Types Reference

Core Types

NodeId

Identifies a node in the OPC UA address space.

use PhpOpcua\Client\Types\NodeId;

$nodeId = NodeId::numeric(0, 85);           // ns=0;i=85
$nodeId = NodeId::string(2, 'Temperature'); // ns=2;s=Temperature
$nodeId = NodeId::guid(1, '550e8400-e29b-41d4-a716-446655440000');
$nodeId = NodeId::opaque(1, 'DEADBEEF');

Properties (public readonly):

Methods:

String format in client methods:

All public client methods that accept a NodeId parameter also accept a NodeId|string union type. Strings are parsed automatically using OPC UA notation. Invalid strings throw InvalidNodeIdException.

// These are equivalent:
$client->read(NodeId::numeric(0, 2259));
$client->read('i=2259');

$client->browse(NodeId::numeric(0, 85));
$client->browse('i=85');

$client->write(NodeId::numeric(2, 1001), 42, BuiltinType::Int32);
$client->write('ns=2;i=1001', 42, BuiltinType::Int32);

Parsing and serialization:

$nodeId = NodeId::parse('ns=2;i=1001');
$nodeId = NodeId::parse('i=85');          // ns=0 implied
$nodeId = NodeId::parse('ns=2;s=MyNode');

echo (string) $nodeId; // "ns=2;i=1001"

Variant

Typed value container. Wraps any OPC UA value with its type information.

use PhpOpcua\Client\Types\Variant;
use PhpOpcua\Client\Types\BuiltinType;

$v = new Variant(BuiltinType::Int32, 42);
$v = new Variant(BuiltinType::String, 'Hello');
$v = new Variant(BuiltinType::Double, 3.14);
$v = new Variant(BuiltinType::Boolean, true);
$v = new Variant(BuiltinType::DateTime, new DateTimeImmutable());

// Arrays
$v = new Variant(BuiltinType::Int32, [1, 2, 3, 4, 5]);
$v = new Variant(BuiltinType::String, ['a', 'b', 'c']);

Properties (public readonly):

Methods:

DataValue

A value with metadata. The inner Variant is private -- use getValue() to unwrap it.

use PhpOpcua\Client\Types\DataValue;

$dv = new DataValue(
    value: new Variant(BuiltinType::Int32, 42),
    statusCode: 0,
    sourceTimestamp: new DateTimeImmutable(),
    serverTimestamp: new DateTimeImmutable(),
);

Properties (public readonly):

Methods:

Tip: getValue() returns the raw scalar or array directly. If you need to know the OPC UA type, call getVariant() instead and check ->type.

Factory methods:

DataValue provides static factory methods for creating instances with common types. Each returns a DataValue with status Good, no timestamps, and the appropriate Variant inside.

use PhpOpcua\Client\Types\DataValue;
use PhpOpcua\Client\Types\BuiltinType;
use PhpOpcua\Client\Types\StatusCode;

// Typed factories
DataValue::ofInt32(42);
DataValue::ofDouble(3.14);
DataValue::ofString('Hello');
DataValue::ofBoolean(true);
DataValue::ofFloat(1.5);
DataValue::ofUInt32(100);
DataValue::ofInt16(7);
DataValue::ofUInt16(8);
DataValue::ofInt64(123456789);
DataValue::ofUInt64(987654321);
DataValue::ofDateTime(new DateTimeImmutable());

// Generic factory — any BuiltinType
DataValue::of(42, BuiltinType::Int32);

// Bad status (no value)
DataValue::bad(StatusCode::BadNodeIdUnknown);

BuiltinType (Enum)

All 25 OPC UA built-in data types:

use PhpOpcua\Client\Types\BuiltinType;

Value Types

QualifiedName

A name qualified by a namespace index.

use PhpOpcua\Client\Types\QualifiedName;

$qn = new QualifiedName(0, 'ServerStatus');

Properties (public readonly):

__toString() returns 'ServerStatus' for ns=0, or '2:Temperature' for ns=2.

LocalizedText

A string with an optional locale.

use PhpOpcua\Client\Types\LocalizedText;

$lt = new LocalizedText('en', 'Server Status');

Properties (public readonly):

__toString() returns the text.

StatusCode

Utility class for OPC UA status codes. All methods are static.

use PhpOpcua\Client\Types\StatusCode;

StatusCode::isGood(0x00000000);      // true
StatusCode::isBad(0x80340000);       // true
StatusCode::isUncertain(0x408F0000); // true
StatusCode::getName(0x80340000);     // 'BadNodeIdUnknown'

Static methods:

Constants:

Browse Types

ReferenceDescription

A reference between nodes, returned by browse().

Properties (public readonly):

BrowseNode

Tree node from browseRecursive(). Wraps a ReferenceDescription with children.

Properties (public readonly):

Access the underlying reference data through $node->reference->nodeId, $node->reference->displayName, etc.

Methods:

See Browsing for tree traversal examples.

BrowseDirection (Enum)

use PhpOpcua\Client\Types\BrowseDirection;

NodeClass (Enum)

use PhpOpcua\Client\Types\NodeClass;

Server Types

EndpointDescription

Server endpoint info, returned by getEndpoints().

Properties (public readonly):

UserTokenPolicy

Authentication method supported by an endpoint.

Properties (public readonly):

ConnectionState (Enum)

use PhpOpcua\Client\Types\ConnectionState;

Used by $client->getConnectionState() and $client->isConnected(). See Connection & Configuration.

AttributeId

Constants for OPC UA node attributes.

use PhpOpcua\Client\Types\AttributeId;

Note: AttributeId::Value (13) is the default for read() and write().

Result DTOs

All result DTOs use public readonly properties.

BrowseResultSet

Returned by browseWithContinuation() and browseNext().

See Browsing.

BrowsePathResult

Returned by translateBrowsePaths(), one per path.

BrowsePathTarget

A single target resolved from a browse path.

CallResult

Returned by call(). See Method Calling.

SubscriptionResult

Returned by createSubscription(). See Subscriptions.

MonitoredItemResult

Returned per item by createMonitoredItems() and createEventMonitoredItem(). See Subscriptions.

PublishResult

Returned by publish(). See Subscriptions.

Each entry in notifications is an associative array. For data changes: type, clientHandle, dataValue. For events: type, clientHandle, eventFields.

TransferResult

Returned per subscription by transferSubscriptions(). See Subscriptions.

Type Discovery

StructureField

Describes a single field within a structure definition. Returned as part of StructureDefinition.

use PhpOpcua\Client\Types\StructureField;

Properties (public readonly):

StructureDefinition

Describes the layout of a custom structure type. Used by discoverDataTypes() to build dynamic codecs.

use PhpOpcua\Client\Types\StructureDefinition;

Properties (public readonly):

ExtensionObject

Represents an OPC UA ExtensionObject — a typed container for custom binary or XML structures.

use PhpOpcua\Client\Types\ExtensionObject;

Properties (public readonly):

Methods:

Behavior with DataValue::getValue():

• With codec registered: getValue() auto-extracts $ext->value — returns the decoded data directly (e.g. ['x' => 1.0, 'y' => 2.0])
• Without codec: getValue() returns the ExtensionObject DTO — access ->typeId, ->body, etc.

$value = $client->read($pointNodeId)->getValue();

if ($value instanceof ExtensionObject) {
    echo $value->typeId;   // raw, no codec
    echo $value->body;     // binary blob
} else {
    echo $value['x'];      // decoded via codec
}

ExtensionObject Codecs

Register codecs to automatically decode ExtensionObjects. Full guide: ExtensionObject Codecs.

$repo = new ExtensionObjectRepository();
$repo->register(NodeId::numeric(2, 5001), MyPointCodec::class);

$client = ClientBuilder::create($repo)
    ->connect('opc.tcp://localhost:4840');

$result = $client->read($pointNodeId);
// $result->getValue() => ['x' => 1.0, 'y' => 2.0, 'z' => 3.0]

Each Client has its own isolated repository. If you do not pass one, the builder creates an empty one internally.