Multi-application workflows in the .NET SDK

Overview

Dapr workflows can call activities or child workflows that are hosted in a different Dapr application. In .NET, multi-application workflows are supported starting with:

• Dapr runtime v1.16.0+
• Dapr .NET SDK v1.17.0+

Conceptual guidance and constraints are covered in Multi Application Workflows.

Requirements

Multi-application workflow calls require:

• The target app ID must exist and must register the activity or workflow you invoke.
• All participating app IDs must be in the same namespace.
• All participating app IDs must use the same workflow (actor) state store.

Call an activity in another application

Set TargetAppId on WorkflowTaskOptions when calling an activity to execute it in another app:

public sealed class BusinessWorkflow : Workflow<string, string>
{
    public override async Task<string> RunAsync(WorkflowContext context, string input)
    {
        var options = new WorkflowTaskOptions { TargetAppId = "App2" };
        var output = await context.CallActivityAsync<string>(nameof(ActivityA), input, options);
        return output;
    }
}

The parent workflow continues to orchestrate locally and receives the activity result.

Call a child workflow in another application

Set TargetAppId on ChildWorkflowTaskOptions when calling a child workflow to execute it in another app:

public sealed class BusinessWorkflow : Workflow<string, string>
{
    public override async Task<string> RunAsync(WorkflowContext context, string input)
    {
        var options = new ChildWorkflowTaskOptions { TargetAppId = "App2" };
        var output = await context.CallChildWorkflowAsync<string>(nameof(Workflow2), input, options);
        return output;
    }
}

Next steps

• Multi Application Workflows
• Workflow management operations