Declaration and Property Equivalenceīefore a queue can be used it has to be declared. This can result in client-side connection recovery failure or exceptions, and create unnecessary confusion That will delete such queues and recovering clients that will try to re-declare them. When auto-delete or exclusive queues use well-known (static) names, in case of client disconnectionĪnd immediate reconnection there will be a natural race condition between RabbitMQ nodes Such queues are supposed toīe used for client-specific or connection (session)-specific data. For example, auto-deleteĪnd exclusive queues should be server-named. Note that not all property combination make sense in practice. Arguments (optional used by plugins and broker-specific features such as message TTL, queue length limit, etc).Auto-delete (queue that has had at least one consumer is deleted when last consumer unsubscribes).Exclusive (used by only one connection and the queue will be deleted when that connection closes).Durable (the queue will survive a broker restart).Of mandatory properties and a map of optional ones: Queues have properties that define how they behave. The instance should also set up appropriateīindings (routing) for the queue, so that publishers can use well-knownĮxchanges instead of the server-generated queue name directly. Otherwise, the names of server-named queues should be known and used only by theĭeclaring application instance. To them (as demonstrated in tutorial six). In nature and specific to a particular consumer (application instance).Īpplications can share such names in message metadata to let other applications respond Server-named queues are meant to be used for state that is transient This works because the channel remembers the last Methods in the same channel by using the empty string where a queue To use this feature, pass an empty string as the queue nameĪrgument: The same generated name may be obtained by subsequent In AMQP 0-9-1, the broker can generate a unique queue name on behalf ofĪn app. Violates this rule will result in a channel-level exception Attempts to declare a queue with a name that Queue names starting with "amq." are reserved for internal Queue names may be up to 255 bytes of UTF-8 characters. Queues have names so that applications can reference them.Īpplications may pick queue names or ask the broker to generate a nameįor them. Optional Queue Arguments ("x-arguments")įor topics related to consumers, see the Consumers guide.Īnd streams also have dedicated guides.Runtime Resource usage by queue replicas.Queue Durability and how it relates to message persistence.The information about RabbitMQ queues covered in this topic includes: Streams provide different features from queues. ![]() Streams is an alternative messaging data structure available in RabbitMQ. However, it is still important to understand the role queues playīecause many features still operate at the queue level, even for those protocols. Some protocols (for example: STOMP and MQTT) are based around the idea of topics.įor these protocols, queues act as a data accumulation buffer for consumers. This information primarily covers queues in the context of the AMQP 0-9-1 protocol, however, much of the content is applicable to other supported protocols. The information in this topic includes an overview of queues in RabbitMQ and also links out to other topics so you can learn more about using queues in RabbitMQ. Some RabbitMQ queue features such as priorities and requeueing by consumers can affect the ordering as observed by consumers. Many features in a messaging system are related to queues. ![]() Many messaging protocols and tools assume that publishers and consumers communicate using a queue-like storage mechanism. Queues play a major role in the messaging technology space. ![]() To define a queue in generic terms, it is a sequential data structure with two primary operations: an item can be enqueued (added) at the tail and dequeued (consumed) from the head. Messages are enqueued and dequeued (delivered to consumers) in a ( FIFO ("first in, first out") manner. ![]() A queue in RabbitMQ is an ordered collection of messages.
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