Activity Input Node

Input Node

An Input Node exposes tokens arriving at an Activity boundary to nodes inside that graph. At the top level, tokens arrive through IActivityBehavior.SendInputAsync; inside a structured node, they arrive from the containing graph. It has no incoming edge in its own scope: declare forwarded token types with AddInput(input => input.AddFlow<TToken>(target)).

flowchart LR
    parent(Parent Activity) -->|Order| input["Input boundary"]
    subgraph nested["Structured Activity"]
        input --> calculate(Calculate total)
    end

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Mermaid approximation: this diagram shows the model's routing, not a complete UML Activity notation. Rounded boxes represent actions; edge labels identify token types or guards. Input/Output boxes name Stateflows boundary APIs, not UML final nodes or a claim that UML uses these box labels. Mermaid does not model pins, activity parameters, or expansion regions natively.

Definition

.AddInitial(initial => initial.AddControlFlow("LoadOrder"))
.AddAction(
    "LoadOrder",
    async c => c.Output(await orders.LoadAsync(
        orderId, c.CancellationToken)),
    node => node.AddFlow<Order>("CalculateTotal"))
.AddStructuredActivity("CalculateTotal", nested => nested
    .AddInput(input => input.AddFlow<Order>("Calculate"))
    .AddInitial(initial => initial.AddControlFlow("Calculate"))
    .AddAction("Calculate", async c =>
    {
        var order = c.GetTokensOfType<Order>().Single();
        c.Output(order.Lines.Sum(line => line.Price * line.Quantity));
    }, node => node.AddFlow<decimal, OutputNode>())
    .AddOutput())

The nested input declaration does not create an application token; it forwards matching parent inputs along its object flows. Use AddInitial separately to begin control execution in the nested graph. For nested results, connect an inner producer to OutputNode and declare AddOutput(). See Structured Activity Node, Output Node, and Data Flow.