Action Node

Overview

Action Node represents a single step or action in an Activity. It is one of the fundamental building blocks of the Activity in Stateflows framework.

Action Nodes can have multiple incoming and outgoing Flows to accept input and pass on output Tokens.

An Action Node consists of:

• Name, uniquely identifying the Action Node within the Activity,
• Logic, code that is invoked when the Action Node is executed,
• Incoming Flows, passing input Tokens into the node,
• Outgoing Flows, passing output Tokens outside the node.

Definition

In UML, an Action Node is represented as a rectangle with rounded corners:

stateDiagram-v2
ActionNode --> NextNode : Result

Loading

Equivalent Stateflows notation of an Action Node:

Lambda style

    /* fragment of Activity definition */
    .AddAction("ProcessData",
        async c =>
        {
            /* logic to process data */
        },
        b => b.AddFlow<Result>("NextNode")
    )
    .AddAction("NextNode",
        async c =>
        {
            /* subsequent logic */
        }
    )

Using lambda style means that the Action Node is defined by its name and logic, with flows specified using a fluent builder.

Typed style

    public class ProcessData : IActionNode
    {
        public async Task ExecuteAsync()
        {
            /* logic to process data */
        }
    }

    public class NextNode : IActionNode
    {
        public async Task ExecuteAsync()
        {
            /* subsequent logic */
        }
    }

    /* fragment of Activity definition */
    .AddAction<ProcessData>(b => b
        .AddFlow<Result, NextNode>()
    )
    .AddAction<NextNode>()

Using typed style means that the Action Node is represented by a class implementing the IActionNode interface.