public String authenticate(Credentials credentials,
    HttpMethod method) throws AuthenticationException
Produces an authorization string for the given set of Credentials .

 public String authenticate(Credentials credentials,
    String method,
    String uri) throws AuthenticationExceptionDeprecated! Use -  #authenticate(Credentials, HttpMethod) 

Produces an authorization string for the given set of Credentials ,
method name and URI using the given authentication scheme in response to
the actual authorization challenge.

 public String getID()Deprecated! no -  longer used

Returns a String identifying the authentication challenge. This is
used, in combination with the host and port to determine if
authorization has already been attempted or not. Schemes which
require multiple requests to complete the authentication should
return a different value for each stage in the request.

Additionally, the ID should take into account any changes to the
authentication challenge and return a different value when appropriate.
For example when the realm changes in basic authentication it should be
considered a different authentication attempt and a different value should
be returned.

 public String getParameter(String name)
Returns authentication parameter with the given name, if available.

 public String getRealm()
Returns authentication realm. If the concept of an authentication
realm is not applicable to the given authentication scheme, returns
null.

 public String getSchemeName()
Returns textual designation of the given authentication scheme.

 public boolean isComplete()
Authentication process may involve a series of challenge-response exchanges.
This method tests if the authorization process has been completed, either
successfully or unsuccessfully, that is, all the required authorization
challenges have been processed in their entirety.

 public boolean isConnectionBased()
Tests if the authentication scheme is provides authorization on a per
connection basis instead of usual per request basis

 public  void processChallenge(String challenge) throws MalformedChallengeException
Processes the given challenge token. Some authentication schemes
may involve multiple challenge-response exchanges. Such schemes must be able
to maintain the state information when dealing with sequential challenges