Logging & Caching

PSR-3 Logging

Every OPC UA client created by OpcuaManager automatically receives Laravel's logger. The logger captures connection events, retries, errors, and protocol details.

Automatic Injection

The OpcuaServiceProvider resolves Psr\Log\LoggerInterface from the container and passes it to OpcuaManager. Every client created through the manager gets this logger via setLogger().

Override Per-Client

use Psr\Log\NullLogger;

$client = Opcua::connect();
$client->setLogger(new NullLogger()); // disable logging for this client

Override Per-Connection Config

Pass a logger explicitly in the connection config array (e.g. via connectTo()):

$client = Opcua::connectTo('opc.tcp://...', [
    'logger' => new NullLogger(),
]);

An explicit logger in the config takes precedence over the default Laravel logger.

What Gets Logged

Daemon Logging

The opcua:session command uses a Laravel log channel for daemon events:

OPCUA_LOG_CHANNEL=stack

Or override via CLI:

php artisan opcua:session --log-channel=stderr

If not specified, the Laravel default log channel is used.

PSR-14 Event System (v4.0+)

The client supports PSR-14 event dispatching. When an event dispatcher is attached, the client fires events for every significant operation -- 47 event types in total covering connections, reads, writes, subscriptions, security, and more.

Attaching an Event Dispatcher

use Psr\EventDispatcher\EventDispatcherInterface;

$client = Opcua::connect();
$client->setEventDispatcher(app(EventDispatcherInterface::class));

Automatic Injection via Laravel

If your application binds Psr\EventDispatcher\EventDispatcherInterface in the container, you can configure OpcuaManager to inject it automatically. The OpcuaServiceProvider will resolve it and pass it to every client created through the manager.

Event Categories

Listening for Events

Use Laravel's event system or any PSR-14 compatible listener provider:

use PhpOpcua\Client\Events\AfterRead;

// In a Laravel EventServiceProvider
protected $listen = [
    AfterRead::class => [
        LogOpcuaReads::class,
    ],
];

Per-Client Override

$client = Opcua::connect();
$client->setEventDispatcher(null); // disable events for this client

PSR-16 Caching

Every OPC UA client created by OpcuaManager automatically receives Laravel's cache store. The cache stores browse results, endpoint discovery, and type discovery data.

Automatic Injection

The OpcuaServiceProvider resolves Psr\SimpleCache\CacheInterface from the container and passes it to OpcuaManager. Every client gets this cache via setCache().

Per-Call Cache Control

Many browse operations accept a useCache parameter:

// Use cache (default)
$refs = $client->browse('i=85', useCache: true);

// Skip cache for this call
$refs = $client->browse('i=85', useCache: false);

// Resolve with cache
$nodeId = $client->resolveNodeId('/Objects/Server', useCache: true);

Methods supporting useCache:

• browse()
• browseAll()
• getEndpoints()
• resolveNodeId()
• discoverDataTypes()

Cache Invalidation

// Invalidate a specific node
$client->invalidateCache('i=85');

// Flush all cached data
$client->flushCache();

Override Per-Client

use PhpOpcua\Client\Cache\InMemoryCache;

$client = Opcua::connect();
$client->setCache(new InMemoryCache(300)); // 300s TTL

Disable Caching

$client->setCache(null);

Available Cache Drivers

The underlying client provides two built-in PSR-16 implementations:

In a Laravel context, you'll typically rely on the automatically injected Laravel cache store (Redis, Memcached, etc.) rather than these built-in drivers.

Daemon Caching

The opcua:session command injects a Laravel cache store into each OPC UA client the daemon creates:

OPCUA_CACHE_STORE=redis

Or override via CLI:

php artisan opcua:session --cache-store=redis

If not specified, the Laravel default cache store is used.

Read Metadata Cache (v4.0+)

When read_metadata_cache is enabled, the client caches non-Value attribute reads (DisplayName, DataType, Description, etc.). These attributes rarely change, so caching them avoids redundant round-trips.

Configuration

OPCUA_READ_METADATA_CACHE=true

Or in config/opcua.php:

'connections' => [
    'default' => [
        // ...
        'read_metadata_cache' => true,
    ],
],

Fluent API

$client = Opcua::connect();
$client->setReadMetadataCache(true);

Refresh Parameter

The read() method accepts a refresh parameter to bypass the metadata cache for a specific call:

// Normal read — uses metadata cache if enabled
$dv = $client->read('ns=2;i=1001');

// Force a fresh read from the server, ignoring any cached metadata
$dv = $client->read('ns=2;i=1001', refresh: true);

This is useful when you know the server has changed metadata (e.g. after reconfiguration) and you want to pick up the latest values.

Write Type Auto-Detection Cache (v4.0+)

When auto_detect_write_type is enabled (the default), the client discovers the OPC UA data type of a node before writing, so you can omit the type parameter on write(). The discovered types are cached for subsequent writes to the same node.

OPCUA_AUTO_DETECT_WRITE_TYPE=true

This caching works alongside PSR-16 caching. The type discovery results are stored in the same cache backend configured for the client.