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The Handle System is a technology specification for assigning, managing, and resolving persistent identifiers for digital objects and other resources on the Internet. The protocols specified enable a distributed computer system to store identifiers (names, or handles) of digital resources and resolve those handles into the information necessary to locate, access, and otherwise make use of the resources. That information can be changed as needed to reflect the current state and/or location of the identified resource without changing the handle. The Handle System was developed by Bob Kahn, co-inventor of the TCP/IP protocols that underlie the operation of the Internet, with support from the Defense Advanced Research Projects Agency DARPA at the Corporation for National Research Initiatives (CNRI), which continues to develop and manage it. The Handle System is currently in use in several applications. The Handle System enables management of objects as first class entities, rather than as packets of bits with dependency on other attributes such as locations. It emerged as part of a wider Framework for Distributed Digital Object Services but has been used in independent applications. The system is designed to be scalable to very large numbers of entities without performance degradation, to allow distributed administration, and to enable resolution to multiple pieces of current data (each of which may be separately managed). It also has further optional features such as public key infrastructure capability to enable trust applications. Resolution is the process in which an identifier is the input request to a network service to receive in return a specific output of one or more pieces of current information (state data) related to the identified entity: e.g., a location (URL). The Domain Name System resolves domain names meaningful to humans into numerical IP addresses (locations of file servers). The Handle System is compatible with DNS but does not necessarily require it, unlike persistent identifiers such as PURLs or ARKs which utilise domain names and are therefore ultimately constrained by them. Other significant differences include the administrative granularity possible with the Handle System (administrators can be different for each handle, and there can also be more than one per handle) and the option for extensible multiple data types to be assigned. DNS has well-recognised problems of security and updating which suggest that it will not be sufficient to assume that existing DNS technology can simply be adapted to deal with new requirements. By explicitly separating names from all associated data, including location, the Handle System addresses a key requirement of future internet architecture. A joint research project by the MIT Laboratory for Computer Science and Air Force Research Laboratory argued that "it is possible to separate the ideas of location and identity, both of which are represented by the IP address in today's Internet, ... the resulting architecture facilitates mobility as well as solving other problems with today's network". ==Specifications== The Handle System is defined in informational RFCs 3650,〔http://www.rfc-editor.org/rfc/rfc3650.txt〕 3651〔http://www.rfc-editor.org/rfc/rfc3651.txt〕 and 3652〔http://www.rfc-editor.org/rfc/rfc3652.txt〕 of the Internet Engineering Task Force (IETF); it includes an open set of protocols, a namespace, and a reference implementation of the protocols. Handles resolve to typed data. Documentation, software, and related information is provided by CNRI on a dedicated website Each handle may have its own administrator(s) and administration of these handles can be done in a distributed environment. The name-to-value bindings may also be secured, both via signatures to verify the data and via challenge response to verify the transmission of the data, allowing handles to be used in trust management applications. The syntax of the handle encompasses any Unicode character and leaves the string construction to the assigner (thereby allowing inclusion of existing identifier strings if desired). Implementation of the Handle System consists of Local Handle Services, each of which is made up of one or more sites that provide the servers that store specific handles. The Global Handle Registry¨ is a unique Local Handle Service which stores information on the prefixes (also known as naming authorities) within the Handle System and can be queried to find out where specific handles are stored on other Local Handle Services within this distributed system. Handles can be used natively, or expressed as Uniform Resource Names (URNs) or Uniform Resource Identifiers (URIs). Although the Handle System is not currently a registered stand-alone implementation of URI or URN, it is a part of the info URI specification, RFC 4452.〔http://www.rfc-editor.org/rfc/rfc4452.txt〕 Handles may also be expressed as Uniform Resource Locators (URLs), by the use of a http proxy server. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Handle System」の詳細全文を読む スポンサード リンク
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