# Interface PushTransport.Callback

Enclosing interface:
  `PushTransport`

public static interface PushTransport.Callback
Receives events emitted by a custom transport.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `void`
  `failed(PushError error)`
  Reports a registration or transport error.
  `void`
  `message(String envelopeJson)`
  Delivers a complete schema-3 JSON envelope.
  `void`
  `registered(PushSubscription subscription)`
  Reports initial registration or a later token rotation.
  `void`
  `unregistered()`
  Confirms that native unregistration completed.

- ## Method Details

  - ### registered

    void registered(PushSubscription subscription)
    Reports initial registration or a later token rotation.
    Parameters:
      `subscription` - the current subscription

  - ### unregistered

    void unregistered()
    Confirms that native unregistration completed.

  - ### message

    void message(String envelopeJson)
    Delivers a complete schema-3 JSON envelope.
    Parameters:
      `envelopeJson` - the encoded envelope

  - ### failed

    void failed(PushError error)
    Reports a registration or transport error.
    Parameters:
      `error` - the error details