abstract public  void addProviderAtEnd(Provider p,
    Oid mech) throws GSSException
This method is used to indicate to the GSSManager that the
application would like a particular provider to be used if no other
provider can be found that supports the given mechanism. When a value
of null is used instead of an Oid for the mechanism, the GSSManager
must use the indicated provider for any mechanism.


Calling this method repeatedly preserves the older settings but
raises them above newer ones in preference thus forming an ordered
list of providers and Oid pairs that grows at the bottom. Thus the
older provider settings will be utilized first before this one is.


If there are any previously existing preferences that conflict with
the preference being set here, then the GSSManager should ignore this
request.


If the GSSManager implementation does not support an SPI with a
pluggable provider architecture it should throw a GSSException with
the status code GSSException.UNAVAILABLE to indicate that the
operation is unavailable.


Suppose an application desired that when a mechanism of Oid m1 is
needed the system default providers always be checked first, and only
when they do not support m1 should a provider A be checked. It would
then make the call:

        GSSManager mgr = GSSManager.getInstance();
        mgr.addProviderAtEnd(A, m1);

Now, if it also desired that for all mechanisms the provider B be
checked after all configured providers have been checked, it would
then call:

        mgr.addProviderAtEnd(B, null);

Effectively the list of preferences now becomes {..., (A, m1), (B,
null)}.


Suppose at a later time the following call is made to the same
GSSManager instance:

        mgr.addProviderAtEnd(B, m2)

then the previous setting with the pair (B, null) subsumes this and
therefore this request should be ignored. The same would happen if a
request is made for the already existing pairs of (A, m1) or (B,
null).


Please note, however, that the following call:

        mgr.addProviderAtEnd(A, null)

is not subsumed by the previous setting of (A, m1) and the list will
effectively become {..., (A, m1), (B, null), (A, null)}

 abstract public  void addProviderAtFront(Provider p,
    Oid mech) throws GSSException
This method is used to indicate to the GSSManager that the
application would like a particular provider to be used ahead of all
others when support is desired for the given mechanism. When a value
of null is used instead of an Oid for the mechanism,
the GSSManager must use the indicated provider ahead of all others
no matter what the mechanism is. Only when the indicated provider
does not support the needed mechanism should the GSSManager move on
to a different provider.


Calling this method repeatedly preserves the older settings but
lowers them in preference thus forming an ordered list of provider
and Oid pairs that grows at the top.


Calling addProviderAtFront with a null Oid will remove
all previous preferences that were set for this provider in the
GSSManager instance. Calling addProviderAtFront with a non-null
Oid will remove any previous preference that was set
using this mechanism and this provider together.


If the GSSManager implementation does not support an SPI with a
pluggable provider architecture it should throw a GSSException with
the status code GSSException.UNAVAILABLE to indicate that the
operation is unavailable.


Suppose an application desired that the provider A always be checked
first when any mechanism is needed, it would call:

        GSSManager mgr = GSSManager.getInstance();
        // mgr may at this point have its own pre-configured list
        // of provider preferences. The following will prepend to
        // any such list:

        mgr.addProviderAtFront(A, null);

Now if it also desired that the mechanism of Oid m1 always be
obtained from the provider B before the previously set A was checked,
it would call:

        mgr.addProviderAtFront(B, m1);

The GSSManager would then first check with B if m1 was needed. In
case B did not provide support for m1, the GSSManager would continue
on to check with A.  If any mechanism m2 is needed where m2 is
different from m1 then the GSSManager would skip B and check with A
directly.


Suppose at a later time the following call is made to the same
GSSManager instance:

        mgr.addProviderAtFront(B, null)

then the previous setting with the pair (B, m1) is subsumed by this
and should be removed. Effectively the list of preferences now
becomes {(B, null), (A, null),
        ... //followed by the pre-configured list.


Please note, however, that the following call:
        mgr.addProviderAtFront(A, m3)

does not subsume the previous setting of (A, null) and the list will
effectively become {(A, m3), (B, null), (A, null), ...}

 abstract public GSSContext createContext(GSSCredential myCred) throws GSSException
Factory method for creating a context on the acceptor' side.  The
context's properties will be determined from the input token supplied
to the accept method.

Some mechanism providers might require that the caller be granted
permission to accept a security context. A failed permission check
might cause a SecurityException 
to be thrown from this method.

 abstract public GSSContext createContext(byte[] interProcessToken) throws GSSException
Factory method for creating a previously exported context.  The
context properties will be determined from the input token and
cannot be modified through the set methods.


Implementations are not required to support the inter-process
transfer of security contexts.  Before exporting a context, calling
the GSSContext.isTransferable 
will indicate if the context is transferable. Calling this method in
an implementation that does not support it will result in a
GSSException with the error
code  GSSException.UNAVAILABLE .

Some mechanism providers might require that the caller be granted
permission to initiate or accept a security context. A failed
permission check might cause a SecurityException  to be thrown from this method.

 abstract public GSSContext createContext(GSSName peer,
    Oid mech,
    GSSCredential myCred,
    int lifetime) throws GSSException
Factory method for creating a context on the initiator's
side.

Some mechanism providers might require that the caller be granted
permission to initiate a security context. A failed permission check
might cause a SecurityException 
to be thrown from this method.


Non-default values for lifetime cannot always be honored by the
underlying mechanism, thus applications should be prepared to call
getLifetime  on the returned
context.

 abstract public GSSCredential createCredential(int usage) throws GSSException
Factory method for acquiring default credentials.  This will cause
the GSS-API to use system specific defaults for the set of mechanisms,
name, and lifetime.


GSS-API mechanism providers must impose a local access-control
policy on callers to prevent unauthorized callers from acquiring
credentials to which they are not entitled. The kinds of permissions
needed by different mechanism providers will be documented on a
per-mechanism basis. A failed permission check might cause a SecurityException  to be thrown from
this method.

 abstract public GSSCredential createCredential(GSSName name,
    int lifetime,
    Oid mech,
    int usage) throws GSSException
Factory method for acquiring a single mechanism credential.


GSS-API mechanism providers must impose a local access-control
policy on callers to prevent unauthorized callers from acquiring
credentials to which they are not entitled. The kinds of permissions
needed by different mechanism providers will be documented on a
per-mechanism basis. A failed permission check might cause a SecurityException  to be thrown from
this method. 


Non-default values for lifetime cannot always be honored by the
underlying mechanisms, thus applications should be prepared to call
getRemainingLifetime 
on the returned credential.

 abstract public GSSCredential createCredential(GSSName name,
    int lifetime,
    Oid[] mechs,
    int usage) throws GSSException
Factory method for acquiring credentials over a set of
mechanisms. This method attempts to acquire credentials for
each of the mechanisms specified in the array called mechs.  To
determine the list of mechanisms for which the acquisition of
credentials succeeded, the caller should use the GSSCredential.getMechs  method.


GSS-API mechanism providers must impose a local access-control
policy on callers to prevent unauthorized callers from acquiring
credentials to which they are not entitled. The kinds of permissions
needed by different mechanism providers will be documented on a
per-mechanism basis. A failed permission check might cause a SecurityException  to be thrown from
this method.


Non-default values for lifetime cannot always be honored by the
underlying mechanisms, thus applications should be prepared to call
getRemainingLifetime 
on the returned credential.

 abstract public GSSName createName(String nameStr,
    Oid nameType) throws GSSException
Factory method to convert a string name from the
specified namespace to a GSSName object. In general, the
GSSName object created  will contain multiple
representations of the name, one for each mechanism that is
supported; two examples that are exceptions to this are when
the namespace type parameter indicates NT_EXPORT_NAME or when the
GSS-API implementation is not multi-mechanism. It is
not recommended to use this method with a NT_EXPORT_NAME type because
representing a previously exported name consisting of abitrary bytes
as a String might cause problems with character encoding schemes. In
such cases it is recommended that the bytes be passed in directly to
the overloaded form of this method  createName .

 abstract public GSSName createName(byte[] name,
    Oid nameType) throws GSSException
Factory method to convert a byte array containing a
name from the specified namespace to a GSSName object. In general,
the GSSName object created  will contain multiple
representations of the name, one for each mechanism that is
supported; two examples that are exceptions to this are when the
namespace type parameter indicates NT_EXPORT_NAME or when the
GSS-API implementation is not multi-mechanism. The bytes that are
passed in are interpreted by each underlying mechanism according to
some encoding scheme of its choice for the given nametype.

 abstract public GSSName createName(String nameStr,
    Oid nameType,
    Oid mech) throws GSSException
Factory method to convert a string name from the
specified namespace to a GSSName object and canonicalize it at the
same time for a mechanism. In other words, this method is
a utility that does the equivalent of two steps: the  createName  and then also the  GSSName.canonicalize .

 abstract public GSSName createName(byte[] name,
    Oid nameType,
    Oid mech) throws GSSException
Factory method to convert a byte array containing a
name from the specified namespace to a GSSName object and canonicalize
it at the same time for a mechanism. In other words, this method is a
utility that does the equivalent of two steps: the  createName  and then also  GSSName.canonicalize .

 public static GSSManager getInstance() 
{
        return new sun.security.jgss.GSSManagerImpl();
}

Returns the default GSSManager implementation.

 abstract public Oid[] getMechs()
Returns a list of mechanisms that are available to GSS-API callers
through this GSSManager. The default GSSManager obtained from the
getInstance()  method includes the Oid
"1.2.840.113554.1.2.2" in its list. This Oid identifies the Kerberos
v5 GSS-API mechanism that is defined in RFC 1964.

 abstract public Oid[] getMechsForName(Oid nameType)
Returns a list of mechanisms that support the indicated name type.


The Kerberos v5 mechanism ("1.2.840.113554.1.2.2") will always be
returned in this list when the indicated nametype is one of
 GSSName.NT_HOSTBASED_SERVICE ,
 GSSName.NT_EXPORT_NAME , or
"1.2.840.113554.1.2.2.1".

 abstract public Oid[] getNamesForMech(Oid mech) throws GSSException
Returns then name types supported by the indicated mechanism.


The default GSSManager instance includes support for the Kerberos v5
mechanism. When this mechanism ("1.2.840.113554.1.2.2") is indicated,
the returned list will contain at least the following nametypes:
 GSSName.NT_HOSTBASED_SERVICE ,
 GSSName.NT_EXPORT_NAME , and the
Kerberos v5 specific Oid "1.2.840.113554.1.2.2.1". The namespace for
the Oid "1.2.840.113554.1.2.2.1" is defined in RFC 1964.