Flexible namespace prioritization

Abstract

Access to resources on a computer may be provided by using a first namespace of resources and a second namespace of resources, where one or more names are common to both namespaces and those names refer to different respective instances of resources. A request is received for a first resource name from an application, where the first resource name exists in the first resource namespace and in the second resource namespace. In response to the request, whether to obtain a resource from the first namespace or from the second namespace is determined by applying one or more resource policies to the first resource namespace and to the second resource namespace.

What is claimed: 
     
         1 . A computer implemented method comprising:
 storing a plurality of policies for prioritizing namespaces;   receiving, by the computer, a request for a first resource name, the computer having a virtualization component that virtualizes access to system resources on the computer and having a first namespace of resources on the computer and a second namespace of resources on the computer, one or more resource names being common to both namespaces and those same resource names corresponding to differing resources in their respective namespaces;   in response to the request, determining relative priorities of the first namespace and the second resource namespace by using the policies to prioritize the first resource namespace and the second resource namespace; and   in accordance with the determining, obtaining from the first resource namespace or the second namespace a resource corresponding to the first resource name.   
     
     
         2 . The method according to  claim 1 , further comprising:
 receiving a request for a second resource name, and in response to the request again determining relative priorities of the first namespace and the second resource namespace by using the selected policies to prioritize the first resource namespace and the second resource namespace; and   in accordance with the again determining, obtaining from the first resource namespace or the second namespace a resource corresponding to the second resource name.   
     
     
         3 . The method according to  claim 1 , further comprising selecting from among the resource policies those policies that are applicable to the first resource name and using those policies for the determining the relative priorities of the first and second namespaces. 
     
     
         4 . The method according to  claim 3 , wherein the policies are selected based on whether they match the first resource name. 
     
     
         5 . The method according to  claim 1 , wherein the policies describe conditions under which they should be used to prioritize a resource namespace, and when such conditions are met the resource namespaces are prioritized based on the policies. 
     
     
         6 . The method according to  claim 5 , wherein a namespace is prioritized by two different policies. 
     
     
         7 . The method according to  claim 6 , wherein a policy's contribution in prioritizing a namespace is proportional to how specific the policy is to the first resource name. 
     
     
         8 . A system, comprising one or more computing devices collectively configured to perform a process for flexibly prioritizing two or more overlapping resource namespaces, the process comprising:
 before a resource is requested by a resource name, storing policy information defining a plurality of resource contexts;   when the resource is requested by the resource name, prioritizing two or more of the overlapping resource namespaces relative to each other based on the policy information, each of the overlapping resource namespaces comprising a plurality of resources and corresponding names thereof, each of the overlapping resource namespaces overlapping such that a same name in two or more overlapping resource namespaces refers to different instances of resources in the respective overlapping resource namespaces; and   obtaining the resource by accessing the prioritized resource namespaces in order of their priority until the resource is found in one of the overlapping resource namespaces.   
     
     
         9 . The system according to  claim 8 , wherein the process is performed such that the overlapping resource namespaces are prioritized relative to each other with a same order of priority independent of an order in which the overlapping resource namespaces are prioritized. 
     
     
         10 . The system according to  claim 8 , wherein the prioritizing is further based on the resource name. 
     
     
         11 . The system according to  claim 10 , the process further comprising passing the resource name, the overlapping resource namespaces, and/or the policy information to a policy engine that performs the prioritizing. 
     
     
         12 . The system according to  claim 8 , wherein the namespaces are prioritized based on which of the resource contexts are most relevant to the requested resource name. 
     
     
         13 . The system according to  claim 8 , wherein a resource context is compared against a context of the request. 
     
     
         14 . The system according to  claim 8 , the process further comprising receiving a request for a second resource name and prioritizing the two or more of the overlapping resource namespaces relative to each other based on the policy information, where the resource namespaces are prioritized in a different order than when they were prioritized for the first resource name. 
     
     
         15 . A computer readable storage medium comprising computer readable instructions that, when executed on a computing device, cause:
 storing a plurality of policies for prioritizing namespaces;   receiving, by the computer, a request for a first resource name, the computer having a virtualization component that virtualizes access to system resources on the computer and having a first namespace of resources on the computer and a second namespace of resources on the computer, one or more resource names being common to both namespaces and those same resource names corresponding to differing resources in their respective namespaces;   in response to the request, determining relative priorities of the first namespace and the second resource namespace by using the policies to prioritize the first resource namespace and the second resource namespace; and   in accordance with the determining, obtaining from the first resource namespace or the second namespace a resource corresponding to the first resource name.   
     
     
         16 . The computer readable storage medium according to  claim 15 , further comprising:
 receiving a request for a second resource name, and in response to the request again determining relative priorities of the first namespace and the second resource namespace by using the selected policies to prioritize the first resource namespace and the second resource namespace; and   in accordance with the again determining, obtaining from the first resource namespace or the second namespace a resource corresponding to the second resource name.   
     
     
         17 . The computer readable storage medium according to  claim 15 , further comprising selecting from among the resource policies those policies that are applicable to the first resource name and using those policies for the determining the relative priorities of the first and second namespaces. 
     
     
         18 . The computer readable storage medium according to  claim 17 , wherein the policies are selected based on whether they match the first resource name. 
     
     
         19 . The computer readable storage medium according to  claim 15 , wherein the policies describe conditions under which they should be used to prioritize a resource namespace, and when such conditions are met the resource namespaces are prioritized based on the policies. 
     
     
         20 . The computer readable storage medium according to  claim 19 , wherein a namespace is prioritized by two different policies.