Monitor transfer channels on FS and put info to memcache to be able do intercep

att_xfer_mon.lua

-- This service can be run as standalone application
-- or from FreeSWITCH using `luarun att_xfer_mon.lua`
--------------------------------------------------------

local EventService  = require "uv_event_service"
local Memcached     = require "lluv.memcached"

local service_name = 'att_xfer'

local service = EventService.new(service_name, { '127.0.0.1', '8021', 'ClueCon',
  reconnect = 5; no_execute_result = true; no_bgapi = true;
  subscribe = {
    'CHANNEL_DESTROY',
  };
  filter = {
    variable_transfer_disposition = 'recv_replace',
  };
})

local log = service:logger()

local cache = Memcached.Connection.new{
  server    = '127.0.0.1:11211';
  reconnect = 5;
}:open()

cache:on('reconnect',  function(self, eventName)
  log.infof('memcached connected')
end)

cache:on('disconnect', function(self, eventName, err)
  log.infof('memcached disconnected: %s', tostring(err or 'closed'))
end)

service:on('esl::event::CHANNEL_DESTROY::**', function(self, eventName, event)
  local refer_uuid, bridge_uuid = event:getVariable('refer_uuid'), event:getVariable('bridge_uuid')
  if refer_uuid and bridge_uuid then
    log.debugf('found refer %s=>%s', refer_uuid, bridge_uuid)
    local key = 'refer:' .. refer_uuid
    cache:set(key, bridge_uuid, 180, function(self, err, status)
      if err then log.errf('can not store key in memcached: %s', tostring(err)) end
    end)
  end
end)

service:run()

att_xfer_mon_fusion.lua

-- implement Attended transfer monitor based on FusionPBX service API
-- without any external deps.

local service_name = 'att_xfer'

require "resources.functions.config"

local log = require "resources.functions.log"[service_name]
local cache = require "resources.functions.cache"
local BasicEventService = require "resources.functions.basic_event_service"

local service = BasicEventService.new(log, service_name)

service:bind("CHANNEL_DESTROY", function(self, name, event)
	local refer_uuid, bridge_uuid = event:getHeader('variable_refer_uuid'), event:getHeader('variable_bridge_uuid')
	if refer_uuid and bridge_uuid then
		log.infof('found refer %s=>%s', refer_uuid, bridge_uuid)
		local key = 'refer:' .. refer_uuid
		local ok, err = cache.set(key, bridge_uuid, 180)
		if not ok then
			if err then log.errf('can not store key in memcached: %s', tostring(err)) end
		end
	end
end)

log.notice("start")

service:run()

log.notice("stop")

channel_utils.lua

require 'resources.functions.config'
require 'resources.functions.trim'

local Database = require 'resources.functions.database'

local api = api or freeswitch.API()

function channel_variable(uuid, name)
	local result = api:executeString("uuid_getvar " .. uuid .. " " .. name)

	if result:sub(1, 4) == '-ERR' then return nil, result end
	if result == '_undef_' then return false end

	return result
end

-- can be used to get some headers like `Call-State` or `Unique-ID`
-- channel_evalute(uuid, '${Unique-ID}')
function channel_evalute(uuid, cmd)
	local cmd = ("eval uuid:%s %s"):format(uuid, cmd)
	local result = api:executeString(cmd)

	if result:sub(1, 4) == '-ERR' then return nil, result end
	if result == '_undef_' then return false end

	return result
end

function channel_transfer(uuid, ext, typ, ctx)
	local cmd = ("uuid_transfer %s %s %s %s"):format(uuid, ext, typ, ctx)
	local result = trim(api:executeString(cmd))
	if result:sub(1, 4) == '-ERR' then return nil, result end
	if result == '_undef_' then return false end
	return result
end

function channel_kill(uuid, cause)
	cause = cause or 'CALL_REJECTED'
	local cmd = ("uuid_kill %s %s"):format(uuid, cause)
	local res = trim(api:executeString(cmd))
	return res == '+OK'
end

function channel_display(uuid, text)
	local cmd = ("uuid_display %s '%s'"):format(uuid, text)
	local result = trim(api:executeString(cmd))
	if result:sub(1, 4) == '-ERR' then return nil, result end
	if result == '_undef_' then return false end
	return result
end

function channel_exists(uuid)
	local cmd = ("uuid_exists %s"):format(uuid)
	local result = trim(api:executeString(cmd))
	if result:sub(1, 4) == '-ERR' then return nil, result end
	return result == 'true'
end

local _switchname
local function switchname()
	if _switchname then return _switchname end

	local result = api:executeString("switchname")

	if result:sub(1, 4) == '-ERR' then return nil, result end
	if result == '_undef_' then return false end

	_switchname = result
	return result
end

function channels_by_number(number, domain)
	local hostname = assert(switchname())
	local dbh = Database.new('switch')

	local full_number = number .. '@' .. (domain or '%')

	local sql = ([[select * from channels where hostname='%s' and (
		(context = '%s' and (cid_name = '%s' or cid_num = '%s'))
		or name like '%s' or presence_id like '%s' or presence_data like '%s'
		)
		order by created_epoch
	]]):format(hostname,
		domain, number, number,
		full_number, full_number, full_number
	)

	local rows = assert(dbh:fetch_all(sql))

	dbh:release()
	return rows
end

intercept.lua

--
--	FusionPBX
--	Version: MPL 1.1
--
--	The contents of this file are subject to the Mozilla Public License Version
--	1.1 (the "License"); you may not use this file except in compliance with
--	the License. You may obtain a copy of the License at
--	http://www.mozilla.org/MPL/
--
--	Software distributed under the License is distributed on an "AS IS" basis,
--	WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
--	for the specific language governing rights and limitations under the
--	License.
--
--	The Original Code is FusionPBX
--
--	The Initial Developer of the Original Code is
--	Mark J Crane <markjcrane@fusionpbx.com>
--	Copyright (C) 2010 - 2016
--	the Initial Developer. All Rights Reserved.
--
--	Contributor(s):
--	Mark J Crane <markjcrane@fusionpbx.com>
--	Errol W Samuels <ewsamuels@gmail.com>

--user defined variables
	local extension = argv[1];
	local direction = argv[2] or extension and 'inbound' or 'all';

-- we can use any number because other box should check sip_h_X_*** headers first
	local pickup_number = '*8' -- extension and '**' or '*8'

--include config.lua
	require "resources.functions.config";

--add the function
	require "resources.functions.explode";
	require "resources.functions.split";
	require "resources.functions.is_uuid";
	require "resources.functions.trim";
	require "resources.functions.channel_utils";

--prepare the api object
	api = freeswitch.API();

--Get cache class
	local cache = require "resources.functions.cache"

--Get intercept logger
	local log = require "resources.functions.log".intercept

--include database class
	local Database = require "resources.functions.database"

--include json library
	local json
	if (debug["sql"]) then
		json = require "resources.functions.lunajson"
	end

--get the hostname
	local hostname = trim(api:execute("switchname", ""));

-- redirect call to another box
	local function make_proxy_call(destination, call_hostname)
		destination = destination .. "@" .. domain_name
		local profile, proxy = "internal", call_hostname;
		local peer = CLUSTER_PEERS and CLUSTER_PEERS[proxy];
		if peer then
			if type(peer) == "string" then
				profile = peer;
			else
				profile = peer[1] or profile;
				proxy = peer[2] or proxy;
			end
		end

		local sip_auth_username = session:getVariable("sip_auth_username");
		local sip_auth_password = api:execute("user_data", sip_auth_username .. "@" .. domain_name .." param password");
		local auth = "sip_auth_username="..sip_auth_username..",sip_auth_password='"..sip_auth_password.."'"
		dial_string = "{sip_invite_domain=" .. domain_name .. "," .. auth .. "}sofia/" .. profile .. "/" .. destination .. ";fs_path=sip:" .. proxy;
		log.notice("Send call to other host....");
		session:execute("bridge", dial_string);
	end

-- check pin number if defined
	local function pin(pin_number)
		if not pin_number then
			return true
		end

		--sleep
			session:sleep(500);
		--get the user pin number
			local min_digits = 2;
			local max_digits = 20;
			local max_tries = "3";
			local digit_timeout = "5000";
			local digits = session:playAndGetDigits(min_digits, max_digits, max_tries, digit_timeout, "#", "phrase:voicemail_enter_pass:#", "", "\\d+");

		--validate the user pin number
			local pin_number_table = explode(",",pin_number);
			for index,pin_number in pairs(pin_number_table) do
				if (digits == pin_number) then
					--set the authorized pin number that was used
						session:setVariable("pin_number", pin_number);
					--done
						return true;
				end
			end

		--if not authorized play a message and then hangup
			session:streamFile("phrase:voicemail_fail_auth:#");
			session:hangup("NORMAL_CLEARING");
			return;
	end

-- do intercept if we get redirected request from another box
	local function proxy_intercept()
		-- Proceed calls from other boxes

		-- Check if this call from other box with setted intercept_uuid
			local intercept_uuid = session:getVariable("sip_h_X-intercept_uuid")

			if intercept_uuid and #intercept_uuid > 0 then
				log.notice("Get intercept_uuid from sip header. Do intercept....")
				session:execute("intercept", intercept_uuid)
				return true
			end

		-- Check if this call from other box and we need parent uuid for channel
			local child_intercept_uuid = session:getVariable("sip_h_X-child_intercept_uuid")
			if (not child_intercept_uuid) or (#child_intercept_uuid == 0) then
				return
			end

		-- search parent uuid
			log.notice("Get child_intercept_uuid from sip header.")
			local parent_uuid =
				channel_variable(child_intercept_uuid, 'ent_originate_aleg_uuid') or
				channel_variable(child_intercept_uuid, 'cc_member_session_uuid') or
				channel_variable(child_intercept_uuid, 'fifo_bridge_uuid') or
				child_intercept_uuid

			if parent_uuid == child_intercept_uuid then
				log.notice("Can not found parent call. Try intercept child.")
				session:execute("intercept", child_intercept_uuid)
				return true
			end

		-- search parent hostname
			call_hostname = hostname
		--[[ parent and child have to be on same box so we do not search it
			log.notice("Found parent channel try detect parent hostname")
			local dbh = Database.new('switch')
			local sql = "SELECT hostname FROM channels WHERE uuid='" .. parent_uuid .. "'"
			local call_hostname = dbh:first_value(sql)
			dbh:release()

			if not call_hostname then
				log.notice("Can not find host name. Channels is dead?")
				return true
			end
		--]]

			if hostname == call_hostname then
				log.notice("Found parent call on local machine. Do intercept....")
				session:execute("intercept", parent_uuid);
				return true
			end

			log.noticef("Found parent call on remote machine `%s`.", call_hostname)
			session:execute("export", "sip_h_X-intercept_uuid="..parent_uuid);
			make_proxy_call(pickup_number, call_hostname)
			return true
	end

-- return array of extensions for group
	local function select_group_extensions()
		-- connect to Fusion database
			local dbh = Database.new('system');

		--get the call groups the extension is a member of
			local sql = "SELECT call_group FROM v_extensions ";
			sql = sql .. "WHERE domain_uuid = :domain_uuid ";
			sql = sql .. "AND (extension = :caller_id_number ";
			sql = sql .. "OR  number_alias = :caller_id_number)";
			sql = sql .. "limit 1";
			local params = {domain_uuid = domain_uuid, caller_id_number = caller_id_number};
			if (debug["sql"]) then
				log.noticef("SQL: %s; params: %s", sql, json.encode(params));
			end
			local call_group = dbh:first_value(sql, params) or ''
			log.noticef("call_group: `%s`", call_group);
			call_groups = explode(",", call_group);

			params = {domain_uuid = domain_uuid};

		--get the extensions in the call groups
			sql = "SELECT extension, number_alias FROM v_extensions ";
			sql = sql .. "WHERE domain_uuid = :domain_uuid ";
			sql = sql .. "AND (";
			for key,call_group in ipairs(call_groups) do
				if key > 1 then sql = sql .. " OR " end
				if #call_group == 0 then
					sql = sql .. "call_group = '' or call_group is NULL";
				else
					local param_name = "call_group_" .. tostring(key)
					sql = sql .. "call_group like :" .. param_name;
					params[param_name] = '%' .. call_group .. '%';
				end
			end
			sql = sql .. ") ";
			if (debug["sql"]) then
				log.noticef("SQL: %s; params: %s", sql, json.encode(params));
			end
			local extensions = {}
			dbh:query(sql, params, function(row)
				local member = row.extension
				if row.number_alias and #row.number_alias > 0 then
					member = row.number_alias
				end
				extensions[#extensions+1] = member
				log.noticef("member `%s`", member)
			end);

		-- release Fusion database
			dbh:release()

		-- return result
			return extensions
	end

--check if the session is ready
	if ( session:ready() ) then
		--answer the session
			session:answer();
		--get session variables
			domain_uuid = session:getVariable("domain_uuid");
			domain_name = session:getVariable("domain_name");
			pin_number = session:getVariable("pin_number");
			context = session:getVariable("context");
			caller_id_number = session:getVariable("caller_id_number");
	end

--check if the session is ready
	if ( session:ready() ) then
		if proxy_intercept() then
			return
		end
	end

--check if the session is ready
	if ( session:ready() ) then
		--if the pin number is provided then require it
			if not pin(pin_number) then
				return
			end
	end

	if ( session:ready() ) then
		-- select intercept mode
			if not extension then
				log.notice("GROUP INTERCEPT")
				extensions = select_group_extensions()
			else
				log.noticef("INTERCEPT %s", extension)
				extensions = {extension}
			end

		--connect to FS database
			local dbh = Database.new('switch')

		--check the database to get the uuid of a ringing call
			call_hostname = "";
			sql = "SELECT uuid, call_uuid, hostname FROM channels ";
			sql = sql .. "WHERE callstate IN ('RINGING', 'EARLY') ";
			-- next check should prevent pickup call from extension
			-- e.g. if extension 100 dial some cell phone and some one else dial *8
			-- he can pickup this call.
			if not direction:find('all') then
				sql = sql .. "AND (1 <> 1 "
				-- calls from freeswitch to user
					if direction:find('inbound') then
						sql = sql .. "OR direction = 'outbound' ";
					end

				-- calls from user to freeswitch
					if direction:find('outbound') then
						sql = sql .. "OR direction = 'inbound' ";
					end
				sql = sql .. ") "
			end

			sql = sql .. "AND (1<>1 ";
			local params = {};
			for key,extension in pairs(extensions) do
				local param_name = "presence_id_" .. tostring(key);
				sql = sql .. "OR presence_id = :" .. param_name .. " ";
				params[param_name] = extension.."@"..domain_name;
			end
			sql = sql .. ") ";
			sql = sql .. "AND call_uuid IS NOT NULL ";
			sql = sql .. "LIMIT 1 ";
			if (debug["sql"]) then
				log.noticef("SQL: %s; params: %s", sql, json.encode(params));
			end
			local is_child, channel_uuid
			dbh:query(sql, params, function(row)
				--for key, val in pairs(row) do
			 	--	log.notice("row "..key.." "..val);
				--end
				--log.notice("-----------------------");
				is_child = (row.uuid == row.call_uuid)
				uuid = row.call_uuid;
				channel_uuid = row.uuid;
				call_hostname = row.hostname;
			end);
			log.notice("uuid: "..uuid);
			log.notice("call_hostname: "..call_hostname);

			-- it is can be attended transfer
			if uuid and not is_child and call_hostname == hostname then
				log.info('<<<<< Try detect attended transfer case >>>>>')
				-- test case with attended transfer when transferer hangup, but transfer
				-- target does not answer. In this case a-leg -- does not exists anymore
				if not channel_exists(uuid) then
					log.info('<<<<< no call channel assume it hangup >>>>>')
					-- external service have to put this info in temporary storage.
					-- It can be done e.g. in xml cdr handler or via Lua script using EventConsumer
					-- or in external ESL service
					local bridge_uuid, err = cache.get('refer:' .. uuid)
					log.info('<<<<< bridge_uuid ' .. tostring(bridge_uuid or err) .. ' >>>>>')
					if not bridge_uuid then
						-- in some cases FS calls `uuid_bridge` app before transfer target answer
						-- se we can try find `transfer_source` header to find out needed channel.
						-- Format is `<timestamp>:<channel_unique_id>:uuid_br:<channel_uuid>
						-- or `<timestamp>:<channel_uuid>:uuid_br:<channel_unique_id>.
						-- Seems we need handle only first one.
						log.info('<<<<< try detect uuid_bridge info >>>>>')
						bridge_uuid, err = channel_variable(channel_uuid, 'transfer_source')
						if bridge_uuid then
							log.info('<<<<< found transfer_source header >>>>>')
							_, bridge_uuid = split_first(bridge_uuid, ':uuid_br:', true)
							log.info('<<<<< bridge_uuid ' .. tostring(bridge_uuid) .. ' >>>>>')
							uuid = bridge_uuid or uuid
						end
					end
					uuid = bridge_uuid or uuid
				end
			end

			if is_child then
				-- we need intercept `parent` call e.g. call in FIFO/CallCenter Queue
				if (call_hostname == hostname) then
					log.notice("Found child call on local machine. Try find parent channel.")
					local parent_uuid = 
						channel_variable(uuid, 'ent_originate_aleg_uuid') or
						channel_variable(uuid, 'cc_member_session_uuid') or
						channel_variable(uuid, 'fifo_bridge_uuid') or
						uuid
					--[[ parent and child have to be on same box so we do not search it
					if parent_uuid ~= uuid then
						local sql = "SELECT hostname FROM channels WHERE uuid='" .. uuid .. "'"
						call_hostname = dbh:first_value(sql)
					end
					--]]

					if call_hostname then
						uuid = parent_uuid
						if call_hostname ~= hostname then
							log.noticef("Found parent call on remote machine `%s`.", call_hostname)
						else
							log.notice("Found parent call on local machine.")
						end
					end

				else
					log.noticef("Found child call on remote machine `%s`.", call_hostname)
					-- we can not find parent on this box because channel on other box so we have to
					-- forward call to this box
					session:execute("export", "sip_h_X-child_intercept_uuid="..uuid);
					return make_proxy_call(pickup_number, call_hostname)
				end
			end

		--release FS database
			dbh:release()
	end

	log.noticef( "Hostname: %s Call Hostname: %s", hostname, call_hostname);

--intercept a call that is ringing
	if (uuid ~= nil) then
		if (session:getVariable("billmsec") == nil) then
			if (hostname == call_hostname) then
				session:execute("intercept", uuid);
			else
				session:execute("export", "sip_h_X-intercept_uuid="..uuid);
				make_proxy_call(pickup_number, call_hostname)
			end
		end
	end

--notes
	--originate a call
		--cmd = "originate user/1007@voip.example.com &intercept("..uuid..")";
		--api = freeswitch.API();
		--result = api:executeString(cmd);

uv_event_service.lua

-- Implement service class for FusionPBX that uses LibUV library to connect to FS.
-- So it can be run from FS like `luarun service.lua` or as standalone process.
--
-- @usage
--
-- local service = EventService.new('blf', { '127.0.0.1', '8021', 'ClueCon',
--   reconnect = 5;
--   subscribe = {'PRESENCE_PROBE'}, filter = { ['Caller-Direction']='inbound' }
-- })
--
-- -- FS receive SUBSCRIBE to BLF from device
-- service:on("esl::event::PRESENCE_PROBE::*", , function(self, eventName, event)
--   local proto = event:getHeader('proto')
-- end)
--
-- service:run()
--

local uv            = require "lluv"
local ut            = require "lluv.utils"
local ESLConnection = require "lluv.esl.connection".Connection
local Logging       = require "log"

local new_uuid
if freeswitch then
  local api  = require "resources.functions.api"
  new_uuid = function()
    return api:execute("create_uuid")
  end
else
  local Uuid = require "uuid"
  new_uuid = function()
    return Uuid.new()
  end
end

-- create new pid file and start monitor on it.
-- if file removed/changed then service terminates
local function service_pid_file(service, pid_path)
  local log = service:logger()
  local service_name = service:name()

  local buffers = {
    push = function(self, v)
      self[#self + 1] = v
      return self
    end;
    pop  = function(self)
      local v = self[#self];
      self[#self] = nil
      return v
    end;
  }

  local function read_file(p, cb)
    local buf = buffers:pop() or uv.buffer(1024)
    uv.fs_open(p, "r", function(file, err, path)
      buffers:push(buf)
      if err then return cb(err) end
      file:read(buf, function(file, err, data, size)
        file:close()
        if err then return cb(err) end
        return cb(nil, data:to_s(size))
      end)
    end)
  end

  local function write_file(p, data, cb)
    uv.fs_open(p, 'w+', function(file, err, path)
    if err then return cb(err) end
    file:write(data, function(file, err)
      file:close()
      return cb(err)
    end)
    end)
  end

  local uuid = new_uuid()
  local pid_file = pid_path .. "/" .. service_name .. ".tmp"

  local pid = {pid = uuid, file = pid_file, valid = true}

  local test_in_progress
  local function test_pid_file()
    if test_in_progress then return end
    test_in_progress = true
    read_file(pid.file, function(err, data)
      test_in_progress = false
      if err then
        log.infof('can not read pid file: %s', tostring(err))
        return uv.stop()
      end

      if data ~= pid.pid then
        log.infof('detect launch second instance of service')
        pid.valid = false -- we do not remove it when stop service
        return uv.stop()
      end
    end)
  end

  -- crete pid file
  uv.fs_mkdir(pid_path, function(loop, err)
    if err and err:no() ~= uv.EEXIST then
      log.errf('can not create pid directory: %s', tostring(err))
      return uv.stop()
    end
    write_file(pid.file, pid.pid, function(err)
      if err then
        log.errf('can not create pid file: %s', tostring(err))
        return uv.stop()
      end

      uv.timer():start(30000, 30000, test_pid_file)

      uv.fs_event():start(pid.file, function(_, err, path, ev, ...)
        if err then
          log.warningf('can not start file monitoring')
        end
        return test_pid_file()
      end)
    end)
  end)

  return pid
end

-- start service process
local function service_start(service)
  local log = service:logger()

  local pid if freeswitch then
    require "resources.functions.config"
    local pid_path = scripts_dir .. "/run"
    pid = service_pid_file(service, pid_path)
  end

  log.infof('service %s started', service:name())

  local ok, err = pcall(uv.run)

  if not ok then
    log.errf('%s', tostring(err))
  end

  log.infof('service %s stopped', service:name())

  if pid and pid.valid then
    os.remove(pid.file)
  end
end

-- register all needed listeners to manage service status
local function service_init_loop(service)
  local log = service:logger()

  service:on("esl::event::CUSTOM::*", function(self, eventName, event)
    if event:getHeader('Event-Subclass') ~= 'fusion::service::control' then
      return
    end

    if service:name() ~= event:getHeader('service-name') then return end

    local command = event:getHeader('service-command')
    if command == "stop" then
      log.infof('receive stop service command')
      return uv.stop()
    end
  end)

  service:on("esl::event::SHUTDOWN::*", function(self, eventName, event)
    log.infof('freeswitch shutdown')
    return uv.stop()
  end)

  service:on('esl::reconnect', function(self, eventName)
    log.infof('esl connected')
  end)

  service:on('esl::disconnect', function(self, eventName, err)
    log.infof('esl disconnected')
  end)

  service:on('esl::error::**', function(self, eventName, err)
    log.errf('esl error: %s', tostring(err))
  end)

  service:on('esl::close', function(self, eventName, err)
    -- print(eventName, err)
  end)

  --! @todo way to stop service if it runnuing not from FS
  -- E.g. using LuaService on Windows and signals on *nix systems

  return service
end

local function append(t, v)
  t[#t + 1] = v
end

local EventService = ut.class(ESLConnection) do
local super = ut.class.super(EventService)

function EventService:__init(service_name, params)
  params = params or {}
  params.subscribe = params.subscribe or {}

  if freeswitch then
    append(params.subscribe, 'CUSTOM::fusion::service::control')
    append(params.subscribe, 'SHUTDOWN')
    if params.filter and next(params.filter) then
        params.filter['Event-Subclass'] = 'fusion::service::control'
        params.filter['Event-name']     = 'SHUTDOWN'
    end
  end

  self = super(self, '__init', params)

  local log do
    local writer if freeswitch then
      writer = require "log.writer.prefix".new('[' .. service_name .. '] ',
        require "log.writer.freeswitch".new()
      )
    else
      writer = require "log.writer.stdout".new()
    end

    log = Logging.new( writer,
      require "log.formatter.pformat".new()
    )

    log.errf     = log.errf     or log.error
    log.warningf = log.warningf or log.warning
    log.infof    = log.infof    or log.info
    log.debugf   = log.debugf   or log.debug
  end
  self._logger = log

  self._service_name = service_name

  service_init_loop(self)

  return self:open()
end

function EventService:run()
  service_start(self)
end

function EventService:stop()
  uv.stop()
end

function EventService:logger()
  return self._logger
end

function EventService:name()
  return self._service_name
end

end

return EventService