text: # -*- coding: utf-8 -*-
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  from linux_metrics import cpu_stat, disk_stat, net_stat, mem_stat
  
  from liota.dccs.iotcc import IotControlCenter
  from liota.lib.utilities.identity import Identity
  from liota.entities.metrics.metric import Metric
  from liota.entities.devices.simulated_device import SimulatedDevice
  from liota.entities.edge_systems.dell5k_edge_system import Dell5KEdgeSystem
  from liota.dcc_comms.websocket_dcc_comms import WebSocketDccComms
  from liota.dccs.dcc import RegistrationFailure
  from liota.lib.utilities.utility import get_default_network_interface, get_disk_name, read_user_config
  
  
  # getting values from conf file
  config = read_user_config('sampleProp.conf')
  
  # Getting edge_system's network interface and disk name
  
  # There are situations where route may not actually return a default route in the
  # main routing table, as the default route might be kept in another table.
  # Such cases should be handled manually.
  network_interface = get_default_network_interface()
  # If edge_system has multiple disks, only first disk will be returned.
  # Such cases should be handled manually.
  disk_name = get_disk_name()
  
  
  
  # some standard metrics for Linux systems
  # agent classes for different IoT system
  # agent classes for different data center components
  # agent classes for different kinds of of devices, connected to the IoT System
  # we are showing here how to create a representation for a Device in IoTCC but
  # using the notion of RAM (because we have no connected devices yet)
  # agent classes for different kinds of layer 4/5 connections from agent to DCC
  # -------User defined functions for getting the next value for a metric --------
  # usage of these shown below in main
  # semantics are that on each call the function returns the next available value
  # from the device or system associated to the metric.
  
  def read_cpu_procs():
      return cpu_stat.procs_running()
  
  
  def read_cpu_utilization(sample_duration_sec=1):
      cpu_pcts = cpu_stat.cpu_percents(sample_duration_sec)
      return round((100 - cpu_pcts['idle']), 2)
      
  
  def read_disk_usage_stats():
      return round(disk_stat.disk_reads_writes(disk_name)[0], 2)
  
  
  def read_network_bytes_received():
      return round(net_stat.rx_tx_bytes(network_interface)[0], 2)
  
  
  def read_mem_free():
      total_mem = round(mem_stat.mem_stats()[1],4)
      free_mem = round(mem_stat.mem_stats()[3],4)
      mem_free_percent = ((total_mem-free_mem)/total_mem)*100
      return round(mem_free_percent, 2)
  
      
  #---------------------------------------------------------------------------
  # In this example, we demonstrate how System health and some simulated data
  # can be directed to data center component IoTCC using Liota.
  # The program illustrates the ease of use Liota brings to IoT application developers.
  
  if __name__ == '__main__':
  
      # create a data center object, IoTCC in this case, using websocket as a transport layer
      # this object encapsulates the formats and protocols necessary for the agent to interact with the dcc
      # UID/PASS login for now.
      identity = Identity(root_ca_cert=config['WebsocketCaCertFile'], username=config['IotCCUID'],
                          password=config['IotCCPassword'],
                          cert_file=config['ClientCertFile'], key_file=config['ClientKeyFile'])
  
      # Initialize DCC object with transport
      iotcc = IotControlCenter(
          WebSocketDccComms(url=config['WebSocketUrl'], verify_cert=config['VerifyServerCert'], identity=identity)
      )
  
      try:
          # create a System object encapsulating the particulars of a IoT System
          # argument is the name of this IoT System
          edge_system = Dell5KEdgeSystem(config['EdgeSystemName'])
  
          # resister the IoT System with the IoTCC instance
          # this call creates a representation (a Resource) in IoTCC for this IoT System with the name given
          reg_edge_system = iotcc.register(edge_system)
  
          # these call set properties on the Resource representing the IoT System
          # properties are a key:value store
          reg_edge_system.set_properties(config['SystemPropList'])
  
          # ---------- Create metrics 'on' the Resource in IoTCC representing the IoT System
          # arguments:
          # local object referring to the Resource in IoTCC on which the metric should be associated
          # metric name
          # unit = An SI Unit (work needed here)
          # sampling_interval = the interval in seconds between called to the user function to obtain the next value for the metric
          # aggregation_size = the number of values collected in a cycle before publishing to DCC
          # value = user defined function to obtain the next value from the device associated with this metric
          cpu_utilization_metric = Metric(
              name="CPU Utilization",
              unit=None,
              interval=10,
              aggregation_size=2,
              sampling_function=read_cpu_utilization
          )
          reg_cpu_utilization_metric = iotcc.register(cpu_utilization_metric)
          iotcc.create_relationship(reg_edge_system, reg_cpu_utilization_metric)
          # call to start collecting values from the device or system and sending to the data center component
          reg_cpu_utilization_metric.start_collecting()
  
          cpu_procs_metric = Metric(
              name="CPU Process",
              unit=None,
              interval=6,
              aggregation_size=8,
              sampling_function=read_cpu_procs
          )
          reg_cpu_procs_metric = iotcc.register(cpu_procs_metric)
          iotcc.create_relationship(reg_edge_system, reg_cpu_procs_metric)
          reg_cpu_procs_metric.start_collecting()
  
          disk_usage_metric = Metric(
              name="Disk Usage Stats",
              unit=None,
              interval=6,
              aggregation_size=6,
              sampling_function=read_disk_usage_stats
          )
          reg_disk_usage_metric = iotcc.register(disk_usage_metric)
          iotcc.create_relationship(reg_edge_system, reg_disk_usage_metric)
          reg_disk_usage_metric.start_collecting()
  
          network_bits_received_metric = Metric(
              name="Network Bytes Received",
              unit=None,
              interval=5,
              sampling_function=read_network_bytes_received
          )
          reg_network_bits_received_metric = iotcc.register(network_bits_received_metric)
          iotcc.create_relationship(reg_edge_system, reg_network_bits_received_metric)
          reg_network_bits_received_metric.start_collecting()
  
          # Here we are showing how to create a device object, registering it in IoTCC, and setting properties on it
          # Since there are no attached devices are as simulating one by considering RAM as separate from the IoT System
          # The agent makes possible many different data models
          # arguments:
          #        device name
          #        Read or Write
          #        another Resource in IoTCC of which the should be the child of a parent-child relationship among Resources
          ram_device = SimulatedDevice(config['DeviceName'], "Device-RAM")
          reg_ram_device = iotcc.register(ram_device)
          iotcc.create_relationship(reg_edge_system, reg_ram_device)
  
          # note that the location of this 'device' is different from the location of the IoTCC. It's not really different
          # but just an example of how one might create a device different from the IoTCC
          mem_free_metric = Metric(
              name="Memory Free",
              unit=None,
              interval=10,
              sampling_function=read_mem_free
          )
          reg_mem_free_metric = iotcc.register(mem_free_metric)
          iotcc.create_relationship(reg_ram_device, reg_mem_free_metric)
          reg_mem_free_metric.start_collecting()
  
      except RegistrationFailure:
          print "Registration to IOTCC failed"
  