1. New England Code Camp 14 02-October-2010
Going Native
Building Cloud-Native Applications on Microsoft’s Windows Azure Stack
New England Code Camp 14
02-October-2010
Not representing my day job
Several slides stolen borrowed (with permission) from ( – Jim O’Neil’s Windows Azure presentation from March 17, 2010 meetup) + from Chris Bowen’s “roadshow” talk (March 2010)
Boston Azure User Group
@bostonazure
Bill Wilder
@codingoutloud
Boston West Toastmasters
Not here with my day job Only Bill’s personal views
Copyright (c) 2010, Bill Wilder

2. Agenda Lightning-quick overview of Azure
Two Major Shifts in Cloud-Native Apps:
Using Scalable and Cost-effective Storage
Using Roles and Queues for Scalability and Resilienceyness
Scalable and Resilient

3. Cloud-Native Applications
Effort focuses on business functionality
Development is highly productive
Time-to-market is short
Modification is straight-forward
Infrastructure is not a limiting factor
Cost structure is a good fit
Downtime is not necessary
Scale is efficient
Innovation / experimentation is enabled

4. [Azure] Cloud Platform
The rise of focused, specialized services
Really good at one thing
True of other Cloud Platforms
“Scalable” Persistent Storage abstractions
Set of Services
Illusion of infinite scale out
Same performance with x clients as with 10x as with 100x as with 1000x as with …
Billing model: pay only for what you use
Friction-free access to add’l or less storage

5. Part A A

6. Part A – Executive Summary
Use Azure Blobs and Tables and your DATA will be resilient to failure and will scale like crazy…

7. Persistent Storage Services – Options
Type of Data
Traditional
Azure Way
Relational
SQL Server
SQL Azure
Blob
File System, or SQL Server
Azure Blobs
File
File System
Azure Drives, or Azure Blobs
Reliable Queue
MSMQ (maybe)
Azure Queues
Non-Relational
Azure Tables

8. Azure Storage Services
Family of specialized, complementary storage services
Abstractions
High level services
Blobs + Queues + Tables [+ Drives + CDN]

9. All Azure Storage is Replicated
Resilient in case of failure
“All data replicated multiple times” – Sriram Krishnan, Programming Windows Azure, p130+
Supports scale-out
Replicate specific data if it gets too hot to keep up

10. Azure Blob Storage The place to put ANY LARGE OBJECT Private or Public
Public blobs can be anonymously accessed
Images, videos, CSS files
Need not be binary
Public blobs can be cached in Azure CDN
20 locations around the world
Different locations than data centers
Time-limited signed-access available
“You have until tomorrow to download this video”
– Windows Azure CDN
– 20 CDN nodes available across the world

11. Azure Blob Storage Two types of Azure Blobs “Block Blob” “Page Blob”
Parallel upload scenarios
Resume download scenarios
Up to 200 GB
“Page Blob”
Random access scenarios
Azure Drives
Up to 1000 GB
– Windows Azure CDN
– 20 CDN nodes available across the world

12. Azure Table Storage Best place for granular, semi-structured data
No rigid database schema
Fast and easy to instantiate
Strongly Consistent
No performance lag
Programming model is WCF Data Services
All data access and data updates
LINQ

13. Azure Table Storage Storage Account Table [*] Entity [*, 1 MB data]
PartitionKey + RowKey
Property [255x]
Name/Value/Type
Up to 64k
Entity is like a Row

14. Azure Table Storage Partition Key Row Key
Along a “logical grouping” – a “shard”
PartitionKey value of up to 64 KB
Row Key
Identify specific row within a partition
RowKey value is String of up to 64 KB
Table access requires Partition Key + Row Key
Not to mention (cryptographic) Access Key (for the digital signing of the http header)

15. Relational Data vs. Azure Tables
Approach
SQL Azure
Azure Tables
Normalization
Normalized
Denormalized
(Duplication)
(No duplication)
(Lots of duplication)
Structure
Schema
Flexible
Transactions
Distributed
Limited scope
Responsibility
Database
Developer
Knobs
Many
Few
Scale
Up (or Sharding)
Out
Cost
Reasonable
Less expensive

17. Pay As You Go – Storage Storage Applies equally to:
$0.15 per GB stored per month
$0.01 per 10,000 storage transactions
Applies equally to:
Queues
Tables
Blobs
Drives

18. Pay As You Go – Data Transfer
North America and Europe regions
$0.10 per GB in
$0.15 per GB out
Asia Pacific Region
$0.30 per GB in
$0.45 per GB out
No charge for transfer within a data center

19. What is Cost of 1 Byte? Azure Storage cost/byte = x
SQL Azure cost/byte = 66x

20. Part B B

21. Part B – Executive Summary
Scale out, not up, and your COMPUTE will be resilient to failure and will scale like crazy…

22. Azure Does Compute Compute Services Web Roles Worker Roles
VM Role (Nov 2010)
Your Code Runs Here
Image:

23. Web Roles vs. Worker Roles
Runs in IIS 7 (always listening)
Built using ASP.NET, MVC
Good to handle interactive users
Addressable over Internet
Good for hosting Web API (WCF)
Runs Continuously
Smarx “The only difference between a web role and a worker role is that in the web role, IIS (actually Hosted Web Core) gets started and pointed at your app data directory. You can still put code in WebRole.cs that does exactly the same thing as you would do in your worker role, so the decision should really be "Do you want IIS?" If so, use a web role. If not, use a worker role.”
One is always running, one is always listening

24. “Out” is the New “Up” Scaling Out has hard limits at CPU, Memory
Architecturally more limiting

25. Azure Storage Services in Concert

26. Key Pattern: Roles + Queues
Web
Role
(IIS)
Worker
Role
Queues
AJAX – orthogonal concern
Worker Role not related to HTML 5 concept of Web Worker
Blobs
Tables

27. Canonical Example: Thumbnails
Web
Role
(IIS)
Worker
Role
Queues
AJAX – orthogonal concern
Worker Role not related to HTML 5 concept of Web Worker
Blobs
Tables

28. Adding to Queue - Conceptual
Queue Name: “thumbnailer-7”

29. Adding to Queue - Actual
314159
265358
979323
Azure Blob Storage
314159
265358
979323

30. Roles + Queues: API queue.AddMessage( new CloudQueueMessage(
statusUpdateMessage));
Web
Role
(IIS)
Worker
Role
Queues
AJAX – orthogonal concern
Worker Role not related to HTML 5 concept of Web Worker
CloudQueueMessage statusUpdateMessage =
queue.GetMessage(
TimeSpan.FromSeconds(10));
… queue.DeleteMessage(statusUpdateMessage);

31. General Case: Rolesn + Queuesn RnQnRn
Worker
Role
Worker
Role
Web
Role
(IIS)
Worker
Role
Web
Role
(IIS)
Worker
Role Type 1
Web
Role
(IIS)
Web
Role
(IIS)
Worker
Role
Worker
Role
Queues
Worker
Role
AJAX – orthogonal concern
Worker Role not related to HTML 5 concept of Web Worker
Worker
Role Type 2

32. Azure Queue Storage Service for RELIABLE message delivery
7 days = default TTL for item to stay in queue
30 seconds = default “invisibility window”
8 KB = max size of a queued item
500 = approx number of transactions a queue can handle per second
Beware of “spinning” – may get throttled, disabled
N = number of queues you can have (N >> 1)

33. Key Metric
Queue length (and trend) is key data point for tuning Role deployment numbers
Available programmatically for monitoring
May vary across queue types

34. RnQnRn enables Responsive
Response to interactive users is as fast as a work request can be persisted
Time consuming work done off-line
Same total resource consumption, better subjective experience
UX challenge – how to express Async to users?
Communicate Progress
Display Final results

35. RnQnRn enables Scalable
Loosely coupled, concern-independent scaling
Blocking is Bane of Scalability
Decoupled front/back ends insulate from other system issues if…
Twitter down
server unreachable
Order processing partner doing maintenance
Internet connectivity interruption

36. RnQnRn enables Distribution
Scale out systems better suited for geographic distribution
More efficient and flexible because more granular
Hard for a mega-machine to be in more than one place
Failure need not be binary
Chainsaw:

37. Optimization is optional
Individual role utilization may be low
Role is a VM – lots of resources
You pay by instance, not resource use within
Make sure VM instances are “right sized”
Small, Medium, Large, XL
Make sure enough roles for uptime
SLA requires minimum of 2 instances
Business Trade-Off for further optimizations
Optimize for CPU utilization (multiple threads)
Combine types of processing into fewer role types

38. RnQnRn requires Idempotent
If we do a task twice, end result same as if we did it once
App-specific concerns dictate approaches
Compensating transactions
Last in wins
Many others possible – hard to say
Example with Thumnailing

39. RnQnRn requires Poison Message Strategy
A Poison Message cannot be processed
Error condition
Non-transient reason
Strategy One:
Fall off the queue (TTL)
Message stays in queue for 7 days (default)
Strategy Two:
Specify retry threshold
Remove poison messages

40. RnQnRn enables Resilient
And Requires that you “Plan for failure”
There will be role restarts
Bake in handling of restarts
Not an exception case! Expect it!
Restarts are routine, system “just keeps working”
If you follow the pattern, the payoff is substantial…

41. What’s Up? Aspirin-free Reliability as EMERGENT PROPERTY
Typical Site
Any Azure Role
Overall System
Operating System Upgrade
Application Update / Deploy
Change Topology
Hardware Failure
Software Bug / Crash / Failure
Security Patch
Tech Windows

42. Questions? ?

43. BostonAzure.org Boston Azure cloud user group
Focused on Microsoft’s cloud solution
Next meeting: 6-8:30 PM Thurs Oct 21st 2010
Hacking on “Boston Azure Project”
Silverlight and Azure – better together
Meetings usually 4th Thursday of month
No cost; food; great topics; growing community; wifi
Join list:
Follow on

44. Slides available from Bill’s blog
hmbl.me is URL shortener running on Azure:

45. Bill Wilder
@codingoutloud