IMAP Extensions Working Group R. Gellens
Internet Draft: IMAP ANNOTATE Extension C. Daboo
Document: draft-ietf-imapext-annotate-08.txt October 2003
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.
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Copyright Notice
Copyright (C) The Internet Society 2003. All Rights Reserved.
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Table of Contents
1 Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . 2
3 Conventions Used in This Document . . . . . . . . . . . . . . 2
4 Change History . . . . . . . . . . . . . . . . . . . . . . . 3
5 Introduction and Overview . . . . . . . . . . . . . . . . . . 4
6 Data Model . . . . . . . . . . . . . . . . . . . . . . . . . 6
6.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . 6
6.2 Namespace of Entries and Attributes . . . . . . . . . . 6
6.2.1 Entry Names . . . . . . . . . . . . . . . . . . . . . 7
6.2.2 Attribute Names . . . . . . . . . . . . . . . . . . 9
7 Private versus Shared and Access Control . . . . . . . . . . 9
8 IMAP Protocol Changes . . . . . . . . . . . . . . . . . . . 10
8.1 General considerations . . . . . . . . . . . . . . . . . 10
8.2 Optional parameters with the SELECT/EXAMINE commands . . 11
8.3 ANNOTATION Message Data Item in FETCH Command . . . . . . 12
8.4 ANNOTATION Message Data Item in FETCH Response . . . . . 13
8.5 ANNOTATION Message Data Item in STORE . . . . . . . . . . 14
8.6 ANNOTATION interaction with COPY . . . . . . . . . . . . 16
8.7 ANNOTATION Message Data Item in APPEND . . . . . . . . . 16
8.8 ANNOTATION Criterion in SEARCH . . . . . . . . . . . . . 16
8.9 ANNOTATION Key in SORT . . . . . . . . . . . . . . . . . 17
9 Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . 18
10 IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
10.1 Entry and Attribute Registration Template . . . . . . . 19
11 Security Considerations . . . . . . . . . . . . . . . . . . . 20
12 Normative References . . . . . . . . . . . . . . . . . . . . 20
13 Informative References . . . . . . . . . . . . . . . . . . . 21
14 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 21
15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 21
16 Full Copyright Statement . . . . . . . . . . . . . . . . . . 21
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 Discussion
Public comments can be sent to the IETF IMAP Extensions mailing
list, <ietf-imapext@imc.org>. To subscribe, send a message to
<ietf-imapext-request@imc.org> with the word SUBSCRIBE as the body.
Private comments should be sent to the authors.
3 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].
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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. Line breaks not preceded by a "C:" or "S:" are
for editorial clarity only.
4 Change History
Changes from -07 to -08:
1. ANNOTATESIZE response changed to use "NIL" for a mailbox that
does not support any type of annotations, and "0" for a mailbox
that only supports read-only annotations.
Changes from -06 to -07:
1. Added text to state entry and attribute names are always
case-insensitive.
2. Removed top-level entry namespace.
3. Added server accept minima for annotation size and count.
4. Added [ANNOTATE TOOBIG] & [ANNOTATE TOOMANY] response codes.
5. Added [ANNOTATESIZE <<n>>] response code.
6. Added comment on suggested CONDSTORE support.
7. Modified append behaviour to account for MULTIAPPEND.
8. Tweaked ABNF.
Changes from -05 to -06:
1. Split references into Normative and Informative.
2. Reworked flags to allow IMAP4 flag prefix to appear in annotation name.
3. Removed smtp-envelope annotation - a future extension can add this.
4. Changed subject to altsubject.
5. Added $MDNSent flag and reference to document.
6. Cleaned up formal syntax to use IMAP string type for entry
and attributes, with requirements on how the string is formatted.
7. Use of ACAP vendor subtree registry for vendor tokens.
8. Fixed STORE syntax.
Changes from -04 to -05:
1. Fixed examples to match formal syntax for FETCH responses where
parenthesis do not appear around entry-att items.
Changes from -03 to -04:
1. Fixed attrib/attrib-match grammar to use "." instead of "/".
2. Add text for server to reject unknown <part-specifier>.
3. Do not allow empty part-specifier.
4. Store NIL to value to delete.
5. Comment on COPY interaction with ANNOTATE.
6. Added comment that IMAP flags are mapped one-to-one with their
corresponding FLAGS items.
7. Added comment that the recent flag annotation is read-only.
Changes from -02 to -03:
1. Removed reference to status modtime item.
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2. Added missing 'notify' and 'ret' dsn annotations for
/message/smtp-envelope.
3. Added requirement to store data permanently - no
'session only' annotations.
4. Removed Access Control section. Replaced with comments
on read-only/read-write mailboxes and storing private or
shared annotations.
5. Removed STORE to default .priv or .shared.
6. Added section on optional select parameters.
Changes from -01 to -02:
1. Now require .priv or .shared on store operations.
Changes from -00 to -01:
1. MODTIME moved to its own draft, which this draft now
depends on. Thus, Conditional Annotation STORE and
related items deleted from this draft.
2. Private versus Shared Annotations: both are possible
(separately addressable using ".priv" and ".shared"
suffixes). There is a per-mailbox setting for the
default. It is an open issue how this is viewed or
changed by the client.
3. In ACLs, the "w" right is needed to updated shared state;
the "s" right is needed to update private state.
4. Various clarifications and text modifications.
5. Added 'forwarded' flag for message parts.
Changes from pre-imapext to -00:
1. Clarified text describing attributions, entries, and
attributes.
2. Changed 'modifiedsince' to 'modtime'; referenced ACAP spec.
3. Deleted 'queued' flag.
4. Expanded and explained smtp-envelope entry.
5. Restricted including ANNOTATION data in unsolicited responses
until the client uses it first. (Open issue as to if needed).
6. Examples now only use valid entries and attributes.
7. Updated Security Considerations.
8. Content-Type now defaults to text/plain.
9. Open Issue: Shared vs. private annotations.
10. Open issue: Annotation Modtime untagged response or VALIDTIME
FETCH data.
11. Open issue: Conditional annotation STORE.
12. ANNOTATION criterion available if both "ANNOTATE" and "SORT"
in CAPABILITY command response.
13. Prohibition on annotations in lieu of base spec functionality.
14. Specified required ACL rights.
15. ANNOTATION message data item in APPEND.
16. ANNOTATION-MODTIME message data item in STATUS.
17. Replaced ATOM_CHAR with utf8-char.
18. Updated other ABNF entries.
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5 Introduction and Overview
The ANNOTATE extension is present in any IMAP4 implementation which
returns "ANNOTATE" as one of the supported capabilities in the
CAPABILITY response.
The ANNOTATE extension adds a new message data item to the FETCH and
STORE commands, as well as adding SEARCH and SORT keys and an APPEND
modifier.
This extension makes the following changes to the IMAP4 protocol:
a) adds a new ANNOTATION message data item for use in FETCH
b) adds a new ANNOTATION message data item for use in STORE
c) adds a new ANNOTATION search criterion for use in SEARCH
d) adds a new ANNOTATION sort key for use in SORT extension
e) adds a new ANNOTATION data item for use in APPEND
f) adds a new requirement on the COPY command
g) adds a extension mechanism for adding parameters to the
SELECT/EXAMINE commands and defines the ANNOTATE parameter
h) adds two new response codes to indicate store failures of
annotations.
i) adds a new untagged response codes for the SELECT or EXAMINE
commands to indicate the maximum size.
The data model used for the storage of annotations is based on that
of the Application Configuration Access Protocol [ACAP]. Note that
there is no inheritance in annotations.
Clients MUST NOT use annotations in lieu of equivalent IMAP base
specification facilities. For example, use of a "seen" flag in the
vendor namespace together with ".PEEK" in fetches. Such behaviour
would significantly reduce IMAP interoperability.
If a server supports annotations, then it MUST store all annotation
data permanently, i.e. there is no concept of 'session only'
annotations that would correspond to the behaviour of 'session'
flags as defined in the IMAP base specification. The exception to
this is IMAP flags (which are accessible directly through
annotations) which may be 'session only' as determined by the FLAGS
and PERMANENTFLAGS responses to a SELECT or EXAMINE command.
This extension also introduces a generalised mechanism for adding
parameters to the SELECT or EXAMINE commands. It is anticipated
that other extensions may want to utilise this, so it is not
strictly dependent on the ANNOTATE extension being present.
In order to provide optimum support for a disconnected client (one
that needs to synchronise annotations for use when offline), servers
SHOULD also support the Conditional STORE [CONDSTORE] extension.
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The rest of this document describes the data model and protocol
changes more rigorously.
6 Data Model
6.1 Overview
The data model used in ANNOTATE is that of a uniquely named entry
which contains a set of standard attributes. A single coherent unit
of "metadata" for a message is stored as a single entry, made up of
several attributes.
For example, a comment added to a message has an entry name of
"/comment". This entry is composed of several attributes such as
"value", "size", etc. which contain the properties and data of 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 (see Section 7 for specifics).
6.2 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 is a string of
zero or more octets.
Entry and attribute names MUST NOT contain asterisk ("*") or percent
("%") characters and MUST be valid UTF-8 strings which do not
contain the NULL octet. Invalid entry or attribute names result in
a BAD response in any IMAP commands where they are used.
Entry and attribute names are case-insensitive.
Use of non-visible UTF-8 characters in entry and attribute names is
strongly 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.
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6.2.1 Entry Names
Entry names MUST be specified in a standards track or IESG approved
experimental RFC, or fall under the vendor namespace. See Section
10.1 for the registration template.
/
Defines the top-level of entries associated with an entire
message. This entry itself does not contain any attributes.
All entries that start with a numeric character ("0" - "9")
refer to an annotation on a specific body part. All other
entries are for annotations on the entire message.
/comment
Defines a comment or note associated with an entire message.
/flags
Defines the top-level of entries for flags associated with an
entire message. The "value" attribute of each of the entries
described below must be either "1", "0" or NIL. "1" corresponds
to the flag being set.
Standard [IMAP4] flags always have a '\' prefix character.
Other standard flags have a '$' prefix. The annotation names
used for all flags uses the complete name for that flag,
including the prefix character.
The set of standard IMAP flags annotations are:
/flags/\answered
/flags/\flagged
/flags/\deleted
/flags/\seen
/flags/\draft
/flags/\recent
Changes to these annotations are reflected in the standard IMAP
flags. The \recent attribute is read only, clients MUST NOT
attempt to change it.
Note that entry names are sent as [IMAP4] string elements which
requires that '\' characters be escaped if sent as a quoted
string as opposed to a literal.
Additional standard flags are:
/flags/$mdnsent
/flags/$redirected
/flags/$forwarded
The '$mdnsent' flag is used to indicate message disposition
notification processing state [MDNSENT].
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The '$redirected' flag indicates that a message has been handed
off to someone else, by resending the message with minimal
alterations, and in such a way that a reply by the new recipient
is addressed to the original author, not the user who performed
the redirection.
The '$forwarded' flag indicates the message was resent to
another user, embedded within or attached to a new message.
/altsubject
Contains text supplied by the message recipient, to be used by
the client instead of the original message Subject.
/vendor/<vendor-token>
Defines the top-level of entries associated with an entire
message as created by a particular product of some vendor.
These sub-entries can be used by vendors to provide
client-specific attributes. The vendor-token MUST be registered
with IANA, using the [ACAP] vendor subtree registry.
/<section-part>
Defines the top-level of entries associated with a specific body
part of a message. This entry itself does not contain any
attributes. The section-part uses the same numeric part
specifier syntax as the BODY message data item in the FETCH
command [IMAP4]. The server MUST return a BAD response if the
client uses an incorrect part specifier (either incorrect syntax
or a specifier referring to a non-existent part). The server
MUST return a BAD response if the client uses an empty part
specifier (which is used in [IMAP4] to represent the entire
message).
/<section-part>/comment
Defines a comment or note associated with a specific body part
of a message.
/<section-part>/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.
/<section-part>/flags/seen
/<section-part>/flags/answered
/<section-part>/flags/flagged
/<section-part>/flags/forwarded
Defines flags for a specific body part of a message. The
"value" attribute of these entries must be either "1", "0" or
NIL.
/<section-part>/vendor/<vendor-token>
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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.
6.2.2 Attribute Names
Attribute names MUST be specified in a standards track or IESG
approved experimental RFC, or fall under the vendor namespace. See
Section 10.1 for the registration template.
All attribute names implicitly have a ".priv" and a ".shared" suffix
which maps to private and shared versions of the entry. Searching
or fetching without using either suffix includes both. The client
MUST specify either a ".priv" or ".shared" suffix when storing an
annotation.
value
A UTF8 string representing the data value of the attribute. To
delete an annotation, the client can store NIL into the value.
size
The size of the value, in octets. Set automatically by the
server, read-only to clients.
content-type
A MIME [MIME] content type and subtype that describes the nature
of the content of the "value" attribute. If not present, a
value of "text/plain; charset=utf8" is assumed.
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, using the [ACAP] vendor subtree registry.
7 Private versus Shared and Access Control
Some IMAP mailboxes are private, accessible only to the owning user.
Other mailboxes are not, either because the owner has set an ACL
[ACL] which permits access by other users, or because it is a shared
mailbox.
This raises the issue of shared versus private annotations.
If all annotations are private, it is impossible to set annotations
in a shared or otherwise non-private mailbox that are visible to
other users. This eliminates what could be a useful aspect of
annotations in a shared environment. An example of such use is a
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shared IMAP folder containing bug reports. Engineers may want to
use annotations to add information to existing messages, indicate
assignments, status, etc. This use requires shared annotations.
If all annotations are shared, it is impossible to use annotations
for private notes on messages in shared mailboxes. Also, modifying
an ACL to permit access to a mailbox by other users may
unintentionally expose private information.
There are also situations in which both shared and private
annotations are useful. For example, an administrator may want to
set shared annotations on messages in a shared folder, which
individual users may wish to supplement with additional notes.
If shared and private annotations are to coexist, we need a clear
way to differentiate them. Also, it should be as easy as possible
for a client to access both and not overlook either. There is also
a danger in allowing a client to store an annotation without knowing
if it is shared or private.
This document proposes two standard suffixes for all attributes:
".shared" and ".priv". A search, fetch, or sort which specifies
neither uses both. Store operations MUST explicitly use .priv or
.shared suffixes.
A user can only store and fetch private annotations on messages in
any mailbox which they can SELECT or EXAMINE, including ones which
only open READ-ONLY. A user can only store and fetch shared
annotations on messages in any mailbox that they can SELECT and
which opens READ-WRITE. If a client attempts to store or fetch a
shared annotation on a READ-ONLY mailbox, the server MUST respond
with a NO response.
8 IMAP Protocol Changes
8.1 General considerations
The server is allowed to impose limitations on the size of any one
annotation or the total number of annotations for a single message.
However, the server MUST accept a minimum annotation data size of at
least 1024 bytes, and a minimum annotation count per message of at
least 10.
The server SHOULD indicate the maximum size for an annotation value
by sending an untagged "ANNOTATESIZE" response during a SELECT or
EXAMINE command. Clients MUST NOT store annotation values of a size
greater than the amount indicated by the server in the
"ANNOTATESIZE" response.
In some cases, servers may be able to offer annotations on some
mailboxes and not others, or may be able to provide only read-only
annotations on some mailboxes. For mailboxes that cannot have
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annotations associated with them, the server MUST return an
"ANNOTATESIZE" response with a value of "NIL" during the SELECT or
EXAMINE command for that mailbox. Clients MUST NOT attempt to fetch
or store annotations on any messages in a mailbox for which the
"ANNOTATESIZE" response was "NIL". For mailboxes that can only have
read-only annotations associated with them, the server MUST return
an "ANNOTATESIZE" response with a value of "0" (zero) during the
SELECT or EXAMINE command for that mailbox. Clients MUST NOT
attempt to store annotations on any messages in a mailbox for which
the "ANNOTATESIZE" response was zero.
8.2 Optional parameters with the SELECT/EXAMINE commands
This extension adds the ability to include one or more parameters
with the IMAP SELECT or EXAMINE commands, to turn on or off certain
standard behaviour, or to add new optional behaviours required for a
particular extension. It is anticipated that other extensions may
want to use this facility, so a generalised approach is given here.
This facility is not dependent on the presence of the ANNOTATE
extension - other extensions can use it with a server that does not
implement ANNOTATE.
Optional parameters to the SELECT or EXAMINE commands are added as a
parenthesised list of atoms or strings, and appear after the mailbox
name in the standard SELECT or EXAMINE command. The order of
individual parameters is arbitrary. Individual parameters may
consist of one or more atoms or strings in a specific order. If a
parameter consists of more than one atom or string, it MUST appear
in its own parenthesised list. Any parameter not defined by
extensions that the server supports MUST be rejected with a NO
response.
Example:
C: a SELECT INBOX (ANNOTATE)
S: ...
S: a OK SELECT complete
In the above example, a single parameter is used with the
SELECT command.
C: a EXAMINE INBOX (ANNOTATE (RESPONSES "UID Responses") MODTIME)
S: ...
S: a OK EXAMINE complete
In the above example, three parameters are used with the
EXAMINE command. The second parameter consists of two
items: an atom followed by a quoted string.
C: a SELECT INBOX (BLURDYBLOOP)
S: a NO Unknown parameter in SELECT command
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In the above example, a parameter not supported by the
server is incorrectly used.
The ANNOTATE extension defines a single optional select parameter
"ANNOTATE", which is used to turn on unsolicited responses for
annotations as described in Section 8.4.
8.3 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 ("/comment" "value"))
S: * 1 FETCH (ANNOTATION ("/comment"
("value.priv" "My comment"
"value.shared" "Group note")))
S: a OK Fetch complete
In the above example, the content of the "value" attribute
for the "/comment" entry is requested by the client and
returned by the server. Since neither ".shared" nor ".priv"
was specified, both are returned.
"*" and "%" wildcard characters can be used in either specifier to
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 specifier). Thus an entry specifier of "/%" matches
entries such as "/comment" and "/subject", but not
"/flags/$redirected".
Examples:
C: a FETCH 1 (ANNOTATION ("/*" ("value.priv" "size.priv")))
S: * 1 FETCH (ANNOTATION
("/comment" ("value.priv" "My comment"
"size.priv" "10")
"/subject" ("value.priv" "Rhinoceroses!"
"size.priv" "13")
"/vendor/foobar/label.priv"
("value.priv" "label43"
"size.priv" "7")
"/vendor/foobar/personality"
("value.priv" "Tallulah Bankhead"
"size.priv" "17")))
S: a OK Fetch complete
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In the above example, the contents of the private "value" and "size"
attributes for any entries in the "" hierarchy are requested by the
client and returned by the server.
C: a FETCH 1 (ANNOTATION ("/%" "value.shared"))
S: * 1 FETCH (ANNOTATION
("/comment" ("value.shared" "Patch Mangler")
"/subject" ("value.shared" "Patches? We don't
need no steenkin patches!")))
S: a OK Fetch complete
In the above example, the contents of the shared "value"
attributes for entries at the top level only of the ""
hierarchy 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
(("/comment" "/subject") "value.priv"))
S: * 1 FETCH (ANNOTATION
("/comment" ("value.priv" "What a chowder-head")
"/subject" ("value.priv" "How to crush beer cans")))
S: a OK Fetch complete
In the above example, the contents of the private "value" attributes
for the two entries "/comment" and "/subject" are requested by the
client and returned by the server.
8.4 ANNOTATION Message Data Item in FETCH Response
The ANNOTATION message data item in the FETCH response displays
information about annotations in a message.
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 ("/comment" "value"))
S: * 1 FETCH (ANNOTATION ("/comment"
("value.priv" "My comment"
"value.shared" NIL)))
S: a OK Fetch complete
In the above example, a single entry with a single attribute-value
pair is returned by the server. Since the client did not specify a
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".shared" or ".priv" suffix, both are returned. Only the private
attribute has a value (the shared value is NIL).
C: a FETCH 1 (ANNOTATION
(("/comment" "/subject") "value"))
S: * 1 FETCH (ANNOTATION
("/comment" ("value.priv" "My comment"
"value.shared" NIL)
"/subject" ("value.priv" "My subject"
"value.shared" NIL)))
S: a OK Fetch complete
In the above example, two entries each with a single attribute-value
pair are returned by the server. Since the client did not specify a
".shared" or ".priv" suffix, both are returned. Only the private
attributes have values; the shared attributes are NIL.
C: a FETCH 1 (ANNOTATION
("/comment" ("value" "size")))
S: * 1 FETCH (ANNOTATION
("/comment"
("value.priv" "My comment"
"value.shared" NIL
"size.priv" "10"
"size.shared" "0")))
S: a OK Fetch complete
In the above example, a single entry with two attribute-value pairs
is returned by the server. Since the client did not specify a
".shared" or ".priv" suffix, both are returned. Only the private
attributes have values; the shared attributes are NIL.
Servers MUST NOT include ANNOTATION data in unsolicited responses
unless the client used the ANNOTATE select parameter when it issued
the last SELECT or EXAMINE command. This restriction avoids sending
ANNOTATION data to a client unless the client explicitly asks for
it.
Servers SHOULD send ANNOTATION message data items in unsolicited
FETCH responses if an annotation entry is changed by a third-party,
and the ANNOTATE select parameter was used. This allows servers to
keep clients updated with changes to annotations by other clients.
8.5 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.
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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.
If the server is unable to store an annotation because the size of
its value is too large, the server MUST return a tagged NO response
with a "[ANNOTATE TOOBIG]" response code.
If the server is unable to store a new annotation because the
maximum number of allowed annotations has already been reached, the
server MUST return a tagged NO response with a "[ANNOTATE TOOMANY]"
response code.
Examples:
C: a STORE 1 ANNOTATION ("/comment"
("value.priv" "My new comment"))
S: a OK Store complete
In the above example, the entry "/comment" is created (if not
already present) and the private attribute "value" with data set to
"My new comment" is created if not already present, or replaced if
it exists.
C: a STORE 1 ANNOTATION ("/comment"
("value.shared" NIL))
S: a OK Store complete
In the above example, the shared "value" attribute of the entry
"/comment" is removed by storing NIL into the attribute.
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 ("/comment"
("value.priv" "Get tix Tuesday")
"/subject"
("value.priv" "Wots On"))
S: a OK Store complete
In the above example, the entries "/comment" and "/subject" are
created (if not already present) and the private attribute "value"
is created for each entry if not already present, or replaced if
they 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 ("/comment"
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("value.priv" "My new comment"
"vendor.foobar.priv" "foo's bar"))
S: a OK Store complete
In the above example, the entry "/comment" is created (if not
already present) and the private attributes "value" and
"vendor.foobar" are created if not already present, or replaced if
they exist.
8.6 ANNOTATION interaction with COPY
The COPY command can be used to move messages from one mailbox to
another on the same server. Servers that support the ANNOTATION
extension MUST copy all the annotation data associated with any
messages being copied via the COPY command. The only exceptions to
this are if the destination mailbox permissions are such that either
the '.priv' or '.shared' annotations are not allowed, or if the
destination mailbox is of a type that does not support annotations
or does not support storing of annotations (a mailbox that returns a
zero or "NIL" value for its ANNOTATESIZE response code).
8.7 ANNOTATION Message Data Item in APPEND
ANNOTATION <parenthesised entry-attribute-value list>
Sets the specified list of entries and attributes in the
resulting message.
The APPEND command can include annotations for the message being
appended via the addition of a new append data item. The new data
item can also be used with the multi-append [MULTIAPPEND] extension
that allows multiple messages to be appended via a single APPEND
command.
Examples:
C: a APPEND drafts ANNOTATION ("/comment"
("value.priv" "Don't send until we hear from Sally")) {310}
S: + Ready for literal data
C: MIME-Version: 1.0
...
C:
S: a OK APPEND completed
In the above example, a comment with a private value is added to a
new message appended to the mailbox. The ellipsis represents the
bulk of the message.
8.8 ANNOTATION Criterion in SEARCH
ANNOTATION <entry-name> <attribute-name> <value>
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The ANNOTATION criterion for the SEARCH command allows a client to
search for a specified string in the value of an annotation entry of
a message.
Messages that have annotations with entries matching <entry-name>
and attributes matching <attribute-name> and 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 "/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 shared or private "value" attribute of the
"/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 (public or private) of any entry
are returned in the search results.
8.9 ANNOTATION Key in SORT
ANNOTATION <entry-name> <attribute-name>
The ANNOTATION criterion for the SORT command [SORT] instructs the
server to return the message numbers or UIDs of a mailbox, sorted
using the values of the specified annotations. The ANNOTATION
criterion is available if the server returns both "ANNOTATE" and
"SORT" as supported capabilities in the CAPABILITY command response.
Messages are sorted using the values of the <attribute-name>
attributes in the <entry-name> entries. (The charset argument
determines sort order, as specified in the SORT extension
description.)
Examples:
C: a SORT (ANNOTATION "/subject" "value.shared") 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 shared "value" attribute of the
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"/subject" entry.
Note that the ANNOTATION sort key must include a fully specified
entry and attribute -- wildcards are not allowed.
9 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.
annotate-param = "ANNOTATE"
; defines the select parameter used with
; ANNOTATE extension
append = "APPEND" SP mailbox [SP flag-list] [SP date-time]
[SP "ANNOTATION" SP att-annotate] SP literal
; modifies original IMAP4 APPEND command
append-message = [SP flag-list] [SP date-time]
[SP "ANNOTATION" SP att-annotate] SP literal
; modifies [MULTIAPPEND] extension behaviour
att-annotate = "ANNOTATION" SP "(" entry-att *(SP entry-att) ")"
att-match = string
; dot-separated attribute name
; MAY contain "*" or "%" for use as wildcards
att-value = attrib SP value
attrib = string
; dot-separated attribute name
; MUST NOT contain "*" or "%"
attribs = att-match /
"(" att-match *(SP att-match) ")"
entries = entry-match /
"(" entry-match *(SP entry-match) ")"
entry = string
; slash-separated path to entry
; MUST NOT contain "*" or "%"
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entry-att = entry SP "(" att-value *(SP att-value) ")"
entry-match = string
; slash-separated path to entry
; MAY contain "*" or "%" for use as wildcards
examine =/ *(SP "(" select-param *(SP select-param) ")"
; modifies the original IMAP4 examine command to
; accept optional parameters
fetch-ann-resp = "ANNOTATION" SP "(" entry-att *(SP entry-att) ")"
fetch-att =/ "ANNOTATION" SP "(" entries SP attribs ")"
; modifies original IMAP4 fetch-att
resp-text-code =/ "ANNOTATE" SP "TOOBIG" /
"ANNOTATE" SP "TOOMANY" /
"ANNOTATESIZE" SP (number / "NIL")
; new response codes for STORE failures
search-key =/ "ANNOTATION" SP entry-match SP att-match
SP value
; modifies original IMAP4 search-key
select =/ *(SP "(" select-param *(SP select-param) ")"
; modifies the original IMAP4 select command to
; accept optional parameters
select-param = astring / "(" astring SP astring *(SP astring) ")"
; parameters to SELECT may contain one or
; more atoms or strings - multiple items
; are always parenthesised
sort-key =/ "ANNOTATION" SP entry SP attrib
; modifies original sort-key [SORT]
store-att-flags =/ att-annotate
; modifies original IMAP4 STORE command
value = nstring
10 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.
10.1 Entry and Attribute Registration Template
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To: iana@iana.org
Subject: IMAP Annotate Registration
Please register the following IMAP Annotate item:
[] Entry [] Attribute
Name: ______________________________
Description: _______________________
____________________________________
____________________________________
Contact person: ____________________
email: ____________________
11 Security Considerations
The ANNOTATE extension does not raise any security considerations
that are not present in the base [IMAP4] protocol, and these issues
are discussed in [IMAP4].
Care must be taken to ensure that annotations whose values are
intended to remain private are not stored in mailboxes which are
accessible to other users. This includes mailboxes owned by the
user by whose ACLs permit access by others as well as any shared
mailboxes.
12 Normative References
[ABNF] Crocker, Overell, "Augmented BNF for Syntax Specifications:
ABNF", RFC 2234, November 1997.
[ACAP] Newman, Myers, "ACAP -- Application Configuration Access
Protocol", RFC 2244, November 1997.
[CONDSTORE] Melnikov, Hole, "IMAP Extension for Conditional STORE
operation",
<http://www.ietf.org/internet-drafts/draft-ietf-imapext-condstore-01.txt,
April 2003.
[IMAP4] Crispin, "Internet Message Access Protocol - Version 4rev1",
RFC 3501, March 2003.
[KEYWORDS] Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, March 1997.
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[MDNSENT] Melnikov, "Message Disposition Notification (MDN) profile
for Internet Message Access Protocol (IMAP)", RFC 3503, March 2003.
[MULTIAPPEND] Crispin, "Internet Message Access Protocol (IMAP) -
MULTIAPPEND Extension", RFC 3502, March 2003.
[SMTP-DSN] Moore, "SMTP Service Extension for Delivery Status
Notifications", RFC 1891, January 1996.
[SORT] Crispin, Murchison, "Internet Message Access Protocol - Sort
and Thread Extension", work in progress.
<http://www.ietf.org/internet-drafts/draft-ietf-imapext-sort-13.txt>
13 Informative References
[ACL] Myers, "IMAP4 ACL extension", RFC 2086, January 1997.
14 Acknowledgments
Many thanks to Chris Newman for his detailed comments on the first
draft of this document, and to the participants at the ACAP working
dinner in Pittsburgh.
15 Authors' Addresses
Randall Gellens
QUALCOMM Incorporated
5775 Morehouse Dr.
San Diego, CA 92121-2779
U.S.A.
Email: randy@qualcomm.com
Cyrus Daboo
Cyrusoft International, Inc.
Suite 780, 5001 Baum Blvd.
Pittsburgh, PA 15213
U.S.A.
Email: daboo@cyrusoft.com
16 Full Copyright Statement
Copyright (C) The Internet Society 2003. 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
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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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