Ncrafts.io - Refactor your software architecture

Refactor your Software Architecture

Who am I?Julien Lavigne du CadetDev lead at Criteo

http://fr.linkedin.com/in/julienlavigneducadet/@julienlavigne

How to structure yourenterprise applications

… a business problem!

We often start with…

That we try to solve with…

That we try to solve with…

Languages

Frameworks

Persistencetechnologies

...and a 3 tiers architecture

Business

Data

UI

…and a 3 tiers architecture

Asp.net MVC

SQL Server

Angular

…and a 3 tiers architecture

WCF

SQL Server

WPF

...and a 3 tiers architecture

Play

Oracle

Ember

With some layers…

DTOApplication LogicBusiness LogicData Access

Database

UI

With some layers…

Application LogicBusiness LogicData Access

Database

UI

And it grows…

And it grows…

… and it gets slow!

And it gets unmaintanable!

Why?Why?

Releases are all or nothing*

Releases are all or nothing**Some people will tell you that’s why we have stored procedures... Don’t trust them :p.

Refactorings are expansiveMigrating to new frameworks requires rewriting a whole layer

One size doesn’t fit allHard to have custom solutions for a vertical

What can we do?

We learned to split in the wrong direction

Split the system into small components…

… releasable independently from each other

Architecture:interfaces and interactions between our components

Business

Database

UI

Or how to go from…

UI

To…

UI

Or more realistically to…

Business

Database

UI

Or even that…

Business

Database

Job Scheduler

How do we proceed?

Start small

Identify one featurethat has few dependencies… Example: sending emails

Define the APIinterface & communication protocol

Choose an architectural style

RESTWEB SERVICESERVICE BUS…

What is the offered service?

What is the offered service?

InputsFROMTOTITLEBODY

What is the offered service?

InputsFROMTOTITLEBODY

OutputsACK / ERROR CODECALLBACKS / EVENTS

UI

Focus on

Implement and deploydeployment should be independent of everything else!

Replace usages everywhere

Go back to step one and… start again**a lot… :-)

The next steps

Start writing all new code in components

Encapsulate legacy codeIt’s fine to have some uglyness in a component as long as the interface is clean!

Define clear boundaries

Make everything accessible through an APIFrom business features to technical features

What did we achieve?

Reuse and centralisation

Independent deployments…and rollbacks!Shorter release cycles, less risks, happy users!

Independent component designsKeep It Simple, Stupid

Independent component designsExperiment!

Replaceable components

Easier testingTest the component & the interactions with the component

In conclusion…

Software architecture is aboutdefining high level principles…

To shorten release cycles…

And keep the system maintenable

My suggestion

build small components…

That communicate throuh defined interfaces

Give it a try!

Thank you!

We’re hiring!http://www.criteo.com/en/jobs