IMAP Extensions Working Group R. Gellens
Internet-Draft QUALCOMM Incorporated
Expires: October 18, 2004 C. Daboo
Cyrusoft International, Inc.
April 19, 2004
IMAP ANNOTATE Extension
draft-ietf-imapext-annotate-09
Status of this Memo
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Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved.
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.
Change History (to be removed prior to publication as an RFC)
Changes from -08 to -09:
1. Fix formatting, ID nits etc.
2. Fix subject -> altsubject in examples.
3. Added text to SELECT/EXAMINE optional parameter definition to
indicate that the option could trigger a global state change or a
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mailbox specific change.
4. Changed entry/attribute names to be case-sensitive to avoid case
mapping issues with utf8 text.
5. Clarify COPY interaction to indicate that only the current user's
'.priv's are copied, not the '.priv's of other users.
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.
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7. Added comment that the recent flag annotation is read-only.
Changes from -02 to -03:
1. Removed reference to status modtime item.
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.
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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.
Table of Contents
1. Introduction and Overview . . . . . . . . . . . . . . . . . 5
2. Data Model . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Namespace of entries and attributes . . . . . . . . . . . . 6
2.2.1 Entry Names . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2.2 Attribute Names . . . . . . . . . . . . . . . . . . . . . . 9
2.3 Private versus Shared and Access Control . . . . . . . . . . 10
3. IMAP Protocol Changes . . . . . . . . . . . . . . . . . . . 11
3.1 General Considerations . . . . . . . . . . . . . . . . . . . 11
3.2 Optional parameters with the SELECT/EXAMINE commands . . . . 11
3.3 ANNOTATION Message Data Item in FETCH Command . . . . . . . 13
3.4 ANNOTATION Message Data Item in FETCH Response . . . . . . . 15
3.5 ANNOTATION Message Data Item in STORE . . . . . . . . . . . 16
3.6 ANNOTATION interaction with COPY . . . . . . . . . . . . . . 18
3.7 ANNOTATION Message Data Item in APPEND . . . . . . . . . . . 18
3.8 ANNOTATION Criterion in SEARCH . . . . . . . . . . . . . . . 18
3.9 ANNOTATION Key in SORT . . . . . . . . . . . . . . . . . . . 19
4. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . 20
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . 22
5.1 Entry and Attribute Registration Template . . . . . . . . . 22
6. Security Considerations . . . . . . . . . . . . . . . . . . 22
Normative References . . . . . . . . . . . . . . . . . . . . 22
Informative References . . . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 23
A. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 24
Intellectual Property and Copyright Statements . . . . . . . 25
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1. 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
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that needs to synchronise annotations for use when offline), servers
SHOULD also support the Conditional STORE [CONDSTORE] extension.
The rest of this document describes the data model and protocol
changes more rigorously.
2. Data Model
2.1 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 2.3 for specifics).
2.2 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-sensitive.
Use of non-visible UTF-8 characters in entry and attribute names is
strongly discouraged.
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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.
2.2.1 Entry Names
Entry names MUST be specified in a standards track or IESG approved
experimental RFC, or fall under the vendor namespace. See Section 5.1
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.
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Note that flag and keyword names in [IMAP4] are case-insensitive,
however the entry names for the corresponding annotations are
case-sensitive. Thus the [IMAP4] flag and keyword names MUST be
mapped to lowercase characters before being used as entry names
for annotations.
Additional standard flags are:
/flags/$mdnsent
/flags/$redirected
/flags/$forwarded
The '$mdnsent' flag is used to indicate message disposition
notification processing state [MDNSENT].
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.
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/<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>
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.
2.2.2 Attribute Names
Attribute names MUST be specified in a standards track or IESG
approved experimental RFC, or fall under the vendor namespace. See
Section 5.1 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>
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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.
2.3 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
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
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annotation on a READ-ONLY mailbox, the server MUST respond with a NO
response.
3. IMAP Protocol Changes
3.1 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
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.
3.2 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.
There are two possible modes of operation:
o A global state change where a single use of the optional parameter
will effect the session state from that time on, irrespective of
subsequent SELECT/EXAMINE commands.
o A per-mailbox state change that will effect the session only for
the duration of the new selected state. A subsequent SELECT/
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EXAMINE without the optional parameter will cancel its effect for
the newly selected mailbox.
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.
Example:
C: a EXAMINE INBOX (ANNOTATE (RESPONSES "UID Responses") CONDSTORE)
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.
Example:
C: a SELECT INBOX (BLURDYBLOOP)
S: a NO Unknown parameter in SELECT command
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 3.4. This option al parameter is
results in a per-mailbox state change, i.e. it must be used in each
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SELECT/EXAMINE command in order to be effective, irrespective of
whether it was used in a previous SELECT/EXAMINE during the same
session.
3.3 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 "/altsubject", but not "/flags/$redirected".
Example:
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C: a FETCH 1 (ANNOTATION ("/*" ("value.priv" "size.priv")))
S: * 1 FETCH (ANNOTATION
("/comment" ("value.priv" "My comment"
"size.priv" "10")
"/altsubject" ("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
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.
Example:
C: a FETCH 1 (ANNOTATION ("/%" "value.shared"))
S: * 1 FETCH (ANNOTATION
("/comment" ("value.shared" "Patch Mangler")
"/altsubject" ("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.
Example:
C: a FETCH 1 (ANNOTATION
(("/comment" "/altsubject") "value.priv"))
S: * 1 FETCH (ANNOTATION
("/comment" ("value.priv" "What a chowder-head")
"/altsubject" ("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 "/altsubject" are
requested by the client and returned by the server.
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3.4 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.
Example:
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
".shared" or ".priv" suffix, both are returned. Only the private
attribute has a value (the shared value is NIL).
Example:
C: a FETCH 1 (ANNOTATION
(("/comment" "/altsubject") "value"))
S: * 1 FETCH (ANNOTATION
("/comment" ("value.priv" "My comment"
"value.shared" NIL)
"/altsubject" ("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.
Example:
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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.
3.5 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.
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.
Example:
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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.
Example:
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")
"/altsubject"
("value.priv" "Wots On"))
S: a OK Store complete
In the above example, the entries "/comment" and "/altsubject" 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"
("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.
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3.6 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, for each message being copied, copy all '.priv'
annotation data for the current user only, and all '.shared'
annotation data along with the message to the new mailbox. 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). Servers MUST NOT copy '.priv' annotation data for
users other than the current user.
3.7 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.
Example:
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.
3.8 ANNOTATION Criterion in SEARCH
ANNOTATION <entry-name> <attribute-name> <value>
The ANNOTATION criterion for the SEARCH command allows a client to
search for a specified string in the value of an annotation entry of
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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.
Example:
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.
Example:
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.
3.9 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.)
Example:
C: a SORT (ANNOTATION "/altsubject" "value.shared") UTF-8 ALL
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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
"/altsubject" entry.
Note that the ANNOTATION sort key must include a fully specified
entry and attribute -- wildcards are not allowed.
4. 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 /
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"(" att-match *(SP att-match) ")"
entries = entry-match /
"(" entry-match *(SP entry-match) ")"
entry = string
; slash-separated path to entry
; MUST NOT contain "*" or "%"
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
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
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value = nstring
5. 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.
5.1 Entry and Attribute Registration Template
To: iana@iana.org
Subject: IMAP Annotate Registration
Please register the following IMAP Annotate item:
[] Entry [] Attribute
Name: ______________________________
Description: _______________________
____________________________________
____________________________________
Contact person: ____________________
email: ____________________
6. 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.
Normative References
[RFC1891] Moore, K., "SMTP Service Extension for Delivery Status
Notifications", RFC 1891, January 1996.
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, November 1997.
[RFC2244] Newman, C. and J. Myers, "ACAP -- Application
Configuration Access Protocol", RFC 2244, November 1997.
[RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION
4rev1", RFC 3501, March 2003.
[RFC3502] Crispin, M., "Internet Message Access Protocol (IMAP) -
MULTIAPPEND Extension", RFC 3502, March 2003.
[RFC3503] Melnikov, A., "Message Disposition Notification (MDN)
profile for Internet Message Access Protocol (IMAP)", RFC
3503, March 2003.
[SORT] Crispin, M. and K. Murchison, "Internet Message Access
Protocol - Sort and Thread Extension",
draft-ietf-imapext-sort-15.txt, April 2004.
Informative References
[CONDSTORE]
Melnikov, A. and S. Hole, "IMAP Extension for Conditional
STORE operation", draft-ietf-imapext-condstore-05.txt,
April 2004.
[RFC2086] Myers, J., "IMAP4 ACL extension", RFC 2086, January 1997.
Authors' Addresses
Randall Gellens
QUALCOMM Incorporated
5775 Morehouse Dr.
San Diego, CA 92121-2779
US
EMail: randy@qualcomm.com
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Cyrus Daboo
Cyrusoft International, Inc.
5001 Baum Blvd.
Suite 650
Pittsburgh, PA 15213
US
EMail: daboo@cyrusoft.com
Appendix A. 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.
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