Durable Functions are an extension of Azure Functions that lets you write stateful functions in a serverless environment. Let’s discuss underline architecture of Durable Functions and patterns it can be used. Let’s discuss it in detail and let me show you the way of implementing it with a real-world scenario such as monthly finance document generation and how to handle workflow rollback and exceptions. Session would cover: 1. What are Durable Functions? 2. Why Durable Functions emerged? 3. How underline architecture manages state? 4. Usage Pattern of Durable Functions 5. Demo: Fan in Fan Out, Function chaining and Sub Orchestration

1. STREAMLINEYOUR BUSINESS WORKFLOW WITH
AZURE DURABLE FUNCTIONS
BY: SAMMANI PALANSURIYA EKANAYAKE
SENIOR TECHNICAL LEAD – 99X TECHNOLOGY

2. What we will discuss
Limitation
Durable
Functions
Architectu
re
Demo
• Scenarios where azure
functions fails
• What is durable functions?
• Components
• How it manages state
• Function Chaining
• Fan In Fan Out
• Exception Handling

3. 1 LimitationsLimitations

4. SOLVING FAN IN FAN OUT PATTERN

5. EXCEPTION HANDLING IN FUNCTION CHAIN
Write Order Details Call External Service to
update inventory
Send email to customer

6. 2 Durable FunctionsDurable Functions

7. AZURE DURABLE FUNCTIONS
Durable Functions are an extension of Azure
Functions that lets you write stateful functions in a
serverless environment.The extension manages
state, checkpoints, and restarts for you.

8. MAIN COMPONENTS
Starter
Orchestrato
r
Activity
• Any Trigger Function which
will start the workflow
• Define the workflow
• Triggers “activity” functions
• Sleeps during activities
• Performs a single step in a
workflow
• Can receive and return data

9. D
e
m
o
Function ChainingFunction Chaining

10. 3 ArchitectureArchitecture

11. MANAGING STATE
Storage Account
 Storage Queue – Storage queue is used as the
communication mechanism to trigger the next
function
 Storage Table – Store the state of the orchestrator
function
Event Sourcing

12. TASK HUB

13. ADVANTAGES
 It allow to Define workflow in code
 Error handling is possible at any point
 State management is fully handled so you don’t need to worry about it

14. D
e
m
o
Fan In Fan OutFan In Fan Out

15. FURTHER READING
 What are the other usage patterns
 Orchestrator Constraints
 https://sammanipalansuriya.blogspot.com/search/label/Azure%20Durable%20Functions
 https://code.msdn.microsoft.com/Azure-Durable-Functions-9099c85f