Lemonade                                                  E. Burger, Ed.
Internet-Draft                                         BEA Systems, Inc.
Updates: RFC 3501                                           June 1, 2007
(if approved)
Intended status: Standards Track
Expires: December 3, 2007


              WITHIN Search extension to the IMAP Protocol
                  draft-ietf-lemonade-search-within-05

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Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   This document describes the WITHIN extension to IMAP SEARCH.  IMAP
   SEARCH returns messages whose internal date is within or outside a
   specified interval.  The mechanism described here, OLDER and YOUNGER,
   differs from BEFORE and SINCE in that the client specifies an
   interval, rather than a date.  WITHIN is useful for persistent
   searches where either the device does not have the capacity to



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   perform the search at regular intervals or the network is of limited
   bandwidth and thus there is a desire to reduce network traffic from
   sending repeated requests and redundant responses.

Conventions Used in this Document

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

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [1].

   When describing the general syntax, we omit some definitions as RFC
   3501 [2] defines them.


.  Introduction

   This extension exposes two new search keys, OLDER and YOUNGER, each
   of which takes a non-zero integer argument corresponding to a time
   interval in seconds.  The server calculates the time of interest by
   subtracting the time interval the client presents.  The server then
   either returnings messages older or younger than the resultant time
   and date, depending on the search key used.


.  Protocol Operation

   An IMAP4 server that supports the capability described here MUST
   return "WITHIN" as one of the server supported capabilities in the
   CAPABILITY command.

   For both the OLDER and YOUNGER search keys, the server calculates a
   target date and time by subtracting the interval, specified in
   seconds, from the current date and time of the server.  The server
   then compares the target time with the INTERNALDATE of the message,
   as specified in IMAP [2].  For OLDER, messages match if the
   INTERNALDATE is less recent than or equal to the target time.  For
   YOUNGER, messages match if the INTERNALDATE is more recent than, or
   equal to, the target time.

   Both OLDER and YOUNGER searches always result in exact matching, to
   the resolution of a second.  However, if one is doing a dynamic
   evaluation, for example, in a context [4], one needs to be aware the
   server might perform the evaluation periodically.  Thus, the server
   may delay the updates.  Clients MUST be aware that dynamic search
   results may not reflect the current state of the mailbox.  If the



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   client needs a search result that reflects the current state of the
   mailbox, we RECOMMEND the client issues a new search.


.  Formal Syntax

   The following syntax specification uses the Augmented Backus-Naur
   Form (ABNF) notation.  Elements not defined here can be found in the
   formal syntax of ABNF [1], IMAP [2], and IMAP Extended ABNF [3]

   This document extends RFC 3501 [2] with two new search keys: OLDER
   <interval> and YOUNGER <interval>.
   search-key =/ ( "OLDER" / "YOUNGER" ) SP nz-number
                  ; search-key defined in RFC 3501


.  Example
   C: a1 SEARCH UNSEEN YOUNGER 259200
   S: a1 * SEARCH 4 8 15 16 23 42

   Search for all unseen messages within the past 3 days, or 259200
   seconds, according to the server's current time.


.  Security Considerations

   The WITHIN extension does not raise any security considerations which
   are not present in the base protocol.  Considerations are the same as
   for IMAP [2].


.  IANA Considerations

   Per the IMAP RFC [2], registration of a new IMAP capablity in the
   IMAP Capability registry requires the publication of a standards
   track RFC or an IESG approved experimental RFC.  The registry is
   currently located at
   <http://www.iana.org/assignments/imap4-capabilities>.  This standards
   track document defines the WITHIN IMAP capability.  We request IANA
   to add this extension to the IANA IMAP Capability registry.


.  References

7.1.  Normative References

   []  Bradner, S., "Key words for use in RFCs to Indicate Requirement
        Levels", RFC 2119, BCP 14, March 1997.



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   []  Crispin, M., "Internet Message Access Protocol - Version 4rev1",
        RFC 3501, March 2003.

   []  Melnikov, A. and C. Daboo, "Collected Extensions to IMAP4 ABNF",
        RFC 4466, April 2006.

7.2.  Informative References

   []  Melnikov, D. and C. Daboo, "Contexts for IMAP4",
        draft-cridland-imap-context-02 (work in progress), May 2006.


Appendix A.  Contributors

   Stephane Maes and Ray Cromwell wrote the original version of this
   document as part of P-IMAP as well as the first drafts for the IETF.
   From an attribution perspective, they are clearly authors.


Appendix B.  Acknowledgements

   The authors want to thank all who have contributed key insight and
   extensively reviewed and discussed the concepts of LPSEARCH and the
   authors of its early introduction in P-IMAP.

   We also want to give a special thanks to Arnt Gilbrandsen, Ken
   Murchison, Zoltan Ordogh, and most especially Dave Cridland for their
   review and suggestions.  A special thank you goes to Alexey Melnikov
   for his choice submission of text.


Author's Address

   Eric W. Burger (editor)
   BEA Systems, Inc.
   USA

   Phone:
   Fax:
   Email: eric.burger@bea.com
   URI:   http://www.standardstrack.com










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