RdKafka¶
rdkafka is a PECL extension providing a PHP client for Apache Kafka, a distributed event-streaming platform. It is a binding around librdkafka, the widely used C client for Kafka, and exposes producer and consumer classes for publishing and reading messages from Kafka topics.
A producer sends messages to a named topic, optionally partitioned by a key, and Kafka retains them for a configurable retention period regardless of whether consumers have read them yet, which is what distinguishes Kafka from a traditional message queue: multiple independent consumer groups can each read the same stream of events at their own pace.
Kafka, and by extension this driver, is commonly used for event-driven architectures, log aggregation, and streaming data pipelines, where the durability and replay-ability of the event log matters more than the low-latency point-to-point delivery that a queue such as Gearman or RabbitMQ provides.
<?php
// Producer
$conf = new RdKafka\Conf();
$conf->set('metadata.broker.list', 'localhost:9092');
$producer = new RdKafka\Producer($conf);
$topic = $producer->newTopic('orders');
$topic->produce(RD_KAFKA_PARTITION_UA, 0, json_encode(['id' => 1]));
$producer->flush(2000);
// Consumer
$consumerConf = new RdKafka\Conf();
$consumerConf->set('group.id', 'order-service');
$consumerConf->set('metadata.broker.list', 'localhost:9092');
$consumer = new RdKafka\KafkaConsumer($consumerConf);
$consumer->subscribe(['orders']);
$message = $consumer->consume(10000);
echo $message->payload;
?>
See also php-rdkafka and Apache Kafka.
Related : Gearman, Queue, Event Driven, Distributed Systems
