A lightning talk on Azure Durable Functions presented at NET Oxford

1. Azure Durable
Funkiness
@stuartleeks
Web and Cloud geek @ Microsoft

2. The Evolution of
Code
C# Edition

3. Sync -> Async -> Parallel -> Distributed

4. Synchronous
void DemoSync()
{
try // try/catch and using work nicely
{
DoStuff();
DoMoreStuff();
DoEvenMoreStuff();
}
catch (Exception ex)
{
// Handle exception
}
}

5. Asynchronous
async Task<string[]> DemoAsync()
{
try // try/catch and using work nicely
{
var x = await DoStuffAsync();
var y = await DoMoreStuffAsync();
var z = await DoEvenMoreStuffAsync();
return new[] { x, y, z };
}
catch (Exception ex)
{
// Handle exception
}
}

6. Asynchronous
async Task<string[]> DemoAsync()
{
try // try/catch and using work nicely
{
var x = await DoStuffAsync();
var y = await DoMoreStuffAsync();
var z = await DoEvenMoreStuffAsync();
return new[] { x, y, z };
}
catch (Exception ex)
{
// Handle exception
}
}

7. Asynchronous
async Task<string[]> Demo2Async()
{
try // try/catch and using work nicely
{
var taskx = DoStuffAsync();
var x = await taskx;
var y = await DoMoreStuffAsync();
var z = await DoEvenMoreStuffAsync();
return new[] { x, y, z };
}
catch (Exception ex)
{
// Handle exception
}
}

8. Parallel
async Task<string> Demo1Parallel()
{
try // try/catch and using work nicely
{
var task1 = DoStuffAsync();
var task2 = DoMoreStuffAsync();
await task1;
await task2;
return await DoStuffAfterOtherStuffAsync(task1.Result, task2.Result);
}
catch (Exception ex)
{
// Handle exception
}
}

9. Parallel
async Task<string> DemoParallel()
{
try // try/catch and using work nicely
{
var task1 = DoStuffAsync();
var task2 = DoMoreStuffAsync();
await Task.WhenAll(task1, task2);
return await DoStuffAfterOtherStuffAsync(task1.Result, task2.Result);
}
catch (Exception ex)
{
// Handle exception
}
}

10. Sync -> Async -> Parallel

11. Azure Durable Functions

12. Sync -> Async -> Parallel -> Distributed

13. Distributed - Chaining
async Task<string[]> Run1(DurableOrchestrationContext ctx)
{
try // try/catch and using work nicely
{
var x = await ctx.CallActivityAsync<string>("DoStuffAsync");
var y = await ctx.CallActivityAsync<string>("DoMoreStuffAsync");
var z = await ctx.CallActivityAsync<string>("DoEvenMoreStuffAsync");
return new[] { x, y, z };
}
catch (Exception)
{
// Handle exception
}
}

14. Distributed – Fan-out/Fan-in
public static async Task<string> Run2(DurableOrchestrationContext ctx)
{
try // try/catch and using work nicely
{
var task1 = ctx.CallActivityAsync<string>("DoStuffASync");
var task2 = ctx.CallActivityAsync<string>("DoMoreStuffASync");
await Task.WhenAll(task1, task2);
return await ctx.CallActivityAsync<string>("DoStuffAfterOtherStuffAsync", task1.Result, task2.Result);
}
catch (Exception)
{
// Handle exception
}
}

15. Durable Functions - Patterns

16. Distributed – Trigger function
[FunctionName("Start")]
public static async Task<HttpResponseMessage> Start(
[HttpTrigger(AuthorizationLevel.Function, "get", "post")] HttpRequestMessage request,
[OrchestrationClient] DurableOrchestrationClient starter)
{
var instanceId = await starter.StartNewAsync("WaitForApproval");
return starter.CreateCheckStatusResponse(request, instanceId);
}

17. Distributed – Timers and External Events
[FunctionName(“WaitForApproval")]
public static async Task<string> WaitForApproval(DurableOrchestrationContext ctx)
{
var approvedTask = ctx.WaitForExternalEvent<string>("Approved");
var cts = new CancellationTokenSource();
var timeoutTask = context.CreateTimer(context.CurrentUtcDateTime.AddMinutes(5), cts.Token);
var winningTask = await Task.WhenAny(approvedTask, timeoutTask);
if (winningTask == timeoutTask)
await ctx.CallActivityAsync<string>(“Escalate");
else
await ctx.CallActivityAsync<string>(“Success");
}

18. Distributed – Timers and External Events
[FunctionName(“Approve")]
public static async Task<HttpResponseMessage> Approve(
[HttpTrigger(AuthorizationLevel.Function, "get", "post")] HttpRequestMessage request,
[OrchestrationClient] DurableOrchestrationClient starter)
{
var instanceId = request.RequestUri.ParseQueryString()["instanceId"];
return starter.RaiseEventAsync(instanceId, "Approved", "Stuart Leeks");
}

19. Durable Functions - Patterns

20. Durable Functions
http://aka.ms/durablefunctions

21. The Evolution of
Code
C# Edition
With Azure Functions
Durable Functions
http://aka.ms/durablefunctions