IMAP Extensions Working Group B. Leiba
Internet-Draft IBM T.J. Watson Research Center
Intended status: Standards Track A. Melnikov
Expires: October 24, 2008 Isode Limited
April 22, 2008
IMAP4 Multimailbox SEARCH Extension
draft-melnikov-imapext-multimailbox-search-03
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Abstract
The IMAP4 specification allows the searching only of the selected
mailbox. A user often wants to search multiple mailboxes, and a
client that wishes to support this must issue a series of SELECT and
SEARCH commands, waiting for each to complete before moving on to the
next. This extension allows a client to search multiple mailboxes
with one command, limiting the round-trips and waiting for various
searches to complete. This also introduces mailbox field in ESEARCH
responses, allowing a client to pipeline the searches if it chooses.
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Note
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, and should be sent to
ietf-imapext@imc.org.
Table of Contents
1. Conventions used in this document . . . . . . . . . . . . . . . 3
2. Extended SEARCH/UID SEARCH command . . . . . . . . . . . . . . 3
3. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
8. Normative References . . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 7
Intellectual Property and Copyright Statements . . . . . . . . 9
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1. Conventions used in this document
In examples, "C:" indicates lines sent by a client that is connected
to a server. "S:" indicates lines sent by the server to the client.
The words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY" are
used in this document as specified in RFC 2119 [Kwds].
2. Extended SEARCH/UID SEARCH command
Arguments: OPTIONAL source options
OPTIONAL result options
OPTIONAL [CHARSET] specification
searching criteria (one or more)
Responses: REQUIRED untagged response: SEARCH or ESEARCH
Result: OK - search completed
NO - search error: cannot search that [CHARSET]
or criteria
BAD - command unknown or arguments invalid
This section further updates definition of the SEARCH command
described in section 2.6.1 of [IMAPABNF] (initially described in
section 6.4.4 of [RFC3501].
The SEARCH command is extended to allow for optional source and
result options. This document does not define any result options.
Unless specified otherwise by a description of a result option,
presence of a search source option REQUIREs that the server returns
ESEARCH responses instead of the corresponding SEARCH responses.
Because message numbers are not useful for mailboxes which are not
selected, each ESEARCH response MUST return information about UIDs
and not message numbers (whether the SEARCH or the UID SEARCH command
was issued), in particular it MUST contain the UID indicator.
Presence of a source option in absence of a result option implies the
"ALL" result option (see [ESEARCH]).
[[anchor3: SEARCH with source options is allowed in authenticated
state (and not just "selected")!!!]]
Source options describe which mailboxes must be searched for
messages. (Without the source options only the current mailbox is
searched.) Note that a SEARCH/UID SEARCH command with source options
doesn't affect which mailbox is currently selected and doesn't
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require any mailbox to be selected. For each mailbox satisfying the
source options, a single ESEARCH response MUST be returned. The
ESEARCH response MUST contain the MAILBOX correlator in addition to
the TAG correlator. Correlators allow clients to issue several
SEARCH/UID SEARCH commands at once (pipelined). The server MAY
perform those searches in parallel; or it MAY instead serialize them.
The source options, if present, MUST contain one or more mailbox list
pattern, any one of them can contain the IMAP mailbox wildcard
characters. The patterns can be optionally followed by other search
source options. Only one such option is defined by this document:
"DEPTH". The option "depth <n>" causes the SEARCH command to
traverse the hierarchy "n" levels down (including the current level).
Thus, mailbox pattern "xyz*" with "depth 2" and mailbox pattern
"xyz/*" with "depth 1" will both match child mailboxes of "xyz", but
will not match child mailboxes of those children (of course, the
former will also match "xyzabc", while the latter will not).
If the server supports the ACL [ACL] extension, then the logged in
user is required to have the 'r' right for each mailbox she wants to
search. Mailboxes matching the source options for which the logged
in user has no 'r' right MUST be ignored by a multimailbox search.
[[anchor4: Borrow syntax from the recent
draft-ietf-lemonade-imap-notify?]]
[[anchor5: Interaction with CONTEXT
(draft-cridland-imap-context-05.txt) needs to be defined. Also,
UPDATE option draft-ietf-lemonade-imap-notify might have to be
prohibited when both CONTEXT and this extension are used.]]
3. Example
C: tag1 SEARCH IN (("folder1" "folder2/*") (depth 1)) unseen
C: tag2 SEARCH IN (("folder1" "folder2/*")) subject "chad"
S: * ESEARCH (TAG "tag1" mailbox "folder1") UID ALL
4001,4003,4005,4007,4009
S: * ESEARCH (TAG "tag1" mailbox "folder1") UID ALL 195001:
195004,169788
S: * ESEARCH (TAG "tag1" mailbox "folder2/banana") UID ALL 3002,4004
S: * ESEARCH (TAG "tag1" mailbox "folder2/peach") UID ALL 921691
S: tag1 OK done
S: * ESEARCH (TAG "tag2" mailbox "folder2/dubya") UID ALL
50003,50006,50009,50012
S: tag2 OK done
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4. Formal Syntax
The following syntax specification uses the augmented Backus-Naur
Form (BNF) as described in [ABNF]. Terms not defined here are taken
from [RFC3501], [LISTEXT] or [IMAPABNF].
[[anchor7: Updates definition in RFC 4466 (added
"[search-source-opts]"):]]
search = "SEARCH" [search-source-opts]
[search-return-opts] SP search-program
[[anchor8: Defined in RFC 4466 (updated to reference
search-criteria):]]
search-program = ["CHARSET" SP charset SP]
search-criteria
;; CHARSET argument to SEARCH MUST be
;; registered with IANA.
search-source-opts = SP "IN" SP "(" mbox-or-pat [SP "(" scope-
options ")"] ")"
scope-option = "DEPTH" SP number /
scope-option-ext
scope-options = scope-option *(SP scope-option)
;; a given option may only appear once
scope-option-name = tagged-ext-label
scope-option-ext = scope-option-name [SP scope-option-value]
scope-option-value= tagged-ext-val
;; This non-terminal shows recommended syntax
;; for future extensions.
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[[anchor9: Also defined in FILTERS:]]
search-criteria = search-key *(SP search-key)
[[anchor10: Redefining search-correlator from RFC 4466:]]
search-correlator = SP "(" single-correlator *(SP single-correlator)
")"
[[anchor11: This is a new non-terminal:]]
single-correlator = "TAG" SP tag-string /
"MAILBOX" SP astring
[[anchor12: The following 2 are borrowed from LISTEXT:]]
mbox-or-pat = list-mailbox / patterns
patterns = "(" list-mailbox *(SP list-mailbox) ")"
5. Security Considerations
[[anchor13: TBD]]
6. IANA Considerations
IMAP4 capabilities are registered by publishing a standards track or
IESG approved experimental RFC. The registry is currently located
at:
http://www.iana.org/assignments/imap4-capabilities
This document defines the X-DRAFT-I03-MMBX [[anchor14: Note to RFC
Editor: fix before publication]] IMAP capability. IANA is requested
to add it to the registry.
7. Acknowledgements
The authors gratefully acknowledge feedback provided by Peter Coates
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and Arnt Gulbrandsen.
8. Normative References
[ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 5234, January 2008.
[ACL] Melnikov, A., "IMAP4 Access Control List (ACL) Extension",
RFC 4314.
[CHARSET] Freed, N. and J. Postel, "IANA Charset Registration
Procedures", RFC 2978, October 2000.
[ESEARCH] Melnikov, A. and D. Cridland, "IMAP4 Extension to SEARCH
Command for Controlling What Kind of Information Is
Returned", RFC 4731, November 2006.
[IMAPABNF]
Melnikov, A. and C. Daboo, "Collected Extensions to IMAP4
ABNF", RFC 4466, April 2006.
[Kwds] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, March 1997.
[LISTEXT] Leiba, B. and A. Melnikov, "IMAP4 LIST Command
Extensions", draft-ietf-imapext-list-extensions-18 (work
in progress), 2006.
[RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION
4rev1", RFC 3501, March 2003.
Authors' Addresses
Barry Leiba
IBM T.J. Watson Research Center
19 Skyline Drive
Hawthorne, NY 10532
US
Phone: +1 914 784 7941
Email: leiba@watson.ibm.com
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Alexey Melnikov
Isode Limited
5 Castle Business Village
36 Station Road
Hampton, Middlesex TW12 2BX
UK
Email: Alexey.Melnikov@isode.com
URI: http://www.melnikov.ca/
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