Getting Off The Monorail

Moving to Service Orientated Architecture

Hello

Problems We Faced

One app

One app
Two app

One app
Two app
Three app

More

Growing Out Of Control

• More features than tests
• Interfaces being sidestepped
• Exponentially increasing complexity
• Invalid assumptions
• Undocumented dependencies

Concurrent Development

• Rapid changes in single source tree
• Constant clobbering and rebasing
• Inconsistent system design
• Deviation between teams goals

Test Suite Slowdown

• Integration tests masquerading as unit tests
• Unit tests as the poor cousin
• Testing the wrong things
• Poor configuration bloating running time

Code Stagnation

• Unused code paths not removed
• Refactoring
• Divergent implementations

Testing The Wrong Things

• Using functional tests as integration tests
• Too many integration tests
• Hitting databases in unit tests
• Testing static views instead of helper methods

Internationalisation

• More than just translation
• More than just localisation
• Opened US office (same language?)
• Finance makes this harder

The Way Out

Adequate Test Coverage

• Documentation for your software
• Implicit contract for interfaces
• Lets you know when things break
• You really need this!

Functional Separation

• Decouple software
• Create logical functional groupings
• Reduce scope of responsibility
• Break separated groupings into applications
• Enforce communication methods

Interface Contracts via APIs

• Harder to sidestep
• Design for external consumption
• Everyone becomes a consumer
• Doesn't have to be HTTP

Logging

• Log everything
• Levels should change per environment
• Ensure it's discoverable
• Must be centrally accessible
• Cause and consequence can be observed

Repeatable Configuration

• Recreate environments on demand
• Invaluable for development and test
• Enables scaling
• Reduces scope to code

12 Factor Apps

• Helped reduce manual processes
• Reduced difference between environments
• Solves many deployment related issues
• Hard to implement everything right

http://12factor.net

Commonality

• Avoid recreating the wheel
• Solve the hard problems once
• Create services via configuration

Help New People Help

Some Different Approaches

JavaScript Client Apps

• Faster page loads
• Improved code re-use
• Leverage browser capabilities
• More 'native' experience

Native Mobile Apps

• Offer functionality not available 'in-browser'
• Still very popular on mobile devices
• Provided quick wins for mobile users

Service-to-Service Clients

• APIs heavily used by institutional investors
• Planning to expand third party offering

Security, Security, Security

Authentication and Authorisation

• Centralise user access out of apps
• Consider different use cases
• Reduce access to logical groups
• Group roles into functional areas

Minimal Viable Caching

• Cache as much as possible
• Use pooled connections

Conclusions

Changing State Is Hard

Tests Are Your Expectations

Focus On Platform Performance