Azure Durable Functions – Documentation

What are Durable Functions?

Durable Functions is an extension of Azure Functions that lets you write stateful functions in a serverless environment. It enables you to define workflows in code, orchestrate long‑running processes, and manage state, checkpoints, and retries automatically.

Key Concepts

Orchestrator functions – define the control flow of your workflow.
Activity functions – perform the actual work.
Entity functions – represent durable, mutable state.
Triggers & bindings – integrate with Azure services.

Sample Orchestration

using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.DurableTask;
using System.Collections.Generic;
using System.Threading.Tasks;

public static class HelloWorldOrchestrator
{
    [FunctionName("HelloWorldOrchestrator")]
    public static async Task<IEnumerable<string>> Run(
        [OrchestrationTrigger] IDurableOrchestrationContext ctx)
    {
        var outputs = new List<string>();

        // Replace "Hello" with the name of your activity function.
        outputs.Add(await ctx.CallActivityAsync<string>("Hello", "Tokyo"));
        outputs.Add(await ctx.CallActivityAsync<string>("Hello", "Seattle"));
        outputs.Add(await ctx.CallActivityAsync<string>("Hello", "London"));

        // returns ["Hello Tokyo!", "Hello Seattle!", "Hello London!"]
        return outputs;
    }

    [FunctionName("Hello")]
    public static string SayHello([ActivityTrigger] string name)
    {
        return $"Hello {name}!";
    }
}

Common Patterns

Next Steps

Ready to dive in? Start with our Getting Started guide or explore specific workflow patterns.