A namespace management module utilizes a persistent reservation store that associates URI namespaces with one or more permissions. The reservation store can contain a number of reservation entries that each include a URI identifying a URI namespace and a corresponding Access Control List ("ACLs") that includes permissions for the identified URI namespace. When a request to register a URI namespace is received, the permissions of an appropriate ACL can be checked to determine if the registration is approved. When a resource request is received, permissions of the ACLs can also be checked to determine if the resource request should be routed to a registered process. Preemptive wildcards can be included in aggregated URIs to identify aggregated URI namespaces. Aggregated URIs can be included in registration requests to override the registration of unauthorized processes.