registry/example/src/aqua/event_example.aqua

-- This file demonstrates how to send events to subscribers of a topic
-- Detailed explanation can be found in the Aqua Book: https://doc.fluence.dev/aqua-book/libraries/aqua-dht#passing-data-to-subscribers

import "@fluencelabs/registry/registry-service.aqua"
import "@fluencelabs/registry/resources-api.aqua"
import PeerId from "@fluencelabs/aqua-lib/builtin.aqua"

-- Application event
data Event:
    value: string

-- API that every subscriber must adhere to
-- You can think of it as an application protocol
service EventAPI:
    receive_event(event: Event)

func notify_peer(rec: Record, event: Event):
    -- topological move to peer via relay
    on rec.peer_id via rec.relay_id:
        -- resolve service on a peer
        EventAPI rec.service_id!
        -- call function
        EventAPI.receive_event(event)

-- send event to every peer registered on route
func send_everyone(key_id: string, event: Event, ack: i16):
    on HOST_PEER_ID:
        -- retrieve all peers registered to the route
        records <- resolveProviders(key_id, ack)
        -- iterate through them
        for rec <- records par:
            notify_peer(rec, event)