diff --git a/lib/blessed-widget/layout.js b/lib/blessed-widget/layout.js
index 8253644..21a7746 100644
--- a/lib/blessed-widget/layout.js
+++ b/lib/blessed-widget/layout.js
@@ -1,14 +1,19 @@
+'use strict'
+
 var blessed = require('blessed')
 var chalk = require('chalk')
 var async = require('async')
 var _ = require('lodash')
+
 var widgets = require('./widgets')
 var conf = require('../util/conf')
 var Log = require('../util/log')
 
+var ignoredENVKeys = ['LS_COLORS']
+var regJSON = /("(\\u[a-zA-Z0-9]{4}|\\[^u]|[^\\"])*"(\s*:)?|\b(true|false|null)\b|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?)/g
+
 module.exports = Layout
 
-var exiting = false
 /**
  * Create layout.
  * @param {Object} options
@@ -17,6 +22,7 @@ function Layout (options) {
   if (!(this instanceof Layout)) {
     return new Layout(options)
   }
+  // initialize options
   options = _.clone(options || {})
   if (!options.hostname) {
     options.hostname = '127.0.0.1'
@@ -24,14 +30,20 @@ function Layout (options) {
   if (!options.port) {
     throw new Error('Port of socket.io server is required!')
   }
-  options.sockets = options.sockets || {}
-  this.options = options
   this._eles = {}
-  this._procCount = 0
+  this._data = {
+    processCount: -1,
+    sockets: options.sockets || {}
+  }
+  delete options.sockets
+  this.options = options
+  Object.freeze(this.options)
 }
 
 /**
  * Render GUI.
+ * @param  {Monitor} monitor
+ * @return {N/A}
  */
 Layout.prototype.render = function (monitor) {
   var self = this
@@ -39,22 +51,19 @@ Layout.prototype.render = function (monitor) {
 
   // Preparing all socket.io clients.
   async.series(Object.keys(conf.NSP).map(function (ns) {
-    return function (callback) {
-      var callbackOnce = _.once(callback)
+    return function (next) {
       var nsl = ns.toLowerCase()
-      if (options.sockets[nsl]) {
-        return callbackOnce()
+      if (self._data.sockets[nsl]) {
+        return next()
       }
-
+      // connect to monitor
       monitor.connect(_.extend({
         namespace: conf.NSP[ns]
-      }, options), function (socket) {
-        console.info('Connected to', socket.nsp)
-        callbackOnce(null, socket)
-      }, function (err, socket) {
+      }, options), function (err, socket) {
         if (err) {
-          return callbackOnce(new Error('Failed to connect to [' + ns + '] due to ' + err.message))
+          return next(new Error('Fatal to connect to ' + socket.nsp + ' due to ' + err))
         }
+        next(null, socket)
       })
     }
   }), function (err, res) {
@@ -62,6 +71,7 @@ Layout.prototype.render = function (monitor) {
       console.error(err.message)
       return process.exit(0)
     }
+    // muted logger.
     Log({
       level: 1000
     })
@@ -69,14 +79,15 @@ Layout.prototype.render = function (monitor) {
     res.forEach(function (socket) {
       connectedSockets[socket.nsp.replace(/^\/+/g, '')] = socket
     })
-    self.sockets = _.extend(connectedSockets, options.sockets)
-    delete options.sockets
+    // cache sockets.
+    _.extend(self._data.sockets, connectedSockets)
 
+    // render layout.
     self._observe()
     self._draw()
-
+    // refresh processes every 1s
     setInterval(function () {
-      self._bindProcesses()
+      self._processesTable()
     }, 1000)
   })
 }
@@ -87,108 +98,121 @@ Layout.prototype.render = function (monitor) {
 Layout.prototype._observe = function () {
   var self = this
   console.info('Listening socket events...')
-  var socketSys = this._socket(conf.NSP.SYS)
-  socketSys.on('procs', function (procs) {
-    self._procs = {
-      data: procs,
-      tick: Date.now()
-    }
-    if (typeof self._procs === 'undefined') {
-      self._bindProcesses()
-    }
-  })
-  socketSys.emit('procs')
+  // watch processes
+  this._socket(conf.NSP.PROCESS)
+    .on(conf.SOCKET_EVENTS.DATA_PROCESSES, function (procs) {
+      self._data.processes = {
+        data: procs,
+        tick: Date.now()
+      }
+      self._processesTable()
+    })
+    .emit(conf.SOCKET_EVENTS.PULL_PROCESSES)
+    .on(conf.SOCKET_EVENTS.DATA_USAGE, function (proc) {
+      if (!self._data.usages || proc.pid !== self._data.usages.pid || self._data.usages.time === proc.time) {
+        return
+      }
+      self._data.usages.time = proc.time
+      self._data.usages.cpu.shift()
+      self._data.usages.cpu.push(Math.min(100, Math.max(proc.usage.cpu, 1)))
+      self._data.usages.mem.shift()
+      self._data.usages.mem.push(Math.min(100, Math.max(proc.usage.memory, 1)))
+    })
 
-  this._socket(conf.NSP.PROC).on('proc', function (proc) {
-    if (!self._usages || proc.pid !== self._usages.pid || self._usages.time === proc.time) {
+  // subscribe logs
+  this._socket(conf.NSP.LOG).on(conf.SOCKET_EVENTS.DATA, function (log) {
+    if (!self._eles.logs || self._data.lastLogPMId !== log.id) {
       return
     }
-    self._usages.time = proc.time
-    self._usages.cpu.shift()
-    self._usages.cpu.push(Math.min(100, Math.max(proc.usage.cpu, 1)))
-    self._usages.mem.shift()
-    self._usages.mem.push(Math.min(100, Math.max(proc.usage.memory, 1)))
-  })
-
-  this._socket(conf.NSP.LOG).on('log', function (log) {
-    if (!self._eles.logs || self._lastLogPMId !== log.pm_id) {
-      return
-    }
-    self._eles.logs.log(log.msg)
+    self._eles.logs.log(log.text)
   })
 }
 
 /**
- * Bind processes to table.
+ * Render processes in a datatable
+ * @return {N/A}
  */
-Layout.prototype._bindProcesses = function () {
-  if (exiting || !this._eles.processes || !this._procs) {
+Layout.prototype._processesTable = function () {
+  if (this._data.exiting || !this._eles.processes || !this._data.processes) {
     return
   }
-  if (this._procs.tick === this._procsLastTick) {
+  if (this._data.processes.tick === this._data.processesLastTick) {
     // Update tick only.
-    return setRows.call(this, true)
+    return this._processesTableRows(true)
   }
 
-  if (typeof this._procsLastTick === 'undefined') {
+  if (_.isUndefined(this._data.processesLastTick)) {
+    // show first process informations.
     this._describeInfo(0)
-    this._eles.processes.rows.on('select', onSelect.bind(this))
+    // bind `select` event on datatable.
+    this._eles.processes.rows.on('select', this._onProcessesTableSelect.bind(this))
   }
+  // cache last tick
+  this._data.processesLastTick = this._data.processes.tick
+  // render rows of datatable
+  this._processesTableRows(true)
+}
 
-  this._procsLastTick = this._procs.tick
+/**
+ * Render processes datatable rows
+ * @param  {Boolean} forceRefresh
+ * @return {N/A}
+ */
+Layout.prototype._processesTableRows = function (forceRefresh) {
+  var rows = []
+  var selectedIndex = this._eles.processes.rows.selected
+  var len = this._data.processes.data.length
 
-  setRows.call(this, true)
+  this._data.processes.data.forEach(function (p, i) {
+    var pm2 = p.pm2_env
+    var index = '[' + (i + 1) + '/' + len + ']'
+    rows.push([
+      ' ' + chalk.grey((index + Array(8 - index.length).join(' '))) + ' ' + p.name,
+      pm2.restart_time,
+      pm2.status !== 'online' ? '0s' : _fromNow(Math.ceil((Date.now() - pm2.pm_uptime) / 1000), true),
+      pm2.status === 'online' ? chalk.green('✔') : chalk.red('✘')
+    ])
+  })
+  this._eles.processes.setData({
+    headers: [' Name', 'Restarts', 'Uptime', ''],
+    rows: rows
+  })
 
-  function setRows (forceRefresh) {
-    var rows = []
-    var selectedIndex = this._eles.processes.rows.selected
-    var len = this._procs.data.length
+  selectedIndex = !_.isUndefined(selectedIndex) ? selectedIndex : 0
+  var maxIndex = this._eles.processes.rows.items.length - 1
+  if (selectedIndex > maxIndex) {
+    selectedIndex = maxIndex
+  }
+  this._eles.processes.rows.select(selectedIndex)
 
-    this._procs.data.forEach(function (p, i) {
-      var pm2 = p.pm2_env
-      var index = '[' + i + '/' + len + ']'
-      rows.push([
-        ' ' + chalk.grey((index + Array(8 - index.length).join(' '))) + ' ' + p.name,
-        pm2.restart_time,
-        pm2.status !== 'online' ? '0s' : _fromNow(Math.ceil((Date.now() - pm2.pm_uptime) / 1000), true),
-        pm2.status === 'online' ? chalk.green('✔') : chalk.red('✘')
-      ])
-    })
-    this._eles.processes.setData({
-      headers: [' Name', 'Restarts', 'Uptime', ''],
-      rows: rows
-    })
+  if (forceRefresh) {
+    this._onProcessesTableSelect()
+  }
+}
 
-    selectedIndex = typeof selectedIndex !== 'undefined' ? selectedIndex : 0
-    var maxIndex = this._eles.processes.rows.items.length - 1
-    if (selectedIndex > maxIndex) {
-      selectedIndex = maxIndex
-    }
-    this._eles.processes.rows.select(selectedIndex)
-
-    if (forceRefresh) {
-      onSelect.call(this)
+/**
+ * Listening select event on processes datatable.
+ * @param  {Object} item
+ * @param  {Number} selectedIndex
+ * @return {N/A}
+ */
+Layout.prototype._onProcessesTableSelect = function (item, selectedIndex) {
+  if (!!item) { // eslint-disable-line no-extra-boolean-cast
+    var lastIndex = this._data.lastSelectedIndex
+    this._data.lastSelectedIndex = selectedIndex
+    if (selectedIndex !== lastIndex) {
+      this._describeInfo(selectedIndex)
     }
   }
-
-  function onSelect (item, selectedIndex) {
-    if (!!item) { // eslint-disable-line no-extra-boolean-cast
-      var lastIndex = this._lastSelectedIndex
-
-      this._lastSelectedIndex = selectedIndex
-      if (selectedIndex !== lastIndex) {
-        this._describeInfo(selectedIndex)
-      }
-    }
-    this._cpuAndMemUsage(this._lastSelectedIndex || 0)
-    this._displayLogs(this._lastSelectedIndex || 0)
-    this.screen.render()
-  }
+  this._cpuAndMemUsage(this._data.lastSelectedIndex || 0)
+  this._displayLogs(this._data.lastSelectedIndex || 0)
+  this._eles.screen.render()
 }
 
 /**
  * Get description of a specified process.
  * @param  {Number} index the selected row index.
+ * @return {N/A}
  */
 Layout.prototype._describeInfo = function (index) {
   var pm2 = this._dataOf(index)
@@ -199,7 +223,9 @@ Layout.prototype._describeInfo = function (index) {
   }
   if (pm2.pm2_env && pm2.pm2_env.env) {
     // Remove useless large-bytes attributes.
-    delete pm2.pm2_env.env['LS_COLORS']
+    ignoredENVKeys.forEach(function (envKey) {
+      delete pm2.pm2_env.env[envKey]
+    })
   }
   delete pm2.monit
   this._eles.json.setContent(_formatJSON(pm2))
@@ -208,60 +234,63 @@ Layout.prototype._describeInfo = function (index) {
 /**
  * CPU and Memory usage of a specific process
  * @param  {Number} index the selected row index.
+ * @return {N/A}
  */
 Layout.prototype._cpuAndMemUsage = function (index) {
   var pm2 = this._dataOf(index)
   if (!pm2) {
     return
   }
-  if (!this._usages) {
-    this._usages = {
+  if (!this._data.usages) {
+    this._data.usages = {
       mem: [],
       cpu: []
     }
     var len = this._eles.cpu.width - 4
     for (var i = 0; i < len; i++) {
-      this._usages.cpu.push(1)
-      this._usages.mem.push(1)
+      this._data.usages.cpu.push(1)
+      this._data.usages.mem.push(1)
     }
   }
-  if (pm2.pid !== 0 && this._procCount === 2) {
-    this._procCount = -1
-    this._socket(conf.NSP.PROC).emit('proc', pm2.pid)
+  // fetch process info every 3 times
+  if (pm2.pid !== 0 && this._data.processCount === 2) {
+    this._data.processCount = -1
+    this._socket(conf.NSP.PROCESS).emit(conf.SOCKET_EVENTS.PULL_USAGE, pm2.pid)
   }
-  this._procCount++
-  this._usages.pid = pm2.pid
+  this._data.processCount++
+  this._data.usages.pid = pm2.pid
 
-  this._eles.cpu.setData(this._usages.cpu, 0, 100)
-  this._eles.cpu.setLabel('CPU Usage (' + (this._usages.cpu[this._usages.cpu.length - 1]).toFixed(2) + '%)')
+  this._eles.cpu.setData(this._data.usages.cpu, 0, 100)
+  this._eles.cpu.setLabel('CPU Usage (' + (this._data.usages.cpu[this._data.usages.cpu.length - 1]).toFixed(2) + '%)')
 
-  this._eles.mem.setData(this._usages.mem, 0, 100)
-  this._eles.mem.setLabel('Memory Usage (' + (this._usages.mem[this._usages.mem.length - 1]).toFixed(2) + '%)')
+  this._eles.mem.setData(this._data.usages.mem, 0, 100)
+  this._eles.mem.setLabel('Memory Usage (' + (this._data.usages.mem[this._data.usages.mem.length - 1]).toFixed(2) + '%)')
 }
 
 /**
  * Display logs.
- * @param  {Number} index [description]
- * @return {[type]}       [description]
+ * @param  {Number} index
+ * @return {N/A}
  */
 Layout.prototype._displayLogs = function (index) {
   var pm2 = this._dataOf(index)
-  if (!pm2 || this._lastLogPMId === pm2.pm_id) {
+  if (!pm2 || this._data.lastLogPMId === pm2.pm_id) {
     return
   }
-  this._killLogs()
-  this._socket(conf.NSP.LOG).emit('tail', this._lastLogPMId = pm2.pm_id, true)
+  this._stopLogging()
+  this._socket(conf.NSP.LOG).emit(conf.SOCKET_EVENTS.PULL_LOGS, pm2.pm_id, true)
+  this._data.lastLogPMId = pm2.pm_id
 }
 
 /**
- * Kill `tail` process
- * @return {[type]}         [description]
+ * Stop logging.
+ * @return {N/A}
  */
-Layout.prototype._killLogs = function () {
-  if (typeof this._lastLogPMId === 'undefined') {
+Layout.prototype._stopLogging = function () {
+  if (_.isUndefined(this._data.lastLogPMId)) {
     return
   }
-  this._socket(conf.NSP.LOG).emit('tail_kill', this._lastLogPMId)
+  this._socket(conf.NSP.LOG).emit(conf.SOCKET_EVENTS.PULL_LOGS_END, this._data.lastLogPMId)
 }
 
 /**
@@ -270,14 +299,15 @@ Layout.prototype._killLogs = function () {
  * @return {Object}
  */
 Layout.prototype._dataOf = function (index) {
-  if (!this._procs || !Array.isArray(this._procs.data) || index >= this._procs.data.length) {
+  if (!this._data.processes || !Array.isArray(this._data.processes.data) || index >= this._data.processes.data.length) {
     return null
   }
-  return this._procs.data[index]
+  return this._data.processes.data[index]
 }
 
 /**
  * Draw elements.
+ * @return {N/A}
  */
 Layout.prototype._draw = function () {
   console.info('Rendering dashboard...')
@@ -289,21 +319,20 @@ Layout.prototype._draw = function () {
 
   // Processes.
   this._eles.processes = grid.get(0, 0)
-  this._bindProcesses()
+  this._processesTable()
 
-  this._eles.cpu = grid.get(1, 0)
-  this._eles.mem = grid.get(1, 1)
+  _.extend(this._eles, {
+    cpu: grid.get(1, 0),
+    mem: grid.get(1, 1),
+    logs: grid.get(2, 0),
+    json: grid.get(0, 2)
+  })
 
-  // Logs.
-  this._eles.logs = grid.get(2, 0)
-
-  // Detail.
-  this._eles.json = grid.get(0, 2)
   var offset = Math.round(this._eles.json.height * 100 / this._eles.json.getScrollHeight())
   var dir
   // Key bindings
   screen.key('s', function (ch, key) {
-    if (exiting) {
+    if (self._data.exiting) {
       return
     }
     var perc = Math.min((dir !== 'down' ? offset : 0) + self._eles.json.getScrollPerc() + 5, 100)
@@ -311,20 +340,19 @@ Layout.prototype._draw = function () {
     self._eles.json.setScrollPerc(perc)
   })
   screen.key('w', function (ch, key) {
-    if (exiting) {
+    if (self._data.exiting) {
       return
     }
     var perc = Math.max(self._eles.json.getScrollPerc() - 5 - (dir !== 'up' ? offset : 0), 0)
     dir = 'up'
     self._eles.json.setScrollPerc(perc)
   })
-
   screen.key(['escape', 'q', 'C-c'], function (ch, key) {
-    if (exiting) {
+    if (self._data.exiting) {
       return
     }
-    exiting = true
-    this._killLogs()
+    self._data.exiting = true
+    this._stopLogging()
     screen.title = 'PM2 Monitor (Exiting...)'
     screen.destroy()
     screen.title = ''
@@ -337,16 +365,17 @@ Layout.prototype._draw = function () {
   }.bind(this))
 
   screen.render()
-  this.screen = screen
+  this._eles.screen = screen
 }
 
 /**
  * Get socket.io object by namespace
  * @param  {String} ns
+ * @return {socket.io}
  */
 Layout.prototype._socket = function (ns) {
-  if (ns && this.sockets) {
-    return this.sockets[(ns || '').replace(/^\/+/g, '').toLowerCase()]
+  if (ns && this._data.sockets) {
+    return this._data.sockets[(ns || '').replace(/^\/+/g, '').toLowerCase()]
   }
   return null
 }
@@ -480,9 +509,9 @@ function _grid (screen) {
  * @private
  */
 function _formatJSON (data) {
-  data = JSON.stringify(typeof data !== 'string' ? data : JSON.parse(data), null, 2)
+  data = JSON.stringify(!_.isString(data) ? data : JSON.parse(data), null, 2)
 
-  return data.replace(/("(\\u[a-zA-Z0-9]{4}|\\[^u]|[^\\"])*"(\s*:)?|\b(true|false|null)\b|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?)/g, function (m) {
+  return data.replace(regJSON, function (m) {
     var color = 'blue'
     if (/^"/.test(m)) {
       color = ['magenta', 'green'][/:$/.test(m) ? 0 : 1]
diff --git a/lib/blessed-widget/widgets.js b/lib/blessed-widget/widgets.js
index 23f3935..3a75bac 100644
--- a/lib/blessed-widget/widgets.js
+++ b/lib/blessed-widget/widgets.js
@@ -1,9 +1,13 @@
+'use strict'
+
 // Inspired by the blessed-contrib, but more powerful and free.
 // (c) Tjatse
 
 var blessed = require('blessed')
+var _ = require('lodash')
 var util = require('util')
-var re_stripANSI = /(?:(?:\u001b\[)|\u009b)(?:(?:[0-9]{1,3})?(?:(?:;[0-9]{0,3})*)?[A-M|f-m])|\u001b[A-M]/g
+
+var regStripANSI = /(?:(?:\u001b\[)|\u009b)(?:(?:[0-9]{1,3})?(?:(?:;[0-9]{0,3})*)?[A-M|f-m])|\u001b[A-M]/g
 
 exports.Grid = Grid
 exports.Table = Table
@@ -14,13 +18,12 @@ exports.Log = Log
  * Grid cells.
  * @param {Object} options
  * @returns {Grid}
- * @constructor
  */
 function Grid (options) {
   if (!(this instanceof Grid)) {
     return new Grid(options)
   }
-  options = util._extend({
+  options = _.extend({
     margin: 2
   }, options || {})
 
@@ -55,7 +58,7 @@ Grid.prototype.set = function (ele) {
     }
     return
   }
-  this.grids[ele.row][ele.col] = util._extend({rowSpan: 1, colSpan: 1}, ele)
+  this.grids[ele.row][ele.col] = _.extend({rowSpan: 1, colSpan: 1}, ele)
 }
 /**
  * Draw grid.
@@ -109,7 +112,7 @@ Grid.prototype.draw = function (screen, rect) {
           left: left
         })
       } else {
-        screen.append(ele.instance = ele.element(util._extend(ele.options || {}, {
+        screen.append(ele.instance = ele.element(_.extend(ele.options || {}, {
           top: top + '%',
           left: left + '%',
           width: width + '%',
@@ -136,7 +139,7 @@ function Table (options) {
 
   blessed.Box.call(this, this.options)
 
-  this.rows = blessed.list(util._extend(this.options.rows || {}, {
+  this.rows = blessed.list(_.extend(this.options.rows || {}, {
     height: 0,
     top: 1,
     width: 0,
@@ -175,7 +178,7 @@ Table.prototype.setData = function (data) {
   var dataToString = function (d) {
     return d.map(function (s, i) {
       s = s.toString()
-      var s1 = s.replace(re_stripANSI, '')
+      var s1 = s.replace(regStripANSI, '')
       var size = !def ? widths : widths[i]
       var len = size - s1.length
 
@@ -208,7 +211,7 @@ function Sparkline (options) {
     return new Sparkline(options)
   }
 
-  this.options = util._extend({
+  this.options = _.extend({
     chars: ['▂', '▃', '▄', '▅', '▆', '▇', '█'],
     tags: true,
     padding: {