LoveNote is a simple abstract message queue server which lets you pass an message payload to one of a pool of endpoints and receive a webhook callback with the result. You can specify that this message be delivered ASAP, but crucially you can also specify a date and time for the delivery.
How it works
It works by POSTing a bit of JSON to a webhook provided by the server that contains a delivery time, an array of servers to try, the payload and an optional callback URL.
When received by the server, the message is queued. When the delivery time is reached the list of servers is randomised and the payload POSTed in sequence until all servers fail, or delivery is achieved. If a callback is specified, a report is then POSTed back to the callback as a JSON blob.
Why this is useful
Simply, this provides a common message passing framework with a unified event driven API, simplifying your architecture somewhat. It is especially handy if you wanted a message to be delivered some time in the future, for example for a credit card renewal or email reminder, where beforehand you’d probably have to write a dedicated server process.
All you now have to do is listen to webhook pings.
What still needs to be done
This is an early version and was written to help out a friend with a specific need, and although I’ve gone on to use it in a couple of client projects, there are still a fair amount of enhancements that could be made.
Some obvious ones are:
- Message IDs: Currently messages in the queue are anonymous. It’d be handy to have message IDs since this would allow more sophisticated process control of scheduled messages.
- Cancel Control: Basic message control to cancel future queued messages.
- Make message queues persistent: Currently the queue is held in memory, which is simple and fast, but far from ideal. We should periodically flush the queue to a persistent storage so that no messages are lost if a server goes down.
Get involved and send your pull requests to the usual place!