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- What RabbitMQ Version Does DMS for RabbitMQ Use?
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- Do Queues Inside a Cluster RabbitMQ Instance Have Any Redundancy Backup?
- Does DMS for RabbitMQ Support Data Persistence? How Do I Perform Scheduled Data Backups?
- How Do I Obtain the Certificate After SSL Has Been Enabled?
- Can I Change the SSL Setting of a RabbitMQ Instance?
- Can RabbitMQ Instances Be Scaled Up?
- Does RabbitMQ Support Two-Way Authentication?
- Does DMS for RabbitMQ Support CPU and Memory Upgrades?
- How Do I Disable the RabbitMQ Management UI?
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Connections
- How Do I Configure a Security Group?
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- Do RabbitMQ Instances Support Cross-Subnet Access?
- What Should I Do If I Fail to Access a RabbitMQ Instance with SSL Encryption?
- Can I Access a RabbitMQ Instance Using DNAT?
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Instances
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More Documents
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User Guide (ME-Abu Dhabi Region)
- Service Overview
- Getting Started
- Process of Using RabbitMQ
- Permissions Management
- Buying a RabbitMQ Instance
- Configuring Virtual Hosts
- Accessing a RabbitMQ Instance
- Managing Messages
- Advanced Features
-
Managing Instances
- Viewing and Modifying Basic Information of a RabbitMQ Instance
- Viewing RabbitMQ Client Connection Addresses
- Managing RabbitMQ Instance Tags
- Resetting the RabbitMQ Instance Password
- Enabling RabbitMQ Plug-ins
- Using the rabbitmq_tracing Plug-in
- Exporting the RabbitMQ Instance List
- Deleting a RabbitMQ Instance
- Logging In to RabbitMQ Management UI
- Modifying RabbitMQ Instance Specifications
- Migrating RabbitMQ Services
- Applying for Increasing RabbitMQ Quotas
- Viewing Metrics and Configuring Alarms
- Viewing RabbitMQ Audit Logs
-
FAQs
-
Instances
- What RabbitMQ Version Does DMS for RabbitMQ Use?
- What SSL Version Does DMS for RabbitMQ Use?
- Why Can't I View the Subnet and Security Group Information During Instance Creation?
- How Are Requests Evenly Distributed to Each VM of a Cluster RabbitMQ Instance?
- Do Queues Inside a Cluster RabbitMQ Instance Have Any Redundancy Backup?
- Does DMS for RabbitMQ Support Data Persistence? How Do I Perform Scheduled Data Backups?
- How Do I Obtain the Certificate After SSL Has Been Enabled?
- Can I Change the SSL Setting of a RabbitMQ Instance?
- Can RabbitMQ Instances Be Scaled Up?
- Does RabbitMQ Support Two-Way Authentication?
- Does DMS for RabbitMQ Support CPU and Memory Upgrades?
- How Do I Disable the RabbitMQ Management UI?
- Can I Change the AZ for an Instance?
- How Do I Obtain the Region ID?
- Why Can't I Select Two AZs?
- How to Change Single-node RabbitMQ Instances to Cluster Ones?
- Can I Change the VPC and Subnet After a RabbitMQ Instance Is Created?
-
Connections
- How Do I Configure a Security Group?
- Why Does a Client Fail to Connect to a RabbitMQ Instance?
- Does DMS for RabbitMQ Support Public Access?
- Does DMS for RabbitMQ Support Cross-Region Deployment?
- Do RabbitMQ Instances Support Cross-VPC Access?
- Do RabbitMQ Instances Support Cross-Subnet Access?
- What Should I Do If I Fail to Access a RabbitMQ Instance with SSL Encryption?
- Can I Access a RabbitMQ Instance Using DNAT?
- Why Can't I Open the Management Web UI?
- Can a Client Connect to Multiple Virtual Hosts of a RabbitMQ Instance?
- Why Does a RabbitMQ Cluster Have Only One Connection Address?
- Messages
- Monitoring & Alarm
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Instances
- Change History
- API Reference (ME-Abu Dhabi Region)
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User Guide (Kuala Lumpur Region)
- Service Overview
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- Quotas
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FAQs
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Instances
- What RabbitMQ Version Does DMS for RabbitMQ Use?
- What SSL Version Does DMS for RabbitMQ Use?
- Why Can't I View the Subnet and Security Group Information During Instance Creation?
- What If One RabbitMQ VM Fails to Be Restarted When a Cluster RabbitMQ Instance Is Being Restarted?
- How Are Requests Evenly Distributed to Each VM of a Cluster RabbitMQ Instance?
- Do Queues Inside a Cluster RabbitMQ Instance Have Any Redundancy Backup?
- Does DMS for RabbitMQ Support Data Persistence? How Do I Perform Scheduled Data Backups?
- How Do I Obtain the Certificate After SSL Has Been Enabled?
- Can I Change the SSL Setting of a RabbitMQ Instance?
- Can RabbitMQ Instances Be Scaled Up?
- Does DMS for RabbitMQ Support MQTT?
- How Do I Clear Queue Data?
- Does DMS for RabbitMQ Support CPU and Memory Upgrades?
- How Do I Disable the RabbitMQ Management UI?
- Can I Change the AZ for an Instance?
-
Connections
- How Do I Configure a Security Group?
- Why Does a Client Fail to Connect to a RabbitMQ Instance?
- Does DMS for RabbitMQ Support Public Access?
- Does DMS for RabbitMQ Support Cross-Region Deployment?
- Does DMS for RabbitMQ Support Cross-VPC Access?
- Does DMS for RabbitMQ Support Cross-Subnet Access?
- What Should I Do If I Fail to Access a RabbitMQ Instance with SSL Encryption?
- Can I Access a RabbitMQ Instance Using DNAT?
- Why Can't I Open the Management Web UI?
- Can a Client Connect to Multiple Virtual Hosts of a RabbitMQ Instance?
- Why Does a RabbitMQ Cluster Have Only One Connection Address?
- Plug-ins
- Messages
- Monitoring & Alarm
-
Instances
- Change History
- API Reference (Kuala Lumpur Region)
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User Guide (ME-Abu Dhabi Region)
- General Reference
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Configuring RabbitMQ Message Acknowledgment
RabbitMQ messages are acknowledged by producers and consumers. Acknowledgments by producers ("producer confirms") and consumers are critical to ensure data reliability. If a connection fails, messages being transmitted may be lost and need to be transmitted again. The message acknowledgment mechanism enables the server and client to know when to retransmit messages. A client may acknowledge a message upon receipt of the message, or after it has completely processed the message.
Producer confirms affect performance and should be disabled if high throughput is required. However, disabling producer confirms leads to lower reliability.
For details about the message acknowledgment mechanism, see Consumer Acknowledgment and Publisher Confirms.
Producer Confirms
The server confirms that it has received the message sent from the producer.
The following example shows how to configure publisher confirms on a Java client.
try { channel.confirmSelect(); // Enable publisher confirms on the channel. // Send messages normally. channel.basicPublish("exchange", "routingKey" , null , "publisher confirm test" .getBytes()); if (!channel.waitForConfirms()) { System.out.println( "send message failed " ) ; // do something else.... } } catch (InterruptedException e) { e.printStackTrace() ; }
After the channel .waitForConfirms method is called, the system waits for a confirmation from the server. Such synchronous waiting affects performance, but is necessary if the publisher requires at-least-once delivery.
Consumer Acknowledgment
The server determines whether to delete a message from a queue based on whether the message is successfully received by the consumer.
Consumer acknowledgments are important to ensure data reliability. Consumer applications should take enough time to process important messages before acknowledging the messages. In this way, we do not have to worry about message losses caused by consumer process exceptions (such as program breakdown and restart) during message processing.
Consumer acknowledgment can be enabled by using the basicConsume method. In most cases, consumer acknowledgments are enabled on channels.
The following example shows how to configure consumer acknowledgments on a Java client (using Channel#basicAck and basic.ack for positive acknowledgment):
// this example assumes an existing channel instance boolean autoAck = false; channel.basicConsume(queueName, autoAck, "a-consumer-tag", new DefaultConsumer(channel) { @Override public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException { long deliveryTag = envelope.getDeliveryTag(); // positively acknowledge a single delivery, the message will // be discarded channel.basicAck(deliveryTag, false); } });
Unacknowledged messages are cached in the memory. If there are too many unacknowledged messages, the memory usage becomes high. In this case, you can limit the number of messages prefetched by the consumer. For details, see Configuring RabbitMQ Message Prefetch.
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