This document provides an overview of Upwork's migration from a legacy PHP/Perl architecture to a new microservices-based architecture called Agora. It discusses the problems with the legacy stack and the goals of the new architecture. Specifically, it aimed to isolate risk, allow independent development teams, and enable advanced deployment techniques. It then describes how the presentation layer was refactored into a microservices-based framework called Agate using Symfony and Angular. Agate services communicate with Agora using Phystrix, an open source library based on Hystrix for circuit breaking and fallback handling. The document concludes with discussions around testing, visibility tools, and planned improvements.

1. Upwork PHP Architecture
Sep Nasiri
Software Architect at Upwork

2. Introduction
● Legacy Stack
● Challenges and reasons for modernization
● Overview of Upwork Architecture
● Focus on Presentation Tier and PHP

3. Legacy Stack
● Presentation Layer
○ PHP / Zend Framework
○ jQuery / Custom CSS
● Perl RPC Layer
● Both layers deployed to a cluster of App
Servers
● Deployed in hardware in our data center

4. Problems with Legacy Stack
● Infrequently releases
○ Weekly, then 3x a week
○ Release blockers - problems in one part
of the application would block other
teams features
● Aging codebase
○ frameworks getting out dated but hard
to upgrade

5. Requirement for New Architecture
● Isolate risk
○ problems in one part of the application
should not affect other parts
● Teams work in independent swimlanes
○ develop, test, and deploy independently
○ deploy features when ready
● Allow advanced deployment techniques
○ Automated
○ Blue/Green
○ Canary

6. New Backend Architecture - Agora
● Replace Perl Layer
● Java
● Microservices
● Netflix Open Source Software
○ Hystrix
○ Eureka
● AWS

7. Extending Microservices to the Frontend
- Agate
● Wanted to extend the benefits of Agora to
the presentation tier.
● Spit up our PHP and client side code (JS,
CSS, HTML) into independent units
● Challenges
○ Dealing with routing
○ Navigation / Header
○ Logging / Visibility

8. Agate Stack
● PHP / Symfony 2
● Angular JS
● Bootstrap

9. Agate Stack
● PHP / Symfony2
○ Lots of custom bundles
■ Distributed using Composer / Satis
● Component Library
○ Bootstrap
○ Angular
● Navigation Service

10. Talking to Agora - Phystrix
● Based on Netflix Hystrix
● Command Pattern
● Circuit breaker
○ prevent cascading failures
● Fallbacks
Open Source - https://github.
com/odesk/phystrix

11. Phystrix Example
use OdeskPhystrixAbstractCommand;
/**
* All commands must extends Phystrix's AbstractCommand
*/
class MyCommand extends AbstractCommand
{
protected $name;
public function __construct($name)
{
$this->name = $name;
}
/**
* This function is called internally by Phystrix, only if the request is allowed
*
* @return mixed
*/
protected function run()
{
return 'Hello ' . $this->name;
}
}

12. Phystrix Example
$myCommand = $phystrix->getCommand('MyCommand', 'Alex'); // 'Alex' is passed to MyCommand's constructor
$result = $myCommand->execute();

13. Visibility
● Metrics
○ graphite
○ metrics bundle
■ times actions
■ allows developers to add custom
timers
● Logstash / Elasticsearch / Kibana
○ aggregate logs

14. Testing
● PHPUnit
● Mocha
○ small test - karma
○ medium tests - protractor
● Jenkins
○ Docker build of each project
○ run tests in Docker

15. Planned improvements
● Docker based deployments
○ unify Agate and Agora deployment
● Continuous Integration / Delivery
○ improve our testing pipeline and Allow
fully automated deployments
● Configuration with Consul to allow Docker
images to move from dev to stage to prod

16. Thank You