Method Calling

Calling a Method

OPC UA methods live on object nodes. You need the object's NodeId and the method's NodeId:

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

$result = $client->call(
    'i=2253',   // Server object (or NodeId::numeric(0, 2253))
    'i=11492',  // GetMonitoredItems method
    [
        new Variant(BuiltinType::UInt32, 1), // subscriptionId argument
    ]
);

if (StatusCode::isGood($result->statusCode)) {
    foreach ($result->outputArguments as $output) {
        echo $output->type->name . ': ' . print_r($output->value, true) . "\n";
    }
}

call() returns a CallResult with three properties:

$result->statusCode -- overall method execution status
$result->inputArgumentResults -- per-argument validation status codes (int[])
$result->outputArguments -- return values (Variant[])

Without Arguments

If the method takes no inputs, just omit the third parameter:

$result = $client->call(
    NodeId::numeric(2, 1000),
    NodeId::numeric(2, 1001),
);

Multiple Arguments

Pass each argument as a Variant with the correct type:

$result = $client->call(
    $objectNodeId,
    $methodNodeId,
    [
        new Variant(BuiltinType::String, 'hello'),
        new Variant(BuiltinType::Double, 3.14),
        new Variant(BuiltinType::Boolean, true),
        new Variant(BuiltinType::Int32, [1, 2, 3]), // array argument
    ]
);

Tip: The server defines what types each argument expects. If you send the wrong type, you will get a BadTypeMismatch status on that argument.

Error Handling

Check the overall status first, then inspect individual arguments if needed:

$result = $client->call($objectId, $methodId, $args);

// Overall method status
if (StatusCode::isBad($result->statusCode)) {
    echo 'Method failed: ' . StatusCode::getName($result->statusCode) . "\n";
}

// Per-argument validation
foreach ($result->inputArgumentResults as $i => $argStatus) {
    if (StatusCode::isBad($argStatus)) {
        echo "Argument $i rejected: " . StatusCode::getName($argStatus) . "\n";
    }
}

Note: A bad statusCode means the method itself failed. Bad entries in inputArgumentResults mean specific arguments were rejected -- the method may not have executed at all.