### Build the project with Maven

Source: https://github.com/eclipse-milo/milo/blob/main/README.md

Execute a clean install of the project using the toolchain managed by mise.

```shell
mise exec -- mvn clean install
```

--------------------------------

### Install project dependencies with mise

Source: https://github.com/eclipse-milo/milo/blob/main/README.md

Use this command to install the project's pinned Java and Maven toolchain versions.

```shell
mise install
```

--------------------------------

### Browse References and Nodes with UaNode API

Source: https://github.com/eclipse-milo/milo/wiki/Client

Use UaNode#browse to get ReferenceDescriptions or UaNode#browseNodes to get target UaNode instances. This example demonstrates browsing for HasProperty references.

```java
BrowseOptions browseOptions = BrowseOptions.builder()
    .setReferenceType(Identifiers.HasProperty)
    .build();

// Browse for HasProperty references
List<ReferenceDescription> references = node.browse(browseOptions);

// Browse for HasProperty references and get the UaNodes they target
List<? extends UaNode> nodes = node.browseNodes(browseOptions);
```

--------------------------------

### Browse Nodes with Custom Options

Source: https://github.com/eclipse-milo/milo/wiki/Client

Use AddressSpace#browseNodes with custom BrowseOptions to filter the types of references to retrieve. This example specifically retrieves nodes referenced by HasProperty.

```java
AddressSpace addressSpace = client.getAddressSpace();

UaNode serverNode = addressSpace.getNode(Identifiers.Server);

BrowseOptions browseOptions = addressSpace.getBrowseOptions().copy(
  b ->
    b.setReferenceType(BuiltinReferenceType.HasProperty)
);

// just UaNodes referenced by HasProperty references
List<? extends UaNode> nodes = addressSpace.browseNodes(serverNode, browseOptions);
```

--------------------------------

### Get Endpoints with DiscoveryClient

Source: https://github.com/eclipse-milo/milo/wiki/Client

Retrieves a list of EndpointDescriptions from a remote OPC UA server using the DiscoveryClient. This is a prerequisite for establishing a connection.

```java
List<EndpointDescription> endpoints = 
    DiscoveryClient.getEndpoints(endpointUrl).get();
```

--------------------------------

### Write Node Value with UaNode API

Source: https://github.com/eclipse-milo/milo/wiki/Client

Write node values using UaNode#writeValue() or UaNode#writeAttribute(). This example demonstrates writing a new value to the Value attribute.

```java
UaVariableNode testNode = (UaVariableNode) addressSpace.getNode(
    new NodeId(2, "TestInt32")
);

// Write the Value attribute; throws UaException if the write fails
testNode.writeValue(new Variant(42));

// Most servers don't allow quality or timestamps to be written,
// hence the use of DataValue.valueOnly(), but this method could
// be used to write to a server that did support it if necessary
StatusCode statusCode = testNode.writeAttribute(
  AttributeId.Value, 
  DataValue.valueOnly(new Variant(42))
);
```

--------------------------------

### Access Local UaNode Attributes

Source: https://github.com/eclipse-milo/milo/wiki/Client

Access local copies of UaNode attributes using get<attribute>() methods. These values are available without a server round-trip.

```java
Use the `get<attribute>()` methods to access these values.
```

--------------------------------

### Read Node Attributes with UaNode API

Source: https://github.com/eclipse-milo/milo/wiki/Client

Read node attributes directly using UaNode methods like readValue() or readAttribute(). This example shows reading the Value and BrowseName attributes.

```java
UaVariableNode testNode = (UaVariableNode) addressSpace.getNode(
    new NodeId(2, "TestInt32")
);

// Read the Value attribute
DataValue value = testNode.readValue();

// Read the BrowseName attribute
QualifiedName browseName = testNode.readBrowseName();

// Read the Description attribute, with timestamps and quality intact
DataValue descriptionValue = testNode.readAttribute(AttributeId.Description);
```

--------------------------------

### Execute build and verification commands

Source: https://github.com/eclipse-milo/milo/blob/main/CONTRIBUTING.md

Commands to run the test suite and apply code formatting using mise and Maven.

```bash
mise exec -- mvn clean verify
```

```bash
mise exec -- mvn spotless:apply
```

--------------------------------

### Configure Wireshark Key Logging for Server

Source: https://github.com/eclipse-milo/milo/blob/main/docs/features/wireshark-key-log.md

Use WiresharkKeyLogWriter to log server-side security keys to a file for later decryption in Wireshark.

```java
Path keyLogFile = Path.of("/tmp/opcua_server_keys.log");
var writer = new WiresharkKeyLogWriter(keyLogFile);

OpcUaServerConfig config = OpcUaServerConfig.builder()
    .setSecurityKeysListener(writer)
    // ... other config ...
    .build();

OpcUaServer server = new OpcUaServer(config, transportFactory);
server.startup().get();

// ... server runs ...

writer.close();
```

--------------------------------

### Run Wireshark Key Log Tests

Source: https://github.com/eclipse-milo/milo/blob/main/docs/features/wireshark-key-log.md

Executes the specific test classes for SecurityKeyset and WiresharkKeyLogWriter using Maven.

```bash
mise exec -- mvn -q verify -pl opc-ua-stack/stack-core \
    -Dtest="SecurityKeysetTest,WiresharkKeyLogWriterTest"
```

--------------------------------

### Configure Wireshark Key Logging for Client

Source: https://github.com/eclipse-milo/milo/blob/main/docs/features/wireshark-key-log.md

Use WiresharkKeyLogWriter to log client-side security keys to a file for later decryption in Wireshark.

```java
Path keyLogFile = Path.of("/tmp/opcua_client_keys.log");
var writer = new WiresharkKeyLogWriter(keyLogFile);

OpcUaClientConfig config = OpcUaClientConfig.builder()
    .setSecurityKeysListener(writer)
    // ... other config ...
    .build();

OpcUaClient client = OpcUaClient.create(config);
client.connect();

// ... use the client ...

writer.close(); // flush and close when done
```

--------------------------------

### Calling Methods

Source: https://github.com/eclipse-milo/milo/wiki/Client

Demonstrates three ways to call methods on an OPC UA server: using UaObjectNode#callMethod, finding a UaMethod and invoking call, and using the lower-level OpcUaClient#call API.

```APIDOC
## Calling Methods

Methods can be called using either the high or low level APIs:

1. Using `UaObjectNode#callMethod`:
   ```java
    UaObjectNode serverNode = addressSpace.getObjectNode(Identifiers.Server);

    Variant[] outputs = serverNode.callMethod(
        "GetMonitoredItems",
        new Variant[]{
            new Variant(subscription.getSubscription().getSubscriptionId())
        }
    );
    ```

2. Finding a `UaMethod` and invoking `UaMethod#call`:
    ```java
    UaObjectNode serverNode = addressSpace.getObjectNode(Identifiers.Server);

    UaMethod getMonitoredItems = serverNode.getMethod("GetMonitoredItems");

    Variant[] outputs = getMonitoredItems.call(
        new Variant[]{
            new Variant(subscription.getSubscription().getSubscriptionId())
        }
    );
    ```

    The `UaMethod` object also has a copy of the input and output defined by the method:
    ```java
    Argument[] inputArguments = getMonitoredItems.getInputArguments();
    Argument[] outputArguments = getMonitoredItems.getOutputArguments();
    ```
    When a method does not define input or output arguments the corresponding `Argument[]` will be empty.

3. `OpcUaClient#call`, a lower level API That takes parameters corresponding directly to those defined by the Call service in the OPC UA spec:

    ```java
    NodeId objectId = NodeId.parse("ns=2;s=HelloWorld");
    NodeId methodId = NodeId.parse("ns=2;s=HelloWorld/sqrt(x)");

    CallMethodRequest request = new CallMethodRequest(
        objectId,
        methodId,
        new Variant[]{new Variant(input)}
    );

    return client.call(request).thenCompose(result -> {
        StatusCode statusCode = result.getStatusCode();

        if (statusCode.isGood()) {
            Double value = (Double) l(result.getOutputArguments()).get(0).getValue();
            return CompletableFuture.completedFuture(value);
        } else {
            StatusCode[] inputArgumentResults = result.getInputArgumentResults();
            for (int i = 0; i < inputArgumentResults.length; i++) {
                logger.error("inputArgumentResults[{}]={}", i, inputArgumentResults[i]);
            }
            
            CompletableFuture<Double> f = new CompletableFuture<>();
            f.completeExceptionally(new UaException(statusCode));
            return f;
        }
    });
    ```

    See `MethodExample.java` in the `client-examples` Maven module for the full source code.
```

--------------------------------

### Create ManagedSubscription

Source: https://github.com/eclipse-milo/milo/wiki/Client

Instantiate a `ManagedSubscription` using `ManagedSubscription.create(client)` for managing subscriptions and monitored items at a higher level.

```java
ManagedSubscription subscription = ManagedSubscription.create(client);

```

```java
ManagedSubscription subscription = ManagedSubscription.create(client, 250.0);

```

--------------------------------

### Browse Nodes with Default Options

Source: https://github.com/eclipse-milo/milo/wiki/Client

Use AddressSpace#browseNodes with default BrowseOptions to retrieve nodes referenced by a given node.

```java
AddressSpace addressSpace = client.getAddressSpace();

UaNode serverNode = addressSpace.getNode(Identifiers.Server);

List<? extends UaNode> nodes = addressSpace.browseNodes(serverNode);
```

--------------------------------

### Low-Level Browse Service

Source: https://github.com/eclipse-milo/milo/wiki/Client

Use OpcUaClient#browse for direct interaction with the Browse service as defined in the OPC UA spec. This method requires manual handling of continuation points for full results.

```java
// Browse for forward hierarchal references from the Objects folder
// that lead to other Object and Variable nodes.
BrowseDescription browse = new BrowseDescription(
    Identifiers.ObjectsFolder,
    BrowseDirection.Forward,
    Identifiers.References,
    true,
    uint(NodeClass.Object.getValue() | NodeClass.Variable.getValue()),
    uint(BrowseResultMask.All.getValue())
);

BrowseResult browseResult = client.browse(browse).get();
```

--------------------------------

### Create Subscription with OpcUaSubscriptionManager

Source: https://github.com/eclipse-milo/milo/wiki/Client

Use OpcUaSubscriptionManager to create a UaSubscription object, which is the entry point for creating MonitoredItems.

```java
`OpcUaSubscriptionManager#createSubscription` is used to create a `UaSubscription` object. MonitoredItems can then be created using `UaSubscription#createMonitoredItems`. The parameters and data structures used in these API calls correspond directly to those defined by the Subscription and MonitoredItems services in the OPC UA spec.
```

--------------------------------

### Apply license header to source files

Source: https://github.com/eclipse-milo/milo/blob/main/CONTRIBUTING.md

Required license header for all new source files in the project.

```java
/*
 * Copyright (c) 2025 the Eclipse Milo Authors
 *
 * This program and the accompanying materials are made
 * available under the terms of the Eclipse Public License 2.0
 * which is available at https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 */
```

--------------------------------

### Low-Level Write Service

Source: https://github.com/eclipse-milo/milo/wiki/Client

Use OpcUaClient#write for direct interaction with the Write service. This requires constructing a list of WriteValue objects specifying the nodes, attributes, and data to write.

```java
List<WriteValue> writeValues = new ArrayList<>();

writeValues.add(
    new WriteValue(
        new NodeId(2, "TestInt32"),
        AttributeId.Value.uid(),
        null, // indexRange
        DataValue.valueOnly(new Variant(42))
    )
);

WriteResponse writeResponse = client.write(writeValues).get();
```

--------------------------------

### Configure Sonatype snapshot repository

Source: https://github.com/eclipse-milo/milo/blob/main/README.md

Add this repository configuration to your pom.xml to access SNAPSHOT releases.

```xml
<repository>
    <id>oss-sonatype</id>
    <name>oss-sonatype</name>
    <url>https://oss.sonatype.org/content/repositories/snapshots/</url>
</repository>
```

--------------------------------

### Add OPC UA Server SDK dependency

Source: https://github.com/eclipse-milo/milo/blob/main/README.md

Include this dependency in your Maven pom.xml to use the Milo server SDK.

```xml
<dependency>
    <groupId>org.eclipse.milo</groupId>
    <artifactId>milo-sdk-server</artifactId>
    <version>1.1.6</version>
</dependency>
```

--------------------------------

### Add OPC UA Client SDK dependency

Source: https://github.com/eclipse-milo/milo/blob/main/README.md

Include this dependency in your Maven pom.xml to use the Milo client SDK.

```xml
<dependency>
    <groupId>org.eclipse.milo</groupId>
    <artifactId>milo-sdk-client</artifactId>
    <version>1.1.6</version>
</dependency>
```

--------------------------------

### Implement Custom SecurityKeysListener

Source: https://github.com/eclipse-milo/milo/blob/main/docs/features/wireshark-key-log.md

Implement the SecurityKeysListener interface to handle derived key material. Implementations must be thread-safe.

```java
SecurityKeysListener listener = keyset -> {
    logger.debug(
        "Keys derived for channel={}, token={}",
        keyset.channelId(),
        keyset.tokenId()
    );
    // write to database, send to remote service, etc.
};

OpcUaClientConfig config = OpcUaClientConfig.builder()
    .setSecurityKeysListener(listener)
    .build();
```

--------------------------------

### OpcUaClient#browse

Source: https://github.com/eclipse-milo/milo/wiki/Client

Low-level API for performing a single browse request, corresponding directly to the OPC UA Browse service. Requires manual handling of continuation points for subsequent requests.

```APIDOC
## OpcUaClient#browse

### Description
Low-level API for performing a single browse request, corresponding directly to the OPC UA Browse service. Requires manual handling of continuation points for subsequent requests.

### Method
```java
CompletableFuture<BrowseResult> client.browse(BrowseDescription browseDescription)
```

### Parameters
- **browseDescription** (BrowseDescription) - The description of the browse request, including node ID, direction, reference type, node class mask, and result mask.

### Request Example
```java
// Browse for forward hierarchal references from the Objects folder
// that lead to other Object and Variable nodes.
BrowseDescription browse = new BrowseDescription(
    Identifiers.ObjectsFolder,
    BrowseDirection.Forward,
    Identifiers.References,
    true,
    uint(NodeClass.Object.getValue() | NodeClass.Variable.getValue()),
    uint(BrowseResultMask.All.getValue())
);

BrowseResult browseResult = client.browse(browse).get();
```

### Response
#### Success Response (200)
- **browseResult** (BrowseResult) - The result of the browse operation, which may include a continuation point.
```

--------------------------------

### Create ManagedDataItem

Source: https://github.com/eclipse-milo/milo/wiki/Client

Create a `ManagedDataItem` to monitor an attribute value using `ManagedSubscription#createDataItem`. Always verify the returned `StatusCode` for success.

```java
ManagedDataItem dataItem = subscription.createDataItem(Identifiers.Server_ServerStatus_CurrentTime);

if (!dataItem.getStatusCode.isGood()) {
    throw new RuntimeException("uh oh!")
}

```

--------------------------------

### ManagedSubscription

Source: https://github.com/eclipse-milo/milo/wiki/Client

Explains how to create and use ManagedSubscription for managing OPC UA subscriptions and monitored items. It covers adding data change listeners.

```APIDOC
## Subscriptions

### ManagedSubscription

`ManagedSubscription` is the entry point in the higher level API for creating Subscriptions and MonitoredItems.

Create a `ManagedSubscription` using an `OpcUaClient` instance like this:

```java
ManagedSubscription subscription = ManagedSubscription.create(client);
```

Optionally, specify a publishing interval when creating the subscription:

```java
ManagedSubscription subscription = ManagedSubscription.create(client, 250.0);
```

Once the Subscription is created you can add a data or event listener to it. This listener will receive all data changes for all items belonging to the subscription.
```java
subscription.addChangeListener(new ChangeListener() {
    @Override
    public void onDataReceived(List<ManagedDataItem> dataItems, List<DataValue> dataValues) {

        // Each item in the dataItems list has a corresponding value at 
        // the same index in the dataValues list.
        // Some items may appear multiple times if the item has a queue 
        // size greater than 1 and the value changed more than once within 
        // the publishing interval of the subscription. 
        // The items and values appear in the order of the changes.
    }
});
```
```

--------------------------------

### Call Method using UaMethod

Source: https://github.com/eclipse-milo/milo/wiki/Client

Find a `UaMethod` by name and then invoke it using `UaMethod#call`. This approach allows inspection of method input and output arguments.

```java
UaObjectNode serverNode = addressSpace.getObjectNode(Identifiers.Server);

UaMethod getMonitoredItems = serverNode.getMethod("GetMonitoredItems");

Variant[] outputs = getMonitoredItems.call(
    new Variant[]{
        new Variant(subscription.getSubscription().getSubscriptionId())
    }
);

```

```java
Argument[] inputArguments = getMonitoredItems.getInputArguments();
Argument[] outputArguments = getMonitoredItems.getOutputArguments();

```

--------------------------------

### Low-Level Read Service

Source: https://github.com/eclipse-milo/milo/wiki/Client

Use OpcUaClient#read for direct interaction with the Read service. This requires constructing a list of ReadValueId objects specifying the nodes and attributes to read.

```java
List<ReadValueId> readValueIds = new ArrayList<>();

readValueIds.add(
    new ReadValueId(
        new NodeId(2, "TestInt32"),
        AttributeId.Value.uid(),
        null, // indexRange
        QualifiedName.NULL_VALUE
    )
);

ReadResponse readResponse = client.read(
  0.0, // maxAge
  TimestampsToReturn.Both, 
  readValueIds
).get();
```

--------------------------------

### Create and Connect OpcUaClient

Source: https://github.com/eclipse-milo/milo/wiki/Client

Creates an OpcUaClient instance by selecting an endpoint that uses SecurityPolicy.None and automatically attempts to reconnect if the connection is lost. Call disconnect() to stop this behavior.

```java
OpcUaClient client = OpcUaClient.create(
    "opc.tcp://milo.digitalpetri.com:62541/milo",
    endpoints ->
        endpoints.stream()
            .filter(e -> e.getSecurityPolicyUri().equals(SecurityPolicy.None.getUri()))
            .findFirst(),
    configBuilder ->
        configBuilder.build()
);

client.connect().get();
```

--------------------------------

### Call Method using OpcUaClient

Source: https://github.com/eclipse-milo/milo/wiki/Client

Utilize `OpcUaClient#call` for direct interaction with the OPC UA Call service. This method requires constructing `CallMethodRequest` objects and handling `CompletableFuture` responses.

```java
NodeId objectId = NodeId.parse("ns=2;s=HelloWorld");
NodeId methodId = NodeId.parse("ns=2;s=HelloWorld/sqrt(x)");

CallMethodRequest request = new CallMethodRequest(
    objectId,
    methodId,
    new Variant[]{new Variant(input)}
);

return client.call(request).thenCompose(result -> {
    StatusCode statusCode = result.getStatusCode();

    if (statusCode.isGood()) {
        Double value = (Double) l(result.getOutputArguments()).get(0).getValue();
        return CompletableFuture.completedFuture(value);
    } else {
        StatusCode[] inputArgumentResults = result.getInputArgumentResults();
        for (int i = 0; i < inputArgumentResults.length; i++) {
            logger.error("inputArgumentResults[{}]={}", i, inputArgumentResults[i]);
        }
        
        CompletableFuture<Double> f = new CompletableFuture<>();
        f.completeExceptionally(new UaException(statusCode));
        return f;
    }
});

```

--------------------------------

### AddressSpace#browse

Source: https://github.com/eclipse-milo/milo/wiki/Client

High-level API for browsing the OPC UA address space with default or custom browse options. Supports blocking or non-blocking operations.

```APIDOC
## AddressSpace#browse

### Description
High-level API for browsing the OPC UA address space with default or custom browse options. Supports blocking or non-blocking operations.

### Method
```java
List<? extends UaNode> addressSpace.browseNodes(UaNode node)
List<? extends UaNode> addressSpace.browseNodes(UaNode node, BrowseOptions options)
```

### Parameters
#### `browseNodes(UaNode node)`
- **node** (UaNode) - The starting node for the browse operation.

#### `browseNodes(UaNode node, BrowseOptions options)`
- **node** (UaNode) - The starting node for the browse operation.
- **options** (BrowseOptions) - Custom options to configure the browse operation.

### Request Example
```java
// Using default BrowseOptions
AddressSpace addressSpace = client.getAddressSpace();
UaNode serverNode = addressSpace.getNode(Identifiers.Server);
List<? extends UaNode> nodes = addressSpace.browseNodes(serverNode);

// Using custom BrowseOptions
AddressSpace addressSpace = client.getAddressSpace();
UaNode serverNode = addressSpace.getNode(Identifiers.Server);
BrowseOptions browseOptions = addressSpace.getBrowseOptions().copy(
  b -> b.setReferenceType(BuiltinReferenceType.HasProperty)
);
List<? extends UaNode> nodes = addressSpace.browseNodes(serverNode, browseOptions);
```

### Response
#### Success Response
- **nodes** (List<? extends UaNode>) - A list of UaNode objects found during the browse operation.
```

--------------------------------

### Create ManagedEventItem with EventFilter

Source: https://github.com/eclipse-milo/milo/wiki/Client

Create an EventFilter to specify event types and fields, then use it to create a ManagedEventItem from a ManagedSubscription.

```java
EventFilter eventFilter = new EventFilter(
    new SimpleAttributeOperand[]{
        new SimpleAttributeOperand(
            Identifiers.BaseEventType,
            new QualifiedName[]{new QualifiedName(0, "EventId")},
            AttributeId.Value.uid(),
            null),
        new SimpleAttributeOperand(
            Identifiers.BaseEventType,
            new QualifiedName[]{new QualifiedName(0, "Time")},
            AttributeId.Value.uid(),
            null),
        new SimpleAttributeOperand(
            Identifiers.BaseEventType,
            new QualifiedName[]{new QualifiedName(0, "Message")},
            AttributeId.Value.uid(),
            null)
    },
    new ContentFilter(null)
);

// Subscribe for Events from the Server Node's EventNotifier attribute.
ManagedEventItem eventItem = subscription.createEventItem(Identifiers.Server, eventFilter);
```

--------------------------------

### UaNode#browse

Source: https://github.com/eclipse-milo/milo/wiki/Client

API for browsing references or nodes directly from a UaNode instance. Allows specifying reference types and other browse options.

```APIDOC
## UaNode#browse

### Description
API for browsing references or nodes directly from a UaNode instance. Allows specifying reference types and other browse options.

### Method
```java
List<ReferenceDescription> node.browse(BrowseOptions options)
List<? extends UaNode> node.browseNodes(BrowseOptions options)
```

### Parameters
- **options** (BrowseOptions) - Options to configure the browse operation, such as reference type.

### Request Example
```java
BrowseOptions browseOptions = BrowseOptions.builder()
    .setReferenceType(Identifiers.HasProperty)
    .build();

// Browse for HasProperty references
List<ReferenceDescription> references = node.browse(browseOptions);

// Browse for HasProperty references and get the UaNodes they target
List<? extends UaNode> nodes = node.browseNodes(browseOptions);
```

### Response
#### Success Response
- **references** (List<ReferenceDescription>) - A list of ReferenceDescription objects.
- **nodes** (List<? extends UaNode>) - A list of UaNode objects referenced by the browse operation.
```

--------------------------------

### OpcUaClient#write

Source: https://github.com/eclipse-milo/milo/wiki/Client

Low-level API for performing a write request, corresponding directly to the OPC UA Write service. Allows writing multiple attribute values in a single request.

```APIDOC
## OpcUaClient#write

### Description
Low-level API for performing a write request, corresponding directly to the OPC UA Write service. Allows writing multiple attribute values in a single request.

### Method
```java
CompletableFuture<WriteResponse> client.write(List<WriteValue> writeValues)
```

### Parameters
- **writeValues** (List<WriteValue>) - A list of WriteValue objects specifying the nodes, attributes, and data to write.

### Request Example
```java
List<WriteValue> writeValues = new ArrayList<>();
writeValues.add(new WriteValue(new NodeId(2, "TestInt32"), AttributeId.Value.uid(), null, DataValue.valueOnly(new Variant(42))));

WriteResponse writeResponse = client.write(writeValues).get();
```

### Response
#### Success Response (200)
- **writeResponse** (WriteResponse) - The response containing the status of the write operations.
```

--------------------------------

### Call Method using UaObjectNode

Source: https://github.com/eclipse-milo/milo/wiki/Client

Use `UaObjectNode#callMethod` for a high-level way to invoke a method by its name. Ensure the `UaObjectNode` and method are accessible.

```java
UaObjectNode serverNode = addressSpace.getObjectNode(Identifiers.Server);

Variant[] outputs = serverNode.callMethod(
    "GetMonitoredItems",
    new Variant[]{
        new Variant(subscription.getSubscription().getSubscriptionId())
    }
);

```

--------------------------------

### UaNode#read

Source: https://github.com/eclipse-milo/milo/wiki/Client

High-level API for reading attributes directly from a UaNode instance. Allows reading specific attributes like Value or BrowseName.

```APIDOC
## UaNode#read

### Description
High-level API for reading attributes directly from a UaNode instance. Allows reading specific attributes like Value or BrowseName.

### Method
```java
DataValue testNode.readValue()
QualifiedName testNode.readBrowseName()
DataValue testNode.readAttribute(AttributeId attributeId)
```

### Parameters
- **attributeId** (AttributeId) - The ID of the attribute to read.

### Request Example
```java
UaVariableNode testNode = (UaVariableNode) addressSpace.getNode(new NodeId(2, "TestInt32"));

// Read the Value attribute
DataValue value = testNode.readValue();

// Read the BrowseName attribute
QualifiedName browseName = testNode.readBrowseName();

// Read the Description attribute
DataValue descriptionValue = testNode.readAttribute(AttributeId.Description);
```

### Response
#### Success Response
- **value** (DataValue) - The data value of the attribute.
- **browseName** (QualifiedName) - The browse name of the node.
- **descriptionValue** (DataValue) - The data value of the description attribute.
```

--------------------------------

### Read Fresh UaNode Attributes

Source: https://github.com/eclipse-milo/milo/wiki/Client

Obtain fresh attribute values from the server using read<attribute>() methods. A successful read also updates the local attribute value.

```java
Fresh attribute values can be obtained using `read<attribute>()` methods and written using the `write<attribute>()` methods. When a read or a write succeeds it also updates the local attribute value.
```

--------------------------------

### OpcUaClient#read

Source: https://github.com/eclipse-milo/milo/wiki/Client

Low-level API for performing a read request, corresponding directly to the OPC UA Read service. Allows reading multiple attribute values in a single request.

```APIDOC
## OpcUaClient#read

### Description
Low-level API for performing a read request, corresponding directly to the OPC UA Read service. Allows reading multiple attribute values in a single request.

### Method
```java
CompletableFuture<ReadResponse> client.read(double maxAge, TimestampsToReturn timestampsToReturn, List<ReadValueId> readValueIds)
```

### Parameters
- **maxAge** (double) - The maximum age of the values to return.
- **timestampsToReturn** (TimestampsToReturn) - Specifies whether to return timestamps.
- **readValueIds** (List<ReadValueId>) - A list of IDs specifying which values to read.

### Request Example
```java
List<ReadValueId> readValueIds = new ArrayList<>();
readValueIds.add(new ReadValueId(new NodeId(2, "TestInt32"), AttributeId.Value.uid(), null, QualifiedName.NULL_VALUE));

ReadResponse readResponse = client.read(0.0, TimestampsToReturn.Both, readValueIds).get();
```

### Response
#### Success Response (200)
- **readResponse** (ReadResponse) - The response containing the requested values.
```

--------------------------------

### UaNode#write

Source: https://github.com/eclipse-milo/milo/wiki/Client

High-level API for writing attribute values directly to a UaNode instance. Supports writing the Value attribute or any other attribute.

```APIDOC
## UaNode#write

### Description
High-level API for writing attribute values directly to a UaNode instance. Supports writing the Value attribute or any other attribute.

### Method
```java
void testNode.writeValue(Variant value)
StatusCode testNode.writeAttribute(AttributeId attributeId, DataValue dataValue)
```

### Parameters
- **value** (Variant) - The new value to write.
- **attributeId** (AttributeId) - The ID of the attribute to write.
- **dataValue** (DataValue) - The DataValue containing the new attribute value.

### Request Example
```java
UaVariableNode testNode = (UaVariableNode) addressSpace.getNode(new NodeId(2, "TestInt32"));

// Write the Value attribute
testNode.writeValue(new Variant(42));

// Write the Value attribute using writeAttribute
StatusCode statusCode = testNode.writeAttribute(AttributeId.Value, DataValue.valueOnly(new Variant(42)));
```

### Response
#### Success Response
- **statusCode** (StatusCode) - The status code of the write operation.
```

--------------------------------

### ManagedDataItem

Source: https://github.com/eclipse-milo/milo/wiki/Client

Details the creation and usage of ManagedDataItem for monitoring attribute values. Emphasizes the importance of checking the StatusCode after creation or modification.

```APIDOC
### ManagedDataItem

A `ManagedDataItem` represents a MonitoredItem monitoring an attribute value (as opposed to an Event).

Create a `ManagedDataItem` using a `ManagedSubscription` instance like this:
```java
ManagedDataItem dataItem = subscription.createDataItem(Identifiers.Server_ServerStatus_CurrentTime);

if (!dataItem.getStatusCode.isGood()) {
    throw new RuntimeException("uh oh!")
}
```

Always check the StatusCode after creating or modifying a `ManagedDataItem`.
```

--------------------------------

### Synchronize UaNode Attributes

Source: https://github.com/eclipse-milo/milo/wiki/Client

Perform a bulk write of local attribute values to the server using UaNode#synchronize() for a specified set of attributes.

```java
`UaNode#synchronize(Set<AttributeId>)` will do a bulk write for the identified set of attributes using the local attribute values.
```

--------------------------------

### Set Local UaNode Attribute Values

Source: https://github.com/eclipse-milo/milo/wiki/Client

Set local attribute values using set<attribute>() methods. These changes only affect the local value and can be written to the server using `#synchronize()`.

```java
Local attribute values can be set using the `set<attribute>()` methods, which affects only the local value. See `#synchronize()` to write these values to the server.
```

--------------------------------

### Register ChangeListener for Events

Source: https://github.com/eclipse-milo/milo/wiki/Client

Register a ChangeListener on a ManagedSubscription to receive events from all associated ManagedEventItems.

```java
subscription.addChangeListener(new ChangeListener() {
    @Override
    public void onEventReceived(List<ManagedEventItem> eventItems, List<Variant[]> eventFields) {
        
        // Each item in the eventItems list has a corresponding set of 
        // event field values at the same index in the eventFields list.
        // The number of fields and their meaning depend on the filter.
    }
});
```

--------------------------------

### Add Change Listener to ManagedSubscription

Source: https://github.com/eclipse-milo/milo/wiki/Client

Attach a `ChangeListener` to a `ManagedSubscription` to receive notifications for data changes on monitored items. The listener's `onDataReceived` method provides lists of `ManagedDataItem` and corresponding `DataValue` objects.

```java
subscription.addChangeListener(new ChangeListener() {
    @Override
    public void onDataReceived(List<ManagedDataItem> dataItems, List<DataValue> dataValues) {

        // Each item in the dataItems list has a corresponding value at 
        // the same index in the dataValues list.
        // Some items may appear multiple times if the item has a queue 
        // size greater than 1 and the value changed more than once within 
        // the publishing interval of the subscription. 
        // The items and values appear in the order of the changes.
    }
});

```

--------------------------------

### Sign-off a Git commit

Source: https://github.com/eclipse-milo/milo/blob/main/CONTRIBUTING.md

Use the -s flag during commit to sign off on changes as required by the Eclipse contribution process.

```bash
$> git commit -s -m "Shave the yak some more"
```

--------------------------------

### Refresh UaNode Attributes

Source: https://github.com/eclipse-milo/milo/wiki/Client

Perform a bulk read for a specified set of attributes using UaNode#refresh() to update local attribute values.

```java
`UaNode#refresh(Set<AttributeId>)` will do a bulk read for the identified set of attributes and update the local attribute values if it succeeds.
```

--------------------------------

### Register EventValueListener on ManagedEventItem

Source: https://github.com/eclipse-milo/milo/wiki/Client

Register an EventValueListener directly on a ManagedEventItem for simpler event handling when dealing with individual items.

```java
eventItem.addEventValueListener(new ManagedEventItem.EventValueListener() {
    @Override
    public void onEventValueReceived(ManagedEventItem item, Variant[] value) {
        
        // A new event arrived, do something with it.
    }
});
```

=== COMPLETE CONTENT === This response contains all available snippets from this library. No additional content exists. Do not make further requests.