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Network Working Group                                     E. Burger, Ed.Request for Comments: 5032                             BEA Systems, Inc.Updates:3501                                             September 2007Category: Standards TrackWITHIN Search Extension to the IMAP ProtocolStatus of This Memo   This document specifies an Internet standards track protocol for the   Internet community, and requests discussion and suggestions for   improvements.  Please refer to the current edition of the "Internet   Official Protocol Standards" (STD 1) for the standardization state   and status of this protocol.  Distribution of this memo is unlimited.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   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.1.  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 from the current   date and time of the server.  The server then either returns messages   older or younger than the resultant time and date, depending on the   search key used.1.1.  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 inRFC 2119 [RFC2119].Burger                      Standards Track                     [Page 1]

RFC 5032                     Search Within                September 2007   When describing the general syntax, we omit some definitions, asRFC3501 [RFC3501] defines them.2.  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 [RFC3501].  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 [CONTEXT], one needs to be   aware that 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 client needs a search result that reflects the   current state of the mailbox, we RECOMMEND that the client issue a   new search.3.  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 [RFC4234] and IMAP [RFC3501].   This document extendsRFC 3501 [RFC3501] with two new search keys:   OLDER <interval> and YOUNGER <interval>.   search-key =/ ( "OLDER" / "YOUNGER" ) SP nz-number                  ; search-key defined inRFC 35014.  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.Burger                      Standards Track                     [Page 2]

RFC 5032                     Search Within                September 20075.  Security Considerations   The WITHIN extension does not raise any security considerations that   are not present in the base protocol.  Considerations are the same as   for IMAP [RFC3501].6.  IANA Considerations   Per the IMAP RFC [RFC3501], registration of a new IMAP capability 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.  IANA   has added this extension to the IANA IMAP Capability registry.7.  References7.1.  Normative References   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels",RFC 2119,BCP 14, March 1997.   [RFC3501]  Crispin, M., "Internet Message Access Protocol - Version              4rev1",RFC 3501, March 2003.   [RFC4234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax              Specifications: ABNF",RFC 4234, October 2005.7.2.  Informative References   [CONTEXT]  Melnikov, D. and C. King,"Contexts for IMAP4", Work              in Progress, May 2006.Burger                      Standards Track                     [Page 3]

RFC 5032                     Search Within                September 2007Appendix A.  Contributors   Stephane Maes and Ray Cromwell wrote the original version of this   document as part of P-IMAP, as well as the first versions 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   who have extensively reviewed and discussed the concepts of LPSEARCH.   They also thank 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   EMail: eric.burger@bea.com   URI:http://www.standardstrack.comBurger                      Standards Track                     [Page 4]

RFC 5032                     Search Within                September 2007Full Copyright Statement   Copyright (C) The IETF Trust (2007).   This document is subject to the rights, licenses and restrictions   contained inBCP 78, and except as set forth therein, the authors   retain all their rights.   This document and the information contained herein are provided on an   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND   THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS   OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF   THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.Intellectual Property   The IETF takes no position regarding the validity or scope of any   Intellectual Property Rights or other rights that might be claimed to   pertain to the implementation or use of the technology described in   this document or the extent to which any license under such rights   might or might not be available; nor does it represent that it has   made any independent effort to identify any such rights.  Information   on the procedures with respect to rights in RFC documents can be   found inBCP 78 andBCP 79.   Copies of IPR disclosures made to the IETF Secretariat and any   assurances of licenses to be made available, or the result of an   attempt made to obtain a general license or permission for the use of   such proprietary rights by implementers or users of this   specification can be obtained from the IETF on-line IPR repository athttp://www.ietf.org/ipr.   The IETF invites any interested party to bring to its attention any   copyrights, patents or patent applications, or other proprietary   rights that may cover technology that may be required to implement   this standard.  Please address the information to the IETF at   ietf-ipr@ietf.org.Burger                      Standards Track                     [Page 5]