RFC2359 - IMAP4 UIDPLUS extension - 王朝网络宽屏版

Network Working Group J. Myers

Request for Comments: 2359 Netscape Communications

Category: Standards Track June 1998

IMAP4 UIDPLUS extension

Status 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.

IESG NOTE

The IMAP extension described here assumes a particular means of using

IMAP to support disconnected operation. However, this means of

supporting disconnected operation is not yet documented. Also, there

are multiple theories about how best to do disconnected operation in

IMAP, and as yet, there is no consensus on which one should be

adopted as a standard.

This document is being approved as a Proposed Standard because it

does not appear to have technical flaws in itelf. However, approval

of this document as a Proposed Standard should not be considered an

IETF endorsement of any particular means of doing disconnected

operation in IMAP.

Table of Contents

1. Abstract .............................................. 2

2. Conventions Used in this Document ..................... 2

3. IntrodUCtion and Overview ............................. 2

4. Features .............................................. 2

4.1. UID EXPUNGE Command ................................... 2

4.2. APPENDUID response code ............................... 3

4.3. COPYUID response code ................................. 4

5. Formal Syntax ......................................... 4

6. References ............................................ 4

7. Security Considerations ............................... 5

8. Author's Address ...................................... 5

9. Full Copyright Statement .............................. 6

1. Abstract

The UIDPLUS extension of the Internet Message Access Protocol [IMAP4]

provides a set of features intended to reduce the amount of time and

resources used by some client operations. The features in UIDPLUS

are primarily intended for disconnected-use clients.

2. 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", "SHOULD", "SHOULD NOT", and "MAY"

in this document are to be interpreted as defined in "Key words for

use in RFCs to Indicate Requirement Levels" [KEYWORDS].

3. Introduction and Overview

The UIDPLUS extension is present in any IMAP4 server implementation

which returns "UIDPLUS" as one of the supported capabilities to the

CAPABILITY command. The UIDPLUS extension contains one additional

command and additional data returned with successful APPEND and COPY

commands.

Clients that wish to use the new command in UIDPLUS must of course

first test for the presence of the extension by issuing a CAPABILITY

command. Each of the features in UIDPLUS are optimizations; clients

can provide the same functionality, albeit more slowly, by using

commands in the base protocol. With each feature, this document

recommends a fallback approach to take when the UIDPLUS extension is

not supported by the server.

4. Features

4.1. UID EXPUNGE Command

Arguments: message set

Data: untagged responses: EXPUNGE

Result: OK - expunge completed

NO - expunge failure (e.g. permission denied)

BAD - command unknown or arguments invalid

The UID EXPUNGE command permanently removes from the currently

selected mailbox all messages that both have the \Deleted flag set

and have a UID that is included in the specified message set. If

a message either does not have the \Deleted flag set or is has a

UID that is not included in the specified message set, it is not

affected.

This command may be used to ensure that a replayed EXPUNGE command

does not remove any messages that have been marked as \Deleted

between the time that the user requested the expunge operation and

the time the server processes the command.

If the server does not support the UIDPLUS capability, the client

should fall back to using the STORE command to temporarily remove

the \Deleted flag from messages it does not want to remove. The

client could alternatively fall back to using the EXPUNGE command,

riSKINg the unintended removal of some messages.

Example: C: A003 UID EXPUNGE 3000:3002

S: * 3 EXPUNGE

S: A003 OK UID EXPUNGE completed

4.2. APPENDUID response code

Successful APPEND commands return an APPENDUID response code in the

tagged OK response. The APPENDUID response code contains as

arguments the UIDVALIDITY of the destination mailbox and the UID

assigned to the appended message.

If the server does not support the UIDPLUS capability, the client can

only discover this information by selecting the destination mailbox

and issuing FETCH commands.

Example: C: A003 APPEND saved-messages (\Seen) {310}

C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST)

C: From: Fred Foobar <foobar@Blurdybloop.COM>

C: Subject: afternoon meeting

C: To: mooch@owatagu.siam.edu

C: Message-Id: <B27397-0100000@Blurdybloop.COM>

C: MIME-Version: 1.0

C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII

C: Hello Joe, do you think we can meet at 3:30 tomorrow?

S: A003 OK [APPENDUID 38505 3955] APPEND completed

4.3. COPYUID response code

Successful COPY and UID COPY commands return a COPYUID response code

in the tagged OK response whenever at least one message was copied.

The COPYUID response code contains as an argument the UIDVALIDITY of

the appended-to mailbox, a message set containing the UIDs of the

messages copied to the destination mailbox, in the order they were

copied, and a message containing the UIDs assigned to the copied

messages, in the order they were assigned. Neither of the message

sets may contain extraneous UIDs or the symbol '*'.

If the server does not support the UIDPLUS capability, the client can

only discover this information by selecting the destination mailbox

and issuing FETCH commands.

Example: C: A003 COPY 2:4 MEETING

S: A003 OK [COPYUID 38505 304,319:320 3956:3958] Done

C: A003 UID COPY 305:310 MEETING

S: A003 OK Done

5. Formal Syntax

The following syntax specification uses the augmented Backus-Naur

Form (BNF) notation as specified in [RFC-822] as modified by [IMAP4].

Non-terminals referenced but not defined below are as defined by

[IMAP4].

Except as noted otherwise, all alphabetic characters are case-

insensitive. The use of upper or lower case characters to define

token strings is for editorial clarity only. Implementations MUST

accept these strings in a case-insensitive fashion.

resp_code_apnd ::= "APPENDUID" SPACE nz_number SPACE uniqueid

resp_code_copy ::= "COPYUID" SPACE nz_number SPACE set SPACE set

uid_expunge ::= "UID" SPACE "EXPUNGE" SPACE set

6. References

[IMAP4] Crispin, M., "Internet Message Access Protocol -

Version 4rev1", RFC2060, December 1996.

[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate

Requirement Levels", BCP 14, RFC2119, March 1997.

[RFC-822] Crocker, D., "Standard for the Format of ARPA Internet

Text Messages", STD 11, RFC822, August 1982.

7. Security Considerations

There are no known security issues with this extension.

8. Author's Address

John Gardiner Myers

Netscape Communications

501 East Middlefield Road

Mail Stop MV-029

Mountain View, CA 94043

EMail: jgmyers@netscape.com

9. Full Copyright Statement

This document and translations of it may be copied and furnished to

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document itself may not be modified in any way, such as by removing

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developing Internet standards in which case the procedures for

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English.

The limited permissions granted above are perpetual and will not be

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