Aviran MordoHead of Back-end Engineering

@aviranm

linkedin.com/in/aviran

aviransplace.com

Scaling with Microservices Architecture and Multi-cloud platforms

Wix in Numbers

Over 66M users

Static storage is >2PB of data

3 data centers + 3 clouds (Google, Amazon, Azure)

2B HTTP requests/day

1000 people work at Wix

Initial Architecture

Built for fast development

Stateful login (Tomcat session), Ehcache, file

uploads

No consideration for performance, scalability and

testing

Intended for short-term use

Tomcat, Hibernate, custom web framework

Lighttpd(file

serving)MySQL

DB

Wix(Tomcat)

The Monolithic Giant

One monolithic server that handled everything

Dependency between features

Changes in unrelated areas of the system caused deployment of the whole system

Failure in unrelated areas will cause system wide downtime

Breaking the System Apart

Concerns and SLA

Data Validation

Security / Authentication

Data consistency

Lots of data

Edit websites

High availability

High performance

Lots of static files

Very high traffic volume

Viewport optimization

Long tail (immutable)

Serving Media

High availability

High performance

High traffic volume

Long tail (mutable)

View sites, created by Wix editor

Wix Segmentation

1. Editor Segment 3. Public Segment2. Media Segment

Networking

HTML Editor

Flash Editor

MSM

Private Media

Public Media

Editor Segment Public Segment

Premium Services

eCommerse

List DB

App Builder

App Store

App Market

Dashboard

Statics/media

Mailer

TimeZone

Public HTML API

Public API (Flash)

MSP

Public Server

HTML Renderer

HTML SEO Renderer

Flash Renderer

Flash SEO Renderer

Sitemap Renderer

Robots.txt Renderer

User Server

Template Viewer

ContactsHUBActivit

y

Site Members

Provided Mailing Service

Comments

Snapshoter

User Pref

Feed Me

Shout-out Hotels

PETRI

Site Pref

Dist LoggerSlicer

eCom Renderer

eCom Cart

eCom Checkout

eCom Catalog

eCom Orders

Payment Facade

Account Info

HTML API

HTML Embeder

BlogMobile

Microservices Guidelines

Each service has its own DB schema (if one is needed)

Only one service should write to a specific DB table(s)

There may be additional read-only services that directly accesses the DB (for performance reasons)

Services are stateless

No DB transactions

Cache is not a building block, but an optimization

TRADE-OFFIt is all about

Microservices TradeoffsEach service has its own DB schema (if one is needed)

Gain - Easy to scale microservices based on service level concerns Tradeoff – system complexity, performance

Only one service should write to a specific DB table(s)Gain - Decoupling architecture – faster development Tradeoff – system complexity / performance

May have additional read-only services that accesses the DBGain - Performance gainTradeoff - coupling

Services are statelessGain - Easy to scale out (just add more servers)Tradeoff - performance / consistency

No DB transactionsGain - Better DB performance, easier to scaleTradeoff - system complexity

1. Editor Segment

Editor Server

Immutable JSON pages (~3M / day)

Site revisions

Active – standby MySQL cross datacenters

Editor Server

MySQL Active Sites

MySQL Archiv

e

Find Your Critical Path

Protect The Data

DB outage with fast recovery = replication

Data poisoning/corruption = revisions / backup

Make the data available at all times = data distribution to multiple locations / providers

Browser

Editor Server

GCS

MySQL Active Sites

MySQL Archiv

e

Saving Editor Data

WixMedia(Amazon)

WixMedia(Google)

Save Page(s)

200 OK

Upload

Save Page

DC replication

Notify

MySQL Archiv

e

MySQL Active Sites

S3

WixMedia(DC-1)

Browser

Editor Server

GCS

MySQL Active Sites

MySQL Archiv

e

WixMedia(Amazon)

WixMedia(Google)

Save Page(s)

200 OK

Upload

Save Page

DC replication

Notify

MySQL Archiv

e

MySQL Active Sites

S3

WixMedia(DC-1)

Self Healing Process

No DB Transactions

Save each page (JSON) as an atomic operation

Page ID is a content based hash (immutable/idempotent)

Finalize transaction by sending site header (list of pages)

Can generate orphaned pages, not a problem in practice

2. Media Segment (WixMP)

Wix Media Platform (WixMP)

Eventual consistent distributed file system(2PB user media files)

Dynamic media processing

Multi datacenter aware

Automatic fallback cross DC

Run on commodity servers & cloud

T

Google Cloud

Prospero – Wix Media Manager

get image.jpg

First fallback

Second

fallback

If not in

CDN

Amazon

x36Tx36

Tx32

Austin

CDN

3. Public Segment

Public Segment Roles

Routing (resolve URLs)

Dispatching (to a renderer)

Rendering (HTML,XML,TXT) Public

Server

HTML Rendere

r

HTML SEO

Renderer

Flash Renderer

Sitemap Rendere

r

Robots.txt

Renderer

www.example.com

Flash SEO

Renderer

Public SLA

Our goal: 99% response time <100ms at peak traffic

Publish Site

Publish site header (a map of pages for a site)

Publish routing table

Publish site header / routes (CQRS)Editor Segment Public Segment

Built For Speed

Minimize out-of-process hops (2 DB, 1 RPC)

Lookup tables are cached in memory, updated every few minutes

Denormalized data – optimize for read by primary key (MySQL)

Minimize business logic

How a Page Gets Rendered

Bootstrap HTML template that contains only data

Only JavaScript imports

JSON data (site-header + dynamic data)

No “real” HTML view

Offload rendering work to the browser

The average Intel Core i750 can push up to 7 GFLOPS without overclocking

Why JSON?

Easy to parse in JavaScript and Java/Scala

Fairly compact text format

Highly compressible (5:1 even for small payloads)

Easy to fix rendering bugs and cross browsers issues (just deploy a new code)

Minimum Number of Public Servers Needed to Serve 66M Sites

4

Public SLABe Available 99.999%

Serving a Site – Sunny Day

Archive

CDN WixMP

Browserhttp://

example.wix.com

Store HTML to cache

HTTP Request

Notify site view

LB

Public

Renderer

HTML

Resources / Media

HTTP Request

Serving a Site – DC Lost

Archive

CDN WixMP

Browserhttp://

example.wix.com

LB

Public

Renderer

LB

Public

Renderer

Change DNS

HTTP Request

Serving a Site – Public Lost

Archive

Browserhttp://

example.wix.com

LB

Public

Renderer

Get Cached HTML Version

HTMLHTTP Request

LB

Public

Renderer

Fallback to 2nd DC

Living in the Browser

CDN WixMP

Browserhttp://

example.wix.com

LB

Public

Renderer

Editor Pages

Fallback

JSON / Media

HTMLHTTP Request

Fallback

Summary

Identify concerns and SLA for different parts of the system

Build redundancy in critical path (for availability)

De-normalize data (for performance)

Minimize out-of-process hops (for performance)

Take advantage of client’s CPU power

Q&A

@aviranm

linkedin.com/in/aviran

aviransplace.com

http://engineering.wix.com

http://goo.gl/t626jU

@WixEng

Aviran MordoHead of Back-end Engineering