One document matched: draft-daboo-imapext-annotate-00.txt
IMAP Extensions Working Group C. Daboo
Internet Draft: IMAP ANNOTATE Extension R. Gellens
Document: draft-daboo-imapext-annotate-00.txt March 2000
IMAP ANNOTATE Extension
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. Internet-Drafts are
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Copyright Notice
Copyright (C) The Internet Society 2000. All Rights Reserved.
Daboo & Gellens Expires September 2000 [Page 1] Internet Draft IMAP ANNOTATE Extension March 2000
Table of Contents
1 Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2 Conventions Used in This Document . . . . . . . . . . . . . 2
3 Introduction and Overview . . . . . . . . . . . . . . . . . . 2
4 Data Model . . . . . . . . . . . . . . . . . . . . . . . . . 3
4.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . 3
4.2 Namespace of entries and attributes . . . . . . . . . . 3
4.2.1 Entry Names . . . . . . . . . . . . . . . . . . . . . 4
4.2.2 Attribute Names . . . . . . . . . . . . . . . . . . 5
5 IMAP Protocol Changes . . . . . . . . . . . . . . . . . . . . 6
5.1 ANNOTATION message data item in FETCH Command . . . . . 6
5.2 ANNOTATION message data item in FETCH Response . . . . . 7
5.3 ANNOTATION message data item in STORE . . . . . . . . . 8
5.4 ANNOTATION criterion in SEARCH . . . . . . . . . . . . . 9
5.5 ANNOTATION key in SORT . . . . . . . . . . . . . . . . . 10
6 Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 11
7 IANA Considerations . . . . . . . . . . . . . . . . . . . . 12
7.1 Entry and Attribute Registration Template . . . . . . . . 12
8 Security Considerations . . . . . . . . . . . . . . . . . . 13
9 References . . . . . . . . . . . . . . . . . . . . . . . . . 13
10 Full Copyright Statement . . . . . . . . . . . . . . . . . . 14
1 Abstract
The ANNOTATE extension to the Internet Message Access Protocol
[IMAP4] permits clients and servers to maintain "metadata" for
messages stored in an IMAP4 mailbox.
2 Conventions Used in This Document
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 [KEYWORDS].
Formal syntax is defined using ABNF [ABNF] as modified by [IMAP4].
In examples, "C:" and "S:" indicate lines sent by the client and
server respectively.
3 Introduction and Overview
The ANNOTATE extension is present in any IMAP4 implementation which
returns "ANNOTATE" as one of the supported capabilities in the
CAPABILITY command response.
The ANNOTATE extension adds a new message data item to the FETCH and
STORE commands, as well as adding SEARCH and SORT keys.
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This extension makes the following changes to the IMAP4 protocol:
a) adds a new ANNOTATION message data item for use in the FETCH
command
b) adds a new ANNOTATION message data item for use in the STORE
command
c) adds a new ANNOTATION search criterion for use in the SEARCH
command
d) adds a new ANNOTATION sort key for use in the SORT command
extension
The data model used for the storage of annotations is based on that
of the Application Configuration Access Protocol [ACAP], with the
exception of inheritence which is not deemed necessary here.
The rest of this document describes the data model and protocol
changes more rigorously.
4 Data Model
4.1 Overview
The data model used in ANNOTATE is one of a uniquely named entry
with a set of uniquely named attributes, each of which has a value.
A message annotation can contain multiple named entries. For
example, a general comment being added to a message may have an
entry name of "/message/comment". This entry could include named
attributes such as "value", "modifiedsince", "acl" etc to represent
properties and data associated with the entry.
The protocol changes to IMAP described below allow a client to
access or change the values of any attributes in any entries in a
message annotation, assuming it has sufficient access rights to do
so.
4.2 Namespace of entries and attributes
Each message annotation is made up of a set of entries. Each entry
has a hierarchical name in UTF-8, with each component of the name
separated by a slash ("/").
Each entry is made up of a set of attributes. Each attribute has a
hierarchical name in UTF-8, with each component of the name
separated by a period (".").
The value of an attribute is NIL (has no value), or a string of zero
or more octets.
Entry and attribute names are not permitted to contain asterisk
("*") or percent ("%") characters and MUST be valid UTF-8 strings
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which do not contain NUL. Invalid entry or attribute names result
in a BAD response in any IMAP commands where they are used.
Use of non-visible UTF-8 characters in entry and attribute names is
discouraged.
This specification defines an initial set of entry and attribute
names available for use in message annotations. In addition an
extension mechanism is described to allow additional names to be
added for extensibility.
4.2.1 Entry Names
Entry names MUST be specified in a standards track or IESG approved
experimental RFC, or fall under the vendor namespace. See section
7.1 for the registration template.
/message
Defines the top-level of entries associated with an entire
message. This entry itself does not have any associated
attributes.
/message/comment
Defines a comment or note associated with an entire message.
/message/flags
Defines the top-level of entries for client-use flags associated
with an entire message. All sub-entries are maintained entirely
by the client. There is no implicit change to any flag by the
server.
/message/flags/redirected
/message/flags/forwarded
/message/flags/queued
Defines client-use flags for an entire message. The "value"
attribute of these entries must be either "1", "0" or NIL. The
"queued" flag MUST only be set for messages which have the DRAFT
flag set. The "queued" flag indicates that a message is
eligible to be sent (submitted into the mail system for
delivery) by any client at any time. The "queued" flag SHOULD
be reset while a client is attempting to submit the message.
/message/smtp-envelope
Defines the SMTP envelope used in delivery of the message. The
client SHOULD NOT modify the /message/smtp-envelope entry or its
attributes, except in messages which have the DRAFT flag set.
/message/subject
Contains text supplied by the message recipient, to be used by
the client instead of the original message Subject.
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/message/vendor/<vendor-token>
Defines the top-level of entries associated with an entire
message as created by a particular product of some vendor. This
entry can be used by vendors to provide client specific
attributes. The vendor-token MUST be registered with IANA.
/body/<part-specifier>
Defines the top-level of entries associated with a specific body
part of a message. This entry itself does not have any
associated attributes. The part-specifier uses the same part
specifier syntax as the BODY message data item in the FETCH
command [IMAP4].
/body/<part-specifier>/comment
Defines a comment or note associated with a specific body part
of a message.
/body/<part-specifier>/flags
Defines the top-level of entries associated with flag state for
a specific body part of a message. All sub-entries are
maintained entirely by the client. There is no implicit change
to any flag by the server.
/body/<part-specifier>/flags/seen
/body/<part-specifier>/flags/answered
/body/<part-specifier>/flags/flagged
Defines flags for a specific body part of a message. The
"value" attribute of these entries must be either "1", "0" or
NIL.
/body/<part-specifier>/vendor/<vendor-token>
Defines the top-level of entries associated with a specific body
part of a message as created by a particular product of some
vendor. This entry can be used by vendors to provide client
specific attributes. The vendor-token MUST be registered with
IANA.
4.2.2 Attribute Names
Attribute names MUST be specified in a standards track or IESG
approved experimental RFC, or fall under the vendor namespace. See
section 7.1 for the registration template.
value
The data value of the attribute.
modifiedsince
An opaque value set by the server when this entry is modified.
It can be used by the client to request notification of which
entries have changed since a particular point in time and is
useful for disconnected/synchronisation operations. (The value
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is intended to be used only for comparisons within a server, not
as an accurate timestamp.)
content-type
A MIME [MIME] content type and subtype that describes the nature
of the content of the "value" attribute.
vendor.<vendor-token>
Defines an attribute associated with a particular product of
some vendor. This attribute can be used by vendors to provide
client specific attributes. The vendor-token MUST be registered
with IANA.
5 IMAP Protocol Changes
5.1 ANNOTATION message data item in FETCH Command
This extension adds an ANNOTATION message data item to the FETCH
command. This allows clients to retrieve annotations for a range of
messages in the currently selected mailbox.
ANNOTATION <entry-specifier> <attribute-specifier>
The ANNOTATION message data item, when used by the client in the
FETCH command, takes an entry specifier and an attribute
specifier.
Example:
C: a FETCH 1 (ANNOTATION ("/message/comment" "value"))
S: * 1 FETCH (ANNOTATION ("/message/comment" (("value" "My comment"))))
S: a OK Fetch complete
In the above example, the contents of the "value" attribute
for the "/message/comment" entry is requested by the client
and returned by the server.
"*" and "%" wildcard characters can be used in either specifier to
match match one or more characters at that position, with the
exception that "%" does not match the hierarchy delimiter for the
specifier it appears in (that is, "/" for an entry specifier or "."
for an attribute specifer). Thus an entry specifier of "/message/%"
matches entries such as "/message/comment" and "/message/subject",
but not "/message/comment/note".
Examples:
C: a FETCH 1 (ANNOTATION ("/message/*" "value"))
S: * 1 FETCH (ANNOTATION
(("/message/comment" ("value" "My comment"))
("/message/version" ("value" "1.1"))
("/message/version/last" ("value" "1.0.1"))))
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S: a OK Fetch complete
In the above example, the contents of the "value" attributes
for any entries in the "/message" hierarchy are requested by
the client and returned by the server.
C: a FETCH 1 (ANNOTATION ("/message/%" "value"))
S: * 1 FETCH (ANNOTATION
(("/message/comment" ("value" "My comment"))
("/message/version" ("value" "1.1"))))
S: a OK Fetch complete
In the above example, the contents of the "value" attributes
for entries at the top level of the "/message" hierarchy
only, are requested by the client and returned by the
server.
Entry and attribute specifiers can be lists of atomic specifiers, so
that multiple items of each type may be returned in a single FETCH
command.
Examples:
C: a FETCH 1 (ANNOTATION
(("/message/comment" "/message/version") "value"))
S: * 1 FETCH (ANNOTATION
(("/message/comment" ("value" "My comment"))
("/message/version" ("value" "1.1")))) S: a OK Fetch complete
In the above example, the contents of the "value" attributes
for the two entries "/message/comment" and
"/message/version" are requested by the client and returned
by the server.
C: a FETCH 1 (ANNOTATION
("/message/comment" ("value" "modifiedsince")))
S: * 1 FETCH (ANNOTATION
(("/message/comment"
("value" "My comment"
"modifiedsince" "19990203205432"))))
S: a OK Fetch complete
In the above example, the contents of the "value" and
"modifiedsince" attributes for the "/message/comment" entry
are requested by the client and returned by the server.
5.2 ANNOTATION message data item in FETCH Response
The ANNOTATION message data item in the FETCH response displays
information about annotations in a message.
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ANNOTATION parenthesised list
The response consists of a list of entries each of which has a
list of attribute-value pairs.
Examples:
C: a FETCH 1 (ANNOTATION ("/message/comment" "value"))
S: * 1 FETCH (ANNOTATION ("/message/comment" (("value" "My comment"))))
S: a OK Fetch complete
In the above example, a single entry with a single
attribute-value pair is returned by the server.
C: a FETCH 1 (ANNOTATION
(("/message/comment" "/message/version") "value"))
S: * 1 FETCH (ANNOTATION
(("/message/comment" ("value" "My comment"))
("/message/version" ("value" "1.1"))))
S: a OK Fetch complete
In the above example, two entries each with a single
attribute-value pair are returned by the server.
C: a FETCH 1 (ANNOTATION
("/message/comment" ("value" "modifiedsince")))
S: * 1 FETCH (ANNOTATION
(("/message/comment"
("value" "My comment"
"modifiedsince" "19990203205432"))))
S: a OK Fetch complete
In the above example, a single entry with two
attribute-value pairs is returned by the server.
Servers SHOULD send ANNOTATION message data items in unsolicted
FETCH responses if the annotation is changed by a third-party,
allowing servers to keep clients updated with changes to annotations
by other clients.
5.3 ANNOTATION message data item in STORE
ANNOTATION <parenthesised entry-attribute-value list>
Sets the specified list of entries by adding or replacing the
specified attributes with the values provided. Clients can use
NIL for values of attributes it wants to remove from entries.
The ANNOTATION message data item used with the STORE command has an
implicit ".SILENT" behaviour. This means the server does not
generate an untagged FETCH in response to the STORE command and
assumes that the client updates its own cache if the command
succeeds.
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Examples:
C: a STORE 1 ANNOTATION ("/message/comment" ("value" "My new comment"))
S: a OK Store complete
In the above example, the entry "/message/comment" is
created (if not already present) and the attribute "value"
with data set to "My new comment" is created if not already
present, or replaced if it previously exists.
C: a STORE 1 ANNOTATION ("/message/comment" ("value" NIL))
S: a OK Store complete
In the above example, the "value" attribute of the entry
"/message/comment" is removed.
Multiple entries can be set in a single STORE command by listing
entry-attribute-value pairs in the list.
Example:
C: a STORE 1 ANNOTATION ("/message/comment" ("value" "My new comment")
"/message/version" ("value" "1.1"))
S: a OK Store complete
In the above example, the entries "/message/comment" and
"/message/version" are created (if not already present) and
the attribute "value" is created for each entry if not
already present, or replaced if they previously exist.
Multiple attributes can be set in a single STORE command by listing
multiple attribute-value pairs in the entry list.
Example:
C: a STORE 1 ANNOTATION ("/message/comment" ("value" "My new comment"
"vendor.foobar" "foo's bar"))
S: a OK Store complete
In the above example, the entry "/message/comment" is
created (if not already present) and the attributes "value"
and "vendor.foobar" are created if not already present, or
replaced if they previously exist.
5.4 ANNOTATION criterion in SEARCH
The ANNOTATION criterion for the SEARCH command allows a client to
search for the specified string in the value of an annotation in a
message.
ANNOTATION <entry-name> <attribute-name> <value>
Messages that have annotations with entries matching
<entry-name> and attributes matching <attribute-name> and
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the specified string <value> in their values are returned in
the SEARCH results. The "*" character can be used in the
entry or attribute name fields to match any content in those
items. The "%" character can be used in the entry or
attribute name fields to match a single level of hierarchy
only.
Examples:
C: a SEARCH ANNOTATION "/message/comment" "value" "IMAP4"
S: * SEARCH 2 3 5 7 11 13 17 19 23
S: a OK Search complete
In the above example, the message numbers of any messages
containing the string "IMAP4" in the "value" attribute of
the "/message/comment" entry are returned in the search
results.
C: a SEARCH ANNOTATION "*" "*" "IMAP4"
S: * SEARCH 1 2 3 5 8 13 21 34
S: a OK Search complete
In the above example, the message numbers of any messages
containing the string "IMAP4" in any attribute of any entry
are returned in the search results.
A special case exists when the "modifiedsince" attribute is used as
the <attribute-name> parameter in the ANNOTATION search criterion.
In this case the server matches messages when the corresponding
"modifiedsince" value is greater than the value supplied in the
ANNOTATION criterion. This allows a client, for example, to find
out which messages contain annotations that have changed since the
last time it updated its disconnected cache.
Example:
C: a SEARCH ANNOTATION "*" "modifiedsince" "1999101713283412"
S: * SEARCH 1 3 6 10 15 21 28 36 45 55
S: a OK Search complete
In the above example, the message numbers of any messages
whose "modifiedsince" attribute of any entry 'exceeds' the
value "1999101713283412" are returned in the search results.
5.5 ANNOTATION key in SORT
The ANNOTATION criterion for the SORT command [SORT-EXT] instructs
the server to return the message numbers or UIDs of a mailbox,
sorted using the values of the specified annotations.
ANNOTATION <entry-name> <attribute-name>
Messages are sorted using the values of the <attribute-name>
attributes in the <entry-name> entries. (The charset
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argument determines sort order, as specified in the SORT
extension description.)
Examples:
C: a SORT (ANNOTATION "/message/subject" "value") UTF-8 ALL
S: * SORT 2 3 4 5 1 11 10 6 7 9 8
S: a OK Sort complete
In the above example, the message numbers of all messages
are returned, sorted according to the "value" attribute of
the "/message/subject" entry.
Note that the ANNOTATION sort key must include a fully specified
entry and attribute -- wildcards are not allowed.
6 Formal Syntax
The following syntax specification uses the Augmented Backus-Naur
Form (ABNF) notation as specified in [ABNF].
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.
fetch-att =/ fetch-annotate
; modifies original IMAP4 fetch-att
fetch-annotate = "ANNOTATION" SP "(" entries SP attribs ")"
fetch-ann-resp = "ANNOTATION" SP "(" entry-att *(SP entry-att) ")"
store-att-flags =/ store-att-annotate
; modifies original IMAP4 STORE command
store-att-annotate = "(" entry-att *(SP entry-att) ")"
search-key =/ search-annotate
; modifies original IMAP4 search-key
search-annotate = "ANNOTATION" SP entry-match SP attrib-match
SP value
sort-key =/ sort-annotate
; modifies original
; draft-crispin-imapext-sort-xx.txt sort-key
sort_annotate = "ANNOTATION" SP entry SP attrib
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entries = entry-match /
"(" entry-match *(SP entry-match) ")"
attribs = attrib-match /
"(" attrib-match *(SP attrib-match) ")"
entry-att = entry SP "(" att-value *(SP att-value) ")
att-value = attrib SP value
atom-slash = any ATOM_CHAR except "/"
atom-dot = any ATOM_CHAR except "."
entry = DQUOTE 1*atom-slash *("/" 1*atom-slash) DQUOTE
entry-match = DQUOTE 1*entry-match-atom
*("/" 1*entry-match-atom) DQUOTE
entry-match-atom = 1*(list-wildcards / atom-slash)
*(list-wildcards / atom-slash)
attrib = DQUOTE 1*atom-dot *("/" 1*atom-dot) DQUOTE
attrib-match = DQUOTE 1*attrib-match-atom
*("/" 1*attrib-match-atom) DQUOTE
attrib-match-atom = 1*(list-wildcards / atom-dot)
*(list-wildcards / atom-dot)
value = nstring
7 IANA Considerations
Both entry names and attribute names MUST be specified in a
standards track or IESG approved experimental RFC, or fall under the
vendor namespace. Vendor names MUST be registered.
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7.1 Entry and Attribute Registration Template
To: iana@iana.org
Subject: IMAP Annotate Registration
Please register the following IMAP Annotate item:
[] Entry [] Attribute
[] Vendor [] Open: RFC _______
Name: ______________________________
Description: _______________________
____________________________________
____________________________________
Contact person: ____________________
email: ____________________
8 Security Considerations
There are no known security issues with this extension.
9 References
[ABNF] Crocker, Overell, "Augmented BNF for Syntax Specifications:
ABNF", RFC 2234, Internet Mail Consortium, Demon Internet Ltd,
November 1997.
[IMAP4] Crispin, M., "Internet Message Access Protocol - Version
4rev1", RFC 2060, University of Washington, December 1996.
[KEYWORDS] Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, Harvard University, March 1997.
[SORT-EXT] Crispin, M., "Internet Message Access Protocol -- SORT
Extension", work in progress.
<http://www.ietf.org/internet-drafts/draft-crispin-imapext-sort-xx.txt>
Cyrus Daboo
Cyrusoft International, Inc.
Suite 780, 5001 Baum Blvd.
Pittsburgh, PA 15213
U.S.A.
Phone: +1 412 605 0499
Daboo & Gellens Expires September 2000 [Page 13] Internet Draft IMAP ANNOTATE Extension March 2000
Email: daboo@cyrusoft.com
Randall Gellens
QUALCOMM Incorporated
5775 Morehouse Dr.
San Diego, CA 92121-2779
U.S.A.
Phone: +1 858 651 5115
Email: randy@qualcomm.com
10 Full Copyright Statement
Copyright (C) The Internet Society 2000. All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph
are included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS 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.
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