The Handle System has a two-level hierarchical service model. The top level consists of a single global service, known as the Global Handle Registry. The lower level consists of all other handle services, which are generically known as Local Handle Services. The global service can be used to manage any namespace. It is unique among handle services only in that it provides the service used to manage the namespace of handle prefixes, all of which are managed as handles. The state information of these prefixes is the service information that clients can use to access and utilize associated local services.

The local handle service layer consists of all local handle services managing all identifiers under their prefixes, providing resolution and administration service for these local names. Local services are intended to be hosted by organizations with administrative responsibility for the identifiers within the service or acting on behalf of the responsible organizations. The way to define local namespaces, and the way to optimize overall Handle System performance, is by prefix. All identifiers under a given prefix must be maintained in one service. Handle services may be responsible for more than one prefix.

A second important component of Handle System architecture is distribution. The Handle System as a whole consists of a number of individual handle services, each of which consists of one or more handle service sites, where each site replicates the complete individual handle service, at least for the purposes of identifier resolution. Each handle service site in turn consists of one or more handle servers. There are no design limits on the total number of handle services which constitute the Handle System, there are no design limits on the number of sites which make up each service, and there are no limits on the number of servers which make up each site. Replication by site, within a service, does not require that each site contain the same number of servers, that is, while each site will have the same replicated set of identifiers, each site may allocate that set of identifiers across a different number of handle servers. This distributed approach is intended to aid scalability and to mitigate problems of single point failure.

To improve resolution performance, any client may select to cache the service information returned from the global service, and/or the resolution result from any local service. A separate handle caching server, either stand-alone or as a piece of a general caching mechanism, may also be used to provide shared caching within a local community. Given a cached resolution result, subsequent queries of the same identifier may be answered locally without contacting any handle service. Given cached service information, clients can send their requests directly to the responsible local service without contacting global.

For more information on Handle System architecture, see the Handle System RFCs referenced in the Interface Specification.