[.NET] Add a Functions-native API for invoking Durable Workflows by cgillum · Pull Request #48 · microsoft/agent-framework-durable-extension

Chris Gillum (cgillum) · 2026-07-24T23:38:38Z

.NET-specific fix for #24.

Summary

Azure Functions can now invoke a registered durable workflow using a strongly typed IWorkflowClient, i.e., without an HttpClient or workflow URL:

[Function(nameof(CancelOrderAsync))]
public async Task<IActionResult> CancelOrderAsync(
    [HttpTrigger(AuthorizationLevel.Anonymous, "post", Route = "orders/{orderId}/cancel")] HttpRequest request,
    string orderId,
    [DurableClient] DurableTaskClient durableClient,
    FunctionContext context)
{
    IWorkflowClient workflows = durableClient.AsWorkflowClient(context);
    IWorkflowRun run = await workflows.RunAsync("CancelOrder", orderId);
    return new AcceptedResult(value: run.RunId, location: null);
}

As shown in the sample above, AsWorkflowClient converts a DurableTaskClient binding parameter to the IWorkflowClient interface, which defines RunAsync and StreamAsync overloads for invoking registered workflows by name.

This PR also fixes Functions-host workflow-result deserialization: host output uses PascalCase, which the source-generated reader previously treated as case-sensitive and could deserialize as null.

Breaking Changes

We're adding new methods to the public IWorkflowClient interface, which is a breaking change for external implementers.
An untyped null first argument to RunAsync is now ambiguous; callers will need to cast it to Workflow when needed.

Starting a durable workflow from inside an Azure Function required building an HttpClient and POSTing to the workflow's generated HTTP route, which coupled function code to that route. IWorkflowClient already existed, but it was only reachable from the console and worker host, and every overload required the Workflow object, which function classes generally don't have a reference to. Add name-based RunAsync and StreamAsync overloads that resolve against the registered workflows, and expose the client to function code through DurableTaskClient.AsWorkflowClient(FunctionContext), mirroring the existing AsDurableAgentProxy pattern. Starting an unregistered name fails fast with the new WorkflowNotRegisteredException. Fixes #24 Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

This PR adds a Functions-native way to invoke Durable Workflows without constructing an HttpClient and calling the generated workflow HTTP endpoints. It does so by extending IWorkflowClient with name-based overloads (with fast-fail when a workflow name isn’t registered) and by exposing an AsWorkflowClient(FunctionContext) extension on DurableTaskClient for Azure Functions code that receives the client via [DurableClient].

Changes:

Add name-based RunAsync/StreamAsync overloads to IWorkflowClient, implemented by DurableWorkflowClient using the registered workflow registry.
Add DurableTaskClientExtensions.AsWorkflowClient(FunctionContext) to bridge the [DurableClient] binding into an IWorkflowClient in Azure Functions.
Demonstrate and validate the feature via the 01_SequentialWorkflow sample plus unit and integration tests.

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
dotnet/tests/Microsoft.Agents.AI.Hosting.AzureFunctions.UnitTests/DurableTaskClientWorkflowExtensionsTests.cs	Adds unit coverage for `DurableTaskClientExtensions.AsWorkflowClient` and expected error cases.
dotnet/tests/Microsoft.Agents.AI.Hosting.AzureFunctions.IntegrationTests/WorkflowSamplesValidation.cs	Extends the existing live-host integration validation to exercise the new “invoke via function code” path.
dotnet/tests/Microsoft.Agents.AI.DurableTask.UnitTests/Workflows/DurableWorkflowClientTests.cs	Adds unit coverage for name-based `IWorkflowClient` overload behavior (success, runId, casing, and error cases).
dotnet/src/Microsoft.Agents.AI.Hosting.AzureFunctions/DurableTaskClientExtensions.cs	Introduces `AsWorkflowClient(context)` extension to construct a workflow client from a `[DurableClient]` binding and DI options.
dotnet/src/Microsoft.Agents.AI.Hosting.AzureFunctions/CHANGELOG.md	Documents the new Azure Functions extension API.
dotnet/src/Microsoft.Agents.AI.DurableTask/Workflows/IWorkflowClient.cs	Adds public name-based overloads for running/streaming registered workflows.
dotnet/src/Microsoft.Agents.AI.DurableTask/Workflows/DurableWorkflowClient.cs	Implements name-based overloads by resolving workflows from `DurableOptions` and delegating to existing workflow-object overloads.
dotnet/src/Microsoft.Agents.AI.DurableTask/WorkflowNotRegisteredException.cs	Adds a dedicated exception to fail fast on typo’d/unregistered workflow names.
dotnet/src/Microsoft.Agents.AI.DurableTask/CHANGELOG.md	Records the breaking interface change and the new overload surface.
dotnet/samples/DurableWorkflows/AzureFunctions/01_SequentialWorkflow/README.md	Documents invoking workflows from function code via `AsWorkflowClient` (no `HttpClient`).
dotnet/samples/DurableWorkflows/AzureFunctions/01_SequentialWorkflow/Program.cs	Adds explanatory comments pointing to the new sample function usage.
dotnet/samples/DurableWorkflows/AzureFunctions/01_SequentialWorkflow/OrderFunctions.cs	Adds sample HTTP-trigger functions that start a registered workflow via `AsWorkflowClient`.
dotnet/samples/DurableWorkflows/AzureFunctions/01_SequentialWorkflow/demo.http	Adds demo requests for the new sample endpoints.

Comments suppressed due to low confidence (2)

dotnet/tests/Microsoft.Agents.AI.Hosting.AzureFunctions.UnitTests/DurableTaskClientWorkflowExtensionsTests.cs:53

CreateServiceProviderWithWorkflows() returns a disposable ServiceProvider, but it’s created inline here and never disposed. Prefer creating it in a using declaration so the container is cleaned up after the test.

        FunctionContext context = CreateContext(CreateServiceProviderWithWorkflows());

dotnet/tests/Microsoft.Agents.AI.Hosting.AzureFunctions.UnitTests/DurableTaskClientWorkflowExtensionsTests.cs:105

This test creates a disposable ServiceProvider inline via CreateServiceProviderWithWorkflows() and never disposes it. Use a using variable to ensure the container is disposed at the end of the test.

        FunctionContext context = CreateContext(CreateServiceProviderWithWorkflows());

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated 1 comment.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated 3 comments.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated no new comments.

The Azure Functions worker serializes orchestration output with the Durable Task default JsonDataConverter, which applies no naming policy and writes PascalCase. DurableWorkflowJsonContext read it back with a camelCase, case-sensitive source-generated context, so every property silently bound to null and the workflow result was lost. The built-in HTTP endpoint was unaffected because it round-trips through the same converter via ReadOutputAs<T>(). Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 15 out of 15 changed files in this pull request and generated no new comments.

Copilot

Pull request overview

Copilot reviewed 15 out of 15 changed files in this pull request and generated 1 comment.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 15 out of 15 changed files in this pull request and generated no new comments.

Copilot

Pull request overview

Copilot reviewed 15 out of 15 changed files in this pull request and generated 1 comment.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 15 out of 15 changed files in this pull request and generated no new comments.

Copilot AI review requested due to automatic review settings July 24, 2026 23:38

Copilot started reviewing on behalf of Chris Gillum (cgillum) July 24, 2026 23:39 View session

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Comment thread ...osoft.Agents.AI.Hosting.AzureFunctions.UnitTests/DurableTaskClientWorkflowExtensionsTests.cs Outdated

Comment thread ...osoft.Agents.AI.Hosting.AzureFunctions.UnitTests/DurableTaskClientWorkflowExtensionsTests.cs Outdated

Dispose ServiceProvider instances in AsWorkflowClient tests

93bc8a8

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot AI review requested due to automatic review settings July 24, 2026 23:52

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Comment thread dotnet/src/Microsoft.Agents.AI.DurableTask/Workflows/DurableWorkflowClient.cs Outdated

Correct ResolveWorkflow exception documentation

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Copilot AI review requested due to automatic review settings July 25, 2026 00:06

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Address review: broaden not-registered guidance and correct returns doc

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Copilot AI review requested due to automatic review settings July 25, 2026 00:19

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Chris Gillum (cgillum) marked this pull request as ready for review July 25, 2026 03:09

Merge latest from main

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Copilot AI review requested due to automatic review settings July 27, 2026 16:47

Copilot started reviewing on behalf of Chris Gillum (cgillum) July 27, 2026 16:48 View session

Chris Gillum (cgillum) changed the title ~~Add a Functions-native API for invoking Durable Workflows~~ [.NET] Add a Functions-native API for invoking Durable Workflows Jul 27, 2026

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Comment thread ...ests/Microsoft.Agents.AI.DurableTask.UnitTests/Workflows/DurableStreamingWorkflowRunTests.cs

Chris Gillum (cgillum) added the breaking-change A breaking change is being introduced by this PR label Jul 27, 2026

Correct host serialization test fixture

8dc21eb

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot AI review requested due to automatic review settings July 27, 2026 17:06

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Merge latest from main

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Copilot AI review requested due to automatic review settings July 27, 2026 22:47

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Comment thread dotnet/tests/Microsoft.Agents.AI.DurableTask.UnitTests/Workflows/DurableWorkflowClientTests.cs

Adapt workflow tests to bulk API removal

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Copilot AI review requested due to automatic review settings July 27, 2026 22:57

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Shyju Krishnankutty (kshyju) approved these changes Jul 28, 2026

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Shyju Krishnankutty (kshyju) mentioned this pull request Jul 28, 2026

.NET Functions host returns unparsable text/plain from workflow HTTP endpoints #56

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Chris Gillum (cgillum) merged commit 3ac4399 into main Jul 28, 2026
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Chris Gillum (cgillum) deleted the cgillum-microsoft-reimagined-journey branch July 28, 2026 20:18

greenie-msft mentioned this pull request Aug 3, 2026

Add a Functions-native API for invoking Durable Workflows #24

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Chris Gillum (cgillum) commented Jul 24, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Chris Gillum (cgillum) commented Jul 24, 2026 •

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