> This page is for Applications Protection.

> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.humansecurity.com/llms.txt.

# Additional Activity Handler

The Additional Activity Handler is a callback function passed to the Enforcer. The Enforcer runs this callback after sending the `page_requested` or `block` activity to the Collector, and before forwarding the request to the next step in the pipeline. A common use case of the Additional Activity Handler is to set the score as a variable or header. Then the application can read the score and implement the application logic.

**TO define the feature:**

1. Open the **PX_CUSTOM.vcl** file.
2. Modify **px_custom_additional_activity_handler** to perform the required logic.

Example

```javascript
sub px_custom_additional_activity_handler {
  set req.http.x-px-score = if(req.http.x-px-validated-request == "1", "0", "100");
}
```

**TO enable the feature:**

**v.8.0.0 and up**

1. Open the **PX_CONFIG.vcl** file.
2. Set the **px_additional_activity_handler_enabled** value to "true" (enabled). The default is "false" (disabled).

```javascript
table px_configs {
  "px_additional_activity_handler_enabled": "true",
}
```

**v7.2.0 and below**

1. Open the **PX_CONFIG.vcl** file.
2. Set the **PX_ENABLE_ADDITIONAL_ACTIVITY_HEADER** value to "1" (enabled). The default is "0" (disabled).

```javascript
table px_configs {
  "PX_ENABLE_ADDITIONAL_ACTIVITY_HEADER": "1",
}
```