Help with Running Temporal Workers on ASP.NET (Core) Web Application

Community Support
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1

Hi,
I am currently building an AspNet (Core) website which aims to trigger long running workflows. I tried following the examples here, however, I am having a hard time in getting things to run, so any insight on what I am doing wrong would be greatly appreciated.

Problem
When triggered the workflow, nothing happens. I get no exceptions, no logs. Sometimes I see something like so dumped onto the server’s console:

{"level":"info","ts":"2023-10-08T13:16:59.095+0200","msg":"none","service":"matching","component":"matching-engine","wf-task-queue-name":"/_sys/MyWorkflow/3","wf-task-queue-type":"Activity","wf-namespace":"novum.local","lifecycle":"Started","logging-call-at":"task_queue_manager.go:331"}

Setup

  • OS: Windows 10
  • Nuget Packages: Temporalio (0.1.0-beta1) and Temporalio.Extensions.Hosting(0.1.0-beta1)
  • Tried with both development temporal setup (./temporal server start-dev) and also standalone temporal server.The outcome is the same.

What I have

  1. I created a TemporalClientProvider, which wraps around the TemporalClient.ConnectAsync(...). This is set to exist as a singleton.
  2. I am calling the AddHostedTemporalWorker, as part of my bootstrapping setup; registering activities and workflows as I go along:
services.AddHostedTemporalWorker(
                temporalConfiguration.TargetHost,
                temporalConfiguration.NameSpace, MyWorkflow.WorkflowQueueName)
            .AddScopedActivities<MyActivity>()
            .AddWorkflow<MyWorkflow>();
  1. I am defining my activities as so:
public class MyActivity
{
    private readonly IDependency _dependency;

    // Parameterless constructor to be used only for deserialization purposes.
    public MyActivity()
    {
        //
    }
    
    public MyActivity(IDependency dependency)
    {
        _dependency = dependency;
    }

    [Activity("My Activity")]
    public async Task DoSomething(MyWorkflowContext ctx)
    {
        _dependency.DoSomething();
    }
}
  1. I am defining my workflows as so (the file has a .workflow.cs extension):
public class MyWorkflow
{
    private const string TaskQueue = nameof(MyWorkFlow);
    private readonly ITemporalClientProvider _temporalClientProvider;
    private static readonly RetryPolicy DefaultRetryPolicy = new()
    {
        MaximumAttempts = 5
    };

    // Parameterless constructor to be used only for deserialization purposes.
    public MyWorkflow()
    {
        //
    }

    public MyWorkflow(ITemporalClientProvider temporalClientProvider)
    {
        _temporalClientProvider = temporalClientProvider;
    }
    
    public const string WorkflowQueueName = $"{nameof(MyWorkflow)}";

    public async Task ExecuteAsync(MyWorkflowContext ctx)
    {
        ITemporalClient temporalClient = await _temporalClientProvider.ConnectAsync();
        await temporalClient.ExecuteWorkflowAsync<MyWorkflow>(
            myWorkFlow=> myWorkFlow.RunAsync(ctx),
            new WorkflowOptions(ConstructWorkflowId(ctx), TaskQueue));
    }

    [WorkflowRun]
    public override async Task RunAsync(MyWorkflowContext ctx)
    {
        await Workflow.ExecuteActivityAsync<MyActivity>(activity=>
            activity.DoSomething(ctx),
        new ActivityOptions
        {
            CancellationToken = ctx.CancellationToken,
            RetryPolicy = DefaultRetryPolicy,
            ActivityId = $"{ctx.TenantId}_{typeof(MyActivity).FullName!}_{DateTime.UtcNow:HH:mm:ss_dd-MM-yy})",
            TaskQueue = TaskQueue,
        });
    }
  1. Lastly, I am calling (from another IHostedService) the workflow like so:
await _myWorkflow..ExecuteAsync(new MyWorkflowContext()
    {
        ...
    });

What’s happening

  • The RunAsync(...) in step 4 is not being called at all. I tried with/without arguments and various other permutations of the entire setup, but to no avail.

Any information on what I am doing wrong is appreciated.

2

A workflow is a standalone set of deterministic code, it should not have client calls within it. Also, your workflow doesn’t have a [Workflow] attribute (which should fail registration). Also, unsure why there are separate constants for TaskQueue and WorkflowQueueName, but usually the task queue is not the same name as the workflow.

Regardless, I would have to understand how/where you are starting the worker (where are you running the generic host or ASP host) and how/where you are starting the workflow. Does this sample work for you? Can you provide a full standalone replication with all of the code in place? If necessary you can just alter that sample showing how yours is not working.

3

Hi Chad,
Thanks for getting back to me so soon, and apologies for taking so long to respond.
Indeed, the workflow I actually have has the [Workflow] class attribute, that was an error from my side when copying things around.

I was following the example you have linked, and also trying to mix and match the one which highlights the usage of workflows and activities. My original assumption was that I was missing something…

I managed to get the minimal example working (somehow), so I will look into this again and compare what’s in the minimal example with the full solution and report back my findings. I will also keep in mind the points you made with regards to queue names.