Overview
The Subscriber side of OPC UA PubSub (Part 14) in pure PHP. Consumes UADP or JSON NetworkMessages over UDP unicast/multicast, demuxes them against configured readers, and hands you decoded DataSetMessages with named fields.
php-opcua/opcua-client-ext-transport-pubsub implements the Subscriber
role of OPC UA PubSub (Part 14), written entirely in PHP. It receives
NetworkMessage frames — UADP binary (Part 14 §6.2) or JSON (Part 14 §7.2) —
over UDP unicast and IPv4 multicast, matches each DataSetMessage against
the readers you configured, and delivers the decoded fields to your
application as typed DTOs.
It is an extension of
php-opcua/opcua-client. The
core client is untouched when you install this package; only the
PhpOpcua\Client\ExtTransportPubSub\* namespace is added.
When to use it
PubSub is the right model when a publisher fans telemetry out to many
consumers without a request/response round trip: high-rate sensor streams,
controller-to-controller messaging, plant-wide broadcast over multicast.
Unlike the classic client/server subscription model (opc.tcp:// with
CreateSubscription / monitored items), PubSub is connectionless — the
subscriber just listens.
Subscriber only
This package implements the Subscriber role. It does not publish
PubSub streams, and it does not change the core opcua-client. MQTT / AMQP
/ WebSocket transports each live in their own package implementing
PubSubTransportInterface.
What ships in v4.4.0
| Component | Status |
|---|---|
SubscriberBuilder / Subscriber (OpcUaSubscriberInterface) |
Yes — run(), poll(), stop(), isRunning() |
UdpTransport + UdpOptions (PubSubTransportInterface) |
Yes — unicast + IPv4 multicast, ext-sockets |
UadpNetworkMessageCodec (Part 14 §6.2) |
Yes — Variant / RawData / DataValue field encodings |
JsonNetworkMessageCodec (Part 14 §7.2) |
Yes — reversible JSON |
DataSetReaderConfig + DataSetMetaData |
Yes — fromArray / fromJsonFile / fromXmlFile / fromXmlString / fromBinary / fetchFromServer |
Group-key security (None / Sign / SignAndEncrypt) |
Yes — StaticGroupKeyProvider, SksGroupKeyProvider |
| 8 PSR-14 event classes | Yes — lifecycle, transport, decode, security |
| 4 exception classes | Yes |
PubSubModule extension point |
Yes — custom kernel hooks without forking |
The shape of a subscriber
use PhpOpcua\Client\ExtTransportPubSub\SubscriberBuilder;
use PhpOpcua\Client\ExtTransportPubSub\Types\DataSetMessage;
use PhpOpcua\Client\ExtTransportPubSub\Types\DataSetMetaData;
use PhpOpcua\Client\ExtTransportPubSub\Types\DataSetReaderConfig;
$subscriber = SubscriberBuilder::create()
->onDataSetMessage(function (DataSetMessage $msg): void {
foreach ($msg->fields as $field) {
echo "{$field->name} = {$field->getScalar()}\n";
}
})
->listenUdp(
endpoint: 'opc.udp://239.0.0.1:4840',
readers: [new DataSetReaderConfig(
publisherId: 100,
writerGroupId: 1,
dataSetWriterId: 1,
dataSetMetaData: DataSetMetaData::fromJsonFile('/etc/opcua/line1.json'),
)],
);
$subscriber->run(); // blocking event loopEverything past the builder is covered in How it works.