Durable functions
- 2. Amresh Krishnamurthy ◈ Technical Architect, JCPenney ◈ BDotNet Member ◈ @amreshkris
- 3. Agenda ◈ Serverless in Azure ◈ Azure Functions ◈ Sample Problem ◈ Why we need Durable Functions ! ◈ What is Durable Functions ! � Activity Functions � Orchestrator � How does it work? � Workflows � Error Handling and Resiliency � Demo
- 4. Azure Serverless Compute ◈ Serverless computing enables developers to build applications faster by eliminating the need for them to manage infrastructure. With serverless applications, the cloud service provider automatically provisions, scales and manages the infrastructure required to run the code. Event Grid Logic Apps Azure Functions
- 5. Azure Functions - FaaS Short Lived Each function is short lived for its executions and resources freed-up after one execution Stateless Functions don’t maintain state Event-driven | Dynamic Scaling Functions are triggered through events such as Http trigger, Timer, Event grid etc. Pay as per you use Pay only for the time the function actively runs.
- 6. Sample Business Usecase & Solution
- 7. Function Chaining Fan out- Fan In Async HTTP API Monitor Aggregato r Approval
- 8. Hello, Durable Functions Orchestration of Azure Functions Durable Functions are extensions of Azure Functions. Azure Function – Stateless Vs Durable Function – Can retain state Long running orchestrations as a single unit. Coordinate and Aggregate across multiple functions/workflows Code driven. No JSON schema files or no designer involved Built on Durable Task Framework and Azure Function. Uses Azure storage for maintaining state.
- 9. Components Activity Function ◈ Activity Function – Performs Activity/Unit of work. Tasks being orchestrated Book Hotel Book Flight Compute Total
- 10. Components Orchestrator Function ◈ Orchestrator Function – Described how actions are executed and the order in which they are run. Orchestrate : Book Vacation
- 11. Components Client Function ◈ Client Function – Entry point for creating an instance of Durable function. Trigger/Event Based Trigger : Book Vacation
- 12. Durable Function Flow Starter Function Orchestrator Function Activity Function
- 13. Demo ◈ Durable Functions – Function Chaining ◈ Fan Out- Fan In ◈ VS Code – Azure Storage Emulator ◈ Source Code - https://github.com/amreshkris/DurableFunctions-FanOutFanIn
- 14. How Durable functions works ! ◈ Pattern Used – Event Sourcing – Maintains each step of the execution in Event/History Table ◈ `` Orchestration Function Called Orchestration Started Activity Function F1 Called Activity Function F1 Scheduled Execution Instance Started Orchestration Completed Activity Function F1 Completed Activity Function F2 Called Orchestration Started Activity Function F2 Scheduled Orchestration Completed Orchestration Started Activity Function F2 Completed Orchestrator Execution Completed
- 15. Error Handling | Resiliency ◈ Demo
- 16. Orchestrator Function Constraints ◈ Must be deterministic ◈ Avoid Date and Time related API – Use ‘CurrentUtcDateTime’ provided in Durable functions context ◈ Random Numbers , Async API , Static Variables , Infinite loops etc theCurrentUtcDateTime