These are the slides for the Azure Durable Functions presentation I gave at the Azure User Group Netherlands (https://www.wazug.nl/) hosted by Xpirit. Source code: https://github.com/marcduiker/demos-azure-durable-functions

2. Marc Duiker
Lead Azure Consultant @ Xpirit

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Durable Functions

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Durable Functions

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Durable Functions

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Durable Functions

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Durable Functions
Multiple Functions & Control Flow

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Durable Functions

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Durable Functions

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Durable Functions

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Durable Functions

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Durable Functions

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Durable Functions

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Durable Functions

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Durable Functions
Durable Functions is based on

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Durable Functions
Function Roles

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Durable Functions
Invocations, Checkpoints & Replay

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Durable Functions
Storage Types used by Durable Functions

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Durable Functions
State is Persisted in Table Storage

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Durable Functions
New Trigger Bindings
[OrchestrationClient] DurableOrchestrationClient(Base)
Function Role: Orchestration Starter

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Durable Functions
DurableOrchestrationClient

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Durable Functions
New Trigger Bindings
[OrchestrationTrigger] DurableOrchestrationContext(Base)
Function Role: Orchestration Function

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Durable Functions
DurableOrchestrationContext

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Durable Functions
New Trigger Bindings
[ActivityTrigger] DurableActivityContext
Function Role: Activity Function

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Durable Functions
DurableActivityContext

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Durable Functions

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Durable Functions
• Visual Studio 2017 15.7+
• Azure Workload
- Extension: Azure Functions & Web Jobs Tools
- Azure Storage Emulator
- Microsoft.Azure.Webjobs.Extensions.DurableTask
Local development with VS2017

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Durable Functions
Hello {name} Demo!
HttpStart HelloName
{name}
HelloNameActivity
{name}

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Durable Functions

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Durable Functions
Function chaining

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Durable Functions
Demo: Function Chaining
Find a Star Wars character and their home planet.
https://swapi.co/

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Durable Functions
Demo: Function Chaining
HttpStart GetCharacterInfo SearchCharacter GetPlanet

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Durable Functions

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Durable Functions
Fan-out/fan-in
FA1 returns a collection of items
FA2 is called for each of the items from FA1

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Durable Functions
Demo: Fan-out/Fan-in
Find a Star Wars planet and their residents.
https://swapi.co/

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Durable Functions
Demo: Fan-out/Fan-in
HttpStart GetPlanetResidents SearchPlanet GetCharacter

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Durable Functions

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Durable Functions
Unit Testing Demo
Testing the GetPlanetResidents orchestration using:
• xUnit
• Moq
• AutoFixture

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Durable Functions
Unit Testing
• Use DurableOrchestrationContextBase in the orchestration.
• Use serializable types with [ActivityTrigger] for the activity
input (because DurableActivityContext can’t be
instantiated/mocked due to internal constructor  ).

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Durable Functions

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Durable Functions
• In and output of functions should be serializable.
• Orchestration Functions should be deterministic:
- DateTime.Now, use CurrentUtcDateTime
- Guid.NewGuid()
- Random generated data
Closing remarks I

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Durable Functions
• Orchestration Functions can only call Activity Functions
in the same Function App.
• Keep your orchestrations small.
• What changes together should be deployed together.
Closing remarks II

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Durable Functions
GitHub: demos-azure-durable-functions
mduiker@xpirit.com
blog.marcduiker.nl
@marcduiker