Application state

On top of processing layer, this one implements application components with init and shutdown logic. See io.resonant.conjector.appstate namespace.

Sysdefs nodes have following properties:

• :init (mandatory) - init/reload function (see below);

• :shutdown (optional) - shutdown function

• :requires, :before - dependencies and reverse dependencies (as vectors of paths);

All nodes that have non-nil :init key will be considered as components.

Init function can be used for in both initialization and reinitialization scenarios. Function returns part of application state and accepts a map with following keys:

• :config - component configuration;

• :old-config - old component configuration;

• :app-config - full application configuration;

• :state - application state (applicable only for shutdown);

• :old-state - old component state;

• :app-state - full application state (built so far);

• :init - true when in initialization/reload mode;

• :shutdown - true when in shutdown mode;

There are three functions implemented in this module. Function app-init builds or rebuilds application state by initializing/reinitializing all components in proper order. Function app-shutdown destroys application state by
calling shutdown handlers on components (if any) in reverse order.

(ns example
  (:require
    [io.resonant.conjector.appstate :as irca]
    [io.resonant.conjector.component :as ircc]))

(def APP-STATE (atom {}))
(def APP-CONF (atom {}))

; This will be suitable for initial configuration and subsequent reloads
(let [conf (read-string (slurp "config.edn"))]
  (reset! APP-STATE (irca/app-init @ircc/APP-DEF conf @APP-STATE @APP-CONF))
  (reset! APP-CONF conf))

; This will shut down application
(irca/app-shutdown @irca/APP-DEF @APP-CONF @APP-STATE)

Also, there is function extract that can be used to extract custom information from application definition data:

(irca/app-extract @irca/APP-DEF (fn [node] (str (:doc node))) "Undocumented")
(irca/app-extract @irca/APP-DEF :config-schema schema.core/Any) 

It accepts traverses application definition data and returns results of provided function on component mode combined into structure resembling application defintion.