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Versions: 00 01 02 rfc2359                                              
Network Working Group                                           J. Myers
Internet Draft                                           Carnegie Mellon
Document: draft-myers-imap-optimize-01.txt                     July 1996


                       IMAP4 OPTIMIZE-1 extension

Status of this Memo

   This document is an Internet Draft.  Internet Drafts are working
   documents of the Internet Engineering Task Force (IETF), its Areas,
   and its Working Groups.  Note that other groups may also distribute
   working documents as Internet Drafts.

   Internet Drafts are draft documents valid for a maximum of six
   months.  Internet Drafts may be updated, replaced, or obsoleted by
   other documents at any time.  It is not appropriate to use Internet
   Drafts as reference material or to cite them other than as a
   ``working draft'' or ``work in progress''.

   To learn the current status of any Internet-Draft, please check the
   1id-abstracts.txt listing contained in the Internet-Drafts Shadow
   Directories on ds.internic.net, nic.nordu.net, ftp.isi.edu, or
   munnari.oz.au.

   A revised version of this draft document will be submitted to the RFC
   editor as a Proposed Standard for the Internet Community.  Discussion
   and suggestions for improvement are requested.  This document will
   expire before December 1996.  Distribution of this draft is
   unlimited.





















J. Myers                                                        [Page i]


Internet DRAFT                 OPTIMIZE-1                  July 22, 1996


1.   Abstract

   The OPTIMIZE-1 extension of the Internet Message Access Protocol
   [IMAP4] provides a set of features intended to reduce the amount of
   time and resources used by some client operations.  The features in
   OPTIMIZE-1 are primarily intended for disconnected-use clients.

2.   Conventions Used in this Document

   In examples, "C:" and "S:" indicate lines sent by the client and
   server respectively.

3.   Introduction and Overview

   The OPTIMIZE-1 extension is present in any IMAP4 server
   implementation which returns "OPTIMIZE-1" as one of the supported
   capabilities to the CAPABILITY command.  The OPTIMIZE-1 extension
   contains two additional commands and additional data returned with
   successful APPEND and COPY commands.

   Clients that wish to use the features in OPTIMIZE-1 must of course
   first test for the presence of the extension by issuing a CAPABILITY
   command.  Each of the features in OPTIMIZE-1 are optimizations;
   clients can provide the same functionality, albeit more slowly, by
   using commands in the base protocol.  With each feature, this
   document recommends a fallback approach to take when the OPTIMIZE-1
   extension is not supported by the server.
























J. Myers                                                        [Page 2]


Internet DRAFT                 OPTIMIZE-1                  July 22, 1996


4.   Features


4.1. GETUIDS Command

   Arguments:  starting uid

   Data:       untagged response: GETUIDS

   Result:     OK - getuids completed
               BAD - command unknown or arguments invalid

      The GETUIDS command returns information about UIDs contained in
      the mailbox.  One untagged GETUIDS response is returned.

      If there is no message in the mailbox with a UID greater than or
      equal to the starting UID, the untagged GETUIDS response contains
      no arguments.

      If there exists at least one message with a UID greater than or
      equal to the starting UID, the untagged GETUIDS response contains
      the lowest message sequence number with a UID greater than or
      equal to the starting UID, followed by a message set.  The message
      set must contain the UIDs of every message in the mailbox with a
      UID greater than or equal to the starting UID.  The message set
      must not contain the symbol '*', the UID of any message which
      previously existed but has since been deleted, or any UID less
      than the starting UID or greater than the UID of the last message
      in the mailbox.  The UIDs in the message set must be in strictly
      ascending order.

      Upon receiving the untagged GETUIDS response, the client knows
      that any message in its cache with a UID greater than or equal to
      the starting UID and not present in a returned message set has
      been expunged.

      If the server does not support the OPTIMIZE-1 capability, the
      client should fall back to using the UID FETCH starting-uid:* UID
      command, where starting-uid is the starting UID.

   Example:    C: A003 GETUIDS 3475
               S: * GETUIDS 17 3509:3519,3525,3590:3599
               S: A003 OK GETUIDS completed
               C: A004 GETUIDS 4000
               S: * GETUIDS
               S: A004 OK GETUIDS completed





J. Myers                                                        [Page 3]


Internet DRAFT                 OPTIMIZE-1                  July 22, 1996


4.2. UID EXPUNGE Command

   Arguments:  message set

   Data:       untagged responses: EXPUNGE

   Result:     OK - expunge completed
               NO - expunge failure (e.g. permision denied)
               BAD - command unknown or arguments invalid

      The UID EXPUNGE command permanently removes from the currently
      selected mailbox all messages that both have the \Deleted flag set
      and have a UID that is included in the specified message set.  If
      a message either does not have the \Deleted flag set or is has a
      UID that is not included in the specified message set, it is not
      affected.

      This command may be used to ensure that a replayed EXPUNGE command
      does not remove any messages that have been marked as \Deleted
      between the time that the user requested the expunge operation and
      the time the server processes the command.

      If the server does not support the OPTIMIZE-1 capability, the
      client should fall back to using the STORE command to temporarily
      remove the \Deleted flag from messages it does not want to remove.
      The client could alternatively fall back to using the EXPUNGE
      command, risking the unintended removal of some messages.

   Example:    C: A003 UID EXPUNGE 3000:3002
               S: * EXPUNGE 3
               S: * EXPUNGE 3
               S: * EXPUNGE 3
               S: A003 OK UID EXPUNGE completed

4.3. APPENDUID response code

   Successful APPEND commands return an APPENDUID response code in the
   tagged OK response.  The APPENDUID response code contains as
   arguments the UIDVALIDITY of the destination mailbox and the UID
   assigned to the appended message.

   If the server does not support the OPTIMIZE-1 capability, the client
   can only discover this information by selecting the destination
   mailbox and issuing FETCH commands.

   Example:    C: A003 APPEND saved-messages (\Seen) {310}
               C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST)
               C: From: Fred Foobar <foobar@Blurdybloop.COM>



J. Myers                                                        [Page 4]


Internet DRAFT                 OPTIMIZE-1                  July 22, 1996


               C: Subject: afternoon meeting
               C: To: mooch@owatagu.siam.edu
               C: Message-Id: <B27397-0100000@Blurdybloop.COM>
               C: MIME-Version: 1.0
               C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII
               C:
               C: Hello Joe, do you think we can meet at 3:30 tomorrow?
               C:
               S: A003 OK [APPENDUID 38505 3955] APPEND completed

4.4. COPYUID response code

   Successful COPY and UID COPY commands return a COPYUID response code
   in the tagged OK response whenever at least one message was copied.
   The COPYUID response code contains as an argument the UIDVALIDITY of
   the appended-to mailbox, a message set containing the UIDs of the
   messages copied to the destination mailbox, in the order they were
   copied, and a message containing the UIDs assigned to the copied
   messages, in the order they were assigned.  Neither of the message
   sets may contain extraneous UIDs or the symbol '*'.

   If the server does not support the OPTIMIZE-1 capability, the client
   can only discover this information by selecting the destination
   mailbox and issuing FETCH commands.

   Example:    C: A003 COPY 2:4 MEETING
               S: A003 OK [COPYUID 38505 304,319:320 3956:3958] Done
               C: A003 UID COPY 305:310 MEETING
               S: A003 OK Done



5.   Formal Syntax

   The following syntax specification uses the augmented Backus-Naur
   Form (BNF) notation as specified in [RFC-822] as modified by [IMAP4].
   Non-terminals referenced but not defined below are as defined by
   [IMAP4].

   Except as noted otherwise, all alphabetic characters are case-
   insensitive.  The use of upper or lower case characters to define
   token strings is for editorial clarity only.  Implementations MUST
   accept these strings in a case-insensitive fashion.

   getuids         ::= "GETUIDS" SPACE uniqueid

   getuids_data    ::= "GETUIDS" [ SPACE nz_number SPACE set ]




J. Myers                                                        [Page 5]


Internet DRAFT                 OPTIMIZE-1                  July 22, 1996


   literal         ::= "{" number ["+"] "}" CRLF *CHAR8
                          ;; Number represents the number of CHAR8 octets

   resp_code_apnd  ::= "APPENDUID" SPACE nz_number SPACE uniqueid

   resp_code_copy  ::= "COPYUID" SPACE nz_number SPACE set SPACE set

   uid_expunge     ::= "UID" SPACE "EXPUNGE" SPACE set

6.   References

   [IMAP4] Crispin, M., "Internet Message Access Protocol - Version 4",
   draft-crispin-imap-base-XX.txt, University of Washington, April 1996.

   [RFC-822] Crocker, D., "Standard for the Format of ARPA Internet Text
   Messages", STD 11, RFC 822.

7.   Security Considerations

   There are no known security issues with this extension.

8.   Author's Address

   John G. Myers
   Carnegie-Mellon University
   5000 Forbes Ave.
   Pittsburgh PA, 15213-3890

   Email: jgm+@cmu.edu






















J. Myers                                                        [Page 6]


Internet DRAFT                 OPTIMIZE-1                  July 22, 1996





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Status of this Memo ...............................................    i
1.   Abstract .....................................................    2
2.   Conventions Used in this Document ............................    2
3.   Introduction and Overview ....................................    2
4.   Features .....................................................    3
4.1. GETUIDS Command ..............................................    3
4.2. UID EXPUNGE Command ..........................................    4
4.3. APPENDUID response code ......................................    4
4.4. COPYUID response code ........................................    5
5.   Formal Syntax ................................................    5
6.   References ...................................................    6
7.   Security Considerations ......................................    6
8.   Author's Address .............................................    6































J. Myers                                                       [Page ii]