rfc2258.txt

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Network Working Group                                         J. Ordille
Request for Comments: 2258                Bell Labs, Lucent Technologies
Category: Informational                                     January 1998





                      Internet Nomenclator Project


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 (1998).  All Rights Reserved.

Abstract

   The goal of the Internet Nomenclator Project is to integrate the
   hundreds of publicly available CCSO servers from around the world.
   Each CCSO server has a database schema that is tailored to the needs
   of the organization that owns it.  The project is integrating the
   different database schema into one query service.  The Internet
   Nomenclator Project will provide fast cross-server searches for
   locating people on the Internet.  It augments existing CCSO services
   by supplying schema integration, more extensive indexing, and two
   kinds of caching -- all this in a system that scales as the number of
   CCSO servers grows.  One of the best things about the system is that
   administrators can incorporate their CCSO servers into Nomenclator
   without changing the servers. All Nomenclator needs is basic
   information about the server.

   This document provides an overview of the Nomenclator system,
   describes how to register a CCSO server in the Internet Nomenclator
   Project, and how to use the Nomenclator search engine to find people
   on the Internet.










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RFC 2258              Internet Nomenclator Project          January 1998


1.  Introduction

   Hundreds of organizations provide directory information through the
   CCSO name service protocol [3]. Although the organizations provide a
   wealth of information about people, finding any one person can be
   difficult because each organization's server is independent.  The
   different servers have different database schemas (attribute names
   and data formats).  The 300+ CCSO servers have more than 900
   different attributes to describe information about people. Very few
   common attributes exist.  Only name and email occur in more than 90%
   of the servers [4].  No special support exists for cross-server
   searches, so searching can be slow and expensive.

   The goal of the Internet Nomenclator Project is to provide fast,
   integrated access to the information in the CCSO servers.  The
   project is the first large-scale use of the  Nomenclator system.
   Nomenclator is a more general system than a white pages directory
   service.  It is a scalable, extensible information system for the
   Internet.

   Nomenclator answers descriptive (i.e. relational) queries.  Users can
   locate information about people, organizations, hosts, services,
   publications, and other objects by describing their attributes.
   Nomenclator achieves fast descriptive query processing through an
   active catalog, and extensive meta-data and data caching.  The active
   catalog constrains the search space for a query by returning a list
   of data repositories where the answer to the query is likely to be
   found.  Meta-data and data caching keep frequently used query
   processing resources close to the user, thus reducing communication
   and processing costs.

   Through the Internet Nomenclator Project, users can query any CCSO
   server, regardless of its attribute names or data formats, by
   specifying the query to Nomenclator (see Figure 1).  Nomenclator
   provides a world view of the data in the different servers.  Users
   express their queries in this world view.  Nomenclator returns the
   answer immediately if it has been cached by a previous query. If not,
   Nomenclator uses its active catalog to constrain the query to the
   subset of relevant CCSO servers.  The speed of the query is
   increased, because only relevant servers are contacted. Nomenclator
   translates the global query into local queries for each relevant CCSO
   server.  It then translates the responses into the format of the
   world view.








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RFC 2258              Internet Nomenclator Project          January 1998


   --------------------------------------------------------------------


                     +-------------+             +-------------+
                     |             |             |             |
         World View  |             | Local View  |             |
         Query       |             | Query       |  Relevant   |
         ----------->|             |------------>|             |
                     | Nomenclator |             |  CCSO       |
                     |             |             |             |
         <-----------|             |<------------|  Server     |
          World View |             |  Local View |             |
          Response   |             |  Response   |             |
                     +-------------+             +-------------+



                      Figure 1:  A Nomenclator Query

                  Nomenclator translates queries to and from
                  the language of the relevant CCSO servers.

   --------------------------------------------------------------------

   The Internet Nomenclator Project makes it easier for users to find a
   particular CCSO server, but it does not send all queries to that
   server.  When Nomenclator constrains the search for a query answer,
   it screens out irrelevant queries from ever reaching the server.
   When Nomenclator finds an answer in its cache, it screens out
   redundant queries from reaching the server.  The server becomes
   easier to find and use without experiencing the high loads caused by
   exhaustive and redundant searches.

   The Internet Nomenclator Project creates the foundation for a much
   broader heterogeneous directory service for the Internet.  The
   current version of Nomenclator provides integrated access to CCSO and
   relational database services. The Nomenclator System Architecture
   supports fast, integrated searches of any collection of heterogeneous
   directories.  The Internet Nomenclator Project can be enhanced to
   support additional name services, or provide intergated query
   services for other application domains. The project is starting with
   CCSO services, because the CCSO services are widely available and
   successful.

   Section 2 describes the Nomenclator system in more detail.  Section 3
   explains how to register a CCSO server as part of the project.
   Section 4 briefly describes how to use Nomenclator.  Section 5
   provides a summary.



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RFC 2258              Internet Nomenclator Project          January 1998


2.  Nomenclator System

   Nomenclator is a scalable, extensible information system for the
   Internet. It supports descriptive (i.e. relational) queries.  Users
   locate information about people, organizations, hosts, services,
   publications, and other objects by describing their attributes.
   Nomenclator achieves fast descriptive query processing through an
   active catalog, and extensive meta-data and data caching.

   The active catalog constrains the search space for a query by
   returning a list of data repositories where the answer to the query
   is likely to be found.  Components of the catalog are distributed
   indices that isolate queries to parts of the network, and smart
   algorithms for limiting the search space by using semantic,
   syntactic, or structural constraints.  Meta-data caching improves
   performance by keeping frequently used characterizations of the
   search space close to the user, thus reducing active catalog
   communication and processing costs.  When searching for query
   responses, these techniques improve query performance by contacting
   only the data repositories likely to have actual responses, resulting
   in acceptable search times.

   Administrators make their data available in Nomenclator by supplying
   information about the location, format, contents, and protocols of
   their data repositories.  Experience with Nomenclator shows that
   gathering a small amount of information from data owners can have a
   substantial positive impact on the ability of users to retrieve
   information.  For example, each CCSO administrator provides a mapping
   from the local view of data (i.e. the local schema) at the CCSO
   server to Nomenclator's world view.  The administrator also supplies
   possible values for any attributes with small domains at the data
   repository (such as the "city" or "state_or_province" attributes).
   With this information, Nomenclator can isolate queries to a small
   percentage of the CCSO data repositories, and provide an integrated
   view of their data.  Nomenclator provides tools that minimize the
   effort that administrators expend in characterizing their data
   repositories.  Nomenclator does not require administrators to change
   the format of their data or the access protocol for their database.

2.1 Components of a Nomenclator System

   A Nomenclator system is comprised of a distributed catalog service
   and a query resolver (see Figure 2).  The distributed catalog service
   gathers meta-data about data repositories and makes it available to
   the query resolver. Meta-data includes constraints on attribute






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RFC 2258              Internet Nomenclator Project          January 1998


   values at a data repository, known patterns of data distribution
   across several data repositories, search and navigation techniques,
   schema and protocol translation techniques, and the differing schema
   at data repositories.

   --------------------------------------------------------------------


                     +-------------+             +-------------+
                     |             |             |             |
         World View  |             |  Meta Data  |             |
         Query       |             |  Request    | Distributed |
         ----------->|   Query     | ----------->|             |
                     |   Resolver  |             |  Catalog    |
                     |             |             |             |
         <-----------|   (caches)  | <-----------|  Service    |
          World View |             |  Meta Data  |             |
          Response   |             |  Response   |             |
                     +-------------+             +-------------+



                   Figure 2: Components of a Nomenclator System

   --------------------------------------------------------------------

   Query resolvers at the user sites retrieve, use, cache, and re-use
   this meta-data in answering user queries.  The catalog is "active" in
   two ways. First, some meta-data moves from the distributed catalog
   service to each query resolver during query processing.  Second, the
   query resolver uses the initial meta-data, in particular the search
   and navigation techniques, to generate additional meta-data that
   guides query processing.  Typically, one resolver process serves a
   few hundred users in an organization, so users can benefit from
   larger resolver caches.

   Query resolvers cache techniques for constraining the search space
   and the results of previously constrained searches (meta-data), and
   past query answers (data) to speed future query processing.  Meta-
   data and data caching tailor the query resolver to the specific needs
   of the users at the query site.  They also increase the scale of a
   Nomenclator system by reducing the load from repeated searches or
   queries on the distributed catalog service, data repositories, and
   communications network.







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