Class Service

Cloud Queues is an open source, scalable, and highly available message and notifications service. Users of this service can create and manage a "producer-consumer" or a "publisher-subscriber" model from one simple API. It is made up of a few basic components: queues, messages, claims, and stats.

In the producer-consumer model, users create queues where producers can post messages. Workers, or consumers, may then claim those messages and delete them once complete. A single claim may contain multiple messages, and administrators are given the ability to query claims for status.

In the publisher-subscriber model, messages are posted to a queue like above, but messages are never claimed. Instead, subscribers, or watchers, simply send GET requests to pull all messages since their last request. In this model, a message will remain in the queue, unclaimed, until the message's time to live (TTL) has expired.

Here is an overview of the Cloud Queues workflow:

1. You create a queue to which producers post messages.
2. Producers post messages to the queue.
3. Workers claim messages from the queue, complete the work in that message, and delete the message.
4. If a worker plans to be offline before its message completes, the worker can retire the claim TTL, putting the message back into the queue for another worker to claim.
5. Subscribers monitor the claims of these queues to keep track of activity and help troubleshoot if things go wrong.

For the majority of use cases, Cloud Queues itself will not be responsible for the ordering of messages. If there is only a single producer, however, Cloud Queueing guarantees that messages are handled in a First In, First Out (FIFO) order.