An example script for webscript.io platform that works with their persistent storage It's an an unfinished script that was meant as an implementation of a very simple push notification service with backend in Apple Push Notification Service (APNS). I didn't finish it as webscript.io promises unlimited storage but it's actually severely limited a…

APNS-in-webscript.lua

--  Finds the index of the device token or -1 if the token doesn't exist in the devices.
function findDeviceIndexForToken(devices, deviceToken)
    for i,v in ipairs(devices) do
        if v.token == deviceToken then
            return i
        end
    end

    return -1
end

--  Adds a new device to the devices, unless it already exists.
function register(devices, deviceToken)
    index = findDeviceIndexForToken(devices, deviceToken)
    if index > 0 then
        return index
    end

    --  Add new device and return the new index
    devices[#devices + 1] = {
        token = deviceToken,
        badgeCounter = 0
    }

    return #devices
end

--  Increments the badge counter for all d evices on the network
--  except for the one that invoked increment
function increment(devices, deviceToken)
    deviceIndex = register(devices, deviceToken)

    for i,device in ipairs(devices) do
        if device.token ~= deviceToken then
            device.badgeCounter = device.badgeCounter + 1

            --  Create the payload
            local payload = {
                aps = {
                    badge = device.badgeCounter,
                    sound = 'default'
                }
            }
            payload['aps']['content-available'] = 1

        end
    end

    return deviceIndex
end

--  Resets the badge counter for the device.
function reset(devices, deviceToken)
    deviceIndex = register(devices, deviceToken)
    devices[deviceIndex].badgeCounter = 0
    return deviceIndex
end

--  The actual script execution starts here.

--  Gets all the query parameters.
local action = request.query.action
if not action then
    return "Invalid action"
end

local appName = request.query.appName
if not appName then
    return "Invalid app name"
end

local networkId = request.query.networkId
if not networkId then
    return "Invalid network ID"
end

local deviceToken = request.query.deviceToken
if not deviceToken then
    return "Invalid device token"
end

--  Creates the key for the application name and network ID.
--  This isolates the application name and its network ID from all the other
--  applications/networks in the persisted storage.
local appNetworkDevicesId = appName .. networkId

--  We acquire a lock on the specific application name and network ID.
--  All leases are released when script finishes.
lease.acquire(appNetworkDevicesId)

local devices = json.parse(storage.appNetworkDevicesId or '[]')
local returnValue

--  Returns all the registered device tokens and their network IDs.
if action == 'get' then
    returnValue = devices
end

--  Registers a new device token with the network.
if action == 'register' then
  returnValue = devices[register(devices, deviceToken)]
end

--  Increments the badges in the network.
if action == 'increment' then
    deviceIndex = increment(devices, deviceToken)
    --  Cannot implement: pushNotification(devices, deviceIndex)
    returnValue = devices[deviceIndex]
end

--  Resets the badge count for the given device.
if action == 'reset' then
    returnValue = devices[reset(devices, deviceToken)]
end

--  Persists the state of devices of the network for the specific app.
storage.appNetworkDevicesId = json.stringify(devices)

--  Explicitly releases the lock to avoid keeping the lock more than strictly necessary.
lease.release(appNetworkDevicesId)

--  Returns the response as JSON.
return json.stringify(returnValue)