Designing Modern Web Applications

Designing Modern Web Applications

by

Lucas Carlson

Programmer18 Years

Author• Ruby Cookbook

• Programming for PaaS

Entrepreneur• AppFog PaaS

• Mog Music Streaming Service

Current Role• Chief Innovation Officer at

CenturyLink

Who Am I?

Structure

1

Who Am I?2

What’s Wrong

With Legacy Web

Architectures?

3

How to Design a

Modern Web

Application

4

The 6 Worst

Web Practices and

How to Avoid Them

5

Getting the

Most From the

Cloud

6

Conclusions

What’s Wrong With

Legacy Web Architectures?

If it ain’t broke, don’t fix it… right?

Legacy Web Architectures

Web

Server2b

5

Application

Server

AppThena

Web App

Other

Web App

Other

Web App

Other

Web App

53

Database

Server

4

Data

CSS

Images

Pages

2a

BROWSE

R


Web

Server2b

5

Application

Server

AppThena

Web App

Other

Web App

Other

Web App

Other

Web App

53

Database

Server

4

Data

CSS

Images

Pages

BROWSE

R

Browser

6

Web

Server2b

5

Application

Server

AppThena

Web App

Other

Web App

Other

Web App

Other

Web App

53

Database

Server

4

Data

CSS

Images

Pages


Limited

Redundancy

Error 500


Web

Server

Application

Server

AppThena

Web App

Other

Web App

Other

Web App

Other

Web App

53

Database

Server

4

Data

CSS

Images

Pages

BROWSE

R


Browser

6

Web

Server

Application

Server

AppThena

Web App

Other

Web App

Other

Web App

Other

Web App

53

Database

Server

4

Data

CSS

Images

Pages

Limited

Scale

Error 500

Limited

Scale


1

5

Browser

6

Web

Server

5

2b

5

Application

Server

AppThena

Web App

Other

Web App

Other

Web App

Other

Web App

53

Database

Server

4

Data

CSS

Images

Pages

2a

Error 500


3-Tier

Systems

Scale… Up to a Point

Databases are

limited by disk size and

IO rates

Applications

are limited by RAM and CPU

As they get

more complex,they end up

breaking

Legacy Web

Architectures are

How to Design a

Modern Web Application

What’s the opposite of

fragile?

Hint: It’s not robustness

What’s the opposite of

fragile?

Answer : Antifragile

Anti-fragile

Definition

Examples

Break under

stress

Don’t care about

stress

Grow under

stress

The “Heart of Africa”

Characteristics

Monolithic Decentralized

Tightly coupled Loosely coupled

Heavyweight Lightweight

Complicated Simple

No redundancy Extra redundancy

AgileSluggish

Locked-in Interoperable

Anti-fragile

actively randomly kills

its own servers to

ensure its architectural

anti-fragility

Web Architectures Are Changing

To lightweight

distributed share-

nothing systems

From heavy

monolithic

backend systems


Web

Server

Application

Server

AppThena

Web App

Other

Web App

Other

Web App

Other

Web App

53

Database

Server

4

Data

CSS

Images

Pages

BROWSE

R

Modern Web Architectures

App App App AppLoad

Balancer

DB DB

BROWSE

R

Worker WorkerLoad

Balancer

Message Bus / Distributed Service Discovery

Resiliency

App App App AppLoad

Balancer

DB DB

BROWSE

R

Worker WorkerLoad

Balancer

Message Bus / Distributed Service Discovery

The 6 Worst Web Practices

and How to Avoid Them

Bad Practice #1:

Synchronicity

3-Tier Systems are like synchronous information factory lines

If one area chokes, the entire system fails

Usually leads to complex logical units

Bad Practice #2:

Dependency on Filesystems

State data (sessions, uploaded

files, etc) stored on hard drives is

very hard to scale

Requires NFS or equivalent which

are complex and chatty

Lock you into monolithic coding

practices

Bad Practice #3:

Heavy Server-Side Processing

Generating all the HTML server-

side made sense when client

hardware was slow

No REST/JSON/Javascript

All the information from a request

needs to be compiled before

returning any data

Bad Practice #4:

Expecting Services to Always Be Available

Designing for Success is Failure

Cloud infrastructure has higher

failure rates than dedicated

hardware

Disaster recovery can be slow

and prone to errors

Bad Practice #5:

Moving to the Cloud without a Plan

Cloud migration is often thought

of as simply a cost issue, not a

technical one

Higher failure rates in cloud

infrastructure will break fragile

applications

Migrations without a good plan

can cost a lot of unexpected

time and money

Bad Practice #6:

Lack of Redundancy

All single points of failure are

terrible monsters (DNS, Load

Balancers, Network, etc.)

Not only choke points, but can

take down an otherwise robust

system

All your eggs in one basket

Good Practice #1:

Asynchronous Processes

Small decoupled apps

Communicate through a queue,

REST APIs, or a message bus

Each one should do one thing very

well: simple and specialized

Good Practice #2:

Distributed Object Storage

Memcached, Redis, MongoDB,

CouchDB, etc.

Use instead of filesystems in legacy

web applications (sessions, file

uploads, etc.)

Consider replacing or caching the

largest and fastest growing relational

database tables with object storage

Good Practice #3:

Micro-Services

Leverage increased CPU capacity on

browsers with client-side Javascript

• AngularJS, Ember, Backbone

Simple and specialized REST APIs

• Java: Spring, Spark, Jersey

• .NET: WCF, OpenRasta

• Ruby: Sinatra

• Python: Flask, Bottle

• PHP: Slim

BONUS: Power your mobile apps

Good Practice #4:

Architecting for Failure

Think about anti-fragility upfront

Pro-actively stress your system

and study how it fails (not just load

testing, think of Netflix’s chaos

monkey)

Make all failures an opportunity to

eliminate bottlenecks, increase

redundancies and prepare for the

unexpected

Good Practice #5:

Use Cloud Migration as an Opportunity to

Modernize Architecture

Don’t half-do it

Not all applications will do well in cloud

environments

Automation is vital in cloud environments

where infrastructure isn’t reliable, traditional

IT can’t respond quickly enough

Good Practice #6:

Redundancy Everywhere

Audit every area of your application

for redundancy

2x or 3x redundancy is not enough

(the failure of one or two will over-

load and choke the remaining

systems)

Google’s rule of thumb is for 5x

redundancy

Be like the Hydra, kill one head and

grow two in its spot

Getting the Most From the Cloud

Portfolio of Cloud Services

EASY

HARD

SaaS and Cloud Managed

Services

IaaS and PaaS

DevOps and Orchestration

SaaS and Cloud Managed Services

Errors

Exceptional, Airbrake

Analytics

Statsmix, NewRelic,

Blitz

Other

Zerigo, CloudFlare,

Recurly, Stripe

Mobile

Urban Airship, Pusher,

Realtime.io

Data

ClearDB, Amazon

RDS, Heroku

Postgres, MongoLab

Search

Searify, Websolr, AWS

CloudSearch

Email

Mailgun, Sendgrid,

CloudMailin

Logging

Loggly, Logentries,

Papertrail

Background

Tasks

Iron.io, CloudAMQP

IaaS and PaaS

Heroku

AppFog

Cloud Foundry

OpenShift

Google App Engine

Azure

IaaS PaaS

AWS

Google

Azure

DigitalOcean

Rackspace

CenturyLink Cloud

DevOps and Orchestration

Apache

Mesos/Mesosphere

Kubernetes

CoreOS Fleet

OpenStack Heat

Chef

Puppet

SaltStack

Ansible

ZooKeeper

DevOps Orchestration

What’s Orchestration?

API-Driven Automation Built on Top of

DevOps Tools for Declaratively Deploying

Complex Cloud Apps

Orchestration :

Before Orchestration

Application

Job Scheduling

Engine

Job

Worker

Job

Worker

Job

Worker

Job

Worker

Database

After Orchestration

Orchestration API

Job Scheduling

Engine

App App DBJob

Worker

Modern App Architecture

Orchestration API

Job Scheduling

Engine

App App DBJob

Worker

App AppLoad

Balancer

DB WorkerLoad

Balancer

Message Bus / Distributed

Service Discovery

Conclusions

Conclusions

1. Legacy web architectures are

fragile

2. Think about anti-fragility (not

scalability) up-front

3. Micro-services are the anti-fragile

future:

Lightweight distributed

Share-nothing systems built with

APIs

1

2

3

Thank You!

@cardmagic

LucasCarlson.com

Designing Modern Web Applications

Technology

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