Create Custom Workflow Class

[DSpirit]

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I was fiddling around with a custom wrapper using Dapr Workflows to store enhanced activity and event data for better tracking but couldn't achieve that. In a nutshell:
Activities registered in Dapr Workflow never execute when using a custom workflow base class that inherits from Workflow<TInput, TOutput>. The CallActivityAsync hangs indefinitely without calling the activity or throwing an exception.

Is this by design?

Code

Custom Base Workflow Class:

public abstract class MyWorkflow<TInput, TOutput> : Workflow<TInput, TOutput>, IWorkflow
{
    public override async Task<TOutput> RunAsync(WorkflowContext context, TInput input)
    {        
        return await RunCustomAsync(context, input);
    }

    protected abstract Task<TOutput> RunCustomAsync(WorkflowContext context, TInput input);
}

Actual Workflow Implementation:

public class CustomWorkflow : MyWorkflow<RequestModel, object>
{
    protected override async Task<object> RunCustomAsync(WorkflowContext context, RequestModel input)
    {
        // This call just passes through without any action when using the MyWorkflow but works with the regular one
        var result = await context.CallActivityAsync<bool>("MyCustomActivity", input);
        return result;
    }
}

Setup

• Dapr Version: 1.15.9
• Framework: .NET 8.0

[WhitWaldo]

Yes, this is by design. The way the workflows and activities themselves are instantiated and run by the framework coupled with the necessity that workflows be deterministic has led to some design restrictions in this space.

I know Workflows have more restrictions on this than Activities (e.g. they don't allow dependency injection). While I haven't tested out wrapping activities with custom types, you might be able to get that to work in a way that Workflows won't.

You might be able to achieve it using a source generator or an AOP framework to wrap the methods at compilation time to do what you're trying to do, but it's hard to speculate without more information about what it is you're trying to do here.

Would you be able to get more into what it is that you're trying to do around the monitoring that necessitates creating such a wrapper?

[DSpirit]

Thanks, so my assumption got confirmed.

You've also outlined the way I got it kind of working - using custom activities.
This actually worked pretty well, enabling me to separately store the activity inputs and outputs in a custom state store. Unfortunately this is limited to activities only, so e.g. external events cannot be handled directly like that.

My goal is to store & retrieve a complete history of every executed activity/event including errors, variables, input & outputs of each step so that I can visualize the complete workflow for a PoC using BPMN.

Nevertheless - thanks for the clarification!

[WhitWaldo]

We've got plans in a future version (got put off this release) to stream the current workflow state out to an endpoint for monitoring/logging at the runtime level.

Separately, I plan on adding a helper to the SDK that'll independently handle storing/retrieving state by reference to take that off a developers' plate (and take the state out of the event log), but that'll likely wait until we've got support for writing to object stores, per this proposal.