; Call these code in app entrypoint.
;; First Step
(setup-custom-namespace "tservice" :sub-ns "events")

;; Second Step (Call it when the app instance is launched.)
(initialize-events!)

; Defined in each event.
;; Define event handler
(defn- test-handler! 
   [{:keys [test-content]}]
   (println test-content))

;; Define events-init function.
(def events-init
  "Automatically called during startup; start event listener for test event."
  (make-events-init "test" test-handler!))

; When you need to trigger an event, call this code 
(publish-event! "test" {:test-content "This is a test."})

Provides a very simply event bus using `core.async` to allow publishing and subscribing to interesting topics
happening throughout the tservice system in a decoupled way. It's based on `metabase.events`.

## Regarding Events Initialization:

Internal Events: The most appropriate way to initialize event listeners in any `tservice.events.*` namespace 
(you can use [[setup-custom-namespace]] to change it) is to implement the
`events-init` function which accepts zero arguments. This function is dynamically resolved and called exactly once
when the application goes through normal startup procedures. Inside this function you can do any work needed and add
your events subscribers to the bus as usual via `start-event-listener!`.

Examples:

```clojure
; Call these code in app entrypoint.
;; First Step
(setup-custom-namespace "tservice" :sub-ns "events")

;; Second Step (Call it when the app instance is launched.)
(initialize-events!)

; Defined in each event.
;; Define event handler
(defn- test-handler! 
   [{:keys [test-content]}]
   (println test-content))

;; Define events-init function.
(def events-init
  "Automatically called during startup; start event listener for test event."
  (make-events-init "test" test-handler!))

; When you need to trigger an event, call this code 
(publish-event! "test" {:test-content "This is a test."})
```

External Events: If you use the event bus in plugin, you need to use [[make-events-init]] to 
generate event initializer and initialize the event in plugin configuration file.
When the above setting is successful, you can use publish-event! to trigger an event.