# Overview

> Trigger-based attended automations can involve the following:

Trigger-based attended automations can involve the following:

* **Forms** – created using the [Form Builder](https://docs.uipath.com/activities/other/latest/user-guide/form-builder) and handled with the [Form.Activities](https://docs.uipath.com/activities/other/latest/user-guide/form) package.
* **Callouts** – created using the [Form Builder](https://docs.uipath.com/activities/other/latest/user-guide/form-builder) and displayed with the [Callout.Activities](https://docs.uipath.com/activities/other/latest/user-guide/callout-activity-package) package.
* **Triggers** – using the [System.Activities](https://docs.uipath.com/activities/other/latest/user-guide/about-the-system-activities-pack) and [UIAutomation.Activities](https://docs.uipath.com/activities/other/latest/user-guide/about-the-ui-automation-next-activities-pack) packages.
* **Global variables** – created from the [Data Manager](https://docs.uipath.com/studio/standalone/latest/user-guide/using-the-data-manager).

Forms and callouts represent a core capability of attended automation. Running them using triggers allows you to build complex scenarios. These scenarios involve multiple events happening at the same time. Moreover, the possibility of triggering actions based on the values of global variables helps you to cover even more attended scenarios.

The diagram below shows a process built using forms, form event triggers, and application event triggers. You can build similar processes based on user event triggers and callouts, as well.

  ![docs image](https://dev-assets.cms.uipath.com/assets/images/studio/studio-docs-image-177673-adfb0aaf.webp)

## Prerequisites

To design and run trigger-based attended automations:

* Install the following activity packages:
  + **Form.Activities version 23.4**
  + **System.Activities 23.4**
  + **UIAutomation.Activities 23.4**
  + **Callout.Activities 23.4**
* If you encounter the following error when trying to create a **Form** file: *Couldn't find a compatible Webview2 Runtime installation to host WebViews*, install [Microsoft Edge WebView2](https://developer.microsoft.com/en-us/microsoft-edge/webview2/).

## Forms

The purpose of forms in attended automation is to collect and process user or application input. With the present form capabilities, you can:

* Create forms outside activities, using a **Form** (**uiform** file) inside your project. You can later build or edit them independently from any activity that uses the forms. This allows you to separate the process of building forms and then using them in the same automation.
* Create forms using custom HTML files. You can work with HTML forms similarly to how you do with **uiform** files.
* Display multiple forms at the same time, using the [Show Form](https://docs.uipath.com/activities/other/latest/user-guide/show-form-activity) activity. Add multiple **Show Form** activities and provide a unique name in the **Instance Name** field for each of them. The **Instance Name** property is available for most activities in the **Form.Activities** package, and it can be used to:
  + Show or perform actions on multiple instances of the same form, by providing unique **Instance Names** for each form that you show.
  + Show or perform actions on all instances, by leaving the **Instance Name** field empty.
* Set a trigger to start based on form events. These events can represent a form that closes or a certain form component that changes. You can achieve this using the [Form Event Trigger](https://docs.uipath.com/activities/other/latest/user-guide/form-trigger-activity) activity.
* Choose to only display a form or display it while the rest of the workflow is running. You can do this by enabling or disabling the **Continue Workflow Execution** property.
* Edit and fetch form values at runtime, using the [Set Form Values](https://docs.uipath.com/activities/other/latest/user-guide/set-form-fields-activity) and [Get Form Values](https://docs.uipath.com/activities/other/latest/user-guide/get-form-fields-activity) activities.
* Change the form properties at runtime, using the [Change Form Properties](https://docs.uipath.com/activities/other/latest/user-guide/change-form-properties-activity) activity.
* Inject custom JavaScript into the form, using the [Run Form Script](https://docs.uipath.com/activities/other/latest/user-guide/execute-script-activity) activity.

## Callouts

The role of callouts in attended automation is to direct the user to a specific UI element inside an application, website, product, or even a form. You can also use callouts to create custom validations for apps, pre-populate fields and trigger multiple automations based on user input.

With callout capabilities, you can:

* Create a callout using a **Form** (**uiform**) file and design it using the **Form Builder**.
* Indicate the UI element next to where you want the callout to display using the **Show Callout** activity.
* Pass values to the elements inside a callout.
  :::note
  A callout is a form bound to an UI element and displayed next to it, using the **Show Callout** activity.
  :::

Although there is a **Callout.Activities** package dedicated to callouts, it is also possible to handle callouts using the **Form.Activities** package, since callouts are **uiform** files just like regular forms. This means that you can work with callouts in the same way that you would work with a regular form if you are using the **Form.Activities** package.

## Triggers

The purpose of triggers in attended automation is:

1. To start workflows based on application or user events. Additionally, you can specify how to execute actions when a trigger is fired, through the **Scheduling mode**:
   * **Sequential** - Actions are executed one after another.
   * **Concurrent** - Actions execution can overlap.
   * **OneTime** - Executes one action and exits monitoring.
   * **Sequential Collapse** - Ignores all upcoming events, except the latest, until the current event finishes execution.
   * **Sequential Drop** - Stops the previous event execution and starts the next event.To trigger workflows based on application or user events use the following activities:

   | Activity | Description |
   | --- | --- |
   | [Form Event Trigger](https://docs.uipath.com/activities/other/latest/user-guide/form-trigger-activity) | Triggers workflows based on an event happening inside a form. |
   | [Application Event Trigger](https://docs.uipath.com/activities/other/latest/user-guide/n-native-event-trigger) | Sets up a trigger based on a native event of any type of element (top-level window or any other indicated UI element). |
   | [Repeat Trigger](https://docs.uipath.com/activities/other/latest/user-guide/repeat-trigger) | This activity allows you to configure a **TimeSpan** as **InArgument**. When the timespan expires, the trigger executes and can be repeated based on the settings. |
   | [Keypress Event Trigger](https://docs.uipath.com/activities/other/latest/user-guide/n-keyboard-trigger) | Sets up a key pressed event trigger on the indicated UI element. |
   | [Click Event Trigger](https://docs.uipath.com/activities/other/latest/user-guide/n-click-trigger) | Sets up a click event trigger on the indicated UI element. |
   | [Hotkey Trigger](https://docs.uipath.com/activities/other/latest/user-guide/hotkey-trigger-v-2) | Monitors a specified system-wide key event. |
   | [Mouse Trigger](https://docs.uipath.com/activities/other/latest/user-guide/mouse-trigger-v-2)***** | Monitors a specified mouse-key combination system-wide event. |
   | [Click Image Trigger](https://docs.uipath.com/activities/other/latest/user-guide/click-image-trigger-v-2)***** | Monitors the Image defined by the target UI element for mouse input. |
   | [System Trigger](https://docs.uipath.com/activities/other/latest/user-guide/system-trigger-v-2)***** | Monitors a specified system-wide key and/or mouse event. |
   | [SAP Session Attributes Changed Trigger](https://docs.uipath.com/activities/other/latest/user-guide/sap-session-trigger)***** | Monitors changes in specified SAP session attributes. |

***** - Can be used both on its own and inside a [Trigger Scope](https://docs.uipath.com/activities/other/latest/user-guide/trigger-scope) activity.
2. To automate multiple attended scenarios that can happen once, in sequence, or at the same time. You can achieve this using the following activities:

   | Activity | Description |
   | --- | --- |
   | [Run Local Triggers](https://docs.uipath.com/activities/other/latest/user-guide/start-triggers) | Initialises and starts all local triggers that listen for events on the user’s machine. |
   | [Stop Local Triggers](https://docs.uipath.com/activities/other/latest/user-guide/stop-local-triggers) | Terminates the execution of local triggers. When executed, it cancels all ongoing actions, including workflows triggered by events. When **Stop Local Triggers** executes, ongoing event-triggered workflows are canceled, but the activities in the main workflow continue as usual. |
   | [Disable Local Trigger](https://docs.uipath.com/activities/other/latest/workflow/disable-local-trigger) | Disables one or more active local triggers that were previously started with the **Run Local Triggers**  activity. |
   | [Enable Local Trigger](https://docs.uipath.com/activities/other/latest/workflow/enable-local-trigger) | Enables one or more active local triggers that were previously started with the **Run Local Triggers** activity. |
3. To start workflows based on the behavior of global variables, that you create in the **Data Manager**. You can achieve this using the following activities:

   | Activity | Description |
   | --- | --- |
   | [Global Variable Changed Trigger](https://docs.uipath.com/activities/other/latest/user-guide/global-variable-changed-trigger) | Pushes a notification to all subscribers when the value of a global variable changes. |
   | [Notify Global Variable Changed](https://docs.uipath.com/activities/other/latest/user-guide/notify-global-variable-changed) | Trigger that starts when the value of a global variable changes. |

### Run Local Triggers

The Run Local Triggers activity enables you to trigger multiple events simultaneously. In the backend, it generates a separate read-only workflow called `Triggereventargs` at runtime or during debugging. This workflow contains multiple **Trigger scope** activities that execute all triggers in parallel within your project.

When you run the project for the first time, each trigger workflow captures the `Triggereventargs` workflow as an argument in the **Arguments** panel. Each trigger workflow has its own `Triggereventargs` argument, which holds information about itself. As you execute the project, the `Triggereventargs` arguments update with the latest run information.

The `Triggereventargs` argument mainly provides the following information specific to each trigger workflow:

* Trigger type
* Trigger name
* Target element that fired the trigger
* Form components (in the case of **Form Trigger Activity**)
* Form instance name (in the case of **Form Trigger Activity**)

To access the information from the `Triggereventargs` argument, you can apply various methods based on the trigger type. For user event triggers, the following methods are available:

1. **TargetElement** - get information about the monitored target element
   1. **Attributes** - Obtain the attributes of the monitored target element
   2. **DisplayDpiScaleFactor** - Determine the size of the target element in pixels
   3. **ImageBase64** - Convert the image of the target element to a Base64 image
   4. **Selector** - Retrieve information about the selector used on the target element

   ![docs image](https://dev-assets.cms.uipath.com/assets/images/studio/studio-docs-image-266410-552969b1.webp)
2. **Trigger type**

For form triggers, you can use the following methods:

1. **FormSourceId** - Access the ID of the form where the trigger fired
2. **Instance Name** - Retrieve the instance name of the form where the trigger fired

### Trigger behavior

* Trigger workflows are workflows that start with a trigger. These can be debugged in the context of the entire project, or independently.
* If you think that a high number of triggers impact performance, you can enable or disable specific triggers, using the [Enable Local Trigger](https://docs.uipath.com/activities/other/latest/workflow/enable-local-trigger) and [Disable Local Trigger](https://docs.uipath.com/activities/other/latest/workflow/disable-local-trigger) activities.
* The **Enable Local Trigger** and **Disable Local Trigger** activities are useful in scenarios where you have multiple workflows monitoring user events that are determined by the phase in the automation that the user has reached.
  + For instance, you can use the **Enable Local Trigger** activity to activate a trigger once the user has entered their username in a form.
  + On the other hand, the **Disable Local Trigger** activity can be utilized to deactivate a trigger that was scheduled to execute sequentially once the user has reached a specific step during a guided product tour, for example.

## Global variables

The purpose of global variables in attended automation is to record information about the user or application events, and then store it inside a variable that you can later use as input or trigger for other activities. This allows you to easily share data between multiple workflows. With global variable capabilities, you can:

* Notify when the value of a global variable changes, using the [Notify Global Variable Changed](https://docs.uipath.com/activities/other/latest/user-guide/notify-global-variable-changed) activity
* Trigger a workflow or activity when the value of a global variable changes, using the [Global Variable Changed Trigger](https://docs.uipath.com/activities/other/latest/user-guide/global-variable-changed-trigger) activity.