imapext-2007
view docs/rfc/rfc3691.txt @ 0:ada5e610ab86
imap-2007e
| author | yuuji@gentei.org |
|---|---|
| date | Mon, 14 Sep 2009 15:17:45 +0900 |
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7 Network Working Group A. Melnikov
8 Request for Comments: 3691 Isode Ltd.
9 Category: Standards Track February 2004
12 Internet Message Access Protocol (IMAP) UNSELECT command
14 Status of this Memo
16 This document specifies an Internet standards track protocol for the
17 Internet community, and requests discussion and suggestions for
18 improvements. Please refer to the current edition of the "Internet
19 Official Protocol Standards" (STD 1) for the standardization state
20 and status of this protocol. Distribution of this memo is unlimited.
22 Copyright Notice
24 Copyright (C) The Internet Society (2004). All Rights Reserved.
26 Abstract
28 This document defines an UNSELECT command that can be used to close
29 the current mailbox in an Internet Message Access Protocol - version
30 4 (IMAP4) session without expunging it. Certain types of IMAP
31 clients need to release resources associated with the selected
32 mailbox without selecting a different mailbox. While IMAP4 provides
33 this functionality (via a SELECT command with a nonexistent mailbox
34 name or reselecting the same mailbox with EXAMINE command), a more
35 clean solution is desirable.
37 Table of Contents
39 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
40 2. UNSELECT command . . . . . . . . . . . . . . . . . . . . . . . 2
41 3. Security Considerations. . . . . . . . . . . . . . . . . . . . 3
42 4. Formal Syntax. . . . . . . . . . . . . . . . . . . . . . . . . 3
43 5. IANA Considerations. . . . . . . . . . . . . . . . . . . . . . 3
44 6. Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . 3
45 7. Normative References . . . . . . . . . . . . . . . . . . . . . 4
46 8. Author's Address . . . . . . . . . . . . . . . . . . . . . . . 4
47 9. Full Copyright Statement . . . . . . . . . . . . . . . . . . . 5
58 Melnikov Standards Track [Page 1]
60 RFC 3691 IMAP UNSELECT command February 2004
63 1. Introduction
65 Certain types of IMAP clients need to release resources associated
66 with the selected mailbox without selecting a different mailbox.
67 While [IMAP4] provides this functionality (via a SELECT command with
68 a nonexistent mailbox name or reselecting the same mailbox with
69 EXAMINE command), a more clean solution is desirable.
71 [IMAP4] defines the CLOSE command that closes the selected mailbox as
72 well as permanently removes all messages with the \Deleted flag set.
74 However [IMAP4] lacks a command that simply closes the mailbox
75 without expunging it. This document defines the UNSELECT command for
76 this purpose.
78 A server which supports this extension indicates this with a
79 capability name of "UNSELECT".
81 "C:" and "S:" in examples show lines sent by the client and server
82 respectively.
84 The keywords "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY" in
85 this document when typed in uppercase are to be interpreted as
86 defined in "Key words for use in RFCs to Indicate Requirement Levels"
87 [KEYWORDS].
89 2. UNSELECT Command
91 Arguments: none
93 Responses: no specific responses for this command
95 Result: OK - unselect completed, now in authenticated state
96 BAD - no mailbox selected, or argument supplied but
97 none permitted
99 The UNSELECT command frees server's resources associated with the
100 selected mailbox and returns the server to the authenticated
101 state. This command performs the same actions as CLOSE, except
102 that no messages are permanently removed from the currently
103 selected mailbox.
105 Example: C: A341 UNSELECT
106 S: A341 OK Unselect completed
114 Melnikov Standards Track [Page 2]
116 RFC 3691 IMAP UNSELECT command February 2004
119 3. Security Considerations
121 It is believed that this extension doesn't raise any additional
122 security concerns not already discussed in [IMAP4].
124 4. Formal Syntax
126 The following syntax specification uses the Augmented Backus-Naur
127 Form (ABNF) notation as specified in [ABNF]. Non-terminals
128 referenced but not defined below are as defined by [IMAP4].
130 Except as noted otherwise, all alphabetic characters are case-
131 insensitive. The use of upper or lower case characters to define
132 token strings is for editorial clarity only. Implementations MUST
133 accept these strings in a case-insensitive fashion.
135 command-select /= "UNSELECT"
137 5. IANA Considerations
139 IMAP4 capabilities are registered by publishing a standards track or
140 IESG approved experimental RFC. The registry is currently located
141 at:
143 http://www.iana.org/assignments/imap4-capabilities
145 This document defines the UNSELECT IMAP capabilities. IANA has added
146 this capability to the registry.
148 6. Acknowledgments
150 UNSELECT command was originally implemented by Tim Showalter in Cyrus
151 IMAP server.
153 Also, the author of the document would like to thank Vladimir Butenko
154 and Mark Crispin for reminding that UNSELECT has to be documented.
155 Also thanks to Simon Josefsson for pointing out that there are
156 multiple ways to implement UNSELECT.
170 Melnikov Standards Track [Page 3]
172 RFC 3691 IMAP UNSELECT command February 2004
175 7. Normative References
177 [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
178 Requirement Levels", BCP 14, RFC 2119, March 1997.
180 [IMAP4] Crispin, M., "Internet Message Access Protocol - Version
181 4rev1", RFC 3501, March 2003.
183 [ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
184 Specifications: ABNF", RFC 2234, November 1997.
186 8. Author's Address
188 Alexey Melnikov
189 Isode Limited
190 5 Castle Business Village
191 Hampton, Middlesex TW12 2BX
193 EMail: Alexey.Melnikov@isode.com
194 URI: http://www.melnikov.ca/
226 Melnikov Standards Track [Page 4]
228 RFC 3691 IMAP UNSELECT command February 2004
231 9. Full Copyright Statement
233 Copyright (C) The Internet Society (2004). This document is subject
234 to the rights, licenses and restrictions contained in BCP 78 and
235 except as set forth therein, the authors retain all their rights.
237 This document and the information contained herein are provided on an
238 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
239 REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE
240 INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR
241 IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
242 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
243 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
245 Intellectual Property
247 The IETF takes no position regarding the validity or scope of any
248 Intellectual Property Rights or other rights that might be claimed
249 to pertain to the implementation or use of the technology
250 described in this document or the extent to which any license
251 under such rights might or might not be available; nor does it
252 represent that it has made any independent effort to identify any
253 such rights. Information on the procedures with respect to
254 rights in RFC documents can be found in BCP 78 and BCP 79.
256 Copies of IPR disclosures made to the IETF Secretariat and any
257 assurances of licenses to be made available, or the result of an
258 attempt made to obtain a general license or permission for the use
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261 at http://www.ietf.org/ipr.
263 The IETF invites any interested party to bring to its attention
264 any copyrights, patents or patent applications, or other
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267 IETF at ietf-ipr@ietf.org.
269 Acknowledgement
271 Funding for the RFC Editor function is currently provided by the
272 Internet Society.
282 Melnikov Standards Track [Page 5]