Application requirements have changed dramatically in recent years, requiring millisecond or even microsecond response times and 100 percent uptime. This change has led to a new wave of andquot;reactive applicationsandquot; with architectures that are event-driven, scalable, resilient, and responsive. In this session, we present the blueprint for building reactive applications on AWS. We compare reactive architecture to the classic n-tier architecture and discuss how it is cost-efficient and easy to implement using AWS. Next, we walk through how to design, build, deploy, and run reactive applications in the AWS cloud, delivering highly responsive user experiences with a real-time feel. This architecture uses Amazon EC2 instances to implement server push to broadcast events to application clients; AWS messaging (Amazon SQS/SNS); Amazon SWF to decouple system components; Amazon DynamoDB to minimize contention; and Elastic Load Balancing, Auto Scaling, Availability Zones, Amazon VPC, and Amazon Route 53 to make reactive applications scalable and resilient.

1. © 2014 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified, or distributed in whole or in partwithout the express consent of Amazon.com, Inc.
November 13, 2014 | Las Vegas, NV
ARC 206ArchitectingReactive Applications on AWS
Atul Shukla, USEReady
Revanth Talari, USEReady

2. Agenda
•N-tier architecture and its limitations
•What is a Reactive Application
•Reactive Application architecture
•AWS for Reactive Applications
•Build a Reactive Application

3. Demo
N-Tier App
PopEvent

4. N-tier architecture
Front-end server
Internal API
Internal API
API
Poll
Poll
Database
Storage
Queries
Synchronous
User waits for update

5. N-tier architecture
•Synchronous communication
•Blocking
–Lower throughput
–Hardware under-utilization and higher costs
•Tightly coupled
–Location dependent
–Difficult to extend and maintain
•Blocking
•Pull-based

6. Application requirements have changed

7. Application requirements have changed
Petabytes of data

8. Application requirements have changed
Petabytes of data
100% uptime

9. Application requirements have changed
Sub seconds
response time
Petabytes of data
100% uptime

10. Change is inevitable
•Users
–Demands richer experiences
–Expects super fast response time
•Applications
–Need to scale-on-demand
–Always-On
–Real-time
•Business
–Need to react to these changing requirements

11. Traditional Style of applications cannot deliver on these requirements any longer

12. Responsive
Elastic
Resilient
Message-driven
Reactive Applications

13. Demo
Reactive App
http://popevent.elasticbeanstalk.com
PopEvent

14. Responsive
Application pushes updates to client in real time
Responsive
Elastic
Resilient
Message-driven

15. Elastic
Scales out and inas demand varies
Responsive
Elastic
Resilient
Message-driven

16. Elastic
Scales out and inas demand varies
Responsive
Elastic
Resilient
Message-driven

17. Responsive
Elastic
Resilient
Message-driven
Resilient
Survives failure of individual components

18. Responsive
Elastic
Resilient
Message-driven
Resilient
Survives failure of individual components

19. Responsive
Elastic
Resilient
Message-driven
Resilient
Survives failure of individual components

20. Messagedriven
Loosely coupled, message-driven components
Responsive
Elastic
Resilient
Message-driven

21. Responsive
Elastic
Resilient
Message-driven
Transition
•Synchronous
•Tightly coupled
•Blocking
•Pull-based
N-Tier
Reactive
N-tier to Reactive

22. N-tier to Reactive
Internal API
Internal API
API
Poll
Poll
Database
Storage
Queries
Synchronous
User waits for update
Front-end server

23. N-tier to Reactive
Front-end server
Internal API
Internal API
API
Database
Storage
Queries
Synchronous
User waits for update
Push
Push/Broadcast

24. N-tier to Reactive
Front-end server
Internal API
Internal API
Database
Storage
Queries
Synchronous
User waits for update
Push
Push/Broadcast
Message handlers

25. N-tier to Reactive
Front-end server
Internal API
Internal API
Database
Storage
Queries
Synchronous
User waits for update
Push
Push/Broadcast
Message handlers
Queue
messages

26. N-tier to Reactive
Front-end server
Internal API
Internal API
Database
Storage
Queries
Asynchronous
User waits for update
Push
Push/Broadcast
Message handlers
Queue
messages

27. Reactive architecture
•Asynchronous message passing
•Non-blocking
–Higher throughput
–Effective hardware utilization and lower costs
•Loosely coupled
–Location independent
–Easy to extend and maintain
•Push-based

28. AWS for Reactive Applications
•Responsive
–Amazon EC2 (Websocket Server)
–Amazon SNS
•Elastic
–Elastic Load Balancing
–Auto Scaling
–Elastic Beanstalk
–Amazon DynamoDB
•Resilient
–Availability Zones
–Amazon Route 53
–Auto Scaling
–Amazon VPC
–DynamoDB
•Message Driven
–Amazon SQS
–Amazon SWF

29. Let's build a reactive application
Goals
•React to Users
•React to Requests
•React to Load
•React to Failures
PopEvent

30. Reacting to users
Responsive
Elastic
Resilient
Message-driven

31. messageTopic
WebSocket
Server (EC2)
Subscribe/Notify
HTML5 Clients
SNS
Responsive
Elastic
Resilient
Message-driven

32. messageTopic
WebSocket
Server (EC2)
HTML5 Clients
WebSocket
Server (EC2)
Subscribe/Notify
SNS
Responsive
Elastic
Resilient
Message-driven

33. Amazon SNS -Overview
•Publish-subscribe model
•Scalable, robust way to implement push
•Topics
•Broadcast messages
Responsive
Elastic
Resilient
Message-driven

34. WebSocket -overview
•HTML5 Technology
•Full-duplex communication over TCP
Responsive
Elastic
Resilient
Message-driven

35. SockJS -overview
•Wrapper library over WebSocket
•Available for both clients and server
•SockJS library -https://github.com/sockjs
–Client side –sockjs-client
–Server Side –sockjs-node
Responsive
Elastic
Resilient
Message-driven

36. Server –Subscribe to Amazon SNS topic

37. Server –Define endpoints

38. Server –Create SockJS server

39. Client –Connect to SockJS server

40. Server –handle client connection

41. Client–Send Message to SockJS server
http://popevent.elasticbeanstalk.com

42. Server -Broadcast to clients

43. Responsive
Elastic
Resilient
Message-driven
messageTopic
WebSocket
Server (EC2)
Subscribe/Notify
HTML5 Clients
SNS
Done!!

44. Responsive
Elastic
Resilient
Message-driven

45. Reacting to requests
Responsive
Elastic
Resilient
Message-driven

46. Amazon SQS -overview
Responsive
Elastic
Resilient
Message-driven
•Enables loose coupling
•Enables location independent components
•Designed to provide high durability
•At least once delivery
•Timeouts to manage failure

47. Message to Tasks –Amazon SWF
Responsive
Elastic
Resilient
Message-driven
•Task based programming models
•Run application workflows
•Asynchronous invocation
•Coordinate distributed application processing
•Ordered execution of application steps
•At most once delivery
•Reliable and auditable

48. DynamoDB-overview
Responsive
Elastic
Resilient
Message-driven
•Fully managed cloud NoSQLdatabase
•Seamless Scaling
•Highly Available
•Flexible data models( key-value/document )

49. messageTopic
WebSocket
Server (EC2)
Subscribe/Notify
HTML5 Clients
Message
Worker
1. Receive
Message
DynamoDB
saveMessage
computePopular
calcPop
Worker
4.QueueMessage
1. Get Message
SQS
SQS
SNS
Responsive
Elastic
Resilient
Message-driven

50. Data Model
Responsive
Elastic
Resilient
Message-driven
•Tables
–Message
•messageId(String) –Primary Hash Key
•timeCreated(Number) –Primary Range Key
–likeCounter
•messageId(String) –Primary Hash Key
•dislikeCount(Number)
•likeCount(Number)

51. Key 1
Key 2
Key 3
Server 1
Server 2
Server 3
Server4
Server 5
Use unique keys to increase throughput

52. Hotkey -likeCounter

53. Responsive
Elastic
Resilient
Message-driven

54. Elastic Beanstalk -overview
•Fast and Simple way to deploy apps
•Makes development process productive
•Provides Auto Scaling and Elastic Load Balancing out of the box
•Complete resource control
•Free!! Pay only for resources used

55. Demo
Deploying with Elastic Beanstalk
PopEvent

56. Making WebSocket work
Select TCP

57. Making WebSocket work
Select None

58. Reacting to load—elastic
Responsive
Elastic
Resilient
Message-driven

59. Auto Scaling -Overview
•Scale-out and scale-in
•Works seamlessly with Amazon CloudWatch
•Define Auto Scaling groups
•Enables fault tolerance
•Enables high availability

60. Elastic Load Balancing -Overview
•Distribute the load automatically
•Works seamlessly with Auto Scaling groups
•Cross-zone load balancing
•Perform health checks

61. Reacting to load—elastic
•Auto Scaling
•Elastic Load Balancing
•Configure in Elastic Beanstalk

62. Auto Scaling

63. Auto Scaling –contd.

64. Elastic Load Balancing -Config

65. Elastic Load Balancing -Config

66. Elastic Load Balancing
Users
Load Balancer
EC2 Instances with Auto Scaling

67. messageTopic
WebSocket
Servers(EC2)
Subscribe/Notify
Message
Worker
1. Receive
Message
DynamoDB
saveMessage
computePopular
4.QueueMessage
1. Get Message
SQS
SQS
SNS
calcPop
Worker
Load Balancer
Users

68. Reacting to failures—resilient
Responsive
Elastic
Resilient
Message-driven

69. Reacting to failures—Level 1
•Avoiding single points of failures
•Auto Scaling and Elastic Load Balancing in a single Availability Zone.
•Configure minimum number of instances
Responsive
Elastic
Resilient
Message-driven

70. Users
Load Balancer
EC2 Instances with Auto Scaling
Reacting to failures—Level 1

71. Reacting to failures—Level 2
Users
Load Balancer
EC2 Instances with Auto Scaling.
Secured with Amazon VPC

72. Reacting to failures—Level 3
•Auto Scaling and Elastic Load Balancing across regions
•Configure minimum number of instances in each zone in each region
•Configure DNS entries in Amazon Route 53
Responsive
Elastic
Resilient
Message-driven

73. Amazon Route 53

74. Across regions –Amazon Route 53
Region 1
Region 2
Based on a routing policy
Amazon Route 53

75. Multi AZ and Multi region
messageTopic
WebSocket
Servers(EC2)
Subscribe/Notify
Message
Worker
1. Receive
Message
DynamoDB
saveMessage
computePopular
4.QueueMessage
1. Get Message
SQS
SQS
SNS
calcPop
Worker
Load Balancer
Users

76. Multi AZ and Multi region
Users
AZ1
AZ2
AZ1
AZ2
Region 1
Region 2

77. Demo
Reacting to failures—resilient

78. Responsive
Elastic
Resilient
Message-driven

79. Responsive
Elastic
Resilient
Message-driven
Reactive Applications

80. Thank You!

81. Please give us your feedback on this session.
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