Implementations of this interface are passed to a CallbackHandler, allowing underlying security services the ability to interact with a calling application to retrieve specific authentication data such as usernames and passwords, or to display certain information, such as error and warning messages. 

An application implements a CallbackHandler and passes it to underlying security services so that they may interact with the application to retrieve specific authentication data, such as usernames and passwords, or to display certain information, such as error and warning messages. 

Underlying security services instantiate and pass a ChoiceCallback to the handle method of a CallbackHandler to display a list of choices and to retrieve the selected choice(s). 

Underlying security services instantiate and pass a ConfirmationCallback to the handle method of a CallbackHandler to ask for YES/NO, OK/CANCEL, YES/NO/CANCEL or other similar confirmations. 

Underlying security services instantiate and pass a LanguageCallback to the handle method of a CallbackHandler to retrieve the Locale used for localizing text. 

Underlying security services instantiate and pass a NameCallback to the handle method of a CallbackHandler to retrieve name information. 

Underlying security services instantiate and pass a PasswordCallback to the handle method of a CallbackHandler to retrieve password information. 

Underlying security services instantiate and pass a TextInputCallback to the handle method of a CallbackHandler to retrieve generic text information. 

Underlying security services instantiate and pass a TextOutputCallback to the handle method of a CallbackHandler to display information messages, warning messages and error messages.