RFC 2259 (rfc2259) - Page 2 of 30
Simple Nomenclator Query Protocol (SNQP)
Alternative Format: Original Text Document
RFC 2259 SNQP January 1998
differ in protocol or data format, it is responsibility of the SNQP
server to translate protocols and data formats to provide one,
integrated answer to the user's query.
SNQP servers share the protocol needs of centralized data
repositories that answer queries with locally stored data. SNQP
servers also require specialized protocol features due to their
distributed search characteristics.
In highly distributed environments, it is unreasonable to expect all
data repositories that need to be searched to be available when
queries are posed. SNQP servers require facilities for returning
partial results in the presence of communications errors with data
repositories. The partial results must indicate how to resubmit the
query only to those data repositories that are unavailable.
In addition, users may pose queries without realizing the cost of the
search for query responses. SNQP provides facilities for informing
users of query costs and advising them on limiting that cost. Costs
and advice are returned before queries are executed.
Finally, SNQP servers may cache data and meta-data to speed query
responses. Servers can inform users of the t-bound for their query
response. A t-bound is the time after which changes may have
occurred to the data that are not reflected in the query response
[6,2]. A t-bound is the time of the oldest cache entry used to
calculate the response. Users can request that query responses are
more current then a particular t-bound. Making such a request
flushes older items from the cache.
SNQP provides support for graphical user interfaces. It also
supports different types of comparison operators, so SNQP servers can
query a variety of back-end data repositories, e.g. relational
databases, CCSO servers [3], and servers providing relational views
of X.500 [10].
SNQP is a connection-oriented protocol. A client initiates a query
session with an SNQP server by making a TCP connection to a well-
known port. The client then executes a series of SNQP commands.
These commands are listed briefly in Table 1. Section 2 provides
some typical scenarios for using these commands, and Section 3
describes the commands fully. The server replies to each command
using the theory of reply codes described for the Simple Mail
Transfer Protocol (SMTP) [9]. The theory of reply codes and the
defined reply codes are described in Section 4.
Elliott & Ordille Informational