.doResolveAndConnect0(Bootstrap.java:200)
    at io.netty.bootstrap.Bootstrap.access[=11=]0(Bootstrap.java:46)
    at io.netty.bootstrap.Bootstrap.operationComplete(Bootstrap.java:180)
    at io.netty.bootstrap.Bootstrap.operationComplete(Bootstrap.java:166)
    at io.netty.util.concurrent.DefaultPromise.notifyListener0(DefaultPromise.java:577)
    at io.netty.util.concurrent.DefaultPromise.notifyListenersNow(DefaultPromise.java:551)
    at io.netty.util.concurrent.DefaultPromise.notifyListeners(DefaultPromise.java:490)
    at io.netty.util.concurrent.DefaultPromise.setValue0(DefaultPromise.java:615)
    at io.netty.util.concurrent.DefaultPromise.setSuccess0(DefaultPromise.java:604)
    at io.netty.util.concurrent.DefaultPromise.trySuccess(DefaultPromise.java:104)
    at io.netty.channel.DefaultChannelPromise.trySuccess(DefaultChannelPromise.java:84)
    at io.netty.channel.AbstractChannel$AbstractUnsafe.safeSetSuccess(AbstractChannel.java:984)
    at io.netty.channel.AbstractChannel$AbstractUnsafe.register0(AbstractChannel.java:504)
    at io.netty.channel.AbstractChannel$AbstractUnsafe.access0(AbstractChannel.java:417)
    at io.netty.channel.AbstractChannel$AbstractUnsafe.run(AbstractChannel.java:474)
    at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
    at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:500)
    at io.netty.util.concurrent.SingleThreadEventExecutor.run(SingleThreadEventExecutor.java:989)
    at io.netty.util.internal.ThreadExecutorMap.run(ThreadExecutorMap.java:74)
    at java.lang.Thread.run(Unknown Source)

使用UaExpert时，“opc.tcp://11.23.1.1:4840”是我在使用Custom Discovery时添加新服务器时输入的服务器地址。当我输入这个时，一个设备显示为该服务器的下拉列表，称为 B&R 嵌入式 OPC-UA 服务器，因为 OPC-UA 服务器托管在机器中的 B&R 设备上。当我 select 要连接到此设备时，我收到以下消息：

用于调用 GetEndpoints (br-automation) 的发现 URL 的主机名已替换为用于调用 FindServers (11.23.1.1) 的主机名。您是否也想用这个主机名替换 EndpointURL 的主机名？

我必须接受此消息才能找到服务器，但我不清楚到底发生了什么。我假设用于查找服务器的端点和用于其他用途的端点有所不同？我发现网上的资源很难理解。在 UaExpert 日志中，连续三行日志报告“Adding Url: ocp.tcp://br-automation:4840”。它还会报告端点：“ocp.tcp://br-automation:4840”、应用程序 URI 和安全策略 (none)。如果我尝试将客户端的 getEndpointUrl 方法中的地址更改为 ocp.tcp://br-automation:4840 那么我会收到以下错误：

[main] INFO  o.e.m.opcua.sdk.client.OpcUaClient - Eclipse Milo OPC UA Client SDK version: 0.4.3-SNAPSHOT
18:37:46.035 [main] ERROR o.e.m.e.client.ClientExampleRunner - Error getting client: java.util.concurrent.ExecutionException: java.net.UnknownHostException: br-automation
org.eclipse.milo.opcua.stack.core.UaException: java.util.concurrent.ExecutionException: java.net.UnknownHostException: br-automation
    at org.eclipse.milo.opcua.sdk.client.OpcUaClient.lambda$create(OpcUaClient.java:204)
    at java.util.Optional.orElseGet(Unknown Source)
    at org.eclipse.milo.opcua.sdk.client.OpcUaClient.create(OpcUaClient.java:204)
    at org.eclipse.milo.opcua.sdk.client.OpcUaClient.create(OpcUaClient.java:201)
    at org.eclipse.milo.examples.client.ClientExampleRunner.createClient(ClientExampleRunner.java:73)
    at org.eclipse.milo.examples.client.ClientExampleRunner.run(ClientExampleRunner.java:94)
    at org.eclipse.milo.examples.client.SubscriptionExample.main(SubscriptionExample.java:42)
Caused by: java.util.concurrent.ExecutionException: java.net.UnknownHostException: br-automation
    at java.util.concurrent.CompletableFuture.reportGet(Unknown Source)
    at java.util.concurrent.CompletableFuture.get(Unknown Source)
    at org.eclipse.milo.opcua.sdk.client.OpcUaClient.create(OpcUaClient.java:180)
    ... 4 common frames omitted
Caused by: java.net.UnknownHostException: br-automation
    at java.net.InetAddress.getAllByName0(Unknown Source)
    at java.net.InetAddress.getAllByName(Unknown Source)
    at java.net.InetAddress.getAllByName(Unknown Source)
    at java.net.InetAddress.getByName(Unknown Source)
    at io.netty.util.internal.SocketUtils.run(SocketUtils.java:148)
    at io.netty.util.internal.SocketUtils.run(SocketUtils.java:145)
    at java.security.AccessController.doPrivileged(Native Method)
    at io.netty.util.internal.SocketUtils.addressByName(SocketUtils.java:145)
    at io.netty.resolver.DefaultNameResolver.doResolve(DefaultNameResolver.java:43)
    at io.netty.resolver.SimpleNameResolver.resolve(SimpleNameResolver.java:63)
    at io.netty.resolver.SimpleNameResolver.resolve(SimpleNameResolver.java:55)
    at io.netty.resolver.InetSocketAddressResolver.doResolve(InetSocketAddressResolver.java:57)
    at io.netty.resolver.InetSocketAddressResolver.doResolve(InetSocketAddressResolver.java:32)
    at io.netty.resolver.AbstractAddressResolver.resolve(AbstractAddressResolver.java:108)
    at io.netty.bootstrap.Bootstrap.doResolveAndConnect0(Bootstrap.java:200)
    at io.netty.bootstrap.Bootstrap.access[=12=]0(Bootstrap.java:46)
    at io.netty.bootstrap.Bootstrap.operationComplete(Bootstrap.java:180)
    at io.netty.bootstrap.Bootstrap.operationComplete(Bootstrap.java:166)
    at io.netty.util.concurrent.DefaultPromise.notifyListener0(DefaultPromise.java:577)
    at io.netty.util.concurrent.DefaultPromise.notifyListenersNow(DefaultPromise.java:551)
    at io.netty.util.concurrent.DefaultPromise.notifyListeners(DefaultPromise.java:490)
    at io.netty.util.concurrent.DefaultPromise.setValue0(DefaultPromise.java:615)
    at io.netty.util.concurrent.DefaultPromise.setSuccess0(DefaultPromise.java:604)
    at io.netty.util.concurrent.DefaultPromise.trySuccess(DefaultPromise.java:104)
    at io.netty.channel.DefaultChannelPromise.trySuccess(DefaultChannelPromise.java:84)
    at io.netty.channel.AbstractChannel$AbstractUnsafe.safeSetSuccess(AbstractChannel.java:984)
    at io.netty.channel.AbstractChannel$AbstractUnsafe.register0(AbstractChannel.java:504)
    at io.netty.channel.AbstractChannel$AbstractUnsafe.access0(AbstractChannel.java:417)
    at io.netty.channel.AbstractChannel$AbstractUnsafe.run(AbstractChannel.java:474)
    at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
    at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:500)
    at io.netty.util.concurrent.SingleThreadEventExecutor.run(SingleThreadEventExecutor.java:989)
    at io.netty.util.internal.ThreadExecutorMap.run(ThreadExecutorMap.java:74)
    at java.lang.Thread.run(Unknown Source)

我不知道这些信息是否足以诊断问题，但如果能帮助我使 Eclipse Milo 服务器执行相同的过程并连接到机器的服务器，我将不胜感激。

Answer 1

问题是您作为运行客户端的计算机无法将主机名“br-automation”解析为 IP 地址。

如果您无法将服务器配置为 return IP 地址，解决方案是手动重建您从 GetEndpoints 服务调用获得的 EndpointDescriptions，以便它们具有端点 URL 包含 IP 地址而不是主机名。这就是 UaExpert 在警告您更换主机名时在幕后所做的事情。

在传递给 OpcUaClientConfig 之前，您可以使用 EndpointUtil#updateUrl 构建一个新的 EndpointDescription。

Answer 2

您可以通过服务器日志找到正确的Hostname/URL连接服务器。服务器日志启动后，它会打印所有有效的 UR

Answer 3

我们能够通过使用主机 IP 和端口手动覆盖从 OPC UA 服务器返回的主机名来解决我们的问题。（见 try 语句的第二行）

public class OpcUaConnection {
    OpcUaClient client;
    final int NAMESPACEINDEX = 6;

    private static final AtomicLong clientHandles = new AtomicLong(1L);

    public OpcUaConnection() {
        try {
            List<EndpointDescription> endpoints = DiscoveryClient.getEndpoints("opc.tcp://192.168.0.122:4840").get();
            EndpointDescription configPoint = EndpointUtil.updateUrl(endpoints.get(0), "192.168.0.122", 4840);

            OpcUaClientConfigBuilder cfg = new OpcUaClientConfigBuilder();
            cfg.setEndpoint(configPoint);

            this.client = OpcUaClient.create(cfg.build());
            client.connect().get();

        } catch (Throwable ex) {
            ex.printStackTrace();
        }
    }

希望这对其他人有帮助！

使用 Eclipse Milo 连接到 OPC-UA 服务器，在 BadHostUnknown 上失败

Connecting to an OPC-UA server using Eclipse Milo, fails on BadHostUnknown

eclipse

opc-ua

milo