add event-driven message hook

[Omarabdul3ziz]

integrating mycelium messaging system into ZOS. from the receiver side, ZOS currently has to continuously poll the popMessage endpoint, which is inefficient and still not truly real-time

suggestion to add an event-driven message hook mechanism (unix socket, or http webhook) this would enable real-time delivery, reduce overhead, and make client integrations much simpler
or if there’s an existing way to achieve this that I may have missed in the documentation

[LeeSmet]

There is a timeout that can be added in the query (https://github.com/threefoldtech/mycelium/blob/master/docs/api.yaml#L311), which specifies some time to wait before a message returns. This way the call only returns after either the timeout passes, or a message is received (which matches the topic if that is provided).

[Omarabdul3ziz]

this can help for waiting a certain time, even hours, but it’s still limited. could we for example allow 0 to be always connected to pop messages? Or better, introduce a push-based mechanism where mycelium message system notifies the connected service zos immediately when a new message arrives

[LeeSmet]

Subscriptions could be added in the jsonrpc api, which could provide a push based functionality. But realistically I doubt there is time to allocate to that right now