Good Enough is Good Enough

“Minimal Viable Architecture” in a Startup

Randy Shoup @randyshoup

linkedin.com/in/randyshoup

http://xkcd.com/974/

Minimal Viable Architecture

• You Ain’t Going to Need It (!)

• Use the Right Tool for the Right Job (at the Right Time!)

• Only Change Incrementally

Phases of a Startup• Search Phase

• Execution Phase

• Scaling Phase

Phases of a Startup• Search Phase

• Execution Phase

• Scaling Phase

Search Phase: “Prototype” Architecture

• Goal: Explore the space as rapidly and cheaply as possible

• Find business model• Find product market fit• Acquire first customers

• Rapid Iteration• *Everything* is a prototype• You *will* throw it all away

“Do things that don’t scale”

-- Paul Graham

Search Phase: “Prototype” Architecture

• Ideally No Technology At All

• I’m serious – what are you even building?!

• If you *really* need to build something …• Familiar technology• Cobble it together

Phases of a Startup• Search Phase

• Execution Phase

• Scaling Phase

Execution Phase: “Just Enough” Architecture

• Goal: Meet near-term, evolving customer needs as cheaply as possible

• Delight first customers• Acquire more

• Rapid Learning and Improvement

• Team Productivity

• NOT about scaling

“The best code you can write now is code you’ll discard in a couple of years time”

-- Martin Fowler

http://martinfowler.com/bliki/SacrificialArchitecture.html

Execution Phase: “Just Enough” Architecture

• Familiar Technology• Ease of Use• Expressive Power• Simple (!)

• Monolithic Architecture• Single database

• Minimal Infrastructure• PaaS over IaaS

The Monolithic Architecture

2-3 monolithic tiers

• {JS, iOS, Android}

• {PHP, Ruby, Python}

• {MySQL, Mongo}

Presentation

Application

Database

The Monolithic Architecture

Simple at first

In-process latencies

Single codebase, deploy unit

Resource-efficient at small scale

Pros

Coordination overhead as team grows

Poor enforcement of modularity

Poor scaling (vertical only)

All-or-nothing deploy (downtime, failures)

Long build times

Cons

X

Execution Phase: “Just Enough” Architecture

• Modularity Discipline• Bound cognitive load• Easy to modify or replace

• Detailed Logging• Insights into user behavior• Diagnosis and recovery

• Continuous Delivery• Deploy many times per day

Phases of a Startup• Search Phase

• Execution Phase

• Scaling Phase

Scaling Phase: “Next-Gen” Architecture

• Goal: Stay ahead of rapidly growing business. Keep the site up (!)

• Scaling the Team

• Scaling the Technology

• Concurrency and Efficiency

“If you don’t end up regretting your early technology decisions, you probably over-engineered”

-- me

Scaling Phase: “Next-Gen” Architecture

• Technology that Scales• Common migrations to {Python, Go, JVM languages}• Concurrency• Asynchrony

• Independent systems• Fit-for-purpose systems: analytics, search• Layered services: caching, etc.• Event queue

• Scalable persistence• Break up the monolithic database• Functional partitioning • Sharding

• Scalable Infrastructure• IaaS for some systems

Scaling Phase: Change Incrementally• Find your worst scaling bottleneck

• Wall it off behind an interface

• Replace it

• Rinse and Repeat

You’re In Good Company

• eBay • 5th generation today• Monolithic Perl Monolithic C++ Java microservices

• Twitter• 3rd generation today• Monolithic Rails JS / Rails / Scala microservices

• Amazon• Nth generation today• Monolithic Perl / C++ Java / Scala microservices