diff --git a/acs.coffee b/acs.coffee
index 4c85dd8..2168feb 100644
--- a/acs.coffee
+++ b/acs.coffee
@@ -26,11 +26,34 @@ db.open( (err, db) ->
 )
 
 
-updateDevice = (deviceId, actions) ->
-  return if not actions?
+updateDevice = (deviceId, actions, callback) ->
+  if not actions?
+    callback() if callback?
+    return
+
+  updates = {}
   if actions.parameterValues?
-    params = common.arrayToHash(actions.parameterValues)
-    devicesCollection.update({'_id' : deviceId}, {'$set' : params}, {upsert: true})
+    for p in actions.parameterValues
+      if common.endsWith(p[0], '.')
+        updates["#{p[0]}_value"] = p[1]
+      else
+        updates["#{p[0]}._value"] = p[1]
+
+  if actions.parameterNames?
+    for p in actions.parameterNames
+      if common.endsWith(p[0], '.')
+        updates["#{p[0]}_writable"] = p[1]
+        updates["#{p[0]}_object"] = true
+      else
+        updates["#{p[0]}._writable"] = p[1]
+
+  if Object.keys(updates).length > 0
+    devicesCollection.update({'_id' : deviceId}, {'$set' : updates}, {upsert: true, safe: true}, (err) ->
+      callback(err) if callback?
+    )
+  else
+    callback() if callback?
+
 
 runTask = (sessionId, deviceId, task, reqParams, response) ->
   resParams = {}
@@ -115,7 +138,7 @@ else
               util.log("#{deviceId}: Added init task #{task._id}")
             )
 
-          devicesCollection.update({'_id' : deviceId}, {'$set' : common.arrayToHash(reqParams.informParameterValues)}, {upsert: true, safe:true}, (err, modified) ->
+          updateDevice(deviceId, {'parameterValues' : reqParams.informParameterValues}, (err) ->
             tr069.response(reqParams.sessionId, response, resParams, cookies)
           )
         )
diff --git a/common.coffee b/common.coffee
index 093d3b5..2ad4b22 100644
--- a/common.coffee
+++ b/common.coffee
@@ -16,3 +16,7 @@ exports.getDeviceId = (deviceIdStruct) ->
 
   return "#{escape(deviceIdStruct['OUI'])}-#{escape(deviceIdStruct['SerialNumber'])}"
 
+exports.extend = (obj, mixin) ->
+  obj[name] = method for name, method of mixin        
+  obj
+
diff --git a/tasks.coffee b/tasks.coffee
index e6e90da..a6a212f 100644
--- a/tasks.coffee
+++ b/tasks.coffee
@@ -2,24 +2,23 @@ common = require './common'
 BATCH_SIZE = 16
 
 this.init = (task, request, response) ->
+  ret = {}
   if not task.subtask?
     task.subtask = {'name' : 'getParameterNames', 'parameterPath' : '', 'nextLevel' : false}
 
   if task.subtask.name == 'getParameterNames'
-    ret = this.getParameterNames(task.subtask, request, response)
-    if ret? and ret.parameterNames? # task finished
+    common.extend(ret, this.getParameterNames(task.subtask, request, response))
+    if ret.parameterNames? # task finished
       parameterNames = []
       for p in ret.parameterNames
         if not common.endsWith(p[0], '.')
           parameterNames.push(p[0])
       task.subtask = {'name' : 'getParameterValues', 'parameterNames' : parameterNames}
-    else
-      return
 
   if task.subtask.name == 'getParameterValues'
-    return this.getParameterValues(task.subtask, request, response)
+    common.extend(ret, this.getParameterValues(task.subtask, request, response))
 
-  throw 'Unspecified error'
+  ret
 
 this.getParameterNames = (task, request, response) ->
   if request.getParameterNamesResponse?