Even Platform as a Service promise to host your application without a change, things are not so simple and you can't send your old EJB 1.0 application to the Cloud without some refactoring. During this session, I'll explain some architecture patterns to apply to your new developments so that your transition to the cloud is as smooth as possible.

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Design Patterns for the Cloud
Rethinking application design for the Cloud
Cyrille Le Clerc
010DEV.nl
Monday, June 24, 13

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Speaker
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Cyrille Le Clerc
@cyrilleleclerc
Open Source
CTO
DevOps, Infra as Code
Solution Architect
Cloud
Monday, June 24, 13

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This talk is
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Greatly inspired by Nicolas de Loof’s presentation
Thanks Nicolas!
Monday, June 24, 13

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IaaS, PaaS & SaaS
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Infrastructure
as a Service
Platform
as a Service
Software
as a Service
Linux + storage
+ network
App runtime
+ middleware
Managed“Traditional” admin
Business App
Managed
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Moving to the cloud
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Cloud On Premises
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Cloud
On PremisesEasy
Maybe difficult
for legacy apps
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Cloud On Premises
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Cloud
On PremisesEasy
Maybe difficult
for legacy apps
refactor
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Green Field Applications
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• Can select modern solutions
Most (not all) frameworks are well designed for Cloud
• Started on cloud,
discover and adapt to constraints
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“Legacy” Applications
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• Not so modern solutions
old frameworks and patterns may not fit with cloud constraints
• Started on premises, single server
hit cloud constraints
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Scale Out
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Scale Up
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M1 Small M1 Large M3 2 XLarge
•Still possible, but up to a limit
•Not optimal
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Scale Up
10
M1 Small M1 Large M3 2 XLarge
•Still possible, but up to a limit
•Not optimal
Low utilization!
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Scale Up
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M1 Small M1 Large M3 2 XLarge
•Still possible, but up to a limit
•Not optimal
Then ???Low utilization!
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M1 Extra Large
• 64 bits
• 15 Gb memory
• 4 Vcore, 2 cpu unit (~2.5Gh)
• 1.6 Tb HD
• aka « your desktop »
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Scale out
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Design for clustering
Scale as you need
Pay as you use
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Multi tenancy - PaaS backstage
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• Multi tenancy at the app level, not at the OS level
• Slice big servers into slices
tomcat
app-x
tomcat
app-x
tomcat
app-x
tomcat
app-x
tomcat
app-x
tomcat
app-x
tomcat
app-x
tomcat
app-x
tomcat
app-x
tomcat
app-x
tomcat
app-x
tomcat
app-x
tomcat
app-x
tomcat
app-x
tomcat
app-x
tomcat
app-x
tomcat
app-x
tomcat
app-x
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Multi Tenancy
• OS level (hypervisor): IaaS
• OS virtualization (cgroups, LXC): PaaS
• Middleware ?
Java 9 to be multi-tenant ?
• Application: SaaS
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Be stateless ... if you can
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An Ideal Stateless RestFul World
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Linear horizontal scaling
But …
• Application / User « conversation » has a state
• Stateless apps often store state in a database!
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State
Are you really stateless ?
Beware of your framework!
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Grails
Spring Security
Security Plugins
Http Session
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Really stateless ?
• Client side state with browser cookies
→higher network traffic, security
• Use http session (servlet frameworks)
→memcache session replication
→sticky session
• Use a central service (DB)
→ SPoF, DB scalability
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Fear the File System
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Cloud uses Schrödinger FS
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Looks like it’s alive, but it’s not anymore
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IaaS / PaaS == Pool of Servers
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Your host at his time
Your host after a redeployment
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Don’t trust the local FS
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• File System is ephemeral and NOT distributed ... at least on
Amazon
• Use a storage engine à la Amazon S3
... and see the local FS as a cache
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Singletons aren’t
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Singletons aren’t
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• Most app servers are NOT clusterized with reliable singletons
• Use Cron as a Service like iron.io
... or trust Quartz with a JDBC store
Cloud Service
Architecture
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Latency matters!
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Latency Matters
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tomcat
app-x
120ms
• Inter Continental is common
• EU to us-east-1 latency: 120ms
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Measure
• Chrome Dev Tools
• Google Pagespeed
• YSlow
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Improve
• HTTP Headers: Expires & Cache Control
• Use CDNs (Content Delivery Network)
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Cloud Services Oriented
Architecture
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*aaS Ecosystem
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• *aaS is about service, not software
• Integrate services, don’t try to setup your own infrastructure
• Amazon AWS, the place to be for *aaS
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*aaS Ecosystem
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Private Cloud ? Non sense ?
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• Size matters!
• Ecosystem matters!
• You already delegate hosting!
• Security: humans vs. firewalls
• Cloud is secure
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Design for Failure
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It may Will fail!
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http://status.cloudbees.com
http://status.aws.amazon.com/
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Design for Failure
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• Don’t fail if a resource is KO
• Be asynchronous and fault tolerant
• Use messaging
• NoSQL is your friend
SNS SQS
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Deployment patterns
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Deployment is
a non-event
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•Git push
•Build
•Test
•Ready for production
•Production
•Git push
•Build
•Test
•Deploy
•Production
Continuous Delivery
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•Git push
•Build
•Test
Integration Deployment Delivery
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Blue Green Deployment
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• Martin Fowler: http://martinfowler.com/
bliki/BlueGreenDeployment.html
• Zero Downtime
• Cloud Elasticity → 2x number of
servers during deployment
• NoSQL is your friend
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Feature Toggle Pattern
• Continuous merging in the “trunk”
• Deploy not yet ready code
• Enable / disable features with a switch,
no redeployment, often no restart
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JMX
persistent
transient
AntiFraudServiceV1Impl
AntiFraudServiceV2Impl
AntiFraudService
DispatchingImpl
AntiFraudService
<<Interface>>
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A/B Testing
• Test different UI / Features
• Measure the impacy
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Canary Testing
• Test new versions on a limited
panel of users
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Thank You!
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Event sponsor
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Questions ?
Monday, June 24, 13