This document discusses key considerations for architecting Azure solutions, including: - Software architecture focuses on the fundamental organization of a system, including its components, relationships, and design principles. - Idempotency is important to address problems like messages being processed multiple times if a worker role fails. Transaction IDs can be used to prevent duplicate processing. - Latency in Azure may be zero, but using bandwidth and other resources has real costs that must be accounted for in architecture. - Service Bus enables secure and reliable messaging across hybrid cloud/on-premises applications and networks.

1. Things to think about whilearchitecting Azure solutions

2. Famous Last Words…“It is a very humbling experience to make a multimillion-dollar mistake, but it is also very memorable….”(Fred Brooks - “Mythical Man-Month” p.47)

3. So, What is Software Architecture exactly?

4. Software architecture is the fundamentalorganization of a system, embodied in its components, their relationships to each other and the environment, and the principles governing its design and evolution

5. Architecture forcesStakeholdersQuality AttributesConstraintsPrinciplesCommunity experienceArchitectArchitecturePatterns & Anti-patternsKeypeopleTechnologyA “deliverable”ProduceIs an input

7. Dequeue/Delete patternThe Network is reliable

8. Dequeue/Delete patternThe Network is reliableStill a problem If we crash here

9. Idempotencyf(x) = f(f(x))

10. Messages Process At Least OnceDebit bank account $100 messageWorker role reads messageBalance debited $100Worker role is torn before message can be deleted3 minutes later, message re-appears on queueWorker role reads messageBalance debited $100Message deleted from queueChaos ensues.....Customer calls bank.....Web RoleWorker RoleBalance = $1000Balance = $900Balance = $800Worker RoleWeb RoleWorker RoleWorker RoleQueueStorageLBLB

11. Solving the Idempotency ProblemDebit bank account $100 message with transaction IDWorker role reads message. Checks transaction ID not present.Writes transaction ID with state ‘Started’ to ‘Replay Log’Balance debited $100Worker role is torn before message can be deleted3 minutes later, message re-appears on queueWorker role reads message. Checks transaction ID. It is present in state started.Compensating message written to another queueMessage deleted from queueCompensatory message processed.Balance = $1000Balance = $900Web RoleWorker RoleWorker RoleWeb RoleStorageWorker RoleWorker RoleQueryQueryQueueQueueTableLBLB

12. Latency is zero

13. It might be infinite for all purposes but it costs…Bandwidth is infinite

14. Authentication with ACSThe Network is SecureSlide by Alik Levin

15. Service BusProvides secure messaging and connectivity across different network topologiesEnables hybrid applications that span on-premises and the cloudEnables various communication protocols and patterns for developers to engage in reliable messagingTopology doesn’t change

16. Enabling hybrid applicationsDatacenterPartnerLOB appMobile DeviceLOB web service

17. Enabling hybrid applicationsDatacenterPartnerACSLOB appSBMobile DeviceLOB web service

18. Enabling hybrid applicationsDatacenterPartnerACSLOB appSBMobile DeviceLOB web service

19. Enabling hybrid applicationsPartnerDatacenterACSLOB appSBMobile DeviceLOB web service

20. Enabling hybrid applicationsPartnerDatacenterACSLOB appSBMobile DeviceLOB web service

21. Electricity Power GridDemo

22. Don’t assume specific instancesVirtual IP : 1.1.1.2Virtual IP : 1.1.1.3Virtual IP : 1.1.1.4Worker RoleWorker RoleWeb RoleService Service IISInstanceInstanceWindows KernelWindows KernelWindows KernelTCP/IPTCP/IPTCP/IPTCP/IPTCP/IPNLB DriverNIC DriverNIC DriverNIC DriverVirtual NICVirtual NICVirtual NICVirtual IP : 1.1.1.1

23. Inter-role communications

24. Reduced Headache on the one handNew challenges on the otherThere is one administrator

25. Azure MMC Snap-in http://code.msdn.microsoft.com/windowsazuremmc

26. Cerebrata – Azure Diagnostics Managerhttp://www.cerebrata.com/Products/AzureDiagnosticsManager/Default.aspx

27. Distribution cost in serialization, time on the wire, security Transport cost is zero

28. A lot of calls to fulfill a business function

29. Bring Data close to computation

30. It isn’t – but it’s abstractedunless of course you use Azure connectThe Network is homogenous Quickly connect on-premise computers with the cloud, no networking configuration requiredSupports standard IP protocols; secured using end-to-end IPSecIntegrated with the Windows Azure Service Model; all role types supported

31. Deployment viewConsider xsmall instances for developmentTest if you can use less than medium for production

32. Cost considerationsYou pay when you’re deployed (there is no “shelving”)Shutdown doesn’t help(keep CPUs running..)

33. 2 Small instances cost the same as 1 medium instance

34. 2 instances can give you better availabilityNeed to be on different fault and upgrade domains

35. I/O performance on smaller instances might be problematic

36. You can control Azure from scripts and code (even dev fabric)Testing

37. Demo Cloudoscope Acceptance Tests

38. IllustrationsSlide 11 http://www.sxc.hu/photo/1201443Slide http://www.sxc.hu/photo/1160486