Azure Durable F#unctions

Serverless architecture is the future of the cloud. Initially, the serverless tech focused on running small isolated tasks in response to cloud events.

The next evolutionary step is to compose complex applications out of those small components. Azure Durable Functions provides powerful abstractions for workflow composition on top of standard Functions.

Join Mikhail, the author of DurableFunctions.FSharp library, to see how F# is the most powerful language to orchestrate stateful, reliable, long-running serverless applications.

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1. Azure Durable F#unctions F# eXchange | April 5 | 2019 Mikhail Shilkov
2. Stateful Workflows Stateless Serverless Cloud Functions
3. Stateful Workflows Stateless Serverless Cloud Functions
4. Stateful Workflows Stateless Serverless Cloud Functions
6. Module A Module B Module C Shared Database
7. Service A Service B Service C Database A Database B Database C
8. Service A Service B Unreliable Network Database A Database B
9. Service A Service B Service C HTTP(S) HTTP(S)
10. Service A Service B Service C HTTP(S) HTTP(S)
11. Service A Service B Service C HTTP(S) HTTP(S)
12. Service A Service B Service C HTTP(S) HTTP(S)
14. Service A Service B Service C Event Event
15. Step One Completed Workflow Started Another Step Completed Next Action Completed Event Log
20. • • • •
21. • • • •    
25. $
26. https://www.serverless360.com/blog/building-reactive-solution-with-azure-event-grid
28. Send Text Record Alert Send Email Event Event
29. Send Text Record Alert Send Email Event Event Record Alert Event Event Send Email Send Text
30. Raise Alert Send Text Event
31. Event Send Telegram Raise Alert Send Text
32. Raise Alarm Send Text Record Alarm Send Email Event Event Event
33. Raise Alert Send Text Send Email Record Alert
35. long-running orchestrations single function maintaining local state complex transactions code-only C#, JavaScript, F# Image by de la Cruz family @pacodelacruz
39. Send Text Record Alert Send Email
40. [<FunctionName("SendText")>] let sendTextFunction([<ActivityTrigger>] message) = let number = Config.alertMobileNumber SmsService.send number message
41. [<FunctionName("SendText")>] let sendTextFunction([<ActivityTrigger>] message) = let number = Config.alertMobileNumber SmsService.send number message
42. [<FunctionName("SendText")>] let sendTextFunction([<ActivityTrigger>] message) = let number = Config.alertMobileNumber SmsService.send number message let sendText = Activity.define "SendText" sendTextFunction
43. Raise Alert Send Text Send Email Record Alert
44. let trivial person = orchestrator { let text = sprintf "Hello %s" person do! Activity.call sendText text }
45. let trivial person = orchestrator { let text = sprintf "Hello %s" person do! Activity.call sendText text } [<FunctionName("TrivialOrchestrator")>] let trivialOrchestrator( [<OrchestrationTrigger>] context: DurableOrchestrationContext) = Orchestrator.run (trivial, context)
46. let trivial person = orchestrator { let text = sprintf "Hello %s" person do! Activity.call sendText text } [<FunctionName("TrivialOrchestrator")>] let trivialOrchestrator( [<OrchestrationTrigger>] context: DurableOrchestrationContext) = Orchestrator.run (trivial, context)
47. let trivial person = orchestrator { let text = sprintf "Hello %s" person do! Activity.call sendText text } [<FunctionName("TrivialOrchestrator")>] let trivialOrchestrator( [<OrchestrationTrigger>] context: DurableOrchestrationContext) = Orchestrator.run (trivial, context)
49. 1 2 3 Raise Alert Send Text Send Email Record Alert
50. let raiseAlert alert = orchestrator { let! text = Activity.call sendText alert let! email = Activity.call sendEmail alert let entry = AlertEntry.make alert text email do! Activity.call recordAlert entry }
51. Orchestrator Activity Message Message Activity is scheduled Activity result is reported back
52. 1. Orchestrator Started 2. ExecutionStarted: RaiseAlert 3. TaskScheduled: SendText 4. OrchestratorCompleted 5. TaskCompleted: "Text sent at 11:33" 6. OrchestratorStarted 7. TaskScheduled: SendEmail 8. OrchestratorCompleted 9. TaskCompleted: “Email sent at 11:35"
53. let raiseAlert alert = orchestrator { let! text = Activity.call sendText alert let! email = Activity.call sendEmail alert let entry = AlertEntry.make alert text email do! Activity.call recordAlert entry }
55. Send Email 1 2 Raise Alert Send Text Record Alert
56. let errorHandling alert = orchestrator { let! text = Activity.call sendText alert let! email = try Activity.call sendEmail alert with | :? FunctionFailedException -> Activity.call sendEmailViaBackupChannel alert let entry = AlertEntry.make alert text email do! Activity.call recordAlert entry }
57. 1 2 Send Email Raise Alert Send Text Record Alert
58. let retries alert = orchestrator { let! text = Activity.call sendText alert let policy = ExponentialBackOff { FirstRetryInterval = minutes 1 BackoffCoefficient = 2.0 MaxNumberOfAttempts = 4 } let! email = Activity.callWithRetries policy sendEmail alert let entry = AlertEntry.make alert text email do! Activity.call recordAlert entry }
60. 1 2 1 Raise Alert Send Text Record Alert Send Email
61. let fanOut alert = orchestrator { let textCall = Activity.call sendText alert let emailCall = Activity.call sendEmail alert let! text = textCall let! email = emailCall let entry = AlertEntry.make alert text email do! Activity.call recordAlert entry }
62. let fanOut alerts = orchestrator { let! emails = alerts |> List.map (Activity.call sendEmail) |> Activity.all // ... }
64. Raise Alert Send Email Send Text Result or Timeout Human Reacts Timeout 1 hour Wait 10 min
65. let schedule alert = orchestrator { let! email = Activity.call sendEmail alert do! Orchestrator.delay (minutes 10) let! isResolved = Activity.call checkStatus alert if (not isResolved) then do! Activity.call sendText alert let! result = Orchestrator.waitForEvent (hours 1) "Ack" match result with | Ok r -> // Acknowledged ... | Error _ -> // Escalate ... }
66. let schedule alert = orchestrator { let! email = Activity.call sendEmail alert do! Orchestrator.delay (minutes 10) let! isResolved = Activity.call checkStatus alert if (not isResolved) then do! Activity.call sendText alert let! result = Orchestrator.waitForEvent (hours 1) "Ack" match result with | Ok r -> // Acknowledged ... | Error _ -> // Escalate ... }
67. let schedule alert = orchestrator { let! email = Activity.call sendEmail alert do! Orchestrator.delay (minutes 10) let! isResolved = Activity.call checkStatus alert if (not isResolved) then do! Activity.call sendText alert let! result = Orchestrator.waitForEvent (hours 1) "Ack" match result with | Ok r -> // Acknowledged ... | Error _ -> // Escalate ... }
68. let schedule alert = orchestrator { let! email = Activity.call sendEmail alert do! Orchestrator.delay (minutes 10) let! isResolved = Activity.call checkStatus alert if (not isResolved) then do! Activity.call sendText alert let! result = Orchestrator.waitForEvent (hours 1) "Ack" match result with | Ok r -> // Acknowledged ... | Error _ -> // Escalate ... }
71.  Event-Driven  Managed Cloud Services  Rapid Development  Pay-as-you-Go
74. https://mikhail.io/2018/12/making-sense-of-azure-durable-functions/ https://mikhail.io/2018/12/fairy-tale-of-fsharp-and-durable-functions/ https://github.com/mikhailshilkov/DurableFunctions.FSharp https://github.com/Azure/azure-functions-durable-extension https://github.com/Azure/durabletask/tree/azure-functions https://aka.ms/durablefunctions
75. @MikhailShilkov https://mikhail.io