Sieve working group R. George
Internet-Draft B. Leiba
Intended status: Standards Track Huawei Technologies
Expires: December 25, 2010 June 23, 2010
Sieve Notification Using Presence Information
draft-ietf-sieve-notify-presence-00
Abstract
This is a further extension to the Sieve mail filtering language
Notification extension, defining presence information that may be
checked through the notify_method_capability feature.
Status of this Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology Used in This Document . . . . . . . . . . . . . . 3
2. Testing presence information . . . . . . . . . . . . . . . . 3
3. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
Sometimes, it's desirable to tailor Sieve [RFC5228] notifications to
a user's current situation. Presence information provides some
information about the user that would be useful to have access to in
these cases. The Notification extension [RFC5435] defines a
mechanism to test for presence (the notify_method_capability
feature), and defines one test for presence (the "online"
notification-capability, described in Section 5 of RFC 5435). This
extension specifies testing of a wider variety of presence
information.
1.1. Terminology 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 [RFC2119].
2. Testing presence information
This extension uses the "notify_method_capability" test, as defined
in the Sieve [RFC5228] Notify extension [RFC5435], to test presence
information. When a Sieve event occurs (mail arrives) for a user, a
Sieve script running on behalf of that user can present the user's
presence URI (in the "notification-uri" parameter) and test a
specific item of notification presence as defined below (in the
"notification-capability" parameter) against one or more values (in
the "key-list" parameter).
This document defines the following items of notification presence,
which may be specified in the notification-capability parameter:
busy - An indication of whether the user is considered "busy" now
(the value "yes") or not (the value "no"). The meaning of
"busy" is left to the implementation, and may be a state that's
synthesized from other information (including "show", below).
show - The availability status of the user, formally specified. Note
that this is similar to the presence element with the same name
that's defined in Section 2.2.2.1 of RFC 3921.[RFC3921] The
value of this item is one of the following:
away - The user is temporarily away.
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chat - The user is online and actively interested in chatting.
dnd - Do Not Disturb; the user should not be disturbed now.
offline - The user is offline.
xa - The user is away for an extended period (xa = "eXtended
Away").
status - A human-readable description of the user's availability
status. There is no formal definition for the values this item
may take. It is free-form, and may be in any language. Direct
comparisons against the value of this field are unlikely to be
useful; rather, it is provided to enable extraction of the value
into a variable [RFC5229] for use elsewhere (see example 3 in
Section 3). Note that this is similar to the presence element
with the same name that's defined in Section 2.2.2.2 of RFC
3921.[RFC3921]
The script tests the values of notification presence items in the
key-list parameter. The values that each item may have are specified
in the list above; in addition, any item may have the value
"unknown", if it is not possible to determine the correct value of
the item.
There is no capability string associated with this extension, but
this requires support for "enotify".[RFC5435] If the implementation
does not support the item being tested, RFC 5435 already specifies
that the test must fail without an error.
Although this feature was conceived to assist in notifications, and
the test requires support of the Sieve Notify feature, it is only a
condition test, and any Sieve action can appear inside it. There are
no Sieve actions that conflict with this extension.
3. Examples
1. This example will send a notification only if the recipient is
not "busy". If the test for "busy" is not supported, this
example WILL NOT send a notification.
require ["enotify"];
if notify_method_capability "xmpp:tim@example.com" "busy" "no"
{
notify :message "You got mail"
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"xmpp:tim@example.com?message;subject=SIEVE";
}
2. This example will send a notification only if the recipient is
not "busy". If the test for "busy" is not supported, this
example WILL send a notification.
require ["enotify"];
if not notify_method_capability "xmpp:tim@example.com" "busy" "yes"
{
notify :message "You got mail"
"xmpp:tim@example.com?message;subject=SIEVE";
}
3. This example uses the vacation extension [RFC5230] to generate an
autoreply [I-D.ietf-sieve-autoreply] if the sender is in the
recipient's address book [I-D.ietf-sieve-external-lists] and the
recipient's presence shows "extended away". The variables
extension [RFC5229] is used to extract the value of the
recipient's presence status message, which will be used in the
response to the sender. If the test for "show" is not supported,
this example WILL NOT send an autoreply.
require ["extlists", "vacation", "enotify", "variables"];
if allof (
envelope :list "from" "tag:example.com,2009-05-28:mylist",
notify_method_capability "xmpp:myjid@example.com" "show" "xa"
) {
# :matches "*" is used here to extract the value
if notify_method_capability :matches
"xmpp:myjid@example.com" "status" "*" {
set "resp_msg" "${1}";
} else {
set "resp_msg" "I'm away from email for a while."
}
vacation :handle "ext-away" "${resp_msg}";
}
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4. Security Considerations
Security considerations for Sieve [RFC5228] and the Notify extension
[RFC5435] apply equally here. In addition, implementations MUST
ensure that users can not create scripts that access the presence
information of others without the proper access controls.
5. IANA Considerations
This registers each presence item as a notification-capability
parameter. Future extensions that add new presence items should
register those items similarly, using the instructions in Section 9.3
of RFC 5435.[RFC5435]
To: iana@iana.org
Subject: Registration of a new notification-capability parameter
Capability name: busy
Description: An indication of whether the user is considered "busy"
now (the value "yes") or not (the value "no"). The meaning of
"busy" is left to the implementation, and may be a state that's
synthesized from other information.
Syntax: Has one of the values "yes", "no", or "unknown". The value
MUST be in lower case.
Permanent and readily available reference(s): this RFC
Contact information: The Sieve discussion list, <sieve@ietf.org>
To: iana@iana.org
Subject: Registration of a new notification-capability parameter
Capability name: show
Description: The availability status of the user. This is similar
to the presence element with the same name that's defined in
Section 2.2.2.1 of RFC 3921.
Syntax: Has one of the values "away", "chat", "dnd", "offline",
"xa", or "unknown". The value MUST be in lower case.
Permanent and readily available reference(s): this RFC
Contact information: The Sieve discussion list, <sieve@ietf.org>
6. Acknowledgments
The authors thank Alexey Melnikov for significant early feedback and
suggestions.
7. References
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7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5228] Guenther, P. and T. Showalter, "Sieve: An Email Filtering
Language", RFC 5228, January 2008.
[RFC5435] Melnikov, A., Leiba, B., Segmuller, W., and T. Martin,
"Sieve Email Filtering: Extension for Notifications",
RFC 5435, January 2009.
7.2. Informative References
[I-D.ietf-sieve-autoreply]
George, R., Leiba, B., and A. Melnikov, "Sieve Email
Filtering: Use of Presence Information with Auto Responder
functionality", draft-ietf-sieve-autoreply-00 (work in
progress), June 2010.
[I-D.ietf-sieve-external-lists]
Melnikov, A. and B. Leiba, "Sieve Extension: Externally
Stored Lists", draft-ietf-sieve-external-lists-02 (work in
progress), May 2010.
[RFC3921] Saint-Andre, P., Ed., "Extensible Messaging and Presence
Protocol (XMPP): Instant Messaging and Presence",
RFC 3921, October 2004.
[RFC5229] Homme, K., "Sieve Email Filtering: Variables Extension",
RFC 5229, January 2008.
[RFC5230] Showalter, T. and N. Freed, "Sieve Email Filtering:
Vacation Extension", RFC 5230, January 2008.
Authors' Addresses
Robins George
Huawei Technologies
Huawei Base, Bantian, Longgang District
Shenzhen, Guangdong 518129
P. R. China
Phone: +86-755-28788314
Email: robinsg@huawei.com
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Barry Leiba
Huawei Technologies
Phone: +1 646 827 0648
Email: barryleiba@computer.org
URI: http://internetmessagingtechnology.org/
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