Architecting to be Cloud Native
Guest lecture at Dino Konstantopoulos’ BU MET CS755 Cloud Computing class 17-April-2014 (7:00 – 9:00 PM EDT)
HELLOmy name isBill Wilder
Aligning your application’s architecture with the architecture
of the cloud… FTW!But the cloud is a friendly place for
non-native apps too!
Who is Bill Wilder?
www.devpartners.com
www.bostonazure.org
www.cloudarchitecturepatterns.com
I will ass-u-me…
1. You know what “the cloud” is2. You have an inkling about Amazon Web Services and
Windows Azure cloud platforms3. You understand that such cloud platforms include
compute services [like hosted virtual machines (VMs), in both IaaS and PaaS modes], SQL and NoSQL database services, file storage services, messaging, DNS, management, etc.
4. You are interested in understanding cloud-native applications and why that’s better than deploying my old-school app to the cloud “as is”
Roadmap for rest of talk… …
1. Lightning-fast overview of Windows Azure2. Cover three specific patterns for building
cloud-native applications3. Mention some other patterns along the way
• Q&A during talk is okay (time permitting)• Q&A at end with any remaining time• Okay to reach out through email or twitter
?
Windows Azure Portal
General informationhttp://www.windowsazure.com
Management Portalhttp://manage.windowsazure.com
“Bring Your Own” ____ as a Service
BYO
UsersBYO
Applications
BYO Virtual Machines
PaaS
IaaS
SaaS
more
less
Responsibility &
Flexibility
NIST: http://csrc.nist.gov/publications/nistpubs/800-145/SP800-145.pdf
Most productive
platforms for
Cloud-Native
Apps
NIST Terminology
• SaaS = Software as a Service (BYO users)• PaaS = Plaform as a Service (BYO apps)• IaaS = Infrastructure as a Service (BYO VMs)
Simplicity
ComplexityFlexibility
RigidityPower?
Power?http://csrc.nist.gov/publications/nistpubs/800-145/SP800-145.pdf
So Architecting for the (Windows Azure, AWS, GAE, …) Cloud is Different…
WHY DID THEY (Microsoft, Amazon, Google, …) DO THIS TO US?
But Why?
Know the rules
“If I had asked people what they wanted, they would have said faster horses.”
- Henry Ford
Faster h
orses w
ould not have
addressed th
e horse m
anure problem
…
late 1800s..
150k horses in
NYC
x 20 lbs m
anure/day/horse
= 3 millio
n lbs o
f manure per d
ay
Know the rules
“If I had asked IT departments what they wanted, they would have said IaaS.”
- Henry Cloud
Cloud Platform Characteristics• Scaling – or “resource allocation” – is horizontal
– and ∞ (“illusion of infinite resources”)
• Resources are easily added or released– self-service portal or API; cloud scaling is automatable
• Pay only for currently allocated resources– costs are operational, granular, controllable, and transparent
• Optimized for cost-efficiency– cloud services are MT, hardware is commodity– MTTR over MTTF
• Rich, robust functionality is simply accessible– like an iceberg
Cloud-Native Application Characteristics
• Application architecture is aligned with the cloud platform architecture–uses the platform in the most natural way– lets the platform do the heavy lifting
The term “cloud” is nebulous…
The definition of “Cloud” is nebulous…
What is different about the cloud?
What's different about the cloud?^public
1/9th above w
ater
TTM & Sleeping well= SOA
MTBF MTTR
commodity hardware + multitenant services= cost-efficient cloud
failure is routine(so you better be good at
handling it)
Architectural Assumptions
Loosely Coupled &Eventually Consistent
Data & WorkflowArchitecture
This bar is always open
*and*
has an APIPay by the Drink
$
∞
• Resource allocation (scaling) is:– Horizontal– Bi-directional– Automatable
The “illusion of infinite resources”
Resource Allocation
Integrated Surface Area
www.pageofphotos.com• Simple idea, simple app• Two-tiers: web tier (one server) + database• What’s the problem?
• But… what’s WRONG with this architecture?
• Different ≠ WRONG. Use the right tool for the job. Some apps are simply not good fit for cloud.
?
www.pageofphotos.com• Simple idea, simple app• Two-tiers: web tier (one server) + database• What can go wrong
• We’ll reexamine1. Scaling the web tier2. Scaling the service tier3. Scaling the data tier4. Handling failure5. Operational efficiency (scale the app, not the team!)
Horizontal Scaling Compute Pattern
pattern 1 of 3
What’s the difference between performance
and scale??
Common Terminology:Scaling Up/Down Vertical ScalingScaling Out/In Horizontal “Scaling” But really is Horizontal Resource Allocation
• Architectural Decision– Big decision… hard to change
Scale Up (and Scale Down??)vs. Horizontal Resourcing
Vertical Scaling (“Scaling Up”)
.
Resources that can be “Scaled Up”• Memory: speed, amount • CPU: speed, number of CPUs• Disk: speed, size, multiple controllers• Bandwidth: higher capacity pipe• … and it sure is EASY
Downsides of Scaling Up• Hard Upper Limit• HIGH END HARDWARE HIGH END CO$T• Lower value than “commodity hardware”• May have no other choice (architectural)
Scaling Horizontally: Adding BoxesAutonomous nodes
for scalability(stateless web servers, shared
nothing DBs, your custom code in
QCW)
Autonomous nodes*and*
Homogeneous nodes for operational simplicity
*and*Anonymous nodes
don‘t get emotionally involved!
This is how the CLOUD works *and*This is how YOUR CLOUD-NATIVE APP WORKS
Load Balancer(Cloud Service)
Managed VMs(Cloud Service)
Example: Web Tier www.pageofphotos.com
1. Auto-Scale • Bidirectional
2. Nodes can fail• Auto-Scale is only one cause• Handle shutdown signals• Stateless (“like a taxi”)
vs. Sticky Sessions• Stateless nodes
vs. Stateless apps• N+1 rule
vs. occasional downtime (UX)
Horizontal Scaling Considerations
How many users does your cloud-native
application need before it needs to be able to
horizontally scale??
Queue-Centric Workflow Pattern
(QCW for short)
pattern 2 of 3
Extend www.pageofphotos.com example into Service Tier
• QCW enables applications where the UI and back-end services are Loosely Coupled
• (Compare to CQRS at end if there is interest)
QCW Example: User Uploads Photo www.pageofphotos.com
Web Server
Compute ServiceReliable Queue
Reliable Storage
QCW
WE NEED:• Compute (VM) resources to run our code
• Reliable Queue to communicate
• Durable/Persistent Storage
Where does Windows Azure fit?
QCW [on Windows Azure]
WE NEED:• Compute (VM) resources to run our code
Web Roles (IIS) and Worker Roles (w/o IIS)• Reliable Queue to communicate
Azure Storage Queues• Durable/Persistent Storage
Azure Storage Blobs & Tables; WASD
QCW on Azure: User Uploads a Photo
WebRole(IIS)
WorkerRoleAzure Queue
Azure Blob
UX implications: user does not wait for thumbnail(architecture!)
ww
w.p
ageo
fpho
tos.
com
push pull
QCW enables Responsive UX
• Response to interactive users is as fast as a work request can be persisted
• Time consuming work done asynchronously• Comparable total resource consumption, arguably
better subjective UX• UX challenge – how to express Async to users?
– Communicate Progress– Display Final results– Long Polling/Web Sockets (e.g., SignalR or Node.io)
QCW enables Scalable App
• Decoupled front/back provides insulation– Blocking is Bane of Scalability– Order processing partner doing maintenance– Twitter down– Email server unreachable– Internet connectivity interruption
• Loosely coupled, concern-independent scaling– (see next slide)– Get Scale Units right
–Key to optimizing operational CO$T$
General Case: Many Roles, Many Queues
WebRole(IIS)
WorkerRole
WebRole(IIS)
WebRole
(Public)
WorkerRoleWorker
RoleWorker
Role Type 1
WorkerRoleWorker
RoleWorkerRoleWorker
Role Type 2
Queue Type 1
Queue Type 2
Queue Type 1
Queue Type 2
Queue Type 3
• Scaling best when Investment α Benefit• Optimize for CO$T EFFICIENCY
• Logical vs. Physical Architecture depends on current scale
WorkerRole
Type 2
WorkerRole
Type 2
WorkerRole
Type 2
WebRole
(Admin)
Reliable Queue & 2-step Delete
(IIS)WebRole
WorkerRole
var url = “http://pageofphotos.blob.core.windows.net/up/<guid>.png”;queue.AddMessage( new CloudQueueMessage( url ) );
var invisibilityWindow = TimeSpan.FromSeconds( 10 );CloudQueueMessage msg = queue.GetMessage( invisibilityWindow );
(… do some processing then …)queue.DeleteMessage( msg );
Queue
QCW requires Idempotent
• Perform idempotent operation more than once, end result same as if we did it once
• Example with Thumbnailing (easy case)• App-specific concerns dictate approaches
– Compensating action, Last write wins, etc.• PARTNERSHIP: division of responsibility
between cloud platform & app– Far cry from database transaction
QCW expects Poison Messages
• A Poison Message cannot be processed– Error condition for non-transient reason– Use dequeue count property
• Be proactive– Falling off the queue may kill your system
• Determine a Max Retry policy per queue– Delete, put on “bad” queue, alert human, …
QCW requires “Plan for Failure”
• VM restarts will happen– Hardware failure, O/S patching, crash (bug)
• Bake in handling of restarts into our apps– Restarts are routine: system “just keeps working”– Idempotent support needed important– Event Sourcing (commonly seen with CQRS) may
help• Not an exception case! Expect it!• Consider N+1 Rule
Typical Site Any 1 Role Inst Overall System
Operating System Upgrade
Application Code Update
Scale Up, Down, or In
Hardware Failure
Software Failure (Bug)
Security Patch
What’s Up? Reliability as EMERGENT PROPERTY
What about the DATA?
• You: Azure Web Roles and Azure Worker Roles– Taking user input, dispatching work, doing work– Follow a decoupled queue-in-the-middle pattern– Stateless compute nodes
• Cloud: “Hard Part”: persistent, scalable data– Azure Queue & Blob Services– Three copies of each byte– Blobs are geo-replicated– Busy Signal Pattern
Database Sharding Pattern
pattern 3 of 3
Database Sharding Pattern
Most Cloud Applications don’t care (much) about (very high) scale
But they do care about developer productivity and operational efficiency
pattern 3 of 3
foo.com
Site
-to-
Site
Virt
ual N
etw
ork
VNET in cloud, connected to on-prem
On-premdatabase
On-prem API
bar.com as Azure Cloud Service
TDS
(nati
ve S
QL
Serv
er
TCP-
base
d w
ire p
roto
col)
SOAP
/ R
EST
/ HT
TP
Azure Cloud
On-prem
Dev Team(Point-to-Site VPN from CoLo Router into Azure)
Off-site/Travel Dev Team(Point-to-Site VPN from laptop to Azure)
foo.com as Azure Web Site running CMS
dedicated MySQL Database to run CMS
bar.com
Global CDN
Public Internet
Blob Storag
e
Blob Stora
ge
Content Editing & Site Admin
Dev Team
Azure SQL Database (WASD)is SQL Server Except…
Common
SQL ServerSpecific(for now)
SQL DatabaseSpecific
“Just change the connection
string…”
• Full Text Search• Transparent Data
Encryption (TDE)• Many more…Limitations• You need to run it• Max VM size
Limitations• 500 GB size limit• Busy Signal PatternExtra Capabilities• Managed Service• Highly Available• Rental model• Premium (reserved)
http://msdn.microsoft.com/en-us/library/ff394115.aspxAdditional information on Differences:
My database instance is limited to 500 GB.
∞ ∞ ∞Does that mean the
cloud doesn’t really offer the illusion of infinite
resources??
Pre-Cloud vs. Cloud-Native
Old-School vs.
Cloud-Native
Control Efficiency
Stable/Static Hardware Dynamic/∞ Resources
Fixed/CapEx Variable/OpEx
Vertical Scaling Horizontal Resourcing
Minimize MTBF Minimize MTTR
Data Storage = RDBMS Scenario-specific Storage
Manage Infrastructure Managed Infrastructure
arch
itect
ural
con
cern
s
Pre-Cloud vs. Cloud-Native
Lessons: being
Cloud-Native
1:15,000 Efficiency
Auto-Scaling via API Dynamic/∞ Resources
Pay-As-You-Go Variable/OpEx
Stateless, Autonomous Horizontal Resourcing
N+1, Idempotent Minimize MTTR
SQL, NoSQL, Blob Scenario-specific Storage
VM, Storage, LB, DR Managed Infrastructure
Know the rules
“Know the rules well, so you can break them effectively.”
- Dalai Lama XIV
Integrated Surface Area
Cloud Architecture Patterns bookPrimer Chapters
1. Scalability2. Eventual Consistency3. Multitenancy and
Commodity Hardware4. Network Latency
Cloud Architecture Patterns book Pattern Chapters
1. Horizontally Scaling Compute Pattern2. Queue-Centric Workflow Pattern3. Auto-Scaling Pattern4. MapReduce Pattern5. Database Sharding Pattern6. Busy Signal Pattern7. Node Failure Pattern8. Colocate Pattern9. Valet Key Pattern10. CDN Pattern11. Multisite Deployment Pattern
Questions?Comments?
More information?
?
Business Card
BostonAzure.org
• Boston Azure cloud user group• Focused on Microsoft’s Public Cloud Platform
• Monthly, 6:00-8:30 PM in Boston area– Food; wifi; free; great topics; growing community
• Follow on Twitter: @bostonazure • More info or to join our Meetup.com group:
http://www.bostonazure.org
Looking for …• consulting help with Windows Azure Platform? • someone to bounce Azure or cloud questions off?• a speaker for your user group or
company technology event?Just Ask!
Bill Wilder@codingoutloudhttp://blog.codingoutloud.comcommunity inquiries: [email protected] inquiries: www.devpartners.com book: www.cloudarchitecturepatterns.com
Contact Me
Find this slide deck here
DONE
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