old_contents: from sfa.util.faults import SfaInvalidArgument
  from sfa.util.xrn import urn_to_hrn
  from sfa.util.method import Method
  from sfa.util.sfatablesRuntime import run_sfatables
  
  from sfa.trust.credential import Credential
  
  from sfa.storage.parameter import Parameter, Mixed
  
  from sfa.rspecs.rspec import RSpec
  
  class CreateSliver(Method):
      """
      Allocate resources to a slice.  This operation is expected to
      start the allocated resources asynchornously after the operation
      has successfully completed.  Callers can check on the status of
      the resources using SliverStatus.
  
      @param slice_urn (string) URN of slice to allocate to
      @param credentials ([string]) of credentials
      @param rspec (string) rspec to allocate
      
      """
      interfaces = ['aggregate', 'slicemgr']
      accepts = [
          Parameter(str, "Slice URN"),
          Mixed(Parameter(str, "Credential string"),
                Parameter(type([str]), "List of credentials")),
          Parameter(str, "RSpec"),
          Parameter(type([]), "List of user information"),
          Parameter(dict, "options"),
          ]
      returns = Parameter(str, "Allocated RSpec")
  
      def call(self, slice_xrn, creds, rspec, users, options={}):
          hrn, type = urn_to_hrn(slice_xrn)
  
          self.api.logger.info("interface: %s\ttarget-hrn: %s\tmethod-name: %s"%(self.api.interface, hrn, self.name))
  
          # Find the valid credentials
          valid_creds = self.api.auth.checkCredentials(creds, 'createsliver', hrn)
          origin_hrn = Credential(string=valid_creds[0]).get_gid_caller().get_hrn()
  
          # make sure users info is specified
          if not users:
              msg = "'users' musst be specified and cannot be null. You may need to update your client." 
              raise SfaInvalidArgument(name='users', extra=msg)  
  
          # flter rspec through sfatables
          if self.api.interface in ['aggregate']:
              chain_name = 'INCOMING'
          elif self.api.interface in ['slicemgr']:
              chain_name = 'FORWARD-INCOMING'
          self.api.logger.debug("CreateSliver: sfatables on chain %s"%chain_name)
          rspec = run_sfatables(chain_name, hrn, origin_hrn, rspec)
          slivers = RSpec(rspec).version.get_nodes_with_slivers()
          if slivers:
              result = self.api.manager.CreateSliver(self.api, slice_xrn, creds, rspec, users, options)
          else:
              result = rspec     
          return result
  
new_contents: from sfa.util.faults import SfaInvalidArgument, InvalidRSpec
  from sfa.util.xrn import urn_to_hrn
  from sfa.util.method import Method
  from sfa.util.sfatablesRuntime import run_sfatables
  from sfa.trust.credential import Credential
  from sfa.storage.parameter import Parameter, Mixed
  from sfa.rspecs.rspec import RSpec
  
  class CreateSliver(Method):
      """
      Allocate resources to a slice.  This operation is expected to
      start the allocated resources asynchornously after the operation
      has successfully completed.  Callers can check on the status of
      the resources using SliverStatus.
  
      @param slice_urn (string) URN of slice to allocate to
      @param credentials ([string]) of credentials
      @param rspec (string) rspec to allocate
      
      """
      interfaces = ['aggregate', 'slicemgr']
      accepts = [
          Parameter(str, "Slice URN"),
          Mixed(Parameter(str, "Credential string"),
                Parameter(type([str]), "List of credentials")),
          Parameter(str, "RSpec"),
          Parameter(type([]), "List of user information"),
          Parameter(dict, "options"),
          ]
      returns = Parameter(str, "Allocated RSpec")
  
      def call(self, slice_xrn, creds, rspec, users, options={}):
          hrn, type = urn_to_hrn(slice_xrn)
  
          self.api.logger.info("interface: %s\ttarget-hrn: %s\tmethod-name: %s"%(self.api.interface, hrn, self.name))
  
          # Find the valid credentials
          valid_creds = self.api.auth.checkCredentials(creds, 'createsliver', hrn)
          origin_hrn = Credential(string=valid_creds[0]).get_gid_caller().get_hrn()
  
          # make sure users info is specified
          if not users:
              msg = "'users' musst be specified and cannot be null. You may need to update your client." 
              raise SfaInvalidArgument(name='users', extra=msg)  
  
          # flter rspec through sfatables
          if self.api.interface in ['aggregate']:
              chain_name = 'INCOMING'
          elif self.api.interface in ['slicemgr']:
              chain_name = 'FORWARD-INCOMING'
          self.api.logger.debug("CreateSliver: sfatables on chain %s"%chain_name)
          rspec = run_sfatables(chain_name, hrn, origin_hrn, rspec)
          slivers = RSpec(rspec).version.get_nodes_with_slivers()
          if not slivers:
              raise InvalidRSpec("Missing <sliver_type> or <sliver> element. Request rspec must explicitly allocate slivers")    
          result = self.api.manager.CreateSliver(self.api, slice_xrn, creds, rspec, users, options)
          return result
  
subject: raise InvalidRSpec exception if request rspec has no slivers