50.3. Interactors

Interactors are classes that are concrete classes derived from the abstract base class CInteractor. They are intended to obtain the authentication credentials from the entity requesting service. If the interactor is in some way interactive, it may also prompt the user for the elements of the credentials required.

The abstract base class CInteractor provides the following member functions as abstract virtual functions that will be implemented differently in each concrete interactor class:

virtual int Read(Uint_t nBytes, void* pData);

Reads data from the interactor. The CAuthenticator base class provides a convenience method that reads an entire line of text from the requestor.

virtual int Write(UInt_t nBytes, void* pData);

Writes data to the entity that's behind the interactor.

virtual int ReadWithPrompt(Uint_t nPromptSize, void* pPrompt, UInt_t nReadSize, void* pReadData);

Prompts for input if the interactor supports prompting and then accepts data from the entitiy.

In addition to CInteractor, the following concrete interactors have been supplied.


This interactor supplies a string that you have gotten by whatever means you got it. It can be used when interactors are not suitable for acquiring the stringified credentials.


This interactor accepts the credentials via an open file descriptor.


This interator uses a pair of other interactors, an output and an input interactor. Prompting is done on the output interactor and the credentials read from the input interactor.