# Designing a Maestro Flow

> Design a Maestro Flow in Studio Web using the Flow canvas, including how to add and connect triggers and nodes, configure properties, manage variables, handle errors, and debug your process.

:::note
Maestro Flow is in Preview.
:::

The Maestro Flow canvas is a visual designer where you build automations by placing nodes and connecting them in sequence.

## The Maestro Flow canvas

The canvas shows your flow as a graph of nodes connected by edges. Execution starts at the trigger node and moves through each connected node in order.

To add a node, select the **+** handle on the outgoing edge of any existing node to open the **Add node** panel. To connect two nodes manually, drag from the output handle of one node to the input handle of another. You can rename any node by double-clicking its label on the Maestro Flow canvas.

The top toolbar provides:

- **Debug on cloud** — runs the flow end-to-end in the cloud.
- **Debug step-by-step** — advances through the flow one node at a time.
- **Publish** — packages and publishes the flow to Orchestrator.

## Adding triggers

The flow starts with a default **Manual Trigger** node that starts the flow on demand. Select the trigger on the canvas to configure it in the **Properties** panel.

### Trigger properties

- **ID** — the trigger’s identifier, used to reference its outputs in expressions (for example, `$vars.manualTrigger1.output.userId`).
- **Label** — the display name of the trigger on the canvas.
- **Variables** — input variables owned by the trigger. When the trigger fires, its inputs are available downstream as `$vars.<triggerId>.output.<inputName>`.

## Adding nodes

To add a node, select the **+** handle on the outgoing edge of any node to open the **Add node** panel, then select a category and choose the node type. For the full list of available node types, see [About Maestro Flow](https://docs.uipath.com/studio-web/automation-cloud/latest/user-guide/about-maestro-flow).

### Node properties

Selecting a node opens its configuration in the **Properties** panel on the right, organized into sections:

- **General** — the node’s **ID** (used in `$vars` expressions), **Label** (display name on the canvas), **Description**, and **Icon color**.
- **Error handling** — toggle **Enable error handling** to add an error output handle to the node. When enabled and the node fails, execution routes to the error path instead of stopping the flow.
- **Update variable** — assign a value to a process variable when the node completes. Select **+ Add variable update**, choose the target variable, and enter the expression to assign.

The **Variables** tab (next to Properties) is where you define process-level variables. Each variable has a name, type (String, Number, Boolean, Object, or Array), and direction (input, output, or bidirectional).

Right-clicking a node on the canvas opens a context menu with: **Add breakpoint**, **Add probe**, **Copy**, **Cut**, **Paste**, and **Delete**.

## Variables and data flow

Nodes do not share data automatically. Downstream nodes access a node’s output through expressions using the `$vars` prefix.

Every node that produces data makes its output available as `$vars.<nodeId>.output`. The node ID is auto-assigned based on the node type — for example, the first API workflow node is `apiWorkflow1`. You can see and edit a node’s ID in the **General** section of the Properties panel.

```javascript
// Access the output of a node named apiWorkflow1
$vars.apiWorkflow1.output

// Access the response body of an HTTP request node
$vars.httpRequest1.output.body
```

Use the **Variables** tab to define variables that must be accessible across the entire process or that define the process inputs and outputs. Variables are referenced as `$vars.<variableName>`.

For the full expression grammar and scoping rules, refer to [Variables and data flow](https://docs.uipath.com/maestro/automation-cloud/latest/user-guide/variables-and-data-flow) in the Maestro documentation.

## Error handling

By default, a failed node stops the entire flow. To handle failures on a specific node, toggle **Enable error handling** in the node’s Properties panel. This adds an error output handle to the bottom-right of the node on the canvas. Connect the error handle to a downstream node to route failures to a separate path.

When a node fails and its error handle is connected, the error details are available as `$vars.<nodeId>.error` on the error path, with fields including `message`, `code`, `status`, and `detail`.

For patterns such as log-and-continue, retry, and alert-and-terminate, refer to [Error handling](https://docs.uipath.com/maestro/automation-cloud/latest/user-guide/flow-error-handling) in the Maestro documentation.

## Debugging a Maestro Flow

Select **Debug on cloud** in the top toolbar to run the flow end-to-end. When the run completes, select any node on the canvas to inspect its output. Nodes that succeeded show a green indicator; failed nodes show the error details when selected.

Select **Debug step-by-step** to advance through the flow one node at a time.

Right-click any node and select **Add breakpoint** to pause execution at that node during a debug run. Select **Add probe** to capture the node’s output without pausing.

## Related links

- [Variables and data flow](https://docs.uipath.com/maestro/automation-cloud/latest/user-guide/variables-and-data-flow)
- [Error handling](https://docs.uipath.com/maestro/automation-cloud/latest/user-guide/flow-error-handling)
- [Subflows](https://docs.uipath.com/maestro/automation-cloud/latest/user-guide/subflows)
- [Control flow](https://docs.uipath.com/maestro/automation-cloud/latest/user-guide/control-flow)
- [Publishing and deploying a Flow](https://docs.uipath.com/studio-web/automation-cloud/latest/user-guide/publishing-and-deploying-a-maestro-flow)