Network Working Group                                      S. Williamson
Request for Comments: 2167                                    M. Kosters
Obsoletes: RFC 1714                                            D. Blacka
Category: Informational                                         J. Singh
                                                             K. Zeilstra
                                                 Network Solutions, Inc.
                                                               June 1997

Referral Whois (RWhois) Protocol V1.5

Status of this Memo

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

Abstract

   This memo describes Version 1.5 of the client/server interaction of
   RWhois.  RWhois provides a distributed system for the discovery,
   retrieval, and maintenance of directory information. This system is
   primarily hierarchical by design. It allows for the deterministic
   routing of a query based on hierarchical tags, referring the user
   closer to the maintainer of the information. While RWhois can be
   considered a generic directory services protocol, it distinguishes
   itself from other protocols by providing an integrated, hierarchical
   architecture and query routing mechanism.

1. Introduction

   Early in the development of the ARPANET, the SRI-NIC established a
   centralized Whois database that provided host and network information
   about the systems connected to the network and the electronic mail
   (email) addresses of the users on those systems [RFC 954]. The
   ARPANET experiment evolved into a global network, the Internet, with
   countless people and hundreds of thousands of end systems. The sheer
   size and effort needed to maintain a centralized database
   necessitates an alternate, decentralized approach to storing and
   retrieving this information.

   The original Whois function was to be a central directory of
   resources and people on ARPANET. However, it could not adequately
   meet the needs of the expanded Internet. RWhois extends and enhances
   the Whois concept in a hierarchical and scaleable fashion. In
   accordance with this, RWhois focuses primarily on the distribution of
   "network objects", or the data representing Internet resources or
   people, and uses the inherently hierarchical nature of these network
   objects (domain names, Internet Protocol (IP) networks, email
   addresses) to more accurately discover the requested information.

   RWhois synthesizes concepts from other, established Internet
   protocols. The RWhois protocol and architecture derive a great deal
   of structure from the Domain Name System (DNS) [RFC 1034] and borrow
   directory service concepts from other directory service efforts,
   primarily [X.500]. The protocol is also influenced by earlier
   established Internet protocols, such as the Simple Mail Transport
   Protocol (SMTP) [RFC 821].

   This RWhois specification defines both a directory access protocol
   and a directory architecture. The directory access protocol
   specifically describes the syntax of the client/server interaction.
   It describes how an RWhois client can search for data on an RWhois
   server, or how the client can modify data on the server. It also
   describes how the server is to interpret input from the client, and
   how the client should interpret the results returned by the server.
   The architecture portion of this document describes the conceptual
   framework behind the RWhois protocol. It details the concepts upon
   which the protocol is based and describes its structural elements.
   The protocol implements the architecture.

   This document uses language like SHOULD and SHALL that have special
   meaning as specified in "Key words for use in RFCs to Indicate
   Requirement Levels". [RFC2119]

2. Architecture

2.1 Overview

   As a directory service, RWhois is a distributed database, where data
   is split across multiple servers to keep database sizes manageable.
   The architecture portion of this document details the concepts upon
   which the protocol is based and describes its structural elements.
   Specifically, the architecture is concerned with how the data is
   split across the different servers. The basis of this splitting is
   the lexically hierarchical label (or tag), which is a text string
   whose position in a hierarchy can be determined from the structure of
   the string itself.

   All data can follow some sort of hierarchy, even if the hierarchy
   seems somewhat arbitrary. For example, person names can be arranged
   into hierarchical groups via geography. If all the people in
   particular towns are grouped into town groups, then all of the town
   groups can be grouped into state (or province) groups, and then all
   of the state groups can be grouped into a country group. Then, a
   particular name would belong in a town group, a state group, and a
   country group. However, just given a name, it would be impossible to
   determine where in the hierarchy it belongs.  Therefore, a person
   name is not lexically hierarchical.

   However, there are certain types of data whose position in the
   hierarchy can be determined by deciphering the data itself, for
   example, phone numbers. A phone number is grouped according to
   country code, area code, local exchange, and local extension. By
   looking at a phone number, it is possible to determine to which of
   all these groups the number belongs:  1-303-555-2367 is in country
   code 1, area code 303, local exchange 555, and has a local extension
   of 2367. Therefore, a phone number is lexically hierarchical.

   On the Internet, two such types of data are widely used: domain names
   and IP networks. Domain names are organized via a label-dot system,
   reading from a more specific label to a more general label left to
   right; for example, war.west.netsol.com is a part of west.netsol.com,
   which is a part of netsol.com, which is a part of com. IP networks
   are also lexically hierarchical labels using the Classless Inter-
   Domain Routing (CIDR) notation, but their hierarchy is not easily
   determined with simple text manipulation; for example, 198.41.0.0/22
   is a part of 198.41.0.0/16, which is a part of 198.40.0.0/15.
   Instead, an IP network's hierarchy is determined by converting the
   network to binary notation and applying successively shorter bit
   masks.

   It is important to note that, while very little real data is
   lexically hierarchical in nature, people often create label systems
   (or namespaces) to help manage the data and provide an element of
   uniqueness, for example, Social Security Numbers, ISBNs, or the Dewey
   Decimal System. RWhois leverages lexically hierarchical labels,
   domain names and IP networks, for its data splitting using the
   concepts of authority areas and referrals. An authority area is
   associated with an RWhois server and a lexically hierarchical label,
   which is considered to be its name. An authority area is a piece of
   the distributed database that speaks with authority about its
   assigned part of the hierarchy. All data associated with a particular
   lexically hierarchical tag should be located within that authority
   area's database. Authority areas are further explained in Section
   2.4.

   RWhois directs clients toward the appropriate authority area by
   generating referrals. Referrals are pointers to other servers that
   are presumed to be closer to the desired data. The client uses this
   referral to contact the next server and ask the same question. The
   next server may respond with data, an error, or another referral (or
   referrals). By following this chain of referrals, the client will
   eventually reach the server with the appropriate authority area. In
   the RWhois architecture, referrals are generated by identifying a
   lexically hierarchical label and deciphering the label to determine
   the next server. Referrals are further explained in Section 2.5.

   When a number of RWhois servers containing authority areas are
   brought on line and informed about each other, they form an RWhois
   tree. The tree has a root authority area, which is the group that
   contains all other groups.  The root authority area must keep
   pointers to the servers and authority areas that form the first level
   of the hierarchy. The authority areas in the first level of the
   hierarchy are then responsible for keeping pointers to the authority
   areas below them and for keeping a pointer to the root.

2.2 Design Philosophy

   The design goals for the RWhois protocol are as follows.

      * It should be a directory access protocol. The server should be
        able to access and update the data residing on it.
      * It should facilitate query routing. An unresolved query should
        be redirected to a server that is presumed to be closer to the
        desired data.
      * It should enable data replication. The server should be able to
        duplicate its data on another server.
      * The server should be lightweight and delegate more functions to
        the client.

The concepts used to achieve these design goals are explained in the
remaining document.

2.3 Schema Model

   As a directory service, RWhois uses various database schema to store
   and represent data. Schema, in this document, has two definitions.
   First, it refers to the entire structure of a database, all the
   tables and fields forming a complete database. When schema is used in
   this context, it is called the "database schema". Database schema
   consists of attributes, classes, and objects. Schema may also refer
   to a single piece of the database, a single table with fields. When
   schema is used in this context, it is just called "schema" or it is
   preceded by the name of the particular piece: contact schema or
   domain schema, for example. In this usage, schema is equivalent to
   "class", defined below.

   There is no standard database schema in the RWhois architecture. Each
   authority area is presumed to be able to define its own local schema.
   However, an authority area that is part of a larger RWhois tree is
   expected to have some part of its schema pertain to the lexically
   hierarchical label upon which the RWhois tree is based. An authority
   area schema may not change throughout much of an RWhois tree.

2.3.1 Attributes

   An attribute is a named field and is the smallest typed unit in the
   database schema. It is equivalent to a relational database's field.
   An attribute is not considered to be data by itself; it is simply
   used to give data a type. When a piece of data has been typed by an
   attribute, it is typically referred to as a value and is represented
   as an attribute-value pair. The RWhois syntax for the attribute-value
   pair is to separate them with a colon, for example:

   First-Name:Bill

   Attributes have a number of properties, some mandated by the RWhois
   protocol and some that are implementation dependent. These properties
   are usually a reflection of the database system used by the server.
   The following is a list of the protocol-mandated properties and their
   descriptions.

    Attribute    This is the name of the attribute.

    Description  This is a natural language description of the
                 attribute.

    Type         This is a parameter that broadly indicates the use
                 of the attribute to the protocol. There are three
                 standard types:  TEXT, ID, and SEE-ALSO. The default is
                 TEXT, which indicates that the value is a text string.
                 ID indicates that the attribute contains the ID of
                 another RWhois object. This type of attribute is used
                 for database normalization.  SEE-ALSO indicates that
                 the attribute contains a pointer (a Uniform Resource
                 Identifier (URI)) to some other kind of external data;
                 for example, a World Wide Web page or FTP site.

    Format       This is an interpretable string that describes the
                 acceptance format of the value. The server (and
                 optionally the client) should match the value to the
                 format string to determine if the value is acceptable.
                 The format of this property is a keyword indicating the
                 syntax of the format string, followed by a colon,
                 followed by the format string itself. Currently, the
                 only keyword recognized is "re" for POSIX.2 extended
                 regular expressions.

    Indexed      This is a true or false flag indicating that this
                 attribute should be indexed (and therefore able to be
                 searched).

    Required     This is a true or false flag indicating that this
                 attribute must have a value in an instance of the
                 class.

    Multi-Line   This is a true or false flag indicating that this
                 attribute may have multiple instances in a class, but
                 all of the instances are to be considered as multiple
                 lines of the same attribute instance. This allows
                 normal line terminators to terminate values.

    Repeatable   This is a true or false flag indicating that there may
                 be multiple instances of this attribute in a class and
                 each instance is to be interpreted as a separate
                 instance (in contrast to Multi-Line). This flag is
                 mutually exclusive with Multi-Line: if Multi-Line is
                 true, then Repeatable must be false and vice versa.

    Primary      This is a true or false flag that indicates that this
                 attribute is a primary key. If more than one attribute
                 in a class is marked as primary, then these attributes
                 together form a single primary key. The primary key is
                 intended to be used to force uniqueness among class
                 instances. Therefore, there can be only one instance of
                 a primary key in a database. The Primary flag implies
                 that the attribute is also required.

    Hierarchical This is a true or false flag that indicates that this
                 attribute is lexically hierarchical.

    Private      This is a true or false flag that indicates whether or
                 not this attribute is private (that is, publicly not
                 viewable).  It defaults to false. If it is true, then
                 only the clients that satisfy the
                 authentication/encryption requirements of a guardian
                 (described below) are able to view the attribute-value
                 pair.

2.3.2 Class

   A class is a collection of attributes; it is a structure, not data.
   The concept is equivalent to that of a relational database table. It
   is also equivalent to the second definition of schema, above.

   A class also has some properties that are sometimes referred to as
   its "meta" information. These properties are listed below.

    Version     This is a time/date stamp that is used to quickly detect
                when a class definition has been changed.

    Description This is a natural language description of the class.

2.3.3 Object

An object is an instance of a class. It is data with a type of
<class>.

2.3.4 Base Class

   While RWhois does not have or advocate using a specific, standardized
   schema, it does impose a few requirements. It requires that all
   defined classes inherit attributes from a particular base class (or
   base schema).  The RWhois specification does not require the actual
   implementation of inheritance. Instead, all classes must include the
   attributes defined in the base class.

   The base class has the following attributes.

    Class-Name    This attribute contains the name of the class to which
                  the object belongs. It is the type of the object
                  itself. It is of type TEXT and is required.

    Auth-Area     This attribute contains the name of the authority area
                  to which the object belongs. It, along with Class-
                  Name, definitively defines the type of the object. It
                  is of type TEXT and is required.

    ID            This attribute is a universal identifier for the
                  object. It is formed by choosing a string that is
                  unique within an authority area and appending the
                  authority area to it, separating the local string from
                  the authority area name with a period. The only
                  restrictions on the local string are that it must be
                  unique within the authority area and not contain the
                  period character. This attribute is hierarchical in
                  nature. It is always generated by the server (for
                  example, during a register operation). It is of type
                  TEXT and is required.

    Updated       This attribute is a time/date stamp that indicates the
                  time of last modification of the object. It is both
                  informational and a form of record locking. It
                  prevents two clients from modifying the same object at
                  the same time. It is of type TEXT and is required.

    Guardian      This attribute is a link to a guardian object
                  (described below). Its value is the ID of a guardian
                  object. It is of type ID and is optional. It is
                  repeatable, since an object may have multiple
                  guardians.

    Private      This attribute is a true or false flag that indicates
                  whether or not an object is private (that is, publicly
                  not viewable). It defaults to false. If it is true,
                  then only the clients that satisfy the
                  authentication/encryption requirements of one of the
                  object's guardians are able to view the object. If the
                  object is publicly viewable, then the Private
                  attribute property of each of its attributes still
                  applies.

    TTL           This attribute is the "time-to-live" of a given
                  object. It is included only if an object has a
                  different time-to-live than the default given in the
                  Start of Authority information. Its value is specified
                  in seconds. It is of type TEXT and is optional.

   The RWhois specification defines two standard classes that should be
   included in all implementations: the referral and guardian classes.

2.3.5 Referral Class

   The referral class is defined to hold referral information (typically
   for link referrals). It consists of attributes defined as part of the
   base class, the protocol-specific attributes described below, and any
   installation-specific attributes.

    Referred-Auth-Area This attribute contains the name of the authority
                       area to which the referral points. It is used as
                       a search key during the query routing. It is of
                       type TEXT and is required. It is repeatable,
                       since referrals can point to servers hosting more
                       than one authority area.

    Referral           This attribute contains the referral itself. It
                       is an RWhois URL. It is of type TEXT and is
                       required. It is repeatable, since more than one
                       server can host a Referred-Auth-Area.

2.3.6 Guardian Class

   The guardian class is defined to hold security information. The
   fundamental concept behind the guardian class is that an object (or
   another structure) is "guarded" by containing a pointer to a guardian
   object [Guardian]. To modify, delete, or possibly view the guarded
   object, the authentication (or encryption, or both) scheme must be
   satisfied. Guardians are intended to not have rank: if an object is
   guarded by more than one guardian object, satisfying any one of those
   guardians is sufficient. A guardian object that does not have any
   Guardian attribute linking it to other guardians guards itself. That
   is, the authentication scheme in the guardian object itself must be
   satisfied to modify, delete, or possibly view it.

   Guardian objects are typically linked to actual database objects with
   the Guardian attribute found in the base class. However, a guardian
   may also be linked to an entire authority area, in which case the
   guardian becomes implicitly linked to all of the objects contained
   within the authority area.

   The guardian class consists of the base class, the protocol-specific
   attributes described below, and any installation-specific attributes.

    Guard-Scheme This attribute contains a keyword indicating the
                 authentication methodology. Its value must be
                 understood by both the client and server, and its value
                 dictates the contents of the Guard-Info attribute. It
                 is of type TEXT and is required.

    Guard-Info   This attribute contains that data that is used by the
                 Guard-Scheme to verify the authentication. Its actual
                 format is dictated by the Guard-Scheme, for example, it
                 could contain a password or Pretty Good Privacy (PGP)
                 public key id [RFC 1991]. For security reasons, it
                 should not be displayed, and its Private attribute
                 property should be set to true. It is of type TEXT and
                 is required.

2.4 Authority Areas

   The concept of authority areas is pivotal to the RWhois architecture.
   When an RWhois tree is created for a particular lexically
   hierarchical namespace, the different pieces of the hierarchy are
   mapped to authority areas. The most important concept behind an
   authority area is the ability for a portion of the RWhois tree to
   definitively control that portion of the hierarchy. This means that
   an authority area is able to state whether or not a hierarchical tag
   is in the whole RWhois tree. It does this either by returning the
   object containing this tag, returning a referral to a sub-authority
   area, or returning a response indicating that no objects were found.

   This structure enables efficient routing of queries based on the
   hierarchical label to the piece of the hierarchy responsible for it.
   For example, in the domain name namespace as served by RWhois, the
   root of the tree would be an authority area named ".", which would
   delegate a "us" sub-authority area, which would delegate "va", "co",
   "md", and "ca" authority areas, and so forth. When the server with
   the "va.us" authority area is asked about "loudoun.va.us", it will be
   able to authoritatively state that either no "loudoun.va.us" exists
   or it will provide an object for or a referral to "loudoun.va.us".
   Further, if the server is asked about "howard.md.us", it cannot
   answer authoritatively, so it must provide a referral to its
   hierarchical parent ("us" or the root).

   This use of authority area strongly indicates where data should be
   stored within an RWhois tree. Because RWhois uses a specific query
   routing model, data needs to be placed under the proper authority
   area. It is certainly possible to place a piece of data under the

   wrong authority area, for example, putting an object for
   "howard.md.us" under the "va.us" authority area. In such cases, the
   data is considered to be misplaced and unable to be found within the
   RWhois tree. However, while data should be placed under the lowest
   (most specific) authority area, it is also possible that it could be
   placed in a higher (least specific) authority area, for example,
   putting an object for "loudoun.va.us" under the "us" authority. This
   may be acceptable since, in most cases, the data would be able to be
   found.

   In addition to controlling a part of an RWhois hierarchy, an
   authority area is considered to be autonomous. Each authority area is
   treated as a separate database by the protocol. However, it is
   recommended that an authority area share some core schema with the
   rest of the RWhois tree for interoperability reasons. Each authority
   area, however, is not bound by the database schema of its
   hierarchical parent or by any of its sub-authority areas.

2.5 Query Routing

   RWhois is not only a directory access protocol but it can also route
   queries. Routing a query involves redirecting the query to another
   server that is presumed to be closer to the desired data. To route a
   query, the server first determines the location of the next server.
   It then either forwards the query to that server and returns the
   result to the client or returns the location of that server to the
   client. The location of the server must contain its host name (or IP
   address), port number, and authority area.

   The location of the server to which a query is routed is called a
   referral.  There are two types of referrals: punt and link referrals.
   A punt referral is a pointer to a server that is further up an RWhois
   tree, and a link referral is a pointer to a server that is further
   down the tree. For example, in Figure 1, when the server for the
   "va.us" authority area routes a query up to the server for the "us"
   authority area, it generates a punt referral. Alternatively, when it
   routes a query down to the server for the "loudon.va.us" authority
   area, it generates a link referral.

   Query routing depends on whether or not the search value in a query
   is lexically hierarchical. If the search value is hierarchical, the
   server can generate punt or link referrals using the association of
   authority areas with lexically hierarchical labels. Otherwise, the
   server may send the query to a special index server that gathers the
   indexing information for both hierarchical and non-hierarchical data
   from the directory servers and returns referrals to these servers
   [CIP]. If the server receives one or more referrals from the index
   server, it should return them to the client.

   It is important to note that the server may route a query whether it
   could resolve the query or not. Even if a query has been resolved
   locally, the server may also return referrals to the client by
   sending the query to the index server. For example, if the server for
   the "com" authority area receives the "domain Org-Name=IBM" query, it
   may return all the domain objects for IBM within the "com" authority
   area. In addition, it may also return referrals to the server for the
   "nl" authority area if that server contains domain objects for IBM in
   the Netherlands and has fed the corresponding indexing information to
   the index server. This way the client can get back information for
   both "ibm.com" and "ibm.nl" domains.

2.5.1 Query Routing Rules

   An RWhois server routes a query based on certain rules. The objective
   is to determine the location of a server to which to route the query.
   A query may contain one or more query terms. The query routing rules
   are applied on each query term until a referral is found. The rules
   are listed below.

      * Is the search value in the query term hierarchical? If not, go
        to the next query term.
      * Parse the hierarchical portion of the search value. Is it is
        within one of the authority areas? If not, go to the next query
        term.
      * Does the found authority area have any referral objects
        (instances of the referral class)? If not, return the "230 No
        objects found" error to the client.
      * Is the hierarchical portion of the search value within the
        Referred-Auth-Area attribute of one of the referral objects? If
        it is, return the value of the Referral attribute of the found
        referral object as a link referral to the client.
      * Are the search values of some of the query terms hierarchical
        but not within any of the authority areas? If they are, return a
        punt referral to the client.
      * Are the search values of all the query terms non-hierarchical?
        If they are, send the query to a special index server that
        gathers the indexing information for both hierarchical and non-
        hierarchical data from the directory servers and returns
        referrals to these servers. If the server receives one or more
        referrals from the index server, return them to the client.

   Note that there can be more than one referral returned to the client.
   These referrals may point to servers serving different authority
   areas. The client may follow them in any order.

   The pseudo code for the above rules is:

   for each query term in the query
    if the search value in the query term is hierarchical
     if the search value is within one of the authority areas
       if the search value is within one of the referred authority areas
        the server sends link referral(s)
       else
        the server sends a "230 No objects found" error
       endif
     endif
    endif
   endfor

   if the search values of some of the query terms are hierarchical but
     not within any of the authority areas
    the server sends Punt referral(s)
   endif

   if the search values of all the query terms are non-hierarchical
    the server sends Referral(s) from an index server
   endif

2.6 Data Replication

   An RWhois server can replicate (duplicate) data from another RWhois
   server on a per-authority area basis. Data replication makes the
   RWhois service more reliable. Further, it increases throughput by
   distributing queries to more than one server.

   There can be two types of servers serving an authority area: a master
   server and a slave server. A master server is where data is
   registered for an authority area. It answers authoritatively to
   queries in that authority area. There must be one and only one master
   server for an authority area. A master server is also called a
   primary server.

   A slave server is where data is replicated from the master server for
   an authority area. It also answers authoritatively to queries in that
   authority area. There may be one or more slave servers for an
   authority area. A slave server is also called a secondary server.
   Note that a slave server must not register data for an authority
   area.

   It is recommended that the master and slave servers for an authority
   area be geographically separate. Therefore, network unreachability at
   one site will not completely shut down the RWhois service for that
   authority area.

2.6.1 Data to Replicate

   In RWhois, data is replicated on a per-authority area basis. The
   smallest type of data a slave server can replicate is an attribute of
   a class.  Therefore, a slave server can replicate data for all the
   classes, some classes, or some attributes of some classes.

   The amount of data a slave server can replicate each time is either
   all of the data or the data that has changed since the last
   replication. The process of replicating all of the data is called
   complete replication. The process of replicating the data that has
   changed since the last replication is called incremental replication.

2.6.2 Start Of Authority Variables

   Each authority area has some administrative variables, defined at the
   master server, to control data replication. These variables are
   called the Start Of Authority (SOA) variables. They are listed below.

    Serial-Number     This is the serial number of the data in an
                      authority area. The master server should update
                      this variable whenever the data in the authority
                      area is changed. Its value is a time/date stamp.

    Refresh-Interval  This is the time interval before a slave server
                      checks for complete replication. Its value is
                      specified in seconds.

    Increment-IntervalThis is the time interval before a slave server
                      checks for incremental replication. Its value is
                      specified in seconds.

    Retry-Interval    This is the time interval before a slave server
                      tries again to connect to a master server that
                      appears to be out-of-service. Its value is
                      specified in seconds.

    Time-To-Live      This is the default time to live for the data in
                      an authority area at a slave server. The slave
                      server should not answer authoritatively to
                      queries for such stale data. Its value is
                      specified in seconds.

    Admin-Contact     This is the email address of an individual or a
                      role account responsible for the data integrity in
                      an authority area at the master server.

    Tech-Contact      This is the email address of an individual or a
                      role account responsible for the operation of the
                      master server for an authority area.

    Hostmaster        This is the email address of an individual or a
                      role account to whom email messages to update the
                      data in an authority area at the master server are
                      sent.

    Primary-Server    This is the location of the master server for an
                      authority area. Its value must contain both the
                      host name (or IP address) and port number of the
                      master server.

3. Protocol

3.1 Overview

   The above sections describe the directory service architecture based
   on the RWhois protocol. The remaining sections describe the syntax of
   the protocol; the sequence and syntax of the information exchanged
   between a server and a client. There are five types of information
   that may be exchanged during a client/server session: directive,
   response, query, result, and info.

3.1.1 Directive

   A directive is a command that a client sends to a server to set a
   control parameter for the session, get the meta-information (class
   definitions and SOA information) about an authority area, or get the
   data in an authority area. The first character of a directive must be
   a "-". The server must support the "-rwhois" directive; all other
   directives are optional. The server must indicate in the banner which
   directives are implemented (see Section 3.1.9).

3.1.2 Response

   A response is the information that a server returns to a client for a
   directive. It is comprised of one or more lines, and the last line
   always indicates the success or failure of the directive. The first
   character of each response line must be a "%". If a server runs a
   directive successfully, the last response line must be "%ok".
   Otherwise, it must be "%error <error-code> <error-text>". A line with
   the string "%ok" or "%error" in the first position must occur only
   once in a server response and must always be the last line. The
   server may send the "%info" response for special messages.

   A client must understand the "%ok", "%error", and "%info" responses.
   The client must also understand directive specific responses, if it
   uses the related directives to communicate with the server. For
   example, if the client sends the "-schema" directive to the server,
   the client must understand the "%schema" response.

3.1.3 Query

   A query is a command that a client sends to a server to access the
   data in an authority area. The first character of a query must not be
   a "-", since the server checks the first character of each command
   from a client to determine whether it is a directive or a query.

3.1.4 Result

   A result is the information that a server returns to a client for a
   query.  It can be either the accessed data or referrals to other
   servers. It is comprised of one or more lines, and the last line
   always indicates the success or failure of the query. If a server
   returns either data or referrals for a query, the last result line
   must be "%ok". Otherwise, it must be "%error <error-code> <error-
   text>".

3.1.5 Info

   An info message contains miscellaneous information that a server
   sends to a client. The server may use it to send special messages,
   for example a "message of the day" (MOTD), to the client. The first
   info line must be "%info on", and the last info line must be "%info
   off".

3.1.6 Client/Server Session

   A typical RWhois client/server session has the following sequence of
   messages.

      * The client connects to the server.
      * The server returns a banner identifying its protocol versions
        and capabilities.
      * The client sends one or more directives to the server.
      * The server returns the response to each directive.
      * The client finally sends a query to the server.
      * The server returns the query results.
      * The server closes the connection, unless the client has directed
        it not to close the connection.

3.1.7 Examples

   This section gives some common examples of the client/server
   interaction.  The notation in the examples uses a prefix to indicate
   from where the information comes. A "C" indicates that the client
   sends the data to the server. An "S" indicates that the server sends
   the data to the client. The line is a comment when "#" is used. The
   space after the prefix is not part of the data.

   The following example illustrates a successful query.

   # The client connects to the server.
   # The server returns a banner identifying its protocol versions and
   # capabilities.
   S %rwhois V-1.5:00ffff:00 master.rwhois.net (Network Solutions V-1.5)
   # The client sends a directive to limit the number of search hits
   # to 20.
   C -limit 20
   # The server returns a successful response.
   S %ok
   # The client sends a query to search for rwhois.net domain.
   C domain rwhois.net
   # The server returns the data for rwhois.net domain.
   S domain:ID:dom-1.rwhois.net
   S domain:Auth-Area:rwhois.net
   S domain:Class-Name:domain
   S domain:Updated:19970107201111000
   S domain:Domain:rwhois.net
   S domain:Server;I:hst-1.rwhois.net
   S domain:Server;I:hst-2.rwhois.net
   S
   S %ok
   # The server closes the connection.

   The following example illustrates the link and punt referrals.

   # The client connects to the server.
   # The server returns a banner identifying its protocol versions and
   # capabilities.
   S %rwhois V-1.5:00ffff:00 master.rwhois.net (Network Solutions V-1.5)
   # The client sends a directive to hold the connection until it sends
   # a directive to close the connection.
   C -holdconnect on
   # The server returns a successful response.
   S %ok
   # The client sends a query to search for a.b.rwhois.net domain.
   C domain a.b.rwhois.net
   # The server returns a link referral to a server serving the

   # b.rwhois.net authority area.
   S %referral rwhois://master.b.rwhois.net:4321/auth-area=b.rwhois.net
   S %ok
   # The client sends a query to search for internic.net domain.
   C domain internic.net
   # The server returns a punt referral to a server serving the root
   # authority area.
   S %referral rwhois://rs.internic.net:4321/auth-area=.
   S %ok
   # The client sends a directive to close the connection.
   C -quit
   S %ok
   # The server closes the connection.

   The following example illustrates a query error.

   # The client connects to the server.
   # The server returns a banner identifying its protocol versions and
   # capabilities.
   S %rwhois V-1.5:00ffff:00 master.rwhois.net (Network Solutions V-1.5)
   # The client sends a query to search for c.rwhois.net domain.
   C domain c.rwhois.net
   # The server returns an error, since neither data nor referrals for
   # c.rwhois.net domain are found within the rwhois.net authority area.
   S %error 230 No objects found
   # The server closes the connection.

3.1.8 Notation

   The following sections use the Augmented Backus-Naur Form (ABNF)
   notation to describe the syntax of the protocol. For further
   information, see Section 2 of [RFC822]. The notation in the examples
   uses a prefix to indicate from where the information comes. A "C"
   indicates that the client sends the data to the server. An "S"
   indicates that the server sends the data to the client. The line is a
   comment when "#" is used. The space after the prefix is not part of
   the data.

3.1.9 General ABNF definitions

   Lexical Tokens

   alpha = "a".."z" / "A".."Z"
   digit = "0".."9"
   hex-digit = digit / "a".."f" / "A".. "F"
   id-char = alpha / digit / "_" / "-"
   any-char = <ASCII 1..255,
              except LF (linefeed) and CR (carriage return)>

   dns-char = alpha / digit / "-"
   email-char = <see [RFC 822]>
   space = " "
   tab = <ASCII TAB (tab)>
   lf = <ASCII LF (linefeed)>
   cr = <ASCII CR (carriage return)>
   crlf = cr lf

   Grammar

   year = 4digit
   month = 2digit
   day = 2digit
   hour = 2digit
   minute = 2digit
   second = 2digit
   milli-second = 3digit
   host-name = dns-char *(dns-char / ".")
   ip-address = 1*3digit "." 1*3digit "." 1*3digit "." 1*3digit
   email = 1*email-char "@" host-name
   authority-area = (dns-char / ".") *(dns-char / "." / "/")
   object-id = 1*id-char "." authority-area
   host-port = (host-name / ip-address) ":" 1*5digit
   class-name = 1*id-char
   attribute-name = 1*id-char
   attribute-value = 1*any-char
   time-stamp = year month day hour minute second milli-second
   on-off = "on" / "off"

   Note that the time-stamp must be in the Greenwich Mean Time (GMT)
   time zone.  Also note that since in the above any-char is 1..255
   ASCII that the RWhois protocol is an 8 bit protocol.

   Response

   The general response for every directive and query is either "%ok" or
   "%error". In addition, a "%info" response may be sent.

   response = ok-response crlf / error-response crlf / info-response
   ok-response = "%ok"
   error-response = "%error" space error-code space error-text
   error-code = 3digit
   error-text = 1*any-char
   info-response = "%info" space "on" crlf *(*any-char crlf) "%info"
           space "off" crlf

   Banner

   The server must send a banner to the client when the connection is
   opened.  The banner contains the version(s) of the protocol the
   server supports and a capability ID of encoded bit flags that
   indicates which directives are implemented. If the server supports
   more than one version of the protocol, the lowest-numbered version
   must be specified first. The bits in extra-id are reserved for future
   use. The end of the banner should contain a free-form string
   indicating the name of the server implementation. A server must
   support at least one version of the protocol, and may accept more
   versions for compatibility reasons.

   rwhois-banner = "%rwhois" space version-list space host-name
         [space implementation] crlf
   version-list = version *("," version)
   version = version-number [":" capability-id]
           / "V-1.5" ":" capability-id
   version-number = "V-" 1*digit "." 1*digit
   capability-id = response-id ":" extra-id
   response-id = 6hex-digit
   extra-id = 2hex-digit
   implementation = 1*any-char

   Protocol

   The entire RWhois protocol can be defined as a series of directives,
   responses, queries, and results.

   rwhois-protocol = client-sends / server-returns
   client-sends = *(directives / rwhois-query)
   server-returns = *(responses / rwhois-query-result)

3.2 Required Directives

The server must implement the following directives.

3.2.1 rwhois

   Description

   The "-rwhois" directive may be issued by the client at the start of
   every session . It tells the server which version of the protocol the
   client can handle. The server must respond with a banner containing
   the protocol version and directives it implements. This banner is the
   same banner that is sent by the server when the connection is opened,
   except that the server must indicate only one version number. The
   banner issued when opening a connection may contain more than one
   version number. The directive flags are encoded into three octets,
   which are described in Appendix D.

   ABNF

   rwhois-dir = "-rwhois" space version-number [space implementation]
                crlf
   rwhois-response = "%rwhois" space version space host-name
           [space implementation] crlf

   Errors

300 Not compatible with version
338 Invalid directive syntax

   Examples

   # When a connection is opened, the server issues the banner.
   S %rwhois V-1.0,V-1.5:00ffff:00 rs.internic.net (NSI Server 1.5.4)
   # The client sends the rwhois directive.
   C -rwhois V-1.5 NSI Client 1.2.3
   S %rwhois V-1.5:00ffff:00 rs.internic.net (NSI Server 1.5.4)
   S %ok

3.3 Optional Directives

The server should implement the following directives.

3.3.1 class

   Description

   The "-class" directive can be used by the client to get the meta-
   information for one or more classes in an authority area. The
   response must contain the description and version number of each
   specified class and may be expanded in the future with additional
   attributes. When no class name is given, the server must return the
   meta-information for all the classes in the authority area. Every
   class record must end with an empty "%class" line.

   ABNF

   class-dir = "-class" space authority-area *(space class-name) crlf
   class-response = *class-record response
   class-record = *class-line "%class" crlf
   class-line = "%class" space class-name ":" "description" ":"
                1*any-char crlf
      / "%class" space class-name ":" "version" ":" time-stamp crlf
      / "%class" space class-name ":" meta-field ":" meta-value crlf
   meta-field = 1*id-char
   meta-value = 1*any-char

   The following fields are required.

    meta-field   meta-value  Description

    description  1*any-char  Class description.
                           Time/date stamp indicating version of class,

    version      time-stamp  must be updated after class definition is
                             changed.

   Errors

   338 Invalid directive syntax
   340 Invalid authority area
   341 Invalid class
   400 Directive not available
   401 Not authorized for directive

   Examples

   C -class rwhois.net domain host
   S %class domain:description:Domain information
   S %class domain:version:19970103101232000
   S %class

   S %class host:description:Host information
   S %class host:version:19970214213241000
   S %class
   S %ok

3.3.2 directive

   Description

   The "-directive" directive can be used by the client to get
   information about the directives that the server supports. The
   response must contain the name and description of each specified
   directive and may be expanded in the future with additional
   attributes. When no directive name is given, the server must return
   information about all the directives. Every directive record must end
   with an empty "%directive" line.

   ABNF

   directive-dir = "-directive" *(space directive-name) crlf
   directive-name = 1*id-char
   directive-response = *directive-record response
   directive-record = "%directive" space "directive" ":" directive-name
                      crlf *directive-line "%directive" crlf
   directive-line = "%directive" space "description" ":" 1*any-char crlf
           / "%directive" space attribute-name ":" attribute-value crlf

   Errors

   338 Invalid directive syntax
   400 Directive not available
   401 Not authorized for directive

   Examples

   Without parameters:

   C -directive
   S %directive directive:rwhois
   S %directive description:RWhois directive
   S %directive
   S %directive directive:quit
   S %directive description:Quit connection
   S %directive
   S %ok

   With parameters:

   C -directive quit
   S %directive directive:quit
   S %directive description:Quit connection
   S %directive
   S %ok

3.3.3 display

   Description

   By default, the server uses the dump format for the output of a query
   result. The output format can be changed with the "-display"
   directive.  When no parameter is given, the server must list all the
   display formats it supports. Every display record must end with an
   empty "%display" line.

   Currently, only the dump format is standard and must be supported by
   the server. Other output formats may be added in the future. See
   Section 3.4 for the definition of the dump format.

   ABNF

   display-dir = "-display" crlf
       / "-display" space display-name crlf
   display-name = 1*id-char
   display-response = *(display-record) response
   display-record = "%display" space "name" ":" display-name crlf
   *display-line "%display" crlf
   display-line = "%display" space attribute-name ":"
                  attribute-value crlf

   Errors

   338 Invalid directive syntax
   400 Directive not available
   401 Not authorized for directive
   436 Invalid display format

   Examples

   # Get the available display formats.
   C -display
   S %display name:dump
   S %display
   S %ok

   # Change the active display format.
   C -display dump
   S %ok

3.3.4 forward

   Description

   The "-forward" directive instructs the server to follow all the
   referrals and return the results to the client. This directive can be
   used to run an RWhois server as a proxy server. The default value
   must be "off". When the value is set to "on", the server must not
   return referrals.

   ABNF

   forward-dir = "-forward" space on-off crlf
   forward-response = response

   Errors

   338 Invalid directive syntax
   400 Directive not available
   401 Not authorized for directive

   Examples

   C -forward on
   S %ok

   C -forward off
   S %ok

3.3.5 holdconnect

   Description

   Normally, the server closes the connection after each query. This
   behavior is controlled by the holdconnect state, which can be changed
   with the "-holdconnect" directive. When the holdconnect state is set
   to "off", the server must close the connection after a query; when it
   is set to "on", the server must not close the connection after a
   query. By default, the holdconnect state must be set to "off" for
   each connection.

   ABNF

   holdconnect-dir = "-holdconnect" space on-off crlf
   holdconnect-response = response

   Errors

   338 Invalid directive syntax
   400 Directive not available
   401 Not authorized for directive

   Examples

   C -holdconnect on
   S %ok

   C -holdconnect off
   S %ok

3.3.6 limit

   Description

   When returning a query result, the server should limit the number of
   objects returned to the client. The "-limit" directive changes this
   limit.  The default and maximum limit is server-dependent. The client
   can get the current limit by using the "-status" directive (see
   Section 3.3.13).

   ABNF

   limit-dir = "-limit" space 1*digit crlf
   limit-response = response

   Errors

   331 Invalid limit
   338 Invalid directive syntax
   400 Directive not available
   401 Not authorized for directive

   Examples

   C -limit 100
   S %ok

3.3.7 notify

   Description

   The "-notify" directive performs several functions.

      * If the server returns a referral that results in an error, the
        client can report the bad referral to the server using the
        "badref" option.
      * When the client follows referrals and goes through the same
        referral twice, that referral is a recursive referral and causes
        a referral loop. The client can report the recursive referral to
        the server using the "recurref" option.
      * When the data in an authority area changes, a master server can
        use the "update" option to notify its slave servers to update
        the data.
      * The "inssec" option allows an RWhois server to register itself
        as a slave server for an authority area with a master server.
        The master server may reject the request on the basis of its
        registration policy.
      * The "delsec" option allows a slave server to cancel its
        registration with the master server.

   ABNF

   notify-dir = "-notify" space "badref" space referral-query crlf
           / "-notify" space "recurref" space referral-query crlf
      / "-notify" space "update" space host-port ":" authority-area crlf
           / "-notify" space "inssec" space host-port ":"
             authority-area crlf
           / "-notify" space "delsec" space host-port ":"
             authority-area crlf
   referral-query = referral-url space [class-name space] query
   notify-response = response

   See Section 3.4 for the definitions of referral-url and query.

   Errors

   338 Invalid directive syntax
   340 Invalid authority area
   342 Invalid host/port
   400 Directive not available
   401 Not authorized for directive

   Examples

   # The client reports a bad referral to rwhois.foobar.com to the
   # server.
   C -notify badref rwhois://rwhois.foobar.com:4321/auth-area=foobar.com
     domain foobar.com
   S %ok

   # The client reports a recursive referral to rwhois.foobar.com to the
   # server.
   C -notify recurref rwhois://rwhois.foobar.com:4321/auth-area=
     foobar.com contact Last-Name="Beeblebrox"
   S %ok

   # The master server for the foobar.com authority area notifies its
   # slave servers to update the data.
   C -notify update master.foobar.com:4321:foobar.com
   S %ok

   # The server rwhois2.foobar.com registers as a slave server for the
   # foobar.com authority area.
   C -notify inssec rwhois2.foobar.com:4321:foobar.com
   S %ok

   # The server rwhois2.foobar.com cancels its registration as a slave
   # server for the foobar.com authority area.
   C -notify delsec rwhois2.foobar.com:4321:foobar.com
   S %ok

3.3.8 quit

   Description

   The "-quit" directive can be used by the client to close the
   connection.  Before the server closes the connection, it must respond
   with "%ok".

   ABNF

   quit-dir = "-quit" crlf
   quit-response = response

   Errors

   No errors.

   Examples

   C -quit
   S %ok

3.3.9 register

   Description

   The "-register" directive can be used by the client to add, modify,
   or delete objects in the server's database. The client must wait to
   send the registration data until the "%ok" response is received from
   the server.  This directive has the following options.

      * The "add" option indicates that the object being sent should be
        added to the server's database.
      * The "mod" option indicates that the object being sent is a
        modification of an object that already resides on the server's
        database. During a modify operation, the "_NEW_" tag is used to
        delineate the end of the original (unmodified) object and the
        beginning of the replacement object. That is, the identifying
        characteristics of the original object are sent first, then the
        "_NEW_" separator is sent, and then the entire replacement
        object is sent.
      The "del" option indicates that the object being sent should be
      deleted from the server's database.

   After a register operation (add, modify, or delete an object) in an
   authority area, the server should update the "Serial-Number" variable
   in the SOA information for the authority area. This is useful for
   data replication because a slave server checks the "Serial-Number"
   variable to detect a data change at the master server (see Section
   3.6.2).

   ABNF

   register-dir = register-on space "add" space maintainer-id crlf
                  register-add register-off
           / register-on space "mod" space maintainer-id crlf
             register-mod register-off
           / register-on space "del" space maintainer-id crlf
             register-del register-off
   register-on = "-register" space "on"
   register-off = "-register" space "off" crlf
   register-add = 1*(register-line crlf)
   register-mod = 1*(register-line crlf) "_NEW_" crlf
                  1*(register-line crlf)
   register-del = 1*(register-line crlf)

   maintainer-id = email
   register-line = attribute-name ":" attribute-value
   register-on-response = response
   register-off-response = "%register" space "ID" ":" object-id crlf
                           response
           / "%register" space "Updated" ":" time-stamp crlf response
           / response

      * The server must return the register-on-response for the
        "-register on" directive and the register-off-response for the
        "-register off" directive.
      * The maintainer-id identifies, for maintenance purposes, the
        sender of registration information. The server should not use it
        to authenticate the sender.
      * For the "add" option, the client must send all the required
        attributes for the object, including the Class-Name and Auth-
        Area attributes.  However, the client must not send the ID and
        Updated attributes. These attributes are assigned by the server
        and returned in the response.
      * For the "mod" option, the client must send the identifying
        information for the object to be modified, followed by the
        "_NEW_" separator and the entire replacement object. The
        identifying information must contain the ID and Updated
        attributes; it may contain other attributes, but the server may
        not check them. The ID, Auth-Area, and Class-Name attributes
        must match in both the original object data and the replacement
        object. The original object data is sent before the replacement
        object to enable the server to lock the record in the database.
      * For the "del" option, the client must send the identifying
        information for the object to be deleted. The identifying
        information must contain the ID and Updated attributes; it may
        contain other attributes, but the server may not check them.

   Errors

   120 Registration deferred
   320 Invalid attribute
   321 Invalid attribute syntax
   322 Required attribute missing
   323 Object reference not found
   324 Primary key not unique
   325 Failed to update outdated object
   336 Object not found
   338 Invalid directive syntax
   340 Invalid authority area
   341 Invalid class
   400 Directive not available
   401 Not authorized for directive

   Examples

   # Add an object.
   C -register on add joe@netsol.com
   S %ok
   C Class-Name:contact
   C Auth-Area:a.com
   C First-Name:Scott
   C Last-Name:Williamson
   C Name:Williamson, Scott
   C Email:scottw@a.com
   C -register off
   S %register ID:23456789.a.com
   S %register Updated:19961205224403000
   S %ok

   # Modify an object.
   C -register on mod joe@netsol.com
   S %ok
   C ID:23456789.a.com
   C Updated:19961205124403000
   C _NEW_
   C Class-Name:contact
   C Auth-Area:a.com
   C ID:23456789.a.com
   C First-Name:Scott
   C Last-Name:Williamson
   C Name:Williamson, Scott
   C Email:sw@a.com
   C -register off
   S %ok

   # Delete an object.
   C -register on del joe@netsol.com
   S %ok
   C ID:23456789.a.com
   C Updated:19961205224403000
   C -register off
   S %ok

3.3.10 schema

   Description

   The "-schema" directive can be used by the client to get the
   attribute definitions of one or more classes in an authority area. If
   the client specifies class names, the server must return the
   attribute definitions of the specified classes. Otherwise, the server

   must return the attribute definitions of all the classes in the
   authority area. Every schema record must end with an empty "%schema"
   line.

   ABNF

   schema-dir = "-schema" space authority-area *(space class-name) crlf
   schema-response = *schema-record response
   schema-record = *schema-line "%schema" crlf
   schema-line = "%schema" space class-name ":" attribute-name ":"
                 attribute-value crlf

   Errors

   338 Invalid directive syntax
   340 Invalid authority area
   341 Invalid class
   400 Directive not available
   401 Not authorized for directive

   Examples

   C -schema map
   S %schema map:attribute:Class-Name
   S %schema map:description:Type of the object
   S %schema map:type:TEXT
   S %schema map:format:re:[a-zA-Z0-9-]+
   S %schema map:indexed:OFF
   S %schema map:required:ON
   S %schema map:multi-line:OFF
   S %schema map:repeatable:OFF
   S %schema map:primary:OFF
   S %schema map:hierarchical:OFF
   S %schema map:private:OFF
   S %schema
   S %schema map:attribute:ID
   S %schema map:description:Globally unique object identifier
   S %schema map:type:TEXT
   S %schema map:format:re:[0-9]+.[a-zA-Z0-9.-]+

   S %schema map:indexed:ON
   S %schema map:required:ON
   S %schema map:multi-line:OFF
   S %schema map:repeatable:OFF
   S %schema map:primary:ON
   S %schema map:hierarchical:OFF
   S %schema map:private:OFF
   S %schema
   # This is an abbreviated example, more attributes usually follow.
   S %ok

3.3.11 security

   Description

   The "-security" directive enables either a client request or a server
   response to be authenticated and/or encrypted. Currently, RWhois uses
   two standard security methods: password and PGP. Password provides
   authentication only, and PGP provides both authentication and
   encryption.  This directive can be used to securely access or update
   any information (meta or data) in an authority area that is protected
   by one or more guardian objects.

   ABNF

   security-dir = "-security" space "on" space direction space
           security-method [space security-data] crlf
           security-payload ["-security" space "off" crlf]
   direction = "request" / "response"
   security-method = "password" / "pgp" / 1*id-char
   security-data = password-data / pgp-data / 1*any-char
   password-data = 1*any-char
   pgp-data = "signed" / "encrypt" [space key-id] / "signed-encrypt"
              [space key-id]
   security-payload = *(*any-char crlf)
   security-response = response

      * The "password" security-method is available in the "request"
        direction only. For password, the security-data is a cleartext
        password.
      * The "pgp" security-method is available in both the "request" and
        "response" directions. For PGP, the security-data indicates how
        to treat the security-payload: signed, encrypted, or signed and
        encrypted. To encrypt the security-payload in the "response"
        direction, the security-data must include the public key ID with
        which to encrypt it.

   Errors

   338 Invalid directive syntax
   352 Invalid security method
   353 Authentication failed
   354 Encryption failed
   400 Directive not available
   401 Not authorized for directive

   Examples

   # Authenticate a request using password.
   C -security on request password hello!1
   S %ok

   # Authenticate a PGP signed request.
   C -security on request pgp signed
   S %ok
   C -register on mod joe@netsol.com
   S %ok
   C -----BEGIN PGP MESSAGE-----
   C Version: 2.6.2
   C
   C owHrZJjKzMpgdP9D9crUhdpBYnwHGRnPbmVhmHlV7Hef9je/n7vyzhmE6589/+Dg
   C jPpVm59tNz92vPSmrFB/4ankBRz+xgY+7z9OUYjefGahbWSNwzzxbw6TpWZGerU+
   C uOUg/Cygs33JBdHqjwEc+wyfZPp+N5p2bu+ywoaOu8eLPyn+m2Mt/T9p1UaG68vP
   C Zd2d9EPw+Ywpio7dco6yh3b/v7zmQxJHcWpyaVFmSSUDEHi6WBkZm5iamVtY6iXq
   C JefnKnCFFqQklqSmWBlaWpoZGhmYGhqZmBgYGxgYKHA55yQWF+v6JeamWiXn55Uk
   C JpcocDmWlmToOhalJlpB9cf7uYbHE6kWi/VumUXFJRB9wcn5JUBdPokwgfDMnJzM
   C xNzi/DwFLjQBHQWoatfcxMwcq+JyB6h5AA==
   C =a0sQ
   C -----END PGP MESSAGE-----
   C -register off
   S %ok

   # Encrypt a response using PGP. 52160EC1 is the public key ID with
   # which the response is encrypted.
   C -security on response pgp encrypt 52160EC1
   S %ok
   C -xfer com class=domain attribute=Domain-Name
     attribute=Organization-Name
   S -----BEGIN PGP MESSAGE-----
   S Version: 2.6.2
   S
   S hIwDqWWhK1IWDsEBBACOXssTzD2CbB7Vjj2cNURScpJc2as2TbUDOQiwkT+8qFgG
   S ZyRfktpwNNTawRIcGOk1Kcs84z8a3vvTA/oje9vZexHtzfJwBHFdiIZxPuCEpvgv
   S 2ppK7WqlmHGcQKVBJJHYw7Fq83CUkeGJB9P1M3CQiXeW8h8MwAuhxSgbgt23PKYA
   S AABuhknJrXeh9Owm81+MvyzgLOyM7sjDYmttU9sj/yuOYmAhS9V+34MT/Mwn4wO8

   S 2BCsJqBHXbwOuYKs02p0se4jyKFtZR8MDPWNm9QyAP+oNMTjsufy6ZRa9PegUC6t
   S HDhXymkiP03mKMMVK1//7X0=
   S =vZ2x
   S -----END PGP MESSAGE-----
   S %ok

3.3.12 soa

   Description

   The "-soa" directive can be used by the client to retrieve the SOA
   information for one or more authority areas. When no authority area
   name is given, the server must return the SOA information for all the
   authority areas. Every SOA record must end with an empty "%soa" line.

   ABNF

   soa-dir = "-soa" *(space authority-area) crlf
   soa-response = *soa-record response
   soa-record = *soa-line "%soa" crlf
   soa-line = "%soa" space "authority" ":" authority-area crlf
      / "%soa" space "ttl" ":" 1*digit crlf
      / "%soa" space "serial" ":" time-stamp crlf
      / "%soa" space "refresh" ":" 1*digit crlf
      / "%soa" space "increment" ":" 1*digit crlf
      / "%soa" space "retry" ":" 1*digit crlf
      / "%soa" space "tech-contact" ":" email crlf
      / "%soa" space "admin-contact" ":" email crlf
      / "%soa" space "hostmaster" ":" email crlf
      / "%soa" space "primary" ":" host-port crlf
      / "%soa" space attribute-name ":" attribute-value crlf

   The server must return the following SOA information for an authority
   area.

attribute-name  attribute-value Comments

authority       authority-area  This is the name of the authority area.

ttl             1*digit         This is the default time to live for
                                 the data in the authority area.

serial          time-stamp      This is the serial number of the data
                                 in the authority area; it changes
                                 when the data changes.

refresh         1*digit         This is the time interval before a
                                 slave server checks for complete
                                 replication.

increment       1*digit         This is the time interval before a
                                 slave server checks for incremental
                                 replication.

retry           1*digit         This is the time interval before a
                                 slave server tries again to connect
                                 to a master server that appears to be
                                 out-of-service.

tech-contact    email           This is the contact for the operation
                                 of the master server.

admin-contact   email           This is the contact for the data
                                 integrity at the master server.

hostmaster      email           This is the contact for sending update
                                 requests at the master server.

primary         host-port       This is the host name (or IP address)
                                 and port number of the master server.

   Errors

   338 Invalid directive syntax
   340 Invalid authority area
   400 Directive not available
   401 Not authorized for directive

   Examples

   C -soa org
   S %soa authority:org
   S %soa ttl:86400
   S %soa serial:19961119111535000
   S %soa refresh:3600
   S %soa increment:1800
   S %soa retry:180
   S %soa tech-contact:tech@internic.net
   S %soa admin-contact:admin@internic.net
   S %soa hostmaster:hostmaster@internic.net
   S %soa primary:rs.internic.net:4321
   S %soa
   S %ok

3.3.13 status

   Description

   The "-status" directive can be used by the client to get various
   status flags from the server. The response must include the number of
   objects in all the authority areas, the current display format, the
   server contact information, and the status flags for the state-
   oriented directives:  "-limit", "-holdconnect", and "-forward".

   ABNF

   status-dir = "-status" crlf
   status-response = *status-line response
   status-line = "%status" space "limit" ":" 1*digit crlf
      / "%status" space "holdconnect" ":" on-off crlf
      / "%status" space "forward" ":" on-off crlf
      / "%status" space "objects" ":" 1*digit crlf
      / "%status" space "display" ":" 1*any-char crlf
      / "%status" space "contact" ":" email crlf
      / "%status" space attribute-name ":" attribute-value crlf

   Errors

   338 Invalid directive syntax
   400 Directive not available
   401 Not authorized for directive

   Examples

   C -status
   S %status limit:20
   S %status holdconnect:OFF
   S %status forward:OFF
   S %status objects:12345
   S %status display:dump
   S %status contact:joe@rwhois.net
   S %ok

3.3.14 xfer

   Description

   The "-xfer" directive can be used by the client (generally, a slave
   server) to transfer the data in an authority area. The client can
   control the amount of data transferred using one of the following
   options.

      * serial-number: The client can transfer all the objects that have
        been added, modified or deleted since a certain time, specifying
        the serial-number that indicates that time. This option is used
        for incremental replication.
      * class: The client can limit the data transfer to one or more
        classes, using the "class=<class-name>" option. The server must
        return data for only the specified classes. If no class name is
        specified, the server must return data for all the classes.
      * attribute: The client can limit the data transfer to one or more
        attributes of a class, using the "attribute=<attribute-name>"
        option in combination with the "class=<class-name>" option. The
        server must return data for only the specified attributes of the
        class. The client can specify multiple "class=" and "attribute="
        pairs.

   ABNF

   xfer-dir = "-xfer" space authority-area *attribute-def
           [space serial-number] crlf
   attribute-def = [space "class=" class-name] *(space "attribute="
                   attribute-name)
   serial-number = time-stamp
   xfer-response = *xfer-record response
   xfer-record = *xfer-line "%xfer" crlf
   xfer-line = "%xfer" space class-name ":" attribute-name ":"
               attribute-value crlf

   Errors

   332 Nothing to transfer
   333 Not master for authority area
   338 Invalid directive syntax
   340 Invalid authority area
   341 Invalid class
   342 Invalid attribute
   400 Directive not available
   401 Not authorized for directive

   Examples

   C -xfer com class=domain attribute=Domain-Name
     attribute=Organization-Name
   S %xfer domain:Domain-Name:acme.com
   S %xfer domain:Organization-Name:Acme Inc.
   S %xfer
   S %xfer domain:Domain-Name:vogon.com
   S %xfer domain:Organization-Name:Vogon Heavy Industries
   S %xfer
   S %ok

3.3.15 X

   Description

   The "-X" directive is used to specify an additional, non-standard
   directive. It can be implemented by executing an external program, by
   internal functions, or by other means. It may interact with the
   client or simply produce output like one of the standard directives.

   ABNF

   x-dir = "-X-" x-directive [space x-arguments] crlf *x-line
   x-directive = 1*id-char
   x-arguments = *any-char
   x-response = *(*any-char crlf) response
   x-line = *any-char crlf

   Errors

   338 Invalid directive syntax
   400 Directive not available
   401 Not authorized for directive

   Examples

   The following example uses an implementation that executes an
   external program, the UNIX "date" command. The server runs the "date"
   command and returns its output to the client.

   C -X-date
   S Mon Jan 6 13:21:20 EST 1997
   S %ok

3.4 Query

   Description

   The query allows the client to retrieve objects from the server's
   database.  The server must support the following types of queries.

      * Unrestricted query: It is a single word or a quoted string. The
        server must return all the matching objects where one or more
        attributes match the query, regardless of the class.
      * Class-restricted query: It is a class name specified in front
        of the unrestricted query. The server must return all the
        matching objects where one or more attributes of the specified
        class match the query.
      * Attribute-restricted query: It is of the
        "<attribute-name>=<search-string>" form. The server must return
        all the matching objects where the specified attribute matches
        the query.

   The server may implement the following types of queries.

      * Boolean operator query: It consists of simpler queries combined
        using the "and" and "or" operators.
      * Wild card query: It consists of an asterisk ("*") in the front
        and/or at the end of the search string. The server may support
        partial matching using the asterisk.

   In response to the query, the server will return the objects that
   match the query. If the server does not support complex queries,
   with, for example, wild cards or boolean operators, the server may
   return the "351 Query too complex" error. When the number of objects
   found exceeds the limit (set by the "-limit" directive), the server
   should return the objects, followed by the "330 Exceeded maximum
   objects limit" error.

   The default object output format is the dump format that uses the
   "<class-name>:<attribute-name>;<type character>:<attribute-value>"
   form.  The type character is optional and identifies the type of the
   attribute value. The type character is a shorthand for the Type field
   of the attribute definition (see Section 2.3.1). The type characters
   are defined as follows.

    Type          Attribute
    character     Type

    T             TEXT

    I             ID

    S             SEE-ALSO

   When no type character is given, the client should assume the "T"
   type character. The server must provide the type character when the
   attribute type is ID or SEE-ALSO. The purpose of the type character
   is to aid the client in displaying the data. For example, when an
   attribute value is an ID, the client may indicate to the end-user
   that it is possible to retrieve the object indicated by the ID.

   The server may return one or more referrals in the "%referral
   rwhois://<host-name>:<port-number>/auth-area=<authority area>" form.
   The client can distinguish multiple referrals by comparing their
   authority areas; if all the referrals refer to the same authority
   area, the client should follow only one of them. Otherwise, the
   client should follow all of them. To follow a referral, the client
   must connect to the specified host name and port number, and issue
   the same query.

   ABNF

   rwhois-query = [class-name space] query crlf
   query = query-string / attribute-query / query bin-boolean query
   query-char = <any-char, except """, space, tab>
   quoted-query-char = query-char / space / tab / "
   query-string = ["*"] 1*query-char ["*"] / """ ["*"]
           1*quoted-query-char ["*"] """
   attribute-query = attribute-name "=" query-string
   bin-boolean = "and" / "or"

   rwhois-query-result = *(query-record / referral-record) response
   query-record = 1*query-line crlf
   query-line = class-name ":" attribute-name [";" type-char] ":"
           attribute-value crlf
   type-char = "T" / "I" / "S"
   referral-record = 1*(referral-line crlf)
   referral-line = "%referral" space referral-url
   referral-url = "rwhois" ":" "//" host-port "/" "auth-area="
                  authority-area

   Errors

   130 Object not authoritative
   230 No objects found
   330 Exceeded maximum objects limit
   340 Invalid authority area
   341 Invalid class
   342 Invalid attribute
   350 Invalid query syntax
   351 Query too complex

   Examples

   This example illustrates a query, where no objects are found.

   C vogon
   S %error 230 No objects found

   This example illustrates a query, where two different objects are
   returned.

   C ibm
   S domain:ID:IBMLIFEPRO-DOM.com
   S domain:Auth-Area:com
   S domain:Domain-Name:IBMLIFEPRO.COM
   S domain:Org-Name:IBM
   S domain:Server;I:NS12345-HST.NET
   S domain:Server;I:NS12345-HST.NET
   S domain:Admin-Contact;I:TW1234.COM
   S domain:Tech-Contact;I:BN123.NET
   S domain:Updated:19961120123455000
   S domain:Updated-By:autoreg@internic.net
   S domain:Class-Name:domain
   S
   S network:ID:NET-IBMNET-3.0.0.0/0
   S network:Auth-Area:0.0.0.0/0
   S network:Network-Name:IBMNET-3
   S network:IP-Network:123.45.67.0/24
   S network:Org-Name:IBM
   S network:Street-Address:1234 Maneck Avenue
   S network:City:Black Plains
   S network:State:NY
   S network:Postal-Code:12345
   S network:Country-Code:US
   S network:Tech-Contact;I:MG305.COM
   S network:Updated:19931120123455000
   S network:Updated-By:joeblo@nic.ddn.mil
   S network:Class-Name:network

   S
   S %ok

   This example illustrates a query with a class restrictor, where the
   number of objects found exceeds the limit set by the "-limit"
   directive.

   C -limit 1
   S %ok
   C domain ibm
   S domain:ID:IBMLIFEPRO-DOM.com
   S domain:Auth-Area:com
   S domain:Domain-Name:IBMLIFEPRO.COM
   S domain:Org-Name:IBM
   S domain:Server;I:NS12345-HST.NET
   S domain:Server;I:NS12345-HST.NET
   S domain:Admin-Contact;I:TW1234.COM
   S domain:Tech-Contact;I:BN123.NET
   S domain:Updated:19961120123455000
   S domain:Updated-By:erice@internic.net
   S domain:Class-Name:domain
   S
   S %error 330 Exceeded maximum objects limit

   This is an example of attribute matching.

   C domain Domain-Name=konabo.com
   S domain:ID:12345678.com
   S domain:Auth-Area:com
   S domain:Domain-Name:konabo.com
   S domain:Org-Name:ACME
   S domain:Server;I:12345670.com
   S domain:Server;I:12345671.com
   S domain:Admin-Contact;I:12345660.com
   S domain:Tech-Contact;I:12345665.com
   S domain:Updated:19961120123455000
   S domain:Updated-By:joeblo@internic.net
   S domain:Class-Name:domain
   S
   S %ok

   This example illustrates a link referral.

   C domain a.b.rwhois.net
   # The server returns a link referral to a server serving the
   # b.rwhois.net authority area.
   S %referral rwhois://master.b.rwhois.net:4321/auth-area=b.rwhois.net
   S %ok

   This example illustrates a punt referral.

   C domain internic.net
   # The server returns a punt referral to a server serving the root
   # authority area.
   S %referral rwhois://rs.internic.net:4321/auth-area=.
   S %ok

   This example illustrates multiple referrals that refer to the same
   authority area. The client should follow only one of them.

   C domain a.b.rwhois.net
   # The server returns link referrals to two RWhois servers serving the
   # b.rwhois.net authority area.
   S %referral rwhois://master.b.rwhois.net:4321/auth-area=b.rwhois.net
   S %referral rwhois://slave.b.rwhois.net:4321/auth-area=b.rwhois.net
   S %ok

   This example illustrates multiple referrals that refer to different
   authority areas. The client should follow all of them.

   C contact Last-Name="Beeblebrox"
   # The server returns a link referral to a server serving the
   # b.rwhois.net authority area.
   S %referral rwhois://master.b.rwhois.net:4321/auth-area=b.rwhois.net
   # The server also returns a punt referral to a server serving the
   # net authority area since the query matched an entry in the
   # non-hierarchical index received from it.
   S %referral rwhois://rs.internic.net:4321/auth-area=net
   S %ok

   This is an example of a boolean operator and wildcard matching.

   C ibm and jubliana*
   S host:ID:JUBLIANA-HST.root
   S host:Auth-Area:.
   S host:Host-Name:JUBLIANA.TRL.IBM.CO.JP
   S host:IP-Address:123.156.220.68
   S host:Org-Name:IBM
   S host:Street-Address:1234 Maneck Avenue
   S host:City:Black Plains
   S host:State:NY
   S host:Postal-Code:12345
   S host:Country-Code:US
   S host:Updated:19961120123455000
   S host:Updated-By:joeblo@nic.ddn.mil
   S host:Class-Name:host
   S
   S %ok

3.5 Connection Model

An RWhois client can connect to an RWhois server using one of the
following transport protocols.

3.5.1 Transmission Control Protocol (TCP)

   TCP provides a reliable stream transport service between a client and
   a server. In RWhois, TCP is the default transport protocol because,
   during a particular session, a client can send more than one query
   and a server can reliably return a large amount of data for each of
   those queries. By default, a TCP RWhois server should run on the
   standard, Internet Assigned Number Authority (IANA)-assigned port
   4321. However, if port 4321 is not available, it may run on an
   available port in the non-reserved range (1024 - 65535).

3.5.2 User Datagram Protocol (UDP)

   UDP provides an unreliable connectionless transport service between a
   client and a server. In RWhois, UDP may be used as the transport
   protocol if a client wants to quickly send only one query, without
   incurring the overhead of establishing a TCP connection with a
   server. By default, a UDP RWhois server should run on the standard,
   IANA-assigned port 4321. However, if port 4321 is not available, it
   may run on an available port in the non-reserved range (1024 -
   65535). A separate document will describe the use of UDP as the
   transport protocol in RWhois.

3.6 Data Replication

   This section discusses when and how a slave server should replicate
   data.  Further, it describes the server registration and location
   mechanisms.

3.6.1 When to Replicate Data

   The time when a slave server may replicate data for an authority area
   is determined by the SOA variables for that authority area. The
   possible times are the following.

      * When the "Refresh-Interval" expires, a slave server may
        completely replicate data.
      * When the "Increment-Interval" expires, a slave server may
        incrementally replicate data.
      * A slave server fails to connect to its master server to
        replicate data. When the "Retry-Interval" expires, it tries
        again to replicate data.
      * When the data in an authority area is changed and its "Serial-
        Number" updated, a master server may notify its slave servers to
        immediately update the data. To notify about the data change,
        the master server should send the "-notify update <host-
        name>:<port-number>:<authority-area>" directive to its slave
        servers.

3.6.2 How to Replicate Data

   To replicate data, a slave server sends a series of directives to its
   master server and checks each response before sending the next
   directive.  The following sections describe the protocols for
   complete and incremental replication.

   Complete Replication

   The protocol between a master server and a slave server to completely
   replicate data for an authority area is as follows.

     1. The slave server should connect to the master server. If there
        is a connection error, the slave server should log an error and
        exit.

     2. The slave server should send the "-soa <authority-area>"
        directive to the master server and parse the SOA variables from
        the response. Let the "Serial-Number" variable in this response
        be called the "old-serial-number".

     3. The slave server should send the "-class <authority-area>"
        directive to the master server and parse the versions of all the
        classes from the response.
     4. The slave server should send the "-schema <authority-area>"
        directive to the master server and parse the definitions of all
        the classes from the response.
     5. The slave server should send the "-xfer <authority-area>"
        directive to the master server and parse the data objects from
        the response. The master server should return all the data
        objects, excluding the deleted ones, in the authority area. The
        slave server should index these data objects.
     6. When the "Refresh-Interval" expires, the slave server should
        to the master server. If there is a connection error, the slave
        server should try again after the "Retry-Interval".
     7. The slave server should send the "-soa <authority-area>"
        directive to the master server and parse the SOA variables from
        the response. Let the "Serial-Number" variable in this response
        be called the "new-serial-number". If the "new-serial-number" is
        not greater than the "old-serial-number", go back to step 6.
        Otherwise, it indicates a data change at the master server.
     8. The slave server should send the "-class <authority-area>"
        directive to the master server and parse the versions of all the
        classes from the response. If the version of any of the classes
        has changed, the slave server should send the "-schema
        <authority-area>" directive to the master server and parse the
        definitions of all the classes from the response.
     9. The slave server should send the "-xfer <authority-area>"
        directive the master server and parse the data objects from the
        response. The master server should return all the data objects,
        excluding the deleted ones, in the authority area. The slave
        server should index these data objects and seamlessly replace
        the old index with the new one. Further, it should assign the
        "new-serial-number" to the "old-serial-number".
     10. Go back to step 6.

   Note that the "-class", "-schema", and "-xfer" directives change when
   a slave server replicates data for only a subset of the schema for an
   authority area.

   In the following example, a slave server completely replicates data
   for all the classes in an authority area. The notation in the example
   uses a prefix to indicate from where the information is coming. An
   "M" indicates that the master server sends the data to the slave
   server. An "S" indicates that the slave server sends the data to the
   master server. The line is a comment when "#" is used. The space
   after the prefix is not part of the data. The example authority area
   is "rwhois.net".

   # The slave server connects to the master server.
   M %rwhois V-1.5:00ffff:00 master.rwhois.net
   S -soa rwhois.net
   M ...
   M %soa serial:19970103102258000
   M %soa refresh:3600
   M ...
   S -class rwhois.net
   # The master server returns the versions of all the classes in the
   # rwhois.net authority area.
   S -schema rwhois.net
   # The master server returns the definitions of all the classes in the
   # rwhois.net authority area.
   S -xfer rwhois.net
   # The master server returns all the data objects, excluding the
   # deleted ones, in the rwhois.net authority area. The slave server
   # indexes these data objects.
   # The refresh interval of 3600 seconds expires.
   S -soa rwhois.net
   M ...
   M %soa serial:19970103103258000
   M %soa refresh:3600
   M ...
   # The new serial number 19970103103258000 is greater than the old
   # serial number 19970103102258000. It indicates a data change at the
   # master server.
   S -class rwhois.net
   # The master server returns the versions of all the classes in the
   # rwhois.net authority area. If the version of any of the classes has
   # changed, the slave server logs an error and closes the connection.
   S -xfer rwhois.net
   # The master server returns all the data objects, excluding the
   # deleted ones, in the rwhois.net authority area. The slave server
   # indexes these data objects and seamlessly replaces the old index.
   # The refresh interval of 3600 seconds expires.
   S ...

   Incremental Replication

   The protocol between a master server and a slave server to
   incrementally replicate data for an authority area is as follows.

     1. The slave server should connect to the master server. If there
        is a connection error, the slave server should log an error and
        exit.

     2. The slave server should send the "-soa <authority-area>"
        directive to the master server and parse the SOA variables from
        the response. Let the "Serial-Number" variable in this response
        be called the "old-serial-number".
     3. The slave server should send the "-class <authority-area>"
        directive to the master server and parse the versions of all the
        classes from the response.
     4. The slave server should send the "-schema <authority-area>"
        directive to the master server and parse the definitions of all
        the classes from the response.
     5. The slave server should send the "-xfer <authority-area>"
        directive to the master server and parse the data objects from
        the response. The master server should return all the data
        objects, excluding the deleted ones, in the authority area. The
        slave server should index these data objects.
     6. When the "Increment-Interval" expires, the slave server should
        connect to the master server. If there is a connection error,
        the slave server should try again after the "Retry-Interval".
     7. The slave server should send the "-soa <authority-area>"
        directive to the master server and parse the SOA variables from
        the response. Let the "Serial-Number" variable in this response
        be called the "new-serial-number". If the "new-serial-number" is
        not greater than the "old-serial-number", go back to step 6.
        Otherwise, it indicates a data change at the master server.
     8. The slave server should send the "-class <authority-area>"
        directive to the master server and parse the versions of all the
        classes from the response. If the version of any of the classes
        has changed, the slave server should send the "-schema
        <authority-area>" directive to the master server and parse the
        definitions of all the classes from the response. The slave
        server should then send the "-xfer <authority-area>" directive
        to the master server and parse the data objects from the
        response. The master server should return all the data objects,
        excluding the deleted ones, in the authority area. The slave
        server should index these data objects and seamlessly replace
        the old index with the new one. Further, it should assign the
        "new-serial-number" to the "old-serial-number". If the version
        of any of the classes has changed, go back to step 6.
     9. The slave server should send the "-xfer <authority-area>
        <old-serial-number>" directive to the master server and parse
        the data objects from the response. The master server should
        return all the data objects in the authority area that have been
        inserted, updated, or deleted since the "old-serial-number". The
        slave server should index all the data again after purging stale
        data objects and seamlessly replace the old index with the new
        one. Further, it should assign the "new-serial-number" to the
        "old-serial-number".
     10. Go back to step 6.

   Note that the "-class", "-schema", and "-xfer" directives change when
   a slave server replicates data for only a subset of the schema for an
   authority area.

   In the following example, a slave server incrementally replicates
   data for all the classes in an authority area. The notation in the
   example uses a prefix to indicate from where the information is
   coming. An "M" indicates that the master server sends the data to the
   slave server. An "S" indicates the slave server sends the data to the
   master server. The line is a comment when "#" is used. The space
   after the prefix is not part of the data. The example authority area
   is "rwhois.net".

   # The slave server connects to the master server.
   M %rwhois V-1.5:00ffff:00 master.rwhois.net
   S -soa rwhois.net
   M ...
   M %soa serial:19970103102258000
   M %soa increment:1800
   M ...
   S -class rwhois.net
   # The master server returns the versions of all the classes in the
   # rwhois.net authority area.
   S -schema rwhois.net
   # The master server returns the definitions of all the classes in the
   # rwhois.net authority area.
   S -xfer rwhois.net
   # The master server returns all the data objects, excluding the
   # deleted ones, in the rwhois.net authority area. The slave server
   # indexes these data objects.
   # The increment interval of 1800 seconds expires.
   S -soa rwhois.net
   M ...
   M %soa serial:19970103103258000
   M %soa increment:1800
   M ...
   # The new serial number 19970103103258000 is greater than the old
   # serial number 19970103102258000. It indicates a data change at
   # the master server.
   S -class rwhois.net
   # The master server returns the versions of all the classes in the
   # rwhois.net authority area. If the version of any of the classes has
   # changed, the slave server logs an error and closes the connection.
   S -xfer rwhois.net 19970103102258000

   # The master server returns all the data objects in the rwhois.net
   # authority area that have been inserted, updated, or deleted since
   # 19970103102258000. The slave server indexes all the data again
   # after purging stale data objects and seamlessly replaces the old
   # index. The increment interval of 1800 seconds expires.
   S ...

3.6.3 Server Registration

   This section discusses how an RWhois server can register itself or
   cancel its registration as a slave server for an authority area with
   a master server.

   The initial list of slave servers for an authority area should be
   manually configured at the master server. To register itself as a
   slave server, the server should send the "-notify inssec <host-
   name>:<port-number>:<authority-area>" directive to the master server.
   The master server may reject the request on the basis of its
   registration policy. To cancel its registration as a slave server,
   the server should send the "-notify delsec <host-name>:<port-
   number>:<authority-area>" directive to the master server. Note that
   the "host-name" and "port-number" in the above directives correspond
   to the requesting server.

3.6.4 Server Location

   To resolve a query in a particular authority area, an RWhois client
   may need to first locate the master and slave servers for that
   authority area.  The different server location mechanisms are as
   follows.

   Referrals

   An RWhois client should know about at least one RWhois server. It
   should send the "referral <authority-area>" query to that server. The
   query may be routed up or down the RWhois tree before getting
   resolved. If the query does get resolved, the result should be a
   referral object for that authority area. The client should parse the
   "Referral" attributes from the result to obtain a list of servers
   serving that authority area.

   The client should then send the "-soa <authority-area>" directive to
   one of the above servers and parse the "Primary-Server" variable from
   the response. The value of this variable is the master server. Then,
   the remaining servers in the list are the slave servers.

   SRV RRs

   The Server Resource Record (SRV RR), defined for DNS, can be used to
   locate the master and slave servers for an authority area. An SRV RR
   specifies the location of a network service in an organization's DNS.
   It is defined in [RFC 2052] as follows.

   Service.Proto.Name TTL Class SRV Priority Weight Port Target

   Since an authority area identifier is generally a domain name or an
   IP address, the RWhois SRV RRs can be added to the DNS file for that
   domain or IP address. For example, the RWhois SRV RRs for the
   "rwhois.net" authority area could be:

   rwhois.tcp.rwhois.net. 86400 IN SRV 10 0 4321 master.rwhois.net.
                                   SRV 20 0 4322 slave.rwhois.net.

   where the "master.rwhois.net" server has a higher priority than the
   "slave.rwhois.net" server. The client must try to connect to the
   server with a higher (lower-numbered) priority.

4. Security Considerations

   RWhois provides security using the guardian class (see Section
   2.3.6). Any information (meta or data) in an authority area can be
   guarded by containing pointers to one or more guardian objects; that
   is, it can be securely updated and accessed. Currently, there are two
   standard security methods: password and PGP (see Section 3.3.11).
   Password provides authentication only, and PGP provides both
   authentication and encryption.  PGP is the recommended security
   method in RWhois.

   The following sections discuss how to securely update and access the
   data in an authority area.

4.1 Data Update

   This involves the ability to securely add, modify, or delete some
   information (meta or data) in an authority area. An authority area,
   on the whole, can be guarded by linking guardians to its SOA and
   schema information. Only these guardians should be allowed to add
   objects to the authority area and modify its SOA and schema
   information. In addition, they can also modify or delete existing
   objects in the authority area. However, the function of modifying or
   deleting existing objects can be delegated to other guardians by
   linking them to objects on a per-object basis.

4.2 Access Control

   There are two access control issues; the first is the ability to
   securely transfer data between the slave and master servers. To
   transfer data for an authority area, a slave server can authenticate
   itself by satisfying one of the guardians linked to the SOA
   information of the authority area at the master server. In addition,
   the master server may encrypt the transferred data.

   The second issue is the ability to make public only a subset of the
   data in an authority area. If all the objects of a particular class
   need to be private, the Private attribute of the class should be set
   to true. If only some attributes of all the objects of a particular
   class need to be private, the Private attribute property of each of
   those attributes should be set to true. The guardians of such objects
   must be able to view them completely.

5. Acknowledgments

   The authors would like to acknowledge the following individuals.

   Stan Borinski
   C. Ming Lu
   Leslie Meador
   Michael Mealling
   Greg Pierce
   Amar Rao

6. References

   [CIP] Allen, J., "The Common Indexing Protocol (CIP)", Bunyip
   Information Systems, November 1996, Work in Progress.

   [Guardian] Singh, J., M. Kosters, "The InterNIC Guardian Object",
   ftp://rs.internic.net/policy/internic/internic-gen-1.txt, Network
   Solutions, February 1996.

   [RFC 821] Postel, J., "Simple Mail Transfer Protocol", STD 10, RFC
   821, ISI, August 1982.

   [RFC 822] Crocker, D, "Standards for the Format of ARPA Internet Text
   Messages", STD 11, RFC 822, University of Delaware, August 1982.

   [RFC 954] Harrenstien, K., Stahl, M., Feinler, E., "NICNAME/WHOIS",
   RFC 954, SRI, October 1985.

   [RFC 1034] Mockapetris, P. V., "Domain names - concepts and
   facilities", STD 13, RFC 1034, November 1987.

   [RFC 1714] Williamson, S., Kosters, M., "Referral Whois Protocol",
   RFC 1714, Network Solutions, November 1994.

   [RFC 1738] T. Berners-Lee, L. Masinter, M. McCahill, "Uniform
   Resource Locators (URL)", RFC 1738, CERN, Xerox Corporation,
   University of Minnesota, December 1994.

   [RFC 1991] Atkins, D.,  W. Stallings, P. Zimmermann, "PGP Message
   Exchange Formats", RFC 1991, MIT, Comp-Comm Consulting, Boulder
   Software Engineering, August 1996.

   [RFC 2052] Gulbrandsen, A., P. Vixie, "A DNS RR for specifying the
   location of services (DNS SRV)", RFC 2052, Troll Technologies, Vixie
   Enterprises, October 1996.

   [X.500] "The Directory: Overview of Concepts, Models and Service",
   CCITT Recommendation X.500, 1988.

Authors' Addresses

   Scott Williamson (scottw@rwhois.net)
   Mark Kosters (markk@internic.net)
   David Blacka (davidb@rwhois.net)
   Jasdip Singh (jasdips@rwhois.net)
   Koert Zeilstra (kzeil@rwhois.net)

   Postal Address:
   505 Huntmar Park Drive
   Herndon, VA 22070-5100
   Telephone: 703-742-0400

Appendix A: Glossary Of Terms

   ABNF: Augmented Backus-Naur Form. Refined version of BNF, defined in
   [RFC 822]. See BNF.

   Attribute: A named field and the smallest typed unit in a database
   schema.  See Database Schema.

   Authority Area: An autonomous part of an RWhois tree. It is
   associated and named after a particular piece of a hierarchy and is
   able to state authoritatively whether or not an instance of
   hierarchical data is present within the RWhois tree. See RWhois Tree.

   Banner: A line sent by a server indicating which protocol versions it
   supports and which directives are implemented. This line is issued by
   the server after a connection is opened and as a response to the "-
   rwhois" directive. See Directive and Response.

   Base Class: A class from which all defined classes in a database
   schema inherit attributes. See Attribute, Class, and Database Schema.

   BNF: Backus-Naur Form. Language to precisely define the syntax of
   protocols and computer languages.

   Class: A collection of attributes. See Attribute.

   Complete Replication: The process of replicating all of the data for
   an authority area. See Replication.

   Database Schema: A collection of all the classes forming an RWhois
   database. See Class.

   Directive: A command that a client sends to a server to set a control
   parameter for the session, get the meta-information (class
   definitions and SOA information) about an authority area, or get the
   data in an authority area. See Class and SOA.

   Guardian Class: A standard class that contains security information.
   An object is guarded by containing a pointer to a guardian object.
   See Class and Object.

   Incremental Replication: The process of replicating the data that has
   changed since the last replication for an authority area. See
   Replication.

   Info: The miscellaneous information that a server sends to a client.

   Lexically Hierarchical Label: A text string whose position in a
   hierarchy is encoded in the string itself.

   Link Referral: A pointer to another server that is further down an
   RWhois tree. It is used to route a query down the tree. See Referral
   and RWhois Tree.

   Master Server: A server where the data is registered for an authority
   area.  It answers authoritatively to queries in the authority area.
   It is also called a primary server. See Authority Area.

   Namespace: A particular naming system defined by a set of rules
   describing the format of a name. Alternately, all of the names
   satisfying the rules.

   Object: An instance of a class. It is data with a type of <class>.
   See Class.

   PGP: Pretty Good Privacy. An authentication and encryption scheme.

   Primary Server: See Master Server.

   Punt Referral: A pointer to another server that is further up an
   RWhois tree. It is used to route a query up the tree. See Referral
   and RWhois Tree.

   Query: A command that a client sends to a server to access the data
   in an authority area.

   Query Routing: Redirecting a query to another server for resolution.
   See Query.

   Referral: A pointer to another server that is presumed to be closer
   to the desired data. It is used to route a query. See Query Routing.

   Referral Class: A standard class that contains referral information
   for an authority area. See Class and Referral.

   Replication: A server duplicating data from another server on a per-
   authority area basis. See Authority Area.

   Response: The information that a server returns to a client for a
   directive. See Directive.

   Result: The information that a server returns to a client for a
   query. It can be either the accessed data or referrals to other
   servers. See Query and Referral.

   RWhois Tree: A data information tree of RWhois servers where the data
   is arranged hierarchically in the authority areas. See Authority
   Area.

   Schema: See Class.

   Secondary Server: See Slave Server.

   Slave Server: A server where the data is replicated from the master
   server for an authority area. It also answers authoritatively to
   queries in the authority area. It is also called a secondary server.
   See Master Server.

   SOA: Start Of Authority. Administrative variables, defined at the
   master server, to control replication for an authority area. See
   Master Server and Replication.

Appendix B: RWhois ABNF

   This specification uses the Augmented Backus-Naur Form (ABNF)
   notation, as defined in Section 2 of [RFC 822].

   General Definitions

   Lexical Tokens

   alpha = "a".."z" / "A".."Z"
   digit = "0".."9"
   hex-digit = digit / "a".."f" / "A".. "F"
   id-char = alpha / digit / "_" / "-"
   any-char = <ASCII 1..255,
              except LF (linefeed) and CR (carriage return)>
   dns-char = alpha / digit / "-"
   email-char = <see [RFC 822]>
   space = " "
   tab = <ASCII TAB (tab)>
   lf = <ASCII LF (linefeed)>
   cr = <ASCII CR (carriage return)>
   crlf = cr lf

   Grammar

   year = 4digit
   month = 2digit
   day = 2digit
   hour = 2digit
   minute = 2digit
   second = 2digit

   milli-second = 3digit
   host-name = dns-char *(dns-char / ".")
   email = 1*email-char "@" host-name
   authority-area = (dns-char / ".") *(dns-char / "." / "/")
   object-id = 1*id-char "." authority-area
   host-port = (host-name / ip-address) ":" 1*5digit
   ip-address = 1*3digit "." 1*3digit "." 1*3digit "." 1*3digit
   class-name = 1*id-char
   attribute-name = 1*id-char
   attribute-value = 1*any-char
   time-stamp = year month day hour minute second milli-second
   on-off = "on" / "off"

   Note that the time-stamp must be in the Greenwich Mean Time (GMT)
   time zone.

   response = ok-response crlf / error-response crlf / info-response
   ok-response = "%ok"
   error-response = "%error" space error-code space error-text
   error-code = 3digit
   error-text = 1*any-char
   info-response = "%info" space "on" crlf *(*any-char crlf) "%info"
           space "off" crlf

   rwhois-banner = "%rwhois" space version-list space host-name
           [space implementation] crlf
   version-list = version *("," version)
   version = version-number [":" capability-id]
           / "V-1.5" ":" capability-id
   version-number = "V-" 1*digit "." 1*digit
   capability-id = response-id ":" extra-id
   response-id = 6hex-digit
   extra-id = 2hex-digit
   implementation = 1*any-char

   rwhois-protocol = client-sends / server-returns
   client-sends = *(directives / rwhois-query)
   server-returns = *(responses / rwhois-query-result)

   directives = rwhois-dir / class-dir / directive-dir / display-dir /
           holdconnect-dir / limit-dir / notify-dir / quit-dir /
           register-dir / schema-dir / security-dir / soa-dir /
           status-dir / xfer-dir / x-dir

   responses = rwhois-response / class-response/ directive-response/
           display-response/ holdconnect-response/ limit-response/
           notify-response/ quit-response/ register-response/
           schema-response / security-response/ soa-response/
           status-response/ xfer-response/ x-response

   Required Directives

   rwhois

   rwhois-dir = "-rwhois" space version-number [space implementation]
                crlf
   rwhois-response = "%rwhois" space version space host-name
           [space implementation] crlf

   Optional Directives

   class

   class-dir = "-class" space authority-area *(space class-name) crlf
   class-response = *class-record response
   class-record = *class-line "%class" crlf
   class-line = "%class" space class-name ":" "description" ":"
                1*any-char crlf
      / "%class" space class-name ":" "version" ":" time-stamp crlf
      / "%class" space class-name ":" meta-field ":" meta-value crlf
   meta-field = 1*id-char
   meta-value = 1*any-char

   directive

   directive-dir = "-directive" *(space directive-name)crlf
   directive-name = 1*id-char
   directive-response = *directive-record response
   directive-record = "%directive" space "directive" ":"
           directive-name crlf *directive-line "%directive" crlf
   directive-line = "%directive" space "description" ":" 1*any-char crlf
           / "%directive" space attribute-name ":" attribute-value crlf

   display

   display-dir = "-display" crlf
      / "-display" space display-name crlf
   display-name = 1*id-char
   display-response = *display-record response
   display-record = "%display" space "name" ":" display-name crlf
   *display-line "%display" crlf
   display-line = "%display" space attribute-name ":" attribute-value
                  crlf

   holdconnect

   holdconnect-dir = "-holdconnect" space on-off crlf
   holdconnect-response = response

   limit

   limit-dir = "-limit" space 1*digit crlf
   limit-response = response

   notify

   notify-dir = "-notify" space "badref" space referral-query crlf
           / "-notify" space "recurref" space referral-query crlf
           / "-notify" space "update" space host-port ":" authority-area
             crlf
           / "-notify" space "inssec" space host-port ":" authority-area
             crlf
           / "-notify" space "delsec" space host-port ":" authority-area
             crlf
   referral-query = referral-url space [class-name space] query
   notify-response = response

   See the query section for the definitions of referral-url and query.

   quit

   quit-dir = "-quit" crlf
   quit-response = response

   register

   register-dir = register-on space "add" space maintainer-id crlf
           register-add register-off
           / register-on space "mod" space maintainer-id crlf
                   register-mod register-off
           / register-on space "del" space maintainer-id crlf
                   register-del register-off
   register-on = "-register" space "on"
   register-off = "-register" space "off" crlf
   register-add = 1*(register-line crlf)
   register-mod = 1*(register-line crlf) "_NEW_" crlf
                  1*(register-line crlf)
   register-del = 1*(register-line crlf)
   maintainer-id = email
   register-line = attribute-name ":" attribute-value
   register-on-response = response
   register-off-response = "%register" space "ID" ":" object-id crlf
                           response
           / "%register" space "Updated" ":" time-stamp crlf response
           / response

   schema

   schema-dir = "-schema" space authority-area *(space class-name) crlf
   schema-response = *schema-record response
   schema-record = *schema-line "%schema" crlf
   schema-line = "%schema" space class-name ":" attribute-name ":"
           attribute-value crlf

   security

   security-dir = "-security" space "on" space direction space
           security-method [space security-data] crlf security-payload
           ["-security" space "off" crlf]
   direction = "request" / "response"
   security-method = "password" / "pgp" / 1*id-char
   security-data = password-data / pgp-data / 1*any-char
   password-data = 1*any-char
   pgp-data = "signed" / "encrypt" [space key-id] / "signed-encrypt"
              [space key-id]
   security-payload = *(*any-char crlf)
   security-response = response

   soa

   soa-dir = "-soa" *(space authority-area) crlf
   soa-response = *soa-record response
   soa-record = *soa-line "%soa" crlf
   soa-line = "%soa" space "authority" ":" authority-area crlf
      / "%soa" space "ttl" ":" 1*digit crlf
      / "%soa" space "serial" ":" time-stamp crlf
      / "%soa" space "refresh" ":" 1*digit crlf
      / "%soa" space "increment" ":" 1*digit crlf
      / "%soa" space "retry" ":" 1*digit crlf
      / "%soa" space "tech-contact" ":" email crlf
      / "%soa" space "admin-contact" ":" email crlf
      / "%soa" space "hostmaster" ":" email crlf
      / "%soa" space "primary" ":" host-port crlf
      / "%soa" space attribute-name ":" attribute-value crlf

   status

   status-dir = "-status" crlf
   status-response = *status-line response
   status-line = "%status" space "limit" ":" 1*digit crlf
      / "%status" space "holdconnect" ":" on-off crlf
      / "%status" space "forward" ":" on-off crlf
      / "%status" space "authority" ":" 1*digit crlf
      / "%status" space "display" ":" 1*any-char crlf
      / "%status" space "contact" ":" email crlf
      / "%status" space attribute-name ":" attribute-value crlf

   xfer

   xfer-dir = "-xfer" space authority-area *attribute-def
           [space serial-number] crlf
   attribute-def = [space "class=" class-name]
                   *(space "attribute=" attribute-name)
   serial-number = time-stamp
   xfer-response = *xfer-record response
   xfer-record = *xfer-line "%xfer" crlf
   xfer-line = "%xfer" space class-name ":" attribute-name ":"
               attribute-value crlf

   X

   x-dir = "-X-" x-directive [space *[x-arguments]] crlf
   x-directive = 1*id-char
   x-arguments = *any-char
   x-response = *(*any-char crlf) response

   Query

   rwhois-query = [class-name space] query crlf
   query = query-string / attribute-query / query bin-boolean query
   query-char = <any-char, except """, space, tab>
   quoted-query-char = query-char / space / tab / "
   query-string = 1*query-char ["*"] / """ 1*quoted-query-char ["*"] """
   attribute-query = attribute-name "=" query-string
   bin-boolean = "and" / "or"

   rwhois-query-result = *(query-record / referral-record) response
   query-record = 1*query-line crlf
   query-line = class-name ":" attribute-name [";" type-char] ":"
           attribute-value crlf
   type-char = "T" / "I" / "S"
   referral-record = 1*(referral-line crlf)
   referral-line = "%referral" space referral-url
   referral-url = "rwhois" ":" "//" host-port "/" "auth-area="
                  authority-area

Appendix C: Error Codes

   When a server fails to run a command (directive or query), it returns
   an error response. The ABNF for an error response is as follows.

   error-response = "%error" space error-code space error-text
   error-code = 3digit
   error-text = 1*any-char

   An error text may be modified, but its meaning must remain the same.
   The server may append additional information to it, for example
   "%error 333 Not master for authority area: foobar.com".

   The following table describes the possible digits in the first,
   second, and third positions of an error code.
    XXX    Description
    1XX    Information only, no action required
    2XX    Information, action required
    3XX    Specific command error, retry that command or try another one
    4XX    Serious for current command, may correct with another command
    5XX    Fatal, must disconnect
    X0X    System wide, no specific command
    X1X    System wide, no specific command
    X2X    Registration error
    X3X    Specific command
    X4X    Specific command
    X5X    Specific command
    X6X    Extended message (version specific)
    XXX    Sequential order

   The following table gives an ordered list of RWhois error codes.
   These codes may be extended with implementation- specific codes. An
   implementation- specific code must have a "6" in the second position.

    Code    Text
    120     Registration deferred
    130     Object not authoritative
    230     No objects found
    300     Not compatible with version
    320     Invalid attribute
    321     Invalid attribute syntax
    322     Required attribute missing
    323     Object reference not found
    324     Primary key not unique
    325     Failed to update outdated object
    330     Exceeded maximum objects limit
    331     Invalid limit
    332     Nothing to transfer
    333     Not master for authority area
    336     Object not found
    338     Invalid directive syntax
    340     Invalid authority area
    341     Invalid class
    342     Invalid host/port
    350     Invalid query syntax
    351     Query too complex
    352     Invalid security method
    353     Authentication failed
    354     Encryption failed
    400     Directive not available
    401     Not authorized for directive

    402     Unidentified error
    420     Registration not authorized
    436     Invalid display format
    500     Memory allocation problem
    501     Service not available
    502     Unrecoverable error
    503     Idle time exceeded

   The following error codes, defined in [RFC 1714], have been made
   obsolete:  100, 200, 231, 334, 335, 337, 421, 431, 432, 433, 434,
   460, 461, and 530.

Appendix D: Capability ID

   The capability ID encodes which directives are implemented in the
   server.  To create a capability ID, perform a logical OR on all the
   hexadecimal numbers corresponding to the implemented directives. The
   resulting number is used in the banner, which is sent by the server
   after opening a connection and as a response to the "-rwhois"
   directive. The eight most significant bits of the capability ID are
   reserved for future use:

    class        000001h
    directive    000002h
    display      000004h
    forward      000008h
    holdconnect  000010h
    limit        000020h
    notify       000040h
    quit         000080h
    register     000100h
    schema       000200h
    security     000400h
    soa          000800h
    status       001000h
    xfer         002000h
    X            004000h

Appendix E: Schema Definitions

Attribute Definition Model

Name         Type  Description

Attribute    N     This is the name of the attribute.

Description  S     This is a free-form description of the attribute.

Type         T     This is a parameter that broadly indicates the use
                    of the attribute to the protocol. There are three
                    standard types: TEXT, ID, and SEE-ALSO. The default
                    is TEXT, which indicates that the value is a text
                    string.  ID indicates that the attribute contains
                    the ID of another RWhois object. This type of
                    attribute is used for database normalization. SEE-
                    ALSO indicates that the attribute contains a pointer
                    (a Uniform Resource Identifier (URI)) to some other
                    kind of external data; for example, a World Wide Web
                    page or FTP site.

Format       S     This is an interpretable string that describes the
                    acceptance format of the value. The server (and
                    optionally the client) should match the value to the
                    format string to determine if the value is
                    acceptable.  The format of this property is a
                    keyword indicating the syntax of the format string,
                    followed by a colon, followed by the format string
                    itself. Currently, the only keyword recognized is
                    "re" for POSIX.2 extended regular expressions.

Indexed      B     This is a true or false flag that indicates that
                    this attribute should be indexed (and therefore able
                    to be searched).

Required     B     This is a true or false flag that indicates that
                    this attribute must have a value.

Multi-Line   B     This is a true or false flag that indicates that
                    this attribute may have multiple instances in an
                    object; all the instances are to be considered as
                    multiple lines of the same attribute instance.

Repeatable   B     This is a true or false flag that indicates that
                    there may be multiple instances of this attribute in
                    a class and each instance is to be interpreted as a
                    separate instance (in contrast to Multi-Line). This
                    flag is mutually exclusive with Multi-Line: if
                    Multi-Line is true, then Repeatable must be false
                    and vice versa.

Primary      B     This is a true or false flag that indicates that
                    this attribute is a primary key. If more than one
                    attribute in a class is marked as primary, then
                    these attributes together form a single primary key.
                    The primary key is intended to be used to force
                    uniqueness among class instances. Therefore, there
                    can be only one instance of a primary key in a
                    database. The Primary flag implies that the
                    attribute is also required.

Hierarchical B     This is a true or false flag that indicates that
                    this attribute is lexically hierarchical.

Private      B     This is a true or false flag that indicates whether
                    or not this attribute is private (that is, publicly
                    not viewable). It defaults to false. If it is true,
                    then only the clients that satisfy the
                    authentication/encryption requirements of a guardian
                    are able to view the attribute-value pair.

   Type is defined as follows:

    Type  ABNF Definition

     B     "ON" / "OFF"
     N     1*id-char
     S     1*any-char
     T     "ID" / "SEE-ALSO" / "TEXT"

   Base Class

Name       Type   Required  RepeatableDescription

Class-Name TEXT   Y         N         This attribute is the name of the
                                       class to which the object
                                       belongs.

Auth-Area  TEXT   Y         N         This attribute is the name of the
                                       authority area to which the
                                       object belongs.

ID         TEXT   Y         N         This attribute is the universal
                                       identifier of the object.

Updated    TEXT   Y         N         This attribute is a time/date
                                       stamp that indicates the time of
                                       last modification of the object.

Guardian   ID     N         Y         This attribute is a link to a
                                       guardian object. Its value is the
                                       ID of a guardian object.

Private    TEXT   N         N         This attribute is a true or false
                                       flag that indicates whether or
                                       not an object is private (that
                                       is, publicly not viewable). It
                                       defaults to false. If it is
                                       true, then only the clients
                                       that satisfy the
                                       authentication/encryption
                                       requirements of one of the
                                       object's guardians are able to
                                       view the object. If the object
                                       is publicly viewable, then the
                                       Private attribute property of
                                       each of its attributes still
                                       applies.

TTL        TEXT   N         N         This attribute is the
                                       "time-to-live" of a given object.
                                       It is included only if an object
                                       has a different time-to-live than
                                       the default given in the Start of
                                       Authority information. Its value
                                       is specified in seconds.

Appendix F: Changes RWhois V1.0 - V1.5

   General

      * Multiple authority areas per server.
      * Data replication.
      * Revised schema model.
      * Revised query routing rules.
      * Revised error codes.
      * Removed unnecessary spaces in responses and results.

   Directives

      * Class: New. Returns meta-information for a class.
      * Display: Can return supported display formats.
      * Load: Obsolete.
      * Notify: Syntax change.
      * Private: Obsolete.
      * Register: Syntax change.
      * Schema: Syntax change.
      * Security: Obsoletes Private.
      * Xfer: Syntax change.

   Query

      * Display option removed.
      * Output format: Only the dump format is standard; optional type
        character added.
      * Attribute-restricted query.
      * Revised referral syntax.