Greetings, I'd like to discuss in a wider space the change proposed here[0]. I'll explain briefly what the proposal is about for those not familiar with the project.
As of now, queue's are a first-class resouce. They need to exist in the backend in order to post messages. In v1.1 of the API queues became lazy resources, therefore they don't have to be created beforehand. Although I believe this is a good step forward, there's still an issue with the current implementation. Queues are wasting space. Each queue needs to be created and depending on the backend this is space being wasted since no valuable information is currently stored there except for the queue's metadata, which is required just when using flavors. At the Juno summit, we discussed the idea of dropping queues as a first-citizen resource and move towards a topic-based messaging system. At that summit, the community feedback was that queue's metadata is important and we shouldn't drop it. At the Kilo summit, this topic came up again and supported by the need of having a v2 of the API, we agreed that it may be a good time to do so. The metadata field will still be kept outside the queue (now called topic) and the topic will be part of the message instead. All previous operations will remain but the API endpoints will have to change. This is quite a big change and it'll break backwards compatibility. We could find a way to change the way the service works under-the-hood without changing the API but that'll bring in lots of inconsistencies that we don't want. I had written a post before the Juno summit, which you can find here[1]. There are other motivations behind this change besides the one mentioned above. For example, moving to topics will emphasize the fact that this is a messaging service and that not all the guarantees that are implicit to queues are guaranteed. The change also allows for future optimizations like message broadcasting without hacking awful things into the API - like comma separated queues in the URL's path. [0] https://review.openstack.org/#/c/134015/2/specs/kilo/migrate-to-topics.rst,cm [1] http://blog.flaper87.com/post/people-dont-like-to-queue-up/ Thoughts? Feedback? Thanks in advance, Flavio -- @flaper87 Flavio Percoco
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