Corporation for National Research Initiatives Handle Types Every handle record consists of one or more typed values: HDL:Type:Value Handle clients rely on types to understand the value and determine the correct action The Handle System per se never validates any type/value pair, although applications may. Handle creators are free to use or create whatever handle value types are needed for their needs Very flexible, works well, BUT - how do you understand the intended meaning of a given type?
Corporation for National Research Initiatives Interpreting Handle Types Every handle value type (HVT) should itself be a registered handle Currently a few registered under 0.Type but it has been a cumbersome process New types should be complete handles, e.g., 10320/loc Legacy, e.g., URL, assumed to be 0.Type Handle Value Type Registry (HVT-R) Search for types Open to whoever has a type to register (policies TBD)
Corporation for National Research Initiatives Handle Value Type Registry (HVT-R) Provides a comprehensive list of all registered HVTs. Provides a search/list capability for users to look for any existing type that may address their needs Service to be accessible to application frameworks for acquiring relevant information about a specific HVT Acquires data from value type handles in the handle system Every value type handle contains a description of type 10320/hvt-desc with a value of a defined XML schema 0.Type/URL : 10320/hvt-desc :
Corporation for National Research Initiatives Handle Value Type Registry (HVT-R)
Corporation for National Research Initiatives HVT Definition Schema Provides all of the information needed to sufficiently define a given HVT so as to promote its interoperable use with the Handle System. The schema consists of 13 top level fields Most fields are simple: –Handle used as the Type –Title –Contact information Some fields require more thought: –Value Description. This field can be complex since it contains all the information that a developer/admin would need to be able to create a valid instance of that HVT. All humanly readable fields accommodate multiple languages. Some fields can be defined in-line or by-reference. –References are to existing HVT types: RFC, MIME types etc…
Corporation for National Research Initiatives Use Case: 10320/loc HVT-R 10320/loc description 4 Handle System 3 Resolve 10320/loc Is there a service that can do location specific URL redirection? 1 HVT: 10320/loc 2 5 Create handles that properly specify 10320/loc handle values to leverage its standard service implementation. 10320/loc enabled Service, e.g., proxy 6 Resolve a handle from Handle AdminA Handle AdminA User 9 Return properly Computed results for HVT 10320/loc 7 Resolve Handle 8 Return 10320/loc Handle values
Corporation for National Research Initiatives Handle Value Type (HVT) Characteristics An HVT should unambiguously identify the nature of a specific handle value. A pragmatic classification of Handle Value Types: –HVTs recognized by the Handle System itself, for system operation. Most of these types are defined within the RFCs. HS_ADMIN, HS_SITE, HS_PUBKEY, HS_VLIST. –HVTs recognized and acted upon by the Handle to Web proxy. URL (0.TYPE/URL), 10320/loc –User defined HVTs. Application specific 100.3/GROUP (ADL) Strong recommendation: new HVTs should themselves be resolvable handles, to facilitate interoperability across handle applications
Corporation for National Research Initiatives Beyond Handle Value Types Registered Non HVT Types are needed to support the development of HVTs. HVT descriptions can reference other HVTs as well as non-handle value types. (e.g. MIME types, services etc…) Non-handle value types can also be identified using a handle and registered in order to be consistently referenced. The current HVT definition schema can be used to describe these non-HVT type definitions. The HVT registry will allow for those types to be registered, indexed and searchable.
Corporation for National Research Initiatives HVT-R Roadmap Make accessible to a controlled set of beta testers. –Operational version for CNRI developers - May 08 –Volunteers solicited Expand the HVT-R to include non-handle value types, e.g., handle aliased MIME types. Produce final documentation and schema spec. Provide public access to the registry. Open up the registration of HVTs to the larger Handle System community.
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