Lemonade E. Burger, Ed. Internet-Draft BEA Systems, Inc. Updates: RFC 3501 June 1, 2007 (if approved) Intended status: Standards Track
R. CromwellExpires: August 27, 2007 S. Maes Oracle Corporation February 23,December 3, 2007 WITHIN Search extension to the IMAP Protocol draft-ietf-lemonade-search-within-04draft-ietf-lemonade-search-within-05 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. 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 and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on August 27,December 3, 2007. 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. We expectWITHIN to be mostis 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 mobile devices.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 . When describing the general syntax, we omit some definitions as RFC 3501  defines them. 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.interval in seconds. The server calculates the time of interest by subtracting the time interval presented bythe client, andclient presents. The server then either returningreturnings messages older or younger than the resultant time and date.date, depending on the search key used. 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 intervalinterval, 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 . For OLDER, messages match if the INTERNALDATE is less recent than,than or equal to,to the target time. For YOUNGER, messages match if the INTERNALDATE is more recent than, or equal to, the target time. In some cases, the server may be unable, or unwilling,Both OLDER and YOUNGER searches always result in exact matching, to use a precisionthe resolution of a singlesecond. ThisHowever, if one is expected to be the case particularlydoing a dynamic evaluation, for dynamically updated searches. In these cases, servers are permittedexample, in a context , one needs to reducebe aware the precision used for date calulcations and comparisons, but SHOULD ensure that a precision of no less than an hour (3600 seconds) is used. Thisserver might mean re- runningperform the search criteria only every hour for a dynamic search, for example.evaluation periodically. Thus, the server may delay the updates. Clients MUST be aware that dynamic search results, whether viewed directly or through some other mechanism, MAYresults may not be accurate as a result. For example, ifreflect the client requests messages that are younger than 4020 (67 minutes), but the server only performs searches with hourly accuracy (as mandated above),current state of the server performs the search as ifmailbox. If the client requestedneeds a 60-minute interval. Notesearch result that reflects the choicecurrent state of rounding up or down is atthe discretion ofmailbox, we RECOMMEND the server. However, rounding down to zero is NOT RECOMMENDED, as this may result in searches for messages YOUNGER thanclient issues a value being rounded to YOUNGER 0, which will always fail.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 , IMAP , and IMAP Extended ABNF  This document extends RFC 3501  with two new search keys: OLDER <interval> and YOUNGER <interval>. search-key /==/ ( "OLDER" |/ "YOUNGER" ) SP nz-number ; search-key defined in RFC 3501 4. 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 (72 hours)days, or 259200 seconds, according to the server's current time. 5. 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 . 6. IANA Considerations None.Per the IMAP RFC , 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. 7. References 7.1. Normative References  Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, BCP 14, March 1997.  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, Alexey Melnikov,Ken Murchison, Zoltan Ordogh, and most especially Dave Cridland for their review and suggestions. Authors' AddressesA 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: firstname.lastname@example.org URI: Ray Cromwell Oracle Corporation 500 Oracle Parkway Redwood Shores, CA 94065 USA Email: email@example.com Stephane H. 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