webapi-eca/coffee/engine.coffee

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CoffeeScript

###
Engine
==================
> The heart of the WebAPI ECA System. The engine loads action invoker modules
> corresponding to active rules actions and invokes them if an appropriate event
> is retrieved.
###
# **Loads Modules:**
# - [Persistence](persistence.html)
db = require './persistence'
# - [Dynamic Modules](dynamic-modules.html)
dynmod = require './dynamic-modules'
# - External Modules:
# [js-select](https://www.npmjs.org/package/js-select)
jsonQuery = require 'js-select'
listUserRules = {}
isRunning = false
###
Module call
-----------
Initializes the Engine and starts polling the event queue for new events.
@param {Object} args
###
exports = module.exports = ( args ) =>
if not isRunning
isRunning = true
@log = args.logger
db args
dynmod args
pollQueue()
module.exports
###
This is a helper function for the unit tests so we can verify that action
modules are loaded correctly
#TODO we should change this to functions returning true or false rather than returning
#the whole list
@public getListUserRules ()
###
exports.getListUserRules = () ->
listUserRules
###
An event associated to rules happened and is captured here. Such events
are basically CRUD on rules.
@public internalEvent ( *evt* )
@param {Object} evt
###
exports.internalEvent = ( evt ) =>
if not listUserRules[evt.user] and evt.event isnt 'del'
listUserRules[evt.user] =
rules: {}
actions: {}
oUser = listUserRules[evt.user]
oRule = evt.rule
if evt.event is 'new' or ( evt.event is 'init' and not oUser.rules[oRule.id] )
oUser.rules[oRule.id] = oRule
updateActionModules oRule, false
if evt.event is 'del' and oUser
delete oUser.rules[oRule.id]
updateActionModules oRule, true
###
As soon as changes were made to the rule set we need to ensure that the aprropriate action
invoker modules are loaded, updated or deleted.
@private updateActionModules ( *oNewRule* )
@param {Object} oNewRule
###
updateActionModules = ( oNewRule, isDeleteOp ) ->
# Remove all action invoker modules that are not required anymore
fRemoveNotRequired = ( oUser ) ->
# Check whether the action is still existing in a rule
fRequired = ( actionName ) ->
# return true for nmRl, oRl of oUser.rules when actionName in oRl.actions
for nmRl, oRl of oUser.rules
for action in oRl.actions
mod = (action.split ' -> ')[0]
if mod is actionName
return true
false
# Go thorugh all actions and check whether the action is still required
for action of oUser.actions
req = fRequired action
if not req
delete oUser.actions[action]
# delete oUser.actions[action] for action of oUser.actions when not fRequired action
fRemoveNotRequired oUser for name, oUser of listUserRules
# Add action invoker modules that are not yet loaded
fAddRequired = ( userName, oUser ) ->
# Check whether the action is existing in a rule and load if not
fCheckRules = ( oRule ) ->
# Load the action invoker module if it was part of the updated rule or if it's new
fAddIfNewOrNotExisting = ( actionName ) ->
moduleName = (actionName.split ' -> ')[0]
if not isDeleteOp and ( not oUser.actions[moduleName] or oRule.id is oNewRule.id )
db.actionInvokers.getModule moduleName, ( err, obj ) ->
params = {}
res = dynmod.compileString obj.data, userName, moduleName, params, obj.lang
oUser.actions[moduleName] = res.module
fAddIfNewOrNotExisting action for action in oRule.actions
# Go thorugh all actions and check whether the action is still required
fCheckRules oRl for nmRl, oRl of oUser.rules
if JSON.stringify( oUser.rules ) is "{}" # TODO check whether this is really doing what it is supposed to do
delete listUserRules[userName]
fAddRequired userName, oUser for userName, oUser of listUserRules
pollQueue = () ->
if isRunning
db.popEvent ( err, obj ) ->
if not err and obj
processEvent obj
setTimeout pollQueue, 50 #TODO adapt to load
###
Checks whether all conditions of the rule are met by the event.
@private validConditions ( *evt, rule* )
@param {Object} evt
@param {Object} rule
###
validConditions = ( evt, rule ) ->
for prop in rule.conditions
return false if jsonQuery( evt, prop ).nodes().length is 0
return true
###
Handles retrieved events.
@private processEvent ( *evt* )
@param {Object} evt
###
processEvent = ( evt ) =>
@log.info 'EN | processing event: ' + evt.event + '(' + evt.eventid + ')'
for userName, oUser of listUserRules
for ruleName, oRule of oUser.rules
if evt.event is oRule.event and validConditions evt, oRule
@log.info 'EN | EVENT FIRED: ' + evt.event + '(' + evt.eventid + ') for rule ' + ruleName
# fStoreAction userName, action for action in oRule.actions
for action in oRule.actions
arr = action.split ' -> '
listUserRules[userName]['actions'][arr[0]][arr[1]] evt
exports.shutDown = () ->
isRunning = false