rfc2972.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

Network Working Group                                            N. Popp
Request for Comments: 2972                         RealNames Corporation
Category: Informational                                      M. Mealling
                                                       Network Solutions
                                                             L. Masinter
                                                               AT&T Labs
                                                              K. Sollins
                                                                     MIT
                                                            October 2000


              Context and Goals for Common Name Resolution

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2000).  All Rights Reserved.

Abstract

   This document establishes the context and goals for a Common Name
   Resolution Protocol.  It defines the terminology used concerning a
   "Common Name" and how one might be "resolved", and establishes the
   distinction between "resolution" and more elaborate search
   mechanisms.  It establishes some expected contexts for use of Common
   Name Resolution, and the criteria for evaluating a successful
   protocol.  It also analyzes the various motivations that would cause
   services to provide Common Name resolution for both public, private
   and commercial use.

   This document is intended as input to the formation of a Common Name
   Resolution Protocol working group.  Please send any comments to
   [e-mail].  To review the mail archives, see
   <http://lists.internic.net/archives/cnrp-ietf.html>

1. Introduction

   People often refer to things in the real world by a common name or
   phrase, e.g., a trade name, company name, or a book title.  These
   names are sometimes easier for people to remember and enter than
   URLs; many people consider URLs hard to remember or type.
   Furthermore, because of the limited syntax of URLs, companies and
   individuals are finding that the ones that might be most reasonable



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   for their resources are already being used elsewhere and therefore
   unavailable.  Common names are not URIs (Uniform Resource
   Identifiers) in that they lack the syntactic structure imposed by
   URIs; furthermore, unlike URNs, there is no requirement of uniqueness
   or persistence of the association between a common name and a
   resource.  These common names are expected to be used primarily by
   humans (as opposed to machine agents).

   Common name "resolution" is a process of mapping from common names to
   Internet resources; a Common Name Resolution Protocol (CNRP) is a
   network protocol used in such a process.

   A useful analogy for understanding the purpose and scope of common
   names, and CNRP, are everyday (human language) dictionaries.  These
   cover a given language (namespace) -- perhaps a spoken language, or
   some specific subset (e.g., technical terms, etc).  Some dictionaries
   give definitions, others give translations (e.g., to other
   languages).  Different entities publish dictionaries that cover the
   same language -- e.g., Larousse and Collins can both publish French-
   language dictionaries.  Thus, the dictionary publisher is the analog
   to the resolution service provider -- the service can provide a
   value-add and build up name recognition for itself, but does not
   impede other entities from providing definitions for precisely the
   same strings in the language.

   Services are arising that offer a mapping from common names to
   Internet resources (e.g., as identified by a URI).  These services
   often resolve common name categories such as company names, trade
   names, or common keywords.  Thus, such a resolution service may
   operate in one or a small number of categories or domains, or may
   expect the client to limit the resolution scope to a limited number
   of categories or domains.  For example, the phrase "Internet
   Engineering Task Force" is a common name in the "organization"
   category, as is "Moby Dick" in the book category.  A single common
   name may be associated with different data records, and more than one
   resolution service is expected to exist.  Any common name may be used
   in any resolution service.

   Two classes of clients of such services are being built: browser
   improvements and web accessible front-end services. Browser
   enhancements modify the "open" or "address" field of a browser so
   that a common name can be entered instead of a URL.  Internet search
   sites integrate common name resolution services as a complement to
   search. In both cases, these may be clients of back-end resolution
   services.  In the browser case, the browser must talk to a service
   that will resolve the common name. The search sites are accessed via





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   a browser.  In some cases, the search site may also be the back-end
   resolution service, but in others, the search site is a front-end to
   a collection of back-end services.

   This effort is about the creation of a protocol for client
   applications to communicate with common name resolution services, as
   exemplified in both the browser enhancement and search site
   paradigms.  Although the protocol's primary function is resolution,
   it is intended to address the issues of internationalization,
   authentication and privacy as well.  Name resolution services are not
   generic search services and thus do not need to provide complex
   Boolean query, relevance ranking or similar capabilities.  The
   protocol is expected to be a simple, minimal interoperable core.
   Mechanisms for extension will be provided, so that additional
   capabilities can be added later.

   Several other issues, while of importance to the deployment of common
   name resolution services, are outside of the resolution protocol
   itself and are not in the initial scope of the proposed effort.
   These include discovery and selection of resolution service
   providers, administration of resolution services, name registration,
   name ownership, and methods for creating, identifying or insuring
   unique common names.

2. Key Goals for a Common Name Resolution Protocol

   The key deliverable is a protocol for parameterized resolution.
   "Resolution" is defined as the retrieval of data associated (a
   priori) with descriptors that match the input request.
   "Parameterized" means the ability to have a multi-component
   descriptor both as part of the query and the response.  These
   descriptors are attribute-value pairs.  They are not required to
   provide unique identification, therefore 0 or more records may be
   returned to meet a specific input query.  The protocol will define:

      - client requests/server responses to identify the specific
        parameters accepted and/or required on input requests

      - client request/server responses to identify properties to be
        returned in the result set

      - expression of parameterized input query

      - expression of result sets

      - standard expression of error conditions





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   To avoid creating a general search protocol with unbounded
   complexity, and to keep the protocol simple enough so that different
   implementations will have similar behavior, the resolution protocol
   should be limited to sub-string matches against parameter values.  To
   support full internationalization, UTF-8 encoding of strings and
   sub-strings is preferred.

   In addition, the working group should define one sample service based
   on this protocol -- the resolution of so-called "common names", or
   resolution of non-unique, registered strings to resource
   descriptions.

3. CNRP goals

   The goal of CNRP is to create a lightweight search protocol with a
   simple query interface, with a focus on making the common case of
   substring search with a single result most efficient.  In addition,
   efficient support for keyed value search is important.  Each key is a
   named meta property of the resource (e.g. category, language,
   geographical region.).  Some of these properties could be
   standardized (e.g. the common name property).  The goal is to support
   partial specification of query parameters and even partial and fuzzy
   matches on names.  CNRP is intended to be simpler than LDAP for
   simple applications.

   Besides simplicity, the CNRP protocol should be consistent with
   efficient implementation of a simple and intuitive user interface.
   The emphasis on the common name as the common denominator to find a
   wide range of resources reduces the UI to its minimal expression (the
   user types a few words in a text box and presses enter).

   CNRP should provide interoperability with multiple common name
   databases (section 4 presents many examples of such databases).  The
   query interface should be extensible and customizable to the specific
   needs of a specific type of resolution service.  However, the need
   for interoperability across databases and resolution services
   combined with the need to ensure the scalability of search (across
   millions of names from multiple providers) have lead this group to
   consider the explicit requirement of supporting categories in CNRP.
   This requirement is discussed further in section 5.

4. Example of common name namespaces

   Commercial companies have already developed and deployed common name
   resolution services such as RealNames (http://www.realnames.com) and
   NetWords (http://www.netword.com).  These commercial implementations
   are mainly focused on trade names, such as company names, brands and




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   trademarks.  These services constitute a concrete example of common
   name namespaces implementation and are useful to understand the scope
   of the CNRP effort.

   CNRP is also directly targeted at directory service providers. CNRP
   is relevant to these services to increase their reach through
   integration into larger Web sites such as the search portals.  For
   example, IAtlas has developed a directory service for businesses that
   it distributes through its Web site and Inktomi.  IAtlas could
   immediately leverage CNRP to distribute their service through their
   external distribution partners.

   Directory services must not be confused with search engines.
   Directory services use highly structured information to identify a
   resource.  This information is external to the actual resource and is
   called metadata.  In contrast, search engines mainly rely on the
   content of the resource (e.g. the text of a Web page).

   CNRP plays well with directory services that present a critical piece
   of information about the resource in the form of a textual
   identifier, a title or a terse description (the common name).
   Numerous examples come instantly to mind: company names, book titles,
   people names, songs, ISBNs, and social security numbers.  In all
   cases, the common name is the natural property for users to lookup
   the resource.  The common name is always simple and intuitive: it has
   no syntax, it is multilingual, memorable and can often be guessed.

   The following list is intended to put in prospective the wide range
   of applications for CNRP:

   - Business directories (SEC, NASDAQ, E*Trade, .).  The resource is
     company information (address, products, SEC filings, stock quotes,
     etc.).  The common name is the company name.

   - White pages (BigFoot, WhoWhere, Switchboard, ...): The resource a
     person (current address, telephone numbers, email addresses,
     employer, ...).  The common name is a last name, a telephone number
     or an email address.

   - E-commerce directories: The resource is a product for sale (car,
     house, furniture, actually almost any type of consumption item).
     The common name is a brand name or a description.

   - Publishing directories: The resource is one of many things: a book,
     a poem, a CD, an MP3 download.  The common name is an ISBN, a song
     title, an artist's name. The common name is typically the title of
     a publication.




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   - Entertainment directories: The resource is an event (a movie, a
     concert, a TV show).  The common name is the name or a description
     for the event, the movie title, a rock band name, a show.

   - Yellow pages services: Here again, the resource can be very
     diverse: a house for sale, a restaurant, a car dealership or other
     type of establishment or service that can be found in the
     traditional yellow pages.  The common name can be a street address,
     the name of a business, or a description.

   - News feeds: The resource is a press article. The common name is the
     headline.

   - Vertical directories: the DNS TLD categories, the ISO country
     codes.

5. Private and public namespaces

   A set of common names within a category (books, news, businesses,
   etc.)  is called a common name "namespace". The term "namespace" only
   refers to the set of names.  It does not encompass the bindings or
   associations between a name and data about the name (such as a
   resource, identified by a URI).  Such bindings might be created and
   maintained by a common name resolution services. Resolution services