Microservices are re-revolutionizing the enterprise technology landscape. With a sudden spurt of services around us we have 2 choices to build clients. A) The imperative style or B) the reactive style. This talk focuses on building modern clients which consume microservice endpoints using the reactive style and its associated advantages. The plot is delivered through a series of logical steps. Starting with the imperative model; we convert it to reactive style programming using RxJava, bake in parallelism using a simple directive and finally bake in fault tolerance using hystrix. We also talk briefly about protocol buffers as a means to have a robust contract between the service and the client. This talk was presented during SapientNitro's Xperience Infinite October 2014 event in Bangalore.

1. THE RESILIENT ENTERPRISE
Master class one

2. Anand is deeply rooted in technology. Over the past 15 years he has been involved
in the realization of several Omni channel commerce implementations across travel,
hospitality and the retail industries. He is amazed at the ‘’constant acceleration’’ of
technology innovation and it’s impact on our daily responsibilities as technologists.
Anand Raman
Director, Technology
Sagar has helped our clients develop leading solutions in social, travel and eRetail
space. Recently his team build a popular & engaging social shopping app for a large
US retailer. Recently Sagar has been developing a POV bridging natural language
processing & machine learning technology spaces.
Sagar Prasad
Architect – Social, Search & Recommendation System

3. https://twitter.com/rajaramc/status/517457240853577729

5. Our World Is Changing on 3 Dimensions
Scale
Complexity
Experience
 Capturing All Interactions
 Market place platforms
 Limited time offers
 Omni channel (flexible fulfilment)
 Integrations
 Legacy systems
 Real time processing
 Analytics & Business Intelligence
 Products as platforms
 Devices / Touch points
 Responsive / Rich / Interactive
 Low latency
 Personalized / Ever present

6. WHAT USED TO BE THIS IS NOW THIS
On-Premise
Hosting
Cloud
Aware
Centralized
RDBMS
Distributed
NoSqls
Monolithic
Arch
Micro-
Services
Buy Build
Vendor
Packages
Open
Source
Async
Everywhere
Automate
Everything
Devops
Polyglot
Architectures
Partition
Everything

7. WHAT WILL YOU BET ON for a
Resilient Enterprise Ecosystem
NEW TOOLS ARE ON THE HORIZON
Microservices
http://wallpapertvs.com/violet-sky/

8. What Are Microservices
http://martinfowler.com/articles/microservices.html
• Well defined scope
• Small enough
• Self contained
• Independently
developed, deployed

9. Why Microservices
• Speed to market
• Maintainable
• Suited for 2-5 year
rewrite cycle
• Multiple teams
• TRULY POLYGLOT
(teams * tech stack)

10. Today’s Use case

11. Client Layer
Search Micro
Service
Listing Micro
Service
WebApplication
Value Objects
Mediator
Search Service
Stub
Review
Service
Stub
Image Service
Stub
Search Service
Review Service
Image Service
ETSY
JSONOverHTTP

12. #1 : Chatty Clients
Initial
Search Call
1
2
3
n
Classic waterfall
Search call is followed by
“pairs” of “synchronous”
review and image calls
How to compose calls
Effectively & Efficiently

13. Client Layer
Search Micro
Service
Listing Micro
Service
WebApplication
Value Objects
Mediator
Search Service
Stub
Review
Service
Stub
Image Service
Stub
Search Service
Review Service
Image Service
JSON
Over
HTTP
#2 : Data Serialization In Polyglot Env.

14. Micro-
services
Data
Serialization
Async
Call
Composition
Resiliency
Declarative
Call
Composition

15. System.out.println(“Hello W

16. Workspace Tour
Reviewed
Image Service
Started
Embedded
Containers
Captured
Call Timeline
Imperative
Composition
Recap

17. TimeLine
Initial
Search Call
1
2
3
n
Classic waterfall
Search call is followed by
“pairs” of “synchronous”
review and image calls

18. Micro-
services
Data
Serialization
Async
Call
Composition
Resiliency
Declarative
Call
Composition

19. ProtoBuf
Define Message Structure
Code Generator
C++ Java Python…
Servers & Clients • Language & Platform neutral,
flexible, efficient way to serialize
structured data
• Binary format
• Implemented in various
languages: Java, C++, Python ,
Go …

20. System.out.println(“Hello W

21. Recap
Updated
Proto Definition
Tested
Restarted
Container
Enhanced
Search Service

22. + Interoperability
+ Size & Performance
+ Backward compatibility
+ Well documented
+ Model schemas efficiently
+ Extensibility & Validations
WHY CHOOSE DATA SERIALIZATION

23. Micro-
services
Data
Serialization
Async
Call
Composition
Resiliency
Declarative
Call
Composition

24. http://upload.wikimedia.org/wikipedia/commons/e/e7/CNW_yard,_Chicago.jpg

25. ReactiveX
+ Composing, Transforming
+ Error Handling
+ Concurrency
Functional Constructs for
Composing Data Streams

26. Rx-Programming
Composes
asynchronous and
event-based data
flows using observable
sequences
Observable f1
Observer,
Subscriber
f2 f3
map merge

27. Another Example

28. Why RxJava
• Well Documented
• Polyglot Implementation
• Composable
• Declarative ( fluent )
• Everything is an Observable
• Future, Promise are hard

29. Imperative (pull) vs. Reactive (push)
Mediator
Service
Stub
Service
Imperative
Mediator
Observable
Stub Service
Reactive
Service Stub

30. 1
2
Code
Ob. StubMed. Service

31. Ob. StubMed. Service

32. Ob. StubMed. Service

33. System.out.println(“Hello W

34. While The Timeline Looks Familiar;
Initial
Search Call
1
2
3
n
Indistinguishable from
Imperative style
Search call is still followed by
“pairs” of “synchronous”
review and image calls

35. We Have an Effective Composition

36. All You May Ever Need
Async
Conditional
Parallel
Processing
Rx
Combining
Error
Handling
Filtering Transform …….

38. Micro-
services
Data
Serialization
Async
Call
Composition
Resiliency
Declarative
Call
Composition

40. System.out.println(“Hello W

41. Recap : TimeLine
Initial
Search Call
Execution profile has changed
completely
After the initial search call all
calls to fetch images and
reviews are Asynchronous
Power of A directive

42. Micro-
services
Data
Serialization
Async
Call
Composition
Resiliency
Declarative
Call
Composition

43. Chronology Of a Failure
https://github.com/Netflix/Hystrix/wiki

45. HystrixCommand
run
failover
constructor
Command Name
Command Properties

49. System.out.println(“Hello W

50. Recap
• CB protected the application
• Prevented poorly performing calls from blocking
main execution thread
• Essential at all layers; especially for external
services

51. http://bit.ly/xi2014-reactive

52. Questions

53. Be social