QCon London 2012: Breaking the monolith

Stefan Tilkov
Track: Architectures evolution

(enterprisy stuff)

3 layer architecture means nothing

• UI is not always helpful
• easy: don’t have to think

System boundaries

• 1 project == 1 system ? this is the worse approach
• architecture design is different from arbitrary system boundaries

Modularization and size

• SLOC grows when number of modules grows
• there’s a size limit to one application: split between different applications

Systems characteristics

• separate / redundant persistence
• internal separated logic
• domain model : implies strategies
• separated UI
• separate evolution
• autonomous operations
• limited interractions with other systems

Separate between different kind of architectures

Micro architecture (internal) VS Macro architecture (different systems)

Choice of different technologies leads to chaos ?

Rules and guidelines

Cross systems: decisions stuck with for a decade

• responsabilities
• UI integration
• communication protocols
• data format
• logging, monitoring

Systems internals: will change in the future

• programmation languages
• dev tools
• frameworks
• process / workflow contros
• design patterns
• code guidelines

Don’t mix these two levels.

Objectives change over time: change decisions, separated systems.

Overtime, first:

• ease of development
• homogeneity
• cohesion
• simplicity

then

• modularity
• decoupling
• (support for) henerogeneity
• autonomy

It’s hard to convince people to do things “first” at the begining of the project (not right first time).

How to integrate systems ?

Data integration VS data replication : why is it good for me ? Each application comes with its database but there are dependancies between databases : data copy. Think of event notification

Summary

• think about the systems that make up your system
• separate macro/micro architectures
• address UI integration and SSO