Publish and receive messages with topics

Prerequisites

Before you begin, make sure that you have:

• SMQ SDK for PHP installed

• An endpoint and access credential configured

Set up the client

All operations in this example require an SMQ client instance. Create the client with your endpoint and access credentials:

<?php
require_once __DIR__ . '/vendor/autoload.php';

use AliyunMNS\Client;
use AliyunMNS\Constants;
use AliyunMNS\Exception\MessageNotExistException;
use AliyunMNS\Model\SubscriptionAttributes;
use AliyunMNS\Requests\PublishBase64MessageRequest;
use AliyunMNS\Requests\PublishMessageRequest;
use AliyunMNS\Requests\CreateTopicRequest;
use AliyunMNS\Requests\CreateQueueRequest;
use AliyunMNS\Exception\MnsException;

// Load credentials from environment variables.
// For credential configuration, see: https://www.alibabacloud.com/help/en/mns/developer-reference/php-configure-access-domain-names-and-credentials
$accessId = getenv(Constants::ALIYUN_AK_ENV_KEY);
$accessKey = getenv(Constants::ALIYUN_SK_ENV_KEY);
$endPoint = "<your-endpoint>";  // Example: https://1234567890123456.mns.cn-hangzhou.aliyuncs.com

$client = new Client($endPoint, $accessId, $accessKey);

Replace the following placeholder with your actual value:

Step 1: Create a topic

Create a topic that serves as the message channel. Messages published to this topic are delivered to all subscribers.

$topicName = "MyTopicExample";
$request = new CreateTopicRequest($topicName);

try {
    $res = $client->createTopic($request);
    echo "Topic created.\n";
} catch (MnsException $e) {
    echo "Failed to create topic: " . $e . "\n";
    return;
}

$topic = $client->getTopicRef($topicName);

Step 2: Create a queue for receiving messages

Create a queue that acts as the subscription endpoint. When messages are published to the topic, SMQ pushes them to this queue.

$queueName = "MyQueueExample";
$request = new CreateQueueRequest($queueName);

try {
    $res = $client->createQueue($request);
    echo "Queue created.\n";
} catch (MnsException $e) {
    echo "Failed to create queue: " . $e . "\n";
    return;
}

$queue = $client->getQueueRef($queueName);

Step 3: Subscribe the queue to the topic

Link the queue to the topic by creating a subscription. The BACKOFF_RETRY strategy retries failed deliveries with exponential backoff. The SIMPLIFIED notify content format sends only the message body without metadata wrappers.

$subscriptionName = "MySubscriptionExample";
$attributes = new SubscriptionAttributes(
    $subscriptionName,
    $topic->generateQueueEndpoint($queueName),  // Generate the queue endpoint URL
    'BACKOFF_RETRY',   // Retry policy
    'SIMPLIFIED'       // Notify content format
);

try {
    $topic->subscribe($attributes);
    echo "Subscription created.\n";
} catch (MnsException $e) {
    echo "Failed to subscribe: " . $e . "\n";
    return;
}

Step 4: Publish messages

$messageBody = "test";
$request = new PublishMessageRequest($messageBody);

try {
    $res = $topic->publishMessage($request);
    echo "Raw message published.\n";
} catch (MnsException $e) {
    echo "Failed to publish raw message: " . $e . "\n";
    return;
}

$messageBody = "test";
$request = new PublishBase64MessageRequest($messageBody);

try {
    $res = $topic->publishMessage($request);
    echo "Base64-encoded message published.\n";
} catch (MnsException $e) {
    echo "Failed to publish Base64-encoded message: " . $e . "\n";
    return;
}

Step 5: Receive messages from the queue

Poll the queue to retrieve messages pushed from the topic. After processing each message, delete it from the queue to prevent redelivery.

while (true) {
    try {
        $res = $queue->receiveMessage(3);  // Wait up to 3 seconds for a message
        echo "Message received: " . $res->getMessageBody() . "\n";

        // Delete the message after processing
        $receiptHandle = $res->getReceiptHandle();
        $queue->deleteMessage($receiptHandle);
        echo "Message deleted.\n";
        break;
    } catch (MessageNotExistException $e) {
        // No message available yet. Retry.
        echo "No new messages. Retrying...\n";
    } catch (MnsException $e) {
        echo "Failed to receive message: " . $e . "\n";
        break;
    }
}

Step 6: Clean up resources

After you finish, remove the subscription, topic, and queue to avoid unnecessary charges.

// Unsubscribe
try {
    $topic->unsubscribe($subscriptionName);
    echo "Unsubscribed.\n";
} catch (MnsException $e) {
    echo "Failed to unsubscribe: " . $e . "\n";
    return;
}

// Delete the topic
try {
    $client->deleteTopic($topicName);
    echo "Topic deleted.\n";
} catch (MnsException $e) {
    echo "Failed to delete topic: " . $e . "\n";
    return;
}

// Delete the queue
try {
    $client->deleteQueue($queueName);
    echo "Queue deleted.\n";
} catch (MnsException $e) {
    echo "Failed to delete queue: " . $e . "\n";
    return;
}

What's next

• Encode a message body -- Choose between raw and Base64 encoding

• Configure endpoints and access credentials -- Credential and endpoint configuration options

• CreateTopicAndPushMessageToQueue.php -- Complete runnable example on GitHub