There are a couple I have in mind. Like many techies, I am a huge fan of RSS for content distribution and XMPP for federated communication.
The really niche one I like is S-expressions as a data format and configuration in place of json, yaml, toml, etc.
I am a big fan of Plaintext formats, although I wish markdown had a few more features like tables.
Since nobody’s brought it up: MQTT.
It got pigeonholed into IoT world, but it’s a pretty decent event pubsub system. It has lots lf security/encryption options, plus a websocket layer, so you can use it anywhere from devices, to mobile, to web.
As of late last year, RabbitMQ started suporting it as a supported server add-on, so it’s easy to use it to create scalable, event-based systems, including for multiuser games.
I spun up a MQTT/Aedes/MongoDB stack on my network recently for some ESP32 sensors.
Fantastic protocol and super easy to work with!
I’m currently on the ZeroMQ boat. What made you go to Rabbit Mq? I need the Pair socket for zeroMq for a project.
Installed RabbitMQ for use in Python Celery (for task queue and crontab). Was pleasantly surprised it also offered MQTT support.
Was originally planning on using a third-party, commercial combo websocket/push notification service. But between RabbitMQ/MQTT with websockets and Firebase Cloud Messaging, I’m getting all of it: queuing, MQTT pubsub, and cross-platform push, all for free. 🎉
It all runs nicely in Docker and when time to deploy and scale, trust RabbitMQ more since it has solid cluster support.