This document discusses the API design, deployment, and architecture of EvoSure's systems. It describes: 1) EvoSure's product architecture which includes a Backbone.js web app that only communicates through the API, and an API built with JRuby, Sinatra, and Postgres. 2) Their process for designing, documenting, testing, and prototyping APIs. 3) How APIs are deployed using immutable infrastructure on AWS with CloudFormation templates, Auto Scaling Groups, Elastic Load Balancer, and Route 53 for high availability and elasticity. 4) Their transition to using messaging to capture business events and allow for multiple actions from one message.

1. Moving from API Design
to Deployment
James Higginbotham
CTO, EvoSure
@launchany

2. About EvoSure

3. Product Architecture
Web App
Backbone.js
JRuby + Rails
Only talks to the API
Provides API endpoints for UX optimization that are not
business capability APIs
API
JRuby + Sinatra
Database
Postgres 9.x

4. Designing APIs

5. API Implementation
Model
Capabilities
Design and Document
Endpoints
Acceptance
Tests
(outside-in)
Prototype
Payload

6. Consuming APIs

7. Internal APIs
No SDKs - direct APIs only
Timeouts
Retries
Local storage when appropriate

8. External APIs
No SDKs - direct APIs only
Timeouts
Retries
Fallback behavior with UX focus

9. Deploying APIs

10. Monolithic vs. Modular
Monolithic = API and Front-end in one app
Modular = separation of subsystems into different apps

11. From Heroku to AWS
Originally on Heroku with 2 apps: api and web
Support for older browsers prevented this
Moved to AWS for elasticity, security, and service offerings
S3
CloudFormation
RDS (PostgreSQL)
Auto Scale Groups (ASGs)
Elastic Load Balancer (ELB)
Route 53 DNS
Chef

12. Immutable Infrastructure
Huh?
Actually not that bad
Infrastructure is a “promise”
When the promise has to change, the stack changes
Blue-green deployment model
Patch deploys in between stack revisions

13. How we deploy to AWS
CloudFormation templates define a stack
Currently two stacks: „dev‟ and „prod‟
Stacks are versioned by name (e.g. dev3, prod3)
New stacks started in parallel
DNS switch when new stack is ready
CNAME with 300 sec TTL

14. The Move to Messaging
Business events are captured
Drive behavior
Allow for multiple actions from one message
Requires eventually consistent view of data

15. Fluentd: Logging + Messaging

16. Thank you.
http://evosure.com/careers
@launchany