ASID Working Group                                       Martin Hamilton
INTERNET-DRAFT                                   Loughborough University
                                                              March 1998

                       WHOIS++ URL Specification
               Filename: draft-ietf-asid-whois-url-02.txt

Status of This Memo

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      This Internet Draft expires September 1998.


   This document defines a new Uniform Resource Locator (URL) scheme
   ''whois++'', which provides a convention within the URL framework for
   referring to WHOIS++ servers and the data held within them.

1. Overview of the WHOIS++ protocol

   RFC 1835 [1] defines a simple Internet directory protocol known as
   WHOIS++.  In order that WHOIS++ may be used within the Uniform
   Resource Locator (URL) framework defined by RFC 1738 [2], a URL
   scheme definition for WHOIS++ is necessary.  This document specifies
   a URL scheme "whois++", for use with the WHOIS++ protocol.

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   WHOIS++ is text based protocol after the fashion of many popular
   Internet application protocols, such as SMTP [3] and FTP [4].
   Although the protocol is TCP based, WHOIS++ is effectively stateless
   - no state information is preserved across requests, there is no
   concept of a session per se since each request/response pair is
   self-contained, and there is no "login" phase.

   WHOIS++ transactions normally consist of a single request from the
   client and response from the server, followed by the TCP connection
   between the two being torn down.  Use of the "hold" constraint in the
   WHOIS++ request makes it possible for the client to indicate that it
   would like to keep the TCP connection open for more than one request/
   response pair, but whether this is actually done is at the discretion
   of the server.

2. WHOIS++ URL specification

   The following information is necessary for a WHOIS++ client to
   formulate and deliver a request:

     o the domain name or IP address of the server to contact
     o the port number of the server (63 by default)
     o the request itself - normally a single line of text

   This is a good match with the generic URL scheme specified in RFC
   1738, and so a URL following the generic syntax is appropriate.

   The WHOIS++ URL scheme is defined as:

     whoisppurl   = "whois++://" hostport [ "/" whoisppsrch ]


     whoisppsrch  = *uchar

   The definitions for "hostport" and "uchar" are imported from the BNF
   style grammar for URLs defined in Section 5 of RFC 1738.  BNF for the
   WHOIS++ request format ("whoisppsrch") is defined in Appendix F of
   RFC 1835.

3. Examples

   The whois++ URL scheme defined above makes it possible to write URLs
   for any of the following:

     (a) a reference particular WHOIS++ server, without implying
           that a search should be done
     (b) a "canned" search of a particular server

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     (c) individual objects within a server

   Case (a) simply requires that the host and optionally the port number
   be specified, e.g.




   When given a WHOIS++ URL of this format, implementations may choose
   to present the user with a search form or dialogue, contact the
   server for information about which WHOIS++ options it supports, and
   so on.  The WHOIS++ default port 63 should be used if the port number
   is not specified.

   Case (b) requires a search specification to be present, e.g.


   This may be sent verbatim to the server, once hex escaped chars in
   the URL have been converted back to normal, e.g.

     name=phil and name=zimmerman

   Case, (c) is effectively an instance of (b).  This may be implemented
   as a search where the request consists of the WHOIS++ "handle" of the
   requested object, e.g.


   Although there are no global constraints specified in these last two
   URLs, the WHOIS++ client may choose to add global constraints of its
   own, e.g.  use of the "hold" constraint to request that the
   connection be held open for a further request.

   If in addition, global constraints are part of the URL, this can
   easily be recognised by the presence of a colon ":" immediately after
   the slash "/" which separates the host and port information from the
   search specifier, e.g.


   At the implementor's discretion, the client may choose to pass these
   global constraints on in any queries which are passed to this server,
   e.g. if this URL was used in a search for "zimmerman", the request
   passed to the server might be either of

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   or "zimmerman", followed by some combination of the global
   constraints specified in the URL and other global constraints
   introduced by the WHOIS++ client.

4. Issues

   4.1 Relationship with WHOIS and RWhois

   The three protocols in the WHOIS family, NICNAME/WHOIS [5], WHOIS++,
   and RWhois [6], are not particularly similar.  WHOIS++ and RWhois use
   different request and response formats, and have different well-known
   port numbers.  WHOIS responses are assumed to be plain text and human
   readable.  Consequently, this document has not attempted to define a
   single URL scheme for use with all three protocols.

   4.2 Localisation

   WHOIS++ requests may contain "difficult characters" such as space,
   and characters drawn from non-ASCII character sets such as the UTF-8
   variant of Unicode [7,8].  Hence, the usual rules about hex-escaping
   illegal and reserved characters should apply - and the definiton of
   the WHOIS++ request as "uchar".  Note that the default WHOIS++ port
   of 63 should be used if the port number component of the "hostport"
   construction is left out.

   4.3 Use of global constraints

   Since global constraints such as authentication information, language
   and character set preferences may be expressed as part of the WHOIS++
   request, it is not thought necessary to specify them separately in a
   mechanism such as the "user@host" construction defined for the FTP

   4.4 Encoding multi-line WHOIS++ requests

   Most WHOIS++ requests can be expected to consist of a single line of
   text, followed by carriage return and line feed characters.  It
   should, however, be noted that it may be necessary to encode multi-
   line requests within WHOIS++ URLs.  Software which implements WHOIS++
   URLs should either be capable of handling this, or fail gracefully.

   4.5 Integration with HTML/HTTP

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   WHOIS++ URLs may be used as hyperlinks in HTML [9] documents, though
   it should be noted that the relative URL syntax defined in RFC 1808
   [10] is not appropriate for use in these links.  This is because
   WHOIS++ requests do not map conveniently onto the generic resource
   locator syntax used for relative URLs - the syntactic conventions
   used in writing a WHOIS++ request are very different from those of
   the generic resource locator.

   The WHOIS++ protocol and the WHOIS++ URL lend themselves to
   implementation via a proxy HTTP [11] gateway, since the information
   necessary to contact the server and deliver the request is embedded
   within the URL itself.  A simple proof-of-concept proxy gateway has
   been implemented which takes an HTTP "GET" request containing a
   WHOIS++ URL, carries out a WHOIS++ transaction and returns the
   results formatted as HTML.  This may be found at:


   It is not appropriate to use any HTTP methods other than "GET" with
   WHOIS++ URLs.

   The appearance of the "+" character in the protocol scheme component
   of a URL is legal, according to RFC 1738.  The author has lingering
   doubts about the ability of all software which processes URLs, for
   example in parsing HTML documents, to cope with this character.  No
   evidence has been found to back these doubts up, however.

5. Security Considerations

   Client software should check both the contents of the WHOIS++ URL and
   the results returned from WHOIS++ search requests for any unsafe
   characters and character strings.

   It is possible to embed requests for other protocols within this URL
   format.  This is an approach which may be used to defeat security
   schemes, spoof protocols, and so on.  Implementors should consider
   requiring user confirmation when requests are directed to reserved
   ports (i.e.  those less than 1024) other than 63 and 43, or well-
   known ports in the unreserved range.

   Implementations should take care not to cache authentication
   information.  In some cases, as with the simple "password"
   authentication shceme defined in RFC 1835, authentication information
   may take the form of clear text user names and passwords.  This is a
   WHOIS++ protocol issue and beyond the scope of this URL

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6. Acknowledgements

   Thanks to Jeff Allen, Lorcan Dempsey, Patrik Faltstrom, Jon Knight,
   William F. Maton, Larry Masinter, and Scott Williamson for their
   comments on draft versions of this document.

   This work was supported by grant 12/39/01 from the UK Electronic
   Libraries Programme (eLib) and grant RE 1004 from the European
   Commission's Telematics for Research Programme.

7. References

   Request For Comments (RFC) and Internet Draft documents are available
   from <URL:> and numerous mirror sites.

         [1]         P. Deutsch, R. Schoultz, P. Faltstrom and C.
                     Weider.  "Architecture of the WHOIS++ service", RFC
                     1835. August 1995.

         [2]         T. Berners-Lee, L. Masinter and M. McCahill (eds).
                     "Uniform Resource Locators (URL)", RFC 1738.
                     December 1994.

         [3]         J. Postel.  "Simple Mail Transfer Protocol", RFC
                     821.  August 1982.

         [4]         J. Postel, J. K. Reynolds.  "File Transfer Proto-
                     col", RFC 959.  October 1985.

         [5]         The Unicode Standard, Worldwide Character Encoding,
                     Version 1.0, Volume 1, Addison-Wesley, 1990. ISBN

         [6]         The Unicode Standard, Worldwide Character Encoding,
                     Version 1.0, Volume 2, Addison-Wesley, 1992. ISBN

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

         [8]         S. Williamson & M. Kosters.  "Referral Whois

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                     Protocol (RWhois)", RFC 1714.  November 1994.

         [9]         T. Berners-Lee, D. Connolly.  "Hypertext Markup
                     Language - 2.0", RFC 1866.  November 1995.

         [10]        R. Fielding. "Relative Uniform Resource Locators",
                     RFC 1808.  June 1995.

         [11]        T. Berners-Lee, R. Fielding, H. Frystyk.  "Hyper-
                     text Transfer Protocol -- HTTP/1.0", RFC 1945.  May

8. Author's address

   Martin Hamilton
   Department of Computer Studies
   Loughborough University of Technology
   Leics. LE11 3TU, UK


                This Internet Draft expires September 1998

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