RFC 2056 (rfc2056) - Page 3 of 7

Uniform Resource Locators for Z39

RFC 2056                    URLs for Z39.50                November 1996


3. The Z39.50 Session URL

   The Z39.50 Session URL may be informally described as providing the
   mechanism to switch the user to a Z39.50 client application.

   -  Host is required.
   -  Port is optional, and defaults to 210.
   -  All other parameters are optional.
   -  The Z39.50 client will start a session to the specified host/port
      (alternatively, it need not explicitly start a session, but may
      instead utilize an already open session to the same host/port).
   -  A database must be included if docid is included.
   -  If docid is included, the client will perform the specified search
      (in the same manner as for the retrieval URL, specified below).
   -  If docid is not included, and other parameters (besides host/port)
      are specified, the client may use those parameters as "hints".
      Various clients may choose to treat them as requirements, or as
      preferences, or ignore them.
   -  In any case (whether a search is performed or not), the client
      will leave the Z39.50 session open for the user, to do
      retrievals, new searches, etc.  (This is the main distinction
      from the Retrieval URL which leaves it up to the client whether
      or not to keep the Z39.50 session open.)

4. The Z39.50 Retrieval URL

   The Z39.50 Retrieval URL is intended to allow a Z39.50 session to be
   used as a transparent transfer mechanism to retrieve a specific
   information object.  A Z39.50 client uses information in the URL to
   formulate a Search Request.  The server's Search Response indicates
   how many records match the Request.  If the number of matching
   records does not equal one, the retrieval is considered unsuccessful,
   and the client application's behavior is not defined.  If the number
   of matching records equals one, the server may have included the
   desired record in the Search Response.  If not, the client requests
   transmission of the record with a Present Request.  After the client
   has received the specified record it may close the Z39.50 session
   immediately, or keep it open for subsequent retrievals.

   -  Host is required.
   -  Port is optional, and defaults to 210.
   -  A database is required.
   -  The meaning of a retrieval URL with no docid is undefined.
   -  The docid is placed into a type-1 query, as the single term, in
      the general format (tag 45), using the Bib-1 attribute set, with
      a Use attribute value of docid, and a structure attribute of URx.
      The docid string is server-defined and completely opaque to the
      client.



Denenberg, et. al.          Standards Track