The notion of "affordances" has played seminal role in transforming our understanding of usable service design. It is key in hypermedia architectural style and enables us to build resilient systems “at the scale of decades”. With the microservice architectural style, we can build systems that have higher degrees of freedom than those having monolith architectures. In such systems, effective orchestration and choreography are crucial. During this presentation, Irakli Nadareishvili, Director of API Strategy, API Academy, explores hypermedia-enabled approach that leads to loosely-coupled, evolvable service design. Seating is limited and available first come-first served. For more information, please visit http://cainc.to/Nv2VOe

1. Hypermedia-Driven Orchestration
in Microservices
Irakli Nadareishvili
DevOps: API Management and Application Development
CA Technologies
Director of Strategy, API Academy
Session DO3T25T
@inadarei
#CAWorld

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© 2015 CA. All rights reserved. All trademarks referenced herein belong to their respective companies.
The content provided in this CA World 2015 presentation is intended for informational purposes only and does not form any type of
warranty. The information provided by a CA partner and/or CA customer has not been reviewed for accuracy by CA.
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Abstract
Hypermedia-Driven Orchestration
in Microservices
The notion of "affordances" has played seminal role in transforming our
understanding of usable service design. It is key in hypermedia
architectural style and enables us to build resilient systems “at the scale
of decades”. With the microservice architectural style, we can build
systems that have higher degrees of freedom than those having
monolith architectures. In such systems, effective orchestration and
choreography are crucial. During this presentation, Irakli Nadareishvili,
Director of API Strategy, API Academy, explores hypermedia-enabled
approach that leads to loosely-coupled, evolvable service design.
Irakli
Nadareishvili
CA Technologies
Director of Strategy,
API Academy

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Architectural Styles and the Design of Network-based Software, 2001
- Roy T. Fielding
“Hypermedia is defined by the presence of application
control information embedded within, or as a layer
above, the presentation of information”
Hypermedia per Fielding

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Let API server dynamically guide a client by
responding to client with not just static data
but also controls describing API affordances.
Or: Response = Data + Controls

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Most common hypermedia controls facilitate:
“single, next step.”
Hypermedia Shortcoming?

7. How do we orchestrate
loosely-coupled microservices
for complex workflows?

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Examples:
E-COMMERCE
BOOKING TRAVEL1
2

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Booking Travel

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Saga: Long-Lived Compensating Transactions
Saga was introduced by Hector Garcia-Molina and Kenneth Salem in 1987.
Example scenario by Clemens Vasters: http://vasters.com/clemensv/2012/09/01/Sagas.aspx
Car Hotel Flight
Routing Slip

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@see: http://rels.messages.io
Link Relations for Saga:
§ rel = “routing-slip” (microformats)
§ rel = “compensatingtx” (microformats)

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E-Commerce

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3 Types of Complex Workflows
BROWSING/DISCOVERY— “HYPERMEDIA MAZE” (AMUNDSEN)
CHECKOUT—SERVICE ORCHESTRATION
POST-PURCHASE—SERVICE CHOREOGRAPHY
1
2
3

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Source: Richardson, Amundsen, Ruby, “RESTful Web APIs,” O’Reilly, 2013.
Maze Problems
– Mike Amundsen
“Problem is too complex to be
understood all at once,
so it’s split up into steps.”

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Maze + XML
Source: Richardson, Amundsen, Ruby, “RESTful Web APIs,” O’Reilly, 2013.

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Checkout
1. Collect Shipping Info 2. Billing Info 3. Authorize Payment
4. Post-Purchase Processing
Checkout: Orchestration

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Orchestration for Wizard-Style WFs:
Standard IANA link relations:
§ rel = “next”
§ rel = “prev”

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Post-Purchase
service
Shipping Service
E-mail Notification Service
SMS Notification Service
Purchase
Completed
event
Push Notification Service
Inspired by a choreography example in:
Sam Newman, Building Microservices, O’Reilly, 2015.
«subscribes to»
Post Purchase: Choreography

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@see: http://rels.messages.io
Service Choreography
§ rel = “hub” (IANA standard)
§ rel = “sub” (new: microformats)
§ rel = “unsub” (new: microformats)
§ rel = “events” (new: microformats)
Async and event-driven.
Standard: Pubsubhubbub

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Types of Complex Workflows
BROWSING/DISCOVERY— “HYPERMEDIA MAZE” (MIKE AMUNDSEN)
CHECKOUT—SERVICE ORCHESTRATION
POST-PURCHASE—SERVICE CHOREOGRAPHY
1
2
3
DISTRIBUTED TRANSACTIONS—SAGA4

21. Are there more workflow types?
Probably, but: next time!

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Q & A