How to Scale your ARI Applications and how to write your production apps

1. ARI Scaling
& Production
Dan Jenkins
@dan_jenkins

2. Dan Jenkins
@dan_jenkins
5th Astricon!
Author of node-asterisk-ami package on github/npm
Lego
dan@nimblea.pe

3. Google Developer Expert
Web Technologies GDE
@dan_jenkins

4. Real Time Communications Consultancy
@nimbleapeltd

5. I've become fairly well
known to use lego images
in my slide decks...
@dan_jenkins

6. They're interesting
@dan_jenkins

7. And I ♥ Lego.
@dan_jenkins

8. So its Lego time!
@dan_jenkins

9. A tale of two parts

10. Scaling ARI
@dan_jenkins

11. Scaling is how we
handle traffic to and
from Asterisk via the
ARI interface in a way
that we can
support load
@dan_jenkins

12. Production
@dan_jenkins

13. How to architect your ARI
app for running in
production, failing over,
monitoring and reporting
@dan_jenkins

14. Who knows of the ARI?
@dan_jenkins

15. Who's built something
with the ARI?
@dan_jenkins

16. Who's deployed an ARI
app to production?
@dan_jenkins

17. Lets deconstruct how things work
with the other Asterisk interfaces...
@dan_jenkins

18. Built in Dialplan Applications
app_queue
app_dial
app_*
@dan_jenkins

19. Built in, no thought needed.
Contributors have sorted
everything...right?
@dan_jenkins

20. AMI
Asterisk Manager Interface
@dan_jenkins

21. TCP connection to
Asterisk
@dan_jenkins

22. Build something to
scale AMI yourself
@dan_jenkins

23. Asterisk
@dan_jenkins

24. Asterisk
@dan_jenkins

25. AMI Proxy
https://github.com/davetroy/astmanproxy
@dan_jenkins

26. AstMan Proxy
Asterisk Asterisk Asterisk
@dan_jenkins

27. (Fast)AGI
Asterisk Gateway Interface
@dan_jenkins

28. AGI adds processes
to our Asterisk
instance
Making our Asterisk instance busier
@dan_jenkins

29. Asterisk Asterisk Asterisk
@dan_jenkins

30. FastAGI allowed
a TCP call out to something,
somewhere else
@dan_jenkins

31. You can load balance
these calls out using a
TCP Proxy
@dan_jenkins

32. TCP Load Balancer
Asterisk Asterisk Asterisk
@dan_jenkins

33. But there are reasons
I love the ARI
compared to
AMI and AGI
@dan_jenkins

34. It does great
things with minimal
fuss and issue@dan_jenkins

35. It does things
"the Web" way
@dan_jenkins

36. Thank you
Asterisk Team!
@dan_jenkins

37. Before we look at how
to scale the ARI, we
need to understand
what it is
@dan_jenkins

38. What makes up the ARI?
@dan_jenkins

39. Dialplan
Its beautiful isn't it? 4 lines. That's it!
(It would be better without the Dialplan)
[Astricon]
exten = 100,1,Verbose(1, "Astricon call, woot")
same = n,Stasis(dangerous-demos)
same = n,Hangup()
@dan_jenkins

40. HTTP Interface and a
Websocket for Events
@dan_jenkins

41. HTTP
curl -v -u asterisk:asterisk -X POST "http://
localhost:8088/ari/channels/1400609726.3/
play?media=sound:hello-world"
@dan_jenkins

42. Websocket
{
"application":"hello-world",
"type":"StasisStart",
"timestamp":"2014-05-20T13:15:27.131-0500",
"args":[],
"channel":{
"id":"1400609726.3",
"state":"Up",
"name":"PJSIP/1000-00000001",
"caller":{
"name":"",
"number":""},
"connected":{
"name":"",
"number":""},
"accountcode":"",
"dialplan":{
"context":"default",
"exten":"1000",
"priority":3},
"creationtime":"2014-05-20T13:15:26.628-0500"}
}
@dan_jenkins

43. Call sessions from
Asterisk are tied to a
Websocket session
@dan_jenkins

44. Writing your ARI app
for Production
@dan_jenkins

45. With Dialplan
Applications we don't
need to care about
latency or load
@dan_jenkins

46. If Asterisk couldn't cope,
then you've got bigger
issues.
@dan_jenkins

47. In attempt to fix that, you'd
put Asterisk on a bigger
box
@dan_jenkins

48. Or spin up another and put
it behind a SIP proxy or
something
@dan_jenkins

49. Its kinda an already solved
problem
@dan_jenkins

50. But writing external
applications to Asterisk is
a different ball game.
@dan_jenkins

51. More moving parts.
@dan_jenkins

52. More connected services.
@dan_jenkins

53. More to monitor.
@dan_jenkins

54. VoIP infrastructure grows
into a Service Oriented
Architecture
@dan_jenkins

55. Where Asterisk is just a
small part of it.
@dan_jenkins

56. So what do we need to
care about when building
& deploying your ARI app?
@dan_jenkins

57. Latency
@dan_jenkins

58. Don't put your ARI
app too far away
@dan_jenkins

59. Its not like a normal
API being consumed.
@dan_jenkins

60. Making decisions and
informing Asterisk of them
shouldn't be hundreds of
milliseconds away
@dan_jenkins

61. Make your app do
your thing
@dan_jenkins

62. Conference engine
with your feature set
@dan_jenkins

63. Outbound Dialer via
your Customer API/
CRM
@dan_jenkins

64. Your specific idea.
@dan_jenkins

65. Your specific issue.
@dan_jenkins

66. Don't aim to replace
app_dial / app_queue /
app_voicemail / *
@dan_jenkins

67. Do your thang!
@dan_jenkins

68. Logging
@dan_jenkins

69. Log out data that is
useful.
@dan_jenkins

70. Pipe that data to a
centralised place
The ELK Stack for example
(Elasticserch | Logstash | Kibana)
@dan_jenkins

71. Think of future you
reading the logs.
Are they useful?
@dan_jenkins

72. Metrics
@dan_jenkins

73. Send stats out of your
application
StatsD - data points specific to your
application
@dan_jenkins

74. And then graph and
utilise them
(Telegraf | InfluxDB | Grafana)
@dan_jenkins

75. Inter process
communication
@dan_jenkins

76. Does your app need to talk
to other apps serving the
same ARI app name?
@dan_jenkins

77. Got a call on another
Asterisk/ARI app and need
to terminate it?
@dan_jenkins

78. How do you tell that other
App to terminate the call?
@dan_jenkins

79. Scaling
@dan_jenkins

80. Lets take a step away
from Asterisk
@dan_jenkins

81. Deploying and scaling
a HTTP Service in
Production
@dan_jenkins

82. HTTP Proxy/Load Balancer
HTTP
Service
HTTP
Service
HTTP
Service
@dan_jenkins

83. Deploying a service
that communicates
with an API
@dan_jenkins

84. Consuming HTTP
Based API
@dan_jenkins

85. HTTP Proxy/Load Balancer
External
API
External
API
External
API
@dan_jenkins

86. Consuming
Websocket Event API
@dan_jenkins

87. HTTP/TCP Proxy/Load Balancer
External
API
External
API
External
API
@dan_jenkins

88. They all have a load
balancer
@dan_jenkins

89. If there is state involved
then the application deals
with that
@dan_jenkins

90. Back to Asterisk
@dan_jenkins

91. The ARI Websocket is
tied to one or many
Stasis/ARI Apps
@dan_jenkins

92. You can't have multiple
Websockets tied to one
Asterisk using the same
App name
@dan_jenkins

93. Asterisk
Stasis App Name "hello-world"
@dan_jenkins

94. Asterisk
Stasis App Name "hello-world"
@dan_jenkins

95. Each Asterisk can
only handle 1
Websocket per App
Name
@dan_jenkins

96. You can have one web
socket handle
multiple app names
@dan_jenkins

97. For example, a
conferencing ARI App
@dan_jenkins

98. Simple
1 Asterisk and 1 ARI App
@dan_jenkins

99. Asterisk
Stasis App Name "conferencing"
@dan_jenkins

100. Pros and Cons
Pros Cons
• Simple • Doesn't scale
• You lose all your calls when
your app fails
@dan_jenkins

101. Not so simple
2 Asterisk and 1 ARI App
@dan_jenkins

102. AsteriskAsterisk
Stasis App Name "conferencing"
@dan_jenkins

103. Pros and Cons
Pros Cons
• Can potentially handle
more calls than a single
Asterisk
• Doesn't scale
• You lose all your calls when
your app fails
• There will eventually be a
bottleneck in your
application
@dan_jenkins

104. Complex
Multiple Asterisk &
Multiple Process (1:1)
@dan_jenkins

105. AsteriskAsteriskAsteriskAsterisk
Stasis App Name
"conferencing"
@dan_jenkins

106. Pros and Cons
Pros Cons
• Fairly simple • You lose all calls on that
Asterisk when your app
fails
• Nightmare configuring it
• Not flexible
@dan_jenkins

107. Really Complex
1 Asterisk & Multiple Processes
(through some dial plan magic)
@dan_jenkins

108. Asterisk
Stasis App Names
"conferencingA"
"conferencingB"
"conferencingC"
"conferencingD"
@dan_jenkins

109. Pros and Cons
Pros Cons
• There are none • Complicated to maintain in
your Dialpan
• If Asterisk dies, you lose all
your calls
@dan_jenkins

110. Add in Automated
infrastructure and
you've got a mess
@dan_jenkins

111. AsteriskAsteriskAsteriskAsterisk
Stasis App Names
"conferencingA"
...
"conferencingZ"
Asterisk
@dan_jenkins

112. AsteriskAsteriskAsteriskAsterisk
Stasis App Names
"conferencingA"
...
"conferencingZ"
Asterisk
@dan_jenkins

113. Pros and Cons
Pros Cons
• There are none • Complicated to maintain in
your Dialpan
• If Asterisk dies, you lose all
your calls
• A huge mess
@dan_jenkins

114. So how do we scale?
@dan_jenkins

115. So how do we scale easily?
@dan_jenkins

116. Quite simply, today,
there is only one way.
@dan_jenkins

117. ARI Proxy &
Message Bus
@dan_jenkins

118. 2 ARI Proxies
Available
Both support the same Message Bus Message format
(https://github.com/nvisibleinc/go-ari-library/wiki/Message-Format)
@dan_jenkins

119. Message Bus
RabbitMQ
NATS (Go Proxy only)
@dan_jenkins

120. AsteriskAsteriskAsteriskAsterisk
Stasis App Name "conferencing"
Message Bus
Proxy Proxy Proxy Proxy
*n
*n
@dan_jenkins

121. Libraries that support it
Go
.Net
Soon Node.js
@dan_jenkins

122. Libraries that support it
Go
.Net
Soon Node.js
What library do you use? PHPARI? ari4java?
@dan_jenkins

123. We need better library
support
@dan_jenkins

124. None of this is perfect
@dan_jenkins

125. I wish Asterisk gave
us a way of easily
scaling with ARI
@dan_jenkins

126. We talked about it at
AstriDevCon this year
@dan_jenkins

127. Should Asterisk do this
or should an external
Proxy do it?
@dan_jenkins

128. I'm not sure.
(And I was the one who brought it up)
@dan_jenkins

129. Building with ARI
is more complicated
than "Using Asterisk"@dan_jenkins

130. But that's no different to
learning how to
ride your bike
without stabilisers
@dan_jenkins

131. And you don't ride
your bike with
stabilisers any more
do you?
@dan_jenkins

132. Its time to get on the bike
and start peddling
@dan_jenkins

133. And hope you don't fall off
@dan_jenkins

134. But if you do, just get back up and try again
@dan_jenkins

135. Thanks!
@dan_jenkins
dan@nimblea.pe

136. Come see Dangerous
Demos Later!

137. https://upload.wikimedia.org/wikipedia/commons/2/21/250_365_-
_Bricks_(4247555680).jpg
https://www.flickr.com/photos/clement127/
(Huge thank you to clement127 for all their pictures over the years)
https://en.wikipedia.org/wiki/Lego#/media/File:LEGO_Building_At_KSC.jpg
https://www.flickr.com/photos/kalexanderson/8145886918
https://c2.staticflickr.com/8/7482/15936739285_460b008ec5_b.jpg
https://www.flickr.com/photos/arul72/23816127556
https://www.flickr.com/photos/kalexanderson/6101914287