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Durable functions
- 1. Durable functions Basic informationabout durable functions
- 2. Introduction Durable Functions isan extension of Azure Functions and Azure WebJobs that lets you write stateful functions in a serverless environment. The extension manages state, checkpoints, and restarts for you. • Basic information about durable functions • Demo in 5 patterns Basic information about durable functions and demo in 5 patterns
- 3. Behind the scenes EventSourcing https://www.youtube.com/watch?v=9a1PqwFrMP0
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- 5. Client Client functions arethe triggered functions that will create new instances of an orchestration
- 6. Orchestrator Orchestrator functions arethe heart of a durable function. Orchestrator functions describe the way and order actions are executed. 1. StartNewAsync 2. GetStatusAsync 3. TerminateAsync 4. RaiseEventAsync
- 7. Orchestrator code contrains •Orchestrator code must be deterministic • Orchestrator code should be non-blocking • Orchestrator code must never initiate any async operation • Infinite loops should be avoided in orchestrator code
- 8. Basic information Activity functionsare the basic unit of work in a durable orchestration. Activity functions are the functions and tasks being orchestrated in the process
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- 10. SUMMARY The primary usecase for Durable Functions is simplifying complex, stateful coordination problems in serverless applications Durable Functions is an advanced extension for Azure Functions that is not appropriate for all applications. The rest of this article assumes that you have a strong familiarity with Azure Functions concepts and the challenges involved in serverless application development.
- 11. More information References • https://docs.microsoft.com/en-us/azure/azure-functions/durable- functions-overview •https://github.com/Azure/azure-functions-durable-extension • https://www.youtube.com/watch?v=9a1PqwFrMP0
- 12. Durable functions –Q&A Thanks for listening!
Editor's Notes
- #8 1. Orchestrator code must be deterministic. It will be replayed multiple times and must produce the same result each time. For example, no direct calls to get the current date/time, get random numbers, generate random GUIDs, or call into remote endpoints. If orchestrator code needs to get the current date/time, it should use the CurrentUtcDateTime API, which is safe for replay. Non-deterministic operations must be done in activity functions. This includes any interaction with other input or output bindings. This ensures that any non-deterministic values will be generated once on the first execution and saved into the execution history. Subsequent executions will then use the saved value automatically. 2. Orchestrator code should be non-blocking. For example, that means no I/O and no calls to Thread.Sleep or equivalent APIs. If an orchestrator needs to delay, it can use the CreateTimer API. 3. Orchestrator code must never initiate any async operation except by using the DurableOrchestrationContext API. For example, no Task.Run, Task.Delay or HttpClient.SendAsync. The Durable Task Framework executes orchestrator code on a single thread and cannot interact with any other threads that could be scheduled by other async APIs. 4. Infinite loops should be avoided in orchestrator code. Because the Durable Task Framework saves execution history as the orchestration function progresses, an infinite loop could cause an orchestrator instance to run out of memory. For infinite loop scenarios, use APIs such as ContinueAsNew to restart the function execution and discard previous execution history.