Asterisk ARI interfacing using Python

With Asterisk 12 and onward, we have a new REST full application development approach.
Asterisk' ARI is a new asynchronous approach to interface your custom telephony applications with Asterisk. The dialplan introduced an application called STASIS. The clients are connected via webrtc. The dialplan blocks the execution on STASIS() and broadcast events on connected clients and wait for actions. The stasis() stop on hangup or end by the ARI client.

In this tutorial, I'll show you how we can play with DTMF, Music on Hold, Music File using STASIS and websocket client.

Configuration steps:
Install Asterisk with webrtc support, version should be Asterisk 12 or greater.
Install the followings.
>> yum install python  pip
>> pip install requests websocket-client

1- http.conf

[general]

enabled = yes

bindaddr = 0.0.0.0




2 - ari.conf

[general]

enabled = yes          

pretty = yes           

[asterisk]

type = user

read_only = no

password = asterisk




3 - extensions.conf

[default]

exten => 1000,1,NoOp()

 same =>      n,Answer()

 same =>      n,Stasis(hello-world)

 same =>      n,Hangup()




----------------------------------------------------------------------------

#Python Websocket based ARI Client.

#  As you dial 1000, this ARI client will play a tt-monkes. 

#  Press 1 to put the call on hold using default class

#  Press 2 to unhold the call

#  Press 3 to put the call on hold using custom MOH class

#  press 4 to stop MOH

############################################################################




#!/usr/bin/python

import json
import sys
import websocket
import threading
import Queue
import requests;
from gevent.ares import channel

class ARIInterface(object):
    def __init__(self, server_addr, username, password):
        self._req_base = "http://%s:8088/ari/" % server_addr
        self._username = username
        self._password = password

    def answer_call(self, channel_id):
        req_str = self._req_base+"channels/%s/answer" % channel_id
        self._send_post_request(req_str)

    def play_sound(self, channel_id, sound_name):
        req_str = self._req_base+("channels/%s/play?media=sound:%s" % (channel_id, sound_name))
        self._send_post_request(req_str)


    def continue_in_dialplan(self, channel_id):
        #print "in continue_in_dialplan()"
        #print  self._req_base+("channels/%s/continue" % (channel_id)) 
        req_str = self._req_base+("channels/%s/continue" % (channel_id))
        self._send_post_request(req_str)

    def music_on_hold(self, channel_id, moh_class):
        print "in music_on_hold()"
        print self._req_base+("channels/%s/moh?mohClass=custom" % (channel_id))
        
        req_str = self._req_base+("channels/%s/moh?mohClass=%s" % (channel_id, moh_class))
        self._send_post_request(req_str)
    
    def music_unhold(self, channel_id):
        print "unhold the music"
        #stopMoh
        print self._req_base+("channels/%s/moh" % (channel_id))
        req_str = self._req_base+("channels/%s/moh" % (channel_id))
        self._send_delete_request(req_str)
        

    def _send_post_request(self, req_str):
        r = requests.post(req_str, auth=(self._username, self._password))
        #print(r.text())

    def _send_delete_request(self, req_str):
        r = requests.delete(req_str, auth=(self._username, self._password)) 
        print r.status_code
        #print(r.text())   

class ARIApp(object):
    def __init__(self, server_addr):
        app_name = 'hello-world'
        username = 'asterisk'
        password = 'asterisk'
        url = "ws://%s:8088/ari/events?app=%s&api_key=%s:%s" % (server_addr, app_name, username, password)
        self.ari = ARIInterface(server_addr, username, password)
        self.ws = websocket.create_connection(url)
        self.channel_id = ''

        try:
            for event_str in iter(lambda: self.ws.recv(), None):
                event_json = json.loads(event_str)

                json.dump(event_json, sys.stdout, indent=2, sort_keys=True,
                          separators=(',', ': '))
                print("\n\nWebsocket event***************************************************\n")

                if event_json['type'] == 'StasisStart':
                    channel_id = event_json['channel']['id']
                    self.on_stasis_start(channel_id)
                    #self.ari.answer_call(event_json['channel']['id'])
                    #self.ari.play_sound(event_json['channel']['id'], 'tt-monkeys')
                    
                elif event_json['type'] =='StasisEnd':
                    channel_id = event_json['channel']['id']
                    self.on_stasis_end(channel_id)
                #ChannelDtmfReceived
                
                elif event_json['type'] =='ChannelDtmfReceived' :  
                    channel_id = event_json['channel']['id']
                    digit = event_json['digit']
                    self.on_channel_dtmf_received(channel_id, digit)


        except websocket.WebSocketConnectionClosedException:
            print("Websocket connection closed")
        except KeyboardInterrupt:
            print("Keyboard interrupt")
        finally:
            if self.ws:
                self.ws.close()



    def on_stasis_start(self, channel_id):
        print "ARI Session started\n";
        self.ari.answer_call(channel_id)
        #self.ari.play_sound(channel_id,'tt-monkeys')
        
                    
    def on_stasis_end(self, channel_id):
        print "Stasis Session ended\n"
        
    def on_channel_dtmf_received(self, channel_id, digit):
        print "DTMF Received: " + digit  
        # on any dtmf stop the stasis Application and goto next prirorty.
        #self.ari.continue_in_dialplan(channel_id)
        if('1' == digit):
            self.ari.music_on_hold(channel_id,'custom')
             
        elif('2' == digit):
            self.ari.music_unhold(channel_id)
        
        if('3' == digit):
            self.ari.music_on_hold(channel_id,'default')
             
        elif('4' == digit):
            self.ari.music_unhold(channel_id)

    def on_ChannelHangupRequest(self, channel_id):
        print "ChannelHangupRequest received" 
    
    def on_PlaybackFinished(self, channel_id):
        print "PlaybackFinished received"
       
if __name__ == "__main__":
    app = ARIApp('192.168.61.135')