Type Serialization

TypeSerializer converts OPC UA types and v4.0.0 DTOs into JSON-safe arrays for IPC transport, and reconstructs them on the other side.

Conversion Table

OPC UA Type	JSON Representation
`NodeId`	`{"ns": 0, "id": 2259, "type": "numeric"}`
`Variant`	`{"type": 6, "value": 42, "dimensions": null}`
`DataValue`	`{"value": 42, "type": 6, "dimensions": null, "statusCode": 0, "sourceTimestamp": "...", "serverTimestamp": "..."}`
`QualifiedName`	`{"ns": 0, "name": "Server"}`
`LocalizedText`	`{"locale": "en", "text": "Server"}`
`ReferenceDescription`	`{"referenceTypeId": {...}, "isForward": true, "nodeId": {...}, "browseName": {...}, "displayName": {...}, "nodeClass": 1, "typeDefinition": {...}}`
`BrowseNode`	`{"reference": {...}, "children": [...]}`
`EndpointDescription`	`{"endpointUrl": "...", "securityMode": 1, "securityPolicyUri": "...", ...}`
`BuiltinType`	`int` (enum value)
`NodeClass`	`int` (enum value)
`BrowseDirection`	`int` (enum value)
`ConnectionState`	`string` (enum name: `"Connected"`, `"Disconnected"`, `"Broken"`)
`DateTimeImmutable`	`string` (ISO 8601)
`null`	`null`
scalars	as-is
arrays	recursively serialized

v4.0.0 DTO Conversion

DTO	JSON Representation
`SubscriptionResult`	`{"subscriptionId": 1, "revisedPublishingInterval": 500.0, "revisedLifetimeCount": 2400, "revisedMaxKeepAliveCount": 10}`
`MonitoredItemResult`	`{"statusCode": 0, "monitoredItemId": 100, "revisedSamplingInterval": 250.0, "revisedQueueSize": 1}`
`CallResult`	`{"statusCode": 0, "inputArgumentResults": [0], "outputArguments": [{"type": 6, "value": 42, "dimensions": null}]}`
`BrowseResultSet`	`{"references": [...], "continuationPoint": "abc123"}`
`PublishResult`	`{"subscriptionId": 1, "sequenceNumber": 42, "moreNotifications": false, "notifications": [...], "availableSequenceNumbers": [1, 2]}`
`BrowsePathResult`	`{"statusCode": 0, "targets": [{"targetId": {...}, "remainingPathIndex": 0}]}`
`BrowsePathTarget`	`{"targetId": {"ns": 2, "id": 100, "type": "numeric"}, "remainingPathIndex": 0}`
`TransferResult`	`{"statusCode": 0, "availableSequenceNumbers": [1, 2, 3]}`

Variant Dimensions

Multi-dimensional arrays preserve their dimensions through serialization:

$variant = new Variant(BuiltinType::Int32, [1, 2, 3, 4], [2, 2]);
$serialized = $serializer->serializeVariant($variant);
// {"type": 6, "value": [1, 2, 3, 4], "dimensions": [2, 2]}

Variant Value Deserialization

Some variant values require type-specific deserialization:

BuiltinType	Deserialization
`DateTime`	ISO 8601 string → `DateTimeImmutable`
`NodeId`	Array → `NodeId` object
`QualifiedName`	Array → `QualifiedName` object
`LocalizedText`	Array → `LocalizedText` object
All others	Returned as-is

Programmatic Usage

use PhpOpcua\SessionManager\Serialization\TypeSerializer;

$serializer = new TypeSerializer();

// Generic serialization (handles any supported type)
$json = $serializer->serialize($anyValue);

// Type-specific serialization
$data = $serializer->serializeNodeId($nodeId);
$data = $serializer->serializeDataValue($dataValue);
$data = $serializer->serializeSubscriptionResult($result);

// Type-specific deserialization
$nodeId = $serializer->deserializeNodeId($data);
$dataValue = $serializer->deserializeDataValue($data);
$result = $serializer->deserializeSubscriptionResult($data);
$result = $serializer->deserializeCallResult($data);
$result = $serializer->deserializeBrowseResultSet($data);
$result = $serializer->deserializePublishResult($data);
$result = $serializer->deserializeBrowsePathResult($data);
$result = $serializer->deserializeTransferResult($data);
$result = $serializer->deserializeMonitoredItemResult($data);