Ordered messages are a type of message provided by ApsaraMQ for RocketMQ. Ordered messages are published and consumed in strict first-in-first-out (FIFO) order. This topic provides sample code on how to send and receive ordered messages by using the HTTP client SDK for PHP.
Background information
Ordered messages are divided into the following types:
Globally ordered message: If messages in a topic are of this type, the messages are published and consumed in first-in-first-out (FIFO) order.
Partitionally ordered messages: If messages in a topic are of this type, the messages are distributed to different partitions by using sharding keys. The messages in each partition are consumed in FIFO order. A sharding key is a key field that is used for ordered messages to identify partitions. A sharding key is different from a message key.
For more information, see Ordered messages.
Prerequisites
Before you start, make sure that the following operations are performed:
Install the SDK for PHP. For more information, see Prepare the environment.
Create the resources that you want to specify in the code in the ApsaraMQ for RocketMQ console. The resources include instances, topics, and consumer groups. For more information, see Create resources.
Obtain the AccessKey pair of your Alibaba Cloud account. For more information, see Create an AccessKey pair.
Send ordered messages
An ApsaraMQ for RocketMQ broker determines the order in which messages are generated based on the order in which the sender uses a single producer or thread to send messages. If the sender uses multiple producers or threads to concurrently send messages, the message order is determined by the order in which the messages are received by the ApsaraMQ for RocketMQ broker. This order may be different from the sending order on the business side.
The following sample code provides an example on how to send ordered messages by using the HTTP client SDK for PHP:
<?php
require "vendor/autoload.php";
use MQ\Model\TopicMessage;
use MQ\MQClient;
class ProducerTest
{
private $client;
private $producer;
public function __construct()
{
$this->client = new MQClient(
// The HTTP endpoint. You can obtain the endpoint in the HTTP Endpoint section of the Instance Details page in the ApsaraMQ for RocketMQ console.
"${HTTP_ENDPOINT}",
// Make sure that the environment variables ALIBABA_CLOUD_ACCESS_KEY_ID and ALIBABA_CLOUD_ACCESS_KEY_SECRET are configured.
// The AccessKey ID that is used for authentication.
getenv("ALIBABA_CLOUD_ACCESS_KEY_ID"),
// The AccessKey secret that is used for authentication.
getenv('ALIBABA_CLOUD_ACCESS_KEY_SECRET')
);
// The topic in which the message is produced. You must create the topic in the ApsaraMQ for RocketMQ console.
$topic = "${TOPIC}";
// The ID of the instance to which the topic belongs. You must create the instance in the ApsaraMQ for RocketMQ console.
// If the instance has a namespace, specify the ID of the instance. If the instance does not have a namespace, set the instanceID parameter to null or an empty string. You can obtain the namespace of the instance on the Instance Details page in the ApsaraMQ for RocketMQ console.
$instanceId = "${INSTANCE_ID}";
$this->producer = $this->client->getProducer($instanceId, $topic);
}
public function run()
{
try
{
for ($i=1; $i<=4; $i++)
{
$publishMessage = new TopicMessage(
"hello mq! "// The message content.
);
// The custom attributes of the message.
$publishMessage->putProperty("a", $i);
// The sharding key that is used to distribute ordered messages to a specific partition. Sharding keys can be used to identify partitions. A sharding key is different from a message key.
$publishMessage->setShardingKey($i % 2);
$result = $this->producer->publishMessage($publishMessage);
print "Send mq message success. msgId is:" . $result->getMessageId() . ", bodyMD5 is:" . $result->getMessageBodyMD5() . "\n";
}
} catch (\Exception $e) {
print_r($e->getMessage() . "\n");
}
}
}
$instance = new ProducerTest();
$instance->run();
?>
Subscribe to ordered messages
The following sample code provides an example on how to subscribe to ordered messages by using the HTTP client SDK for PHP:
<?php
require "vendor/autoload.php";
use MQ\MQClient;
class ConsumerTest
{
private $client;
private $consumer;
public function __construct()
{
$this->client = new MQClient(
// The HTTP endpoint. You can obtain the endpoint in the HTTP Endpoint section of the Instance Details page in the ApsaraMQ for RocketMQ console.
"${HTTP_ENDPOINT}",
// Make sure that the environment variables ALIBABA_CLOUD_ACCESS_KEY_ID and ALIBABA_CLOUD_ACCESS_KEY_SECRET are configured.
// The AccessKey ID that is used for authentication.
getenv("ALIBABA_CLOUD_ACCESS_KEY_ID"),
// The AccessKey secret that is used for authentication.
getenv('ALIBABA_CLOUD_ACCESS_KEY_SECRET')
);
// The topic in which the message is produced. You must create the topic in the ApsaraMQ for RocketMQ console.
$topic = "${TOPIC}";
// The ID of the consumer group that you created in the ApsaraMQ for RocketMQ console.
$groupId = "${GROUP_ID}";
// The ID of the instance to which the topic belongs. You must create the instance in the ApsaraMQ for RocketMQ console.
// If the instance has a namespace, specify the ID of the instance. If the instance does not have a namespace, set the instanceID parameter to null or an empty string. You can obtain the namespace of the instance on the Instance Details page in the ApsaraMQ for RocketMQ console.
$instanceId = "${INSTANCE_ID}";
$this->consumer = $this->client->getConsumer($instanceId, $topic, $groupId);
}
public function ackMessages($receiptHandles)
{
try {
$this->consumer->ackMessage($receiptHandles);
} catch (\Exception $e) {
if ($e instanceof MQ\Exception\AckMessageException) {
// If the handle of a message times out, the broker cannot receive an acknowledgement (ACK) for the message from the consumer.
printf("Ack Error, RequestId:%s\n", $e->getRequestId());
foreach ($e->getAckMessageErrorItems() as $errorItem) {
printf("\tReceiptHandle:%s, ErrorCode:%s, ErrorMsg:%s\n", $errorItem->getReceiptHandle(), $errorItem->getErrorCode(), $errorItem->getErrorCode());
}
}
}
}
public function run()
{
// Cyclically consume messages in the current thread. We recommend that you use multiple threads to concurrently consume messages.
while (True) {
try {
// Consume messages in long polling mode. The consumer may pull partitionally ordered messages from multiple partitions. The consumer consumes messages from the same partition in the order that the messages are sent.
// Assume that the consumer pulls partitionally ordered messages from one partition. If the broker fails to receive an ACK for a message from the consumer, the broker delivers the message to the consumer again.
// The consumer can consume the next batch of messages from a partition only after all the messages pulled from the partition in the previous batch are acknowledged as consumed.
// Consume messages in long polling mode. If no message in the topic is available for consumption, the request is suspended on the broker for a period of time, which is known as the long polling period. If a message becomes available for consumption within this period of time, the broker immediately sends a response to the consumer.
$messages = $this->consumer->consumeMessageOrderly(
3, // The maximum number of messages that can be consumed at a time. In this example, the value is specified as 3. The maximum value that you can specify is 16.
3 // The duration of a long polling period. Unit: seconds. In this example, the value is specified as 3. The maximum value that you can specify is 30.
);
} catch (\MQ\Exception\MessageResolveException $e) {
// If messages cannot be parsed due to invalid characters in the message body, this exception is thrown.
// The messages that can be parsed as expected.
$messages = $e->getPartialResult()->getMessages();
// The messages that cannot be parsed as expected.
$failMessages = $e->getPartialResult()->getFailResolveMessages();
$receiptHandles = array();
foreach ($messages as $message) {
// The message consumption logic.
$receiptHandles[] = $message->getReceiptHandle();
printf("MsgID %s\n", $message->getMessageId());
}
foreach ($failMessages as $failMessage) {
// Handle the message that cannot be parsed due to invalid characters in the message body.
$receiptHandles[] = $failMessage->getReceiptHandle();
printf("Fail To Resolve Message. MsgID %s\n", $failMessage->getMessageId());
}
$this->ackMessages($receiptHandles);
continue;
} catch (\Exception $e) {
if ($e instanceof MQ\Exception\MessageNotExistException) {
// If no message is available for consumption in the topic, the long polling mode continues to take effect.
printf("No message, contine long polling!RequestId:%s\n", $e->getRequestId());
continue;
}
print_r($e->getMessage() . "\n");
sleep(3);
continue;
}
print "======>consume finish, messages:\n";
// The message consumption logic.
$receiptHandles = array();
foreach ($messages as $message) {
$receiptHandles[] = $message->getReceiptHandle();
printf("MessageID:%s TAG:%s BODY:%s \nPublishTime:%d, FirstConsumeTime:%d, \nConsumedTimes:%d, NextConsumeTime:%d,ShardingKey:%s\n",
$message->getMessageId(), $message->getMessageTag(), $message->getMessageBody(),
$message->getPublishTime(), $message->getFirstConsumeTime(), $message->getConsumedTimes(), $message->getNextConsumeTime(),
$message->getShardingKey());
print_r($message->getProperties());
}
// If the broker fails to receive an ACK for a message from the consumer before the period of time specified in $message->getNextConsumeTime() elapses, the broker delivers the message to the consumer again.
// A unique timestamp is specified for the handle of a message each time the message is consumed.
print_r($receiptHandles);
$this->ackMessages($receiptHandles);
print "=======>ack finish\n";
}
}
}
$instance = new ConsumerTest();
$instance->run();
?>