Slides of the presentation I gave at Experts Live 2018 in Ede about the Durable Functions extension for Azure Functions. The source code containing all the demos (HelloWorld, Function Chaning and Fan-out/Fan-in) is located in this repo: https://github.com/marcduiker/demos-azure-durable-functions

2. Marc Duiker
Lead Consultant @ Xpirit

3. Marc Duiker
Durable Functions
• Shift to Serverless
• What are orchestrations?
• Why do we need them?
• What is Durable Functions?
• Local development
• Demos
• Hello World / Hello Name
• Function chaining
• Fan-out/Fan-in
• Unit Testing

4. Marc Duiker
Durable Functions

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Durable Functions
IaaS PaaS SaaSFaaS
+ Less maintenance
+ Pay as you go
+ More fine grained scalability
- Less control
- More moving parts

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Durable Functions

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Durable Functions
Control flow

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Durable Functions

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Durable Functions
Orchestration?
Orchestration is the automated arrangement, coordination, and
management of computer systems, middleware, and services.

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Durable Functions

11. Marc Duiker
Durable Functions

12. Marc Duiker
Durable Functions

13. Marc Duiker
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
New Trigger Bindings
[OrchestrationClient] DurableOrchestrationClient
Function Role: Orchestration Starter

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Durable Functions
DurableOrchestrationClient

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Durable Functions
New Trigger Bindings
[OrchestrationTrigger] DurableOrchestrationContext
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
Invocations, Checkpoints & Replay
Function invocation Execution history

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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
Considerations when using Durable Functions
- In and output of functions should be serializable.
- Orchestration Functions should be deterministic:
- DateTime.Now, use CurrentUtcDateTime
- Guid.NewGuid()
- Random generated data

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Durable Functions

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Durable Functions
Visual Studio 2017 15.7+
- “Azure development tools” workload
- Extension: Azure Functions & Web Jobs Tools
- Azure Storage Emulator
- Azure Storage Explorer
Local development

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Durable Functions
Hello World Demo!
HelloWorld HelloWorldActivityHttpStart

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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 GetSwCharacterInfo 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 GetSwPlanetResidents SearchPlanet GetCharacter

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Durable Functions

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Durable Functions
Unit Testing Demo
Testing the GetSwPlanetAndResidentials 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  ).

44. Marc Duiker
Durable Functions

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

46. Marc Duiker
Durable Functions
GitHub: demos-azure-durable-functions
blog.marcduiker.nl
@marcduiker