Azure Cloud Patterns
Download as PPT, PDF1 like952 views
The document discusses cloud architecture patterns used to address scalability and performance issues in software systems, illustrated through the example of a coffee shop facing operational challenges. Key concepts include message centric processing, retry logic for transient faults, circuit breaker patterns to prevent resource wastage, and the cache aside strategy to optimize data retrieval. Additional references and resources for further reading on cloud design patterns are provided.
![Service Bus Messaging – Dead letters
• the name of the sub-queue is [queueName]/
$DeadLetterQueue
• The path can be obtained using the
FormatDeadLetterPath method of the
QueueClient
• Can be consumed by any other consumer
and check the messages, log them etc.](https://image.slidesharecdn.com/azurecloudpatterns-tamirdresher-devgeekweek2014-140625021035-phpapp02/85/Azure-Cloud-Patterns-30-320.jpg)
![Circuit Breaker States
Closed Open
Success
Fail [threshold reached]
Half
Open
Retry Timeout
Fail
Success
Fail [under threshold]](https://image.slidesharecdn.com/azurecloudpatterns-tamirdresher-devgeekweek2014-140625021035-phpapp02/85/Azure-Cloud-Patterns-45-320.jpg)
Azure Cloud Patterns
- 2. About Me • Software architect, consultant and instructor • Software Engineering Lecturer @ Ruppin Academic Center • Technology addict • .NET and Native Windows Programming @tamir_dresher [email protected] http://www.TamirDresher.com.
- 4. Agenda • What are Cloud Patterns • Queue Centric • Poison Messages • Retry Logic • Circuit Breaker • Cache Aside
- 5. What are Cloud Patterns • Architectural Patterns: “A design pattern in architecture and computer science is a formal way of documenting a solution to a design problem in a particular field of expertise” (http://en.wikipedia.org/wiki/Architectural_patterns)
- 6. Meet The Problem DevGeek Coffee Shop
- 7. DevGeek Coffee Shop • DevGeek Coffee is a well known and established coffee shop • In business for 20 years • Lately, with the increasing competition, sales are dropping • Lets Help!
- 8. DevGeek Coffee Shop - Operations coffee
- 9. DevGeek Coffee Shop - Operations coffee#!$@
- 10. What does this has to do with software? • Cashier == Server • Basically, this is a scalability issue • Running in the cloud (potentially) makes scaling problem appear faster
- 11. Scale Up • Add More Resources to a Node • Faster cashier – Better CPU to the server – More Memory • Faster Coffee machine – Use a better algorithm/service
- 12. Everything has a limit MoneyMoney CPUCPU MEMMEMBANDWIDTH BANDWIDTH StorageStorage
- 13. Scale out • Add More Nodes – More Cashiers • Load Distribution – Round Robin – Performance – Other (location, expertise, etc)
- 15. Meet The Problem 2 DevGeek Coffee Shop
- 16. DevGeek Coffee Shop – The clients complaints • Long standing • Sometimes orders gets lost • Sometimes the line is so long that the workers close the doors
- 17. DevGeek Coffee Shop – Latency and throughput • Latency is a time interval between the stimulation and response – Time between ordering and receiving the coffee • Throughput is the number of requests that can be served per unit time
- 18. DevGeek Coffee Shop – Aroma model coffee .
- 19. Message Centric Web Sites worker role : : worker roleweb role
- 20. Message Centric – Load Leveling : : Request Received at variable rate Messages Processed at consistent rate
- 21. Message Centric – Resilency : : X X
- 22. Message Centric – Delayed Processing : :
- 23. Azure Queuing Options • Azure Storage Queues – Simple, Reliable, Persistent Queue – Max 200TB and 7 days TTL per message • Azure Service Bus – Broader capabilities: publish/subscribe, remoting, integration patterns – Max 80GB and unlimited TTL per message http://msdn.microsoft.com/en-us/library/hh767287.aspx
- 24. Azure Service Bus – Queueing
- 25. Service Bus Messaging - Queue • Two parts: 1. key/value properties 2. binary message body. • Example: a sales application sends message properties: • *Seller="Ava" • *Amount=10000. • body : The sale's signed contract scanned image
- 27. C2 2 1 2 1 1 1 1 1 Removing Poison Messages 1 1 1 1 2 1 2 1 334 0 4 0 Producers Consumers 3 0 3 0 2. GetMessage(Q, 30 s) msg 2 1. GetMessage(Q, 30 s) msg 1 1 1 1 1 2 1 2 1 1 0 1 0 2 0 2 0 P2 P1 C1
- 28. C2 P2 P1 C1 Removing Poison Messages 34 0 4 0 Producers Consumers 1 1 1 1 2 1 2 1 2. GetMessage(Q, 30 s) msg 2 3. C2 consumed msg 2 4. DeleteMessage(Q, msg 2) 7. GetMessage(Q, 30 s) msg 1 1. GetMessage(Q, 30 s) msg 1 5. C1 crashed 1 1 1 1 2 1 2 1 6. msg1 visible 30 s after Dequeue3 0 3 0 1 2 1 2 1 1 1 1 1 2 1 2
- 29. C2 P2 P1 C1 Removing Poison Messages 34 0 4 0 Producers Consumers 1 2 1 2 2. Dequeue(Q, 30 sec) msg 2 3. C2 consumed msg 2 4. Delete(Q, msg 2) 7. Dequeue(Q, 30 sec) msg 1 8. C2 crashed 1. Dequeue(Q, 30 sec) msg 1 5. C1 crashed 10. C1 restarted 11. Dequeue(Q, 30 sec) msg 1 12. DeliveryCount > 2 13. msg1.DeadLetter 1 2 1 2 6. msg1 visible 30s after Dequeue 9. msg1 visible 30s after Dequeue 3 0 3 0 1 3 1 3 1 2 1 2 1 3 1 3
- 30. Service Bus Messaging – Dead letters • the name of the sub-queue is [queueName]/ $DeadLetterQueue • The path can be obtained using the FormatDeadLetterPath method of the QueueClient • Can be consumed by any other consumer and check the messages, log them etc.
- 31. Priority Queue • The queue may hold message with different priorities (3-High, 1-Low) Web Sites worker role : : worker roleweb role :
- 34. Meet The Problem 3 DevGeek Coffee Shop
- 35. DevGeek Coffee Shop – The clients complaints 1. Sometimes the soy milk ran out 2. the barista calls to the storeroom 3. The line is busy 4. The barista move to next order 5. Customer receive an order cancellation
- 36. Transient Faults • “Transient fault is a fault that is no longer present if power is disconnected for a short time and then restored.” (http ://en.wikipedia.org/wiki/Transient_fault#Transient_fault) • Many faults in connectivity to cloud are transient by nature • Commonly occur when connecting to service or database
- 37. Retry Pattern • If at first you don’t succeed, try try again (William Edward Hickson) • Retry Logic – Linear – every fixed amount of time – Exponential – if the server is heavy-used (throttling) we don’t want to flood it immediate….1 sec….5 seconds….etc. – Other
- 38. Operation With Basic Retry int currentRetry = 0; while (currentRetry < MaxRetries) { try { // Calling external service. await TransientOperationAsync(); } catch (Exception ex) { currentRetry++; // Check if the exception thrown was a transient exception if (!IsTransient(ex)) { // If this is not a transient error // or we should not retry re-throw the exception. throw; } } await Task.Delay(TimeBetweenRetries); }
- 39. Retry Pattern – Solutions • Azure Storage IRetryPolicy • Azure Service Bus RetryPolicy IRetryPolicy noRetryPolicy = new NoRetry(); BlobRequestOptions requestOptions = new BlobRequestOptions() { RetryPolicy = noRetryPolicy, }; MessagingFactory factory = MessagingFactory.Create(); factory.RetryPolicy = RetryExponential.Default; factory.RetryPolicy = RetryPolicy.NoRetry;
- 40. The Transient Fault Handling Application Block var retryPolicy = new Incremental(5, TimeSpan.FromSeconds(1), TimeSpan.FromSeconds(2)); retryPolicy.Retrying += (sender, args) => { Trace.WriteLine(args.LastException, "Information"); }; try { retryPolicy.ExecuteAction(() => { TranisentErrorOperation(); }); } catch (Exception) { // All the retries failed. } http://msdn.microsoft.com/en-us/library/hh680934(v=pandp.50).aspx
- 41. Circuit Breaker
- 42. Retry Logic – Not Always Not all The time • Baristas keeps retrying/failing – Time Consuming • Maybe we can call someone else? • The remote service still might get flooded • If a failure is not transient, we wish that next attempts fail immediately
- 43. Circuit Breaker • Circuit Breaker pattern prevent repeatedly trying to execute an operation that is likely to fail • continue without waiting for the fault to be rectified • Prevents wasting valuable resources because of the wait
- 44. Circuit Breaker • The Circuit Breaker is a proxy • Monitor the number of recent failures • Decide if to proceed or do something else – Throw exception – Try different destination
- 45. Circuit Breaker States Closed Open Success Fail [threshold reached] Half Open Retry Timeout Fail Success Fail [under threshold]
- 46. Cache Aside
- 47. Deja vu • We fetch the same data • We run the same calculation • We query the same service
- 48. Cache Aside
- 49. Azure Caching • Azure Managed Cache • Azure Redis Cache • In-Role Cache
- 50. In Role Cache – co-located
- 51. In Role Cache - Dedicated
- 52. InRole Cache
- 53. Summery • What are Cloud Patterns • Queue Centric • Poison Messages • Retry Logic • Circuit Breaker • Cache Aside
- 54. References • P&P Cloud Design Patterns - http://msdn.microsoft.com/en-us/library/dn568099.aspx • http://cloudpatterns.org/ • Cloud Architecture Patterns
- 56. Images References 1. http://en.wikipedia.org/wiki/List_of_cloud_types 2. http://www.freedigitalphotos.net/images/Emotions_g96- Arms_Up_Character_Shows_Shock_And_Surprise_p142355.html 3. http://www.freedigitalphotos.net/images/Hot_drinks_g184- Coffee_In_White_Cup_p96634.html