---
title: Backchannel callbacks
description: Nodes use these callbacks to recover additional information from the request, such as a header or a certificate.
component: pingoneaic-api
page_id: pingoneaic-api:am-authentication:callbacks-backchannel
canonical_url: https://developer.pingidentity.com/pingoneaic-api/am-authentication/callbacks-backchannel.html
keywords: ["Authentication", "Callbacks", "REST API"]
page_aliases: ["authentication-guide:authn-backchannel-callbacks.adoc", "authn-backchannel-callbacks.adoc"]
section_ids:
  httpcallback: HttpCallback
  languagecallback: LanguageCallback
  scripttextoutputcallback: ScriptTextOutputCallback
  x509certificatecallback: X509CertificateCallback
---

# Backchannel callbacks

Nodes use these callbacks to recover additional information from the request, such as a header or a certificate.

## HttpCallback

Accesses user credentials sent in the `Authorization` header:

```
Authorization: Basic bXlDbGllbnQ6Zm9yZ2Vyb2Nr
```

Class to import in scripts: `com.sun.identity.authentication.spi.HttpCallback`

## LanguageCallback

Retrieves the locale from the request header for localizing text presented to the user.

Class to import in scripts: `javax.security.auth.callback.LanguageCallback`

Learn more in [LanguageCallback](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/javax/security/auth/callback/LanguageCallback.html).

## ScriptTextOutputCallback

Inserts a script into the page presented to the user; for example, to collect data about the user's environment.

Class to import in scripts: `com.sun.identity.authentication.callbacks.ScriptTextOutputCallback`

## X509CertificateCallback

Retrieves an X.509 certificate, for example, from a header.

Class to import in scripts: `com.sun.identity.authentication.spi.X509CertificateCallback`