source: TI12-security/trunk/NDG_XACML/ndg/xacml/core/context/pdp.py @ 6775

"""NDG Security Policy Decision Point type definition

NERC DataGrid Project
"""
__author__ = "P J Kershaw"
__date__ = "25/02/10"
__copyright__ = "(C) 2010 Science and Technology Facilities Council"
__contact__ = "Philip.Kershaw@stfc.ac.uk"
__license__ = "BSD - see LICENSE file in top-level directory"
__contact__ = "Philip.Kershaw@stfc.ac.uk"
__revision__ = "$Id: $"
from abc import ABCMeta, abstractmethod
from ndg.xacml.core.context.request import Request


class PDPInterface:
    __metaclass__ = ABCmeta
    
    @classmethod
    def __subclasshook__(cls, C):
        """Derived class must implement __call__"""
        if cls is PDPInterface:
            if any("evaluate" in B.__dict__ for B in C.__mro__):
                return True
            
        return NotImplemented

    @abstractmethod
    def evaluate(self, request):
        '''evaluate the input request and return an access control decision
        in the returned response
        
        @param request: XACML context request
        @type request: ndg.xacml.core.context.request.Request
        @return: XACML context response
        @rtype: ndg.xacml.core.context.response.Response
        '''
        if not isinstance(request, Request):
            raise TypeError('Expecting %r type for input request; got %r '
                            'instead' % (Request, type(request))