# Node Action Flow

Action flow determines which nodes will be executed. You determine the action flow with Lifeline connections and every Lifeline starts with a Lifeline generator node.

## Default Lifeline Generator Nodes

<div align="left"><img src="https://3312042618-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F9sVaJpWJhPbmscipukhh%2Fuploads%2Fgit-blob-b1a7981786cb4c51bdf6249a461115c97ed40371%2Fimage.png?alt=media" alt=""></div>

Default layer nodes: **Tick**, **On Begin,** or **On End**.

## Other Lifeline Generator Nodes

![Several nodes have New message lifeline output](https://3312042618-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F9sVaJpWJhPbmscipukhh%2Fuploads%2Fgit-blob-83faf7285f1a148f9fda6dba31410a628f732b78%2Fimage.png?alt=media)

There are a lot of nodes that have **New message** lifeline output. These nodes are primarily designed to receive messages from the network and work in conjunction with receiving *Device nodes*.

{% hint style="info" %}
**Good to know:** A good indicator that a layer is active, is blinking connection lines.
{% endhint %}