SIPPING WG R. Mahy
Internet-Draft Cisco Systems, Inc.
Expires: October 30, 2002 May 2002
A Message Summary and Message Waiting Indication Event Package for
the Session Initiation Protocol (SIP)
draft-ietf-sipping-mwi-00.txt
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 working documents of the Internet Engineering
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This Internet-Draft will expire on October 30, 2002.
Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract
This draft proposes a SIP event package to carry message waiting
status and message summaries from a messaging system to an interested
User Agent.
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Table of Contents
1. Conventions . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Background and Appropriateness . . . . . . . . . . . . . . . 3
3. Event Package Formal Definition . . . . . . . . . . . . . . 4
3.1 Event Package Name . . . . . . . . . . . . . . . . . . . . . 4
3.2 Event Package Parameters . . . . . . . . . . . . . . . . . . 4
3.3 SUBSCRIBE Bodies . . . . . . . . . . . . . . . . . . . . . . 4
3.4 Subscription Duration . . . . . . . . . . . . . . . . . . . 4
3.5 NOTIFY Bodies . . . . . . . . . . . . . . . . . . . . . . . 4
3.6 Subscriber generation of SUBSCRIBE requests . . . . . . . . 5
3.7 Notifier processing of SUBSCRIBE requests . . . . . . . . . 6
3.8 Notifier generation of NOTIFY requests . . . . . . . . . . . 6
3.9 Subscriber processing of NOTIFY requests . . . . . . . . . . 7
3.10 Handling of Forked Requests . . . . . . . . . . . . . . . . 7
3.11 Rate of notifications . . . . . . . . . . . . . . . . . . . 7
3.12 State Agents . . . . . . . . . . . . . . . . . . . . . . . . 7
3.13 Behavior of a Proxy Server . . . . . . . . . . . . . . . . . 8
4. Examples of Usage . . . . . . . . . . . . . . . . . . . . . 8
4.1 Example Message Flow . . . . . . . . . . . . . . . . . . . . 8
4.2 Example Usage with Caller Preferences . . . . . . . . . . . 13
5. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . 14
5.1 New event-package definition . . . . . . . . . . . . . . . . 14
5.2 Body Format Syntax . . . . . . . . . . . . . . . . . . . . . 14
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . 15
6.1 SIP Event Package Registration for message-summary . . . . . 15
6.2 MIME Registration for application/simple-message-summary . . 16
7. Security Considerations . . . . . . . . . . . . . . . . . . 16
8. Revision history . . . . . . . . . . . . . . . . . . . . . . 16
8.1 Open Issues . . . . . . . . . . . . . . . . . . . . . . . . 17
8.2 Changes from draft-mahy-sipping-mwi-00 . . . . . . . . . . . 17
8.3 Changes from draft-mahy-sip-mwi-01 . . . . . . . . . . . . . 17
8.4 Changes from draft-mahy-sip-mwi-00 . . . . . . . . . . . . . 18
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 18
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 18
Normative References . . . . . . . . . . . . . . . . . . . . 19
Informational References . . . . . . . . . . . . . . . . . . 19
Author's Address . . . . . . . . . . . . . . . . . . . . . . 19
Full Copyright Statement . . . . . . . . . . . . . . . . . . 20
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1. Conventions
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 [3].
2. Background and Appropriateness
Messaging Waiting Indication is a common feature of telephone
networks. It typically involves playing a special dial tone (called
message-waiting dial tone), lighting a light or indicator on the
phone, or both. Message-waiting dial tone is similar but distinct
from stutter dial tone. Both are defined in GR-506 [10].
The methods in the SIP [1] base specification were only designed to
solve the problem of session initiation for multimedia sessions, and
rendezvous. Since Message Waiting Indication is really status
information orthogonal to a session, it was not clear how an IP
telephone acting as a SIP User Agent would implement comparable
functionality. Members of the telephony community viewed this as a
shortcoming of SIP.
Users want the useful parts of the functionality they had using
traditional analog and PBX telephones. It is also desirable to
provide comparable functionality in a flexible way that allows for
more customization and new features.
SIP Specific Event Notification SIP Events [2] is an appropriate
mechanism to use in this environment, as it preserves the user
mobility and rendezvous features which SIP provides.
Using SIP-Specific Event Notification, A Subscriber User Agent
(typically an IP phone or SIP software User Agent) subscribes to the
status of their messages. A SIP User Agent acting on behalf of the
user's messaging system then notifies the Subscriber whenever the
account's messages have changed. The Notifier sends this message
summary information in the body of the NOTIFY, encoded in a new MIME
type defined later in this draft. A User Agent can also explicitly
fetch the current status.
A SIP User Agent MAY subscribe to multiple accounts (distinguished by
the Request URI). Multiple SIP User Agents MAY subscribe to the same
account.
Before any subscriptions or notifications are sent, each interested
User Agent must be made aware of its messaging server(s). This MAY
be manually configured on interested User Agents, manually configured
on an appropriate SIP Proxy, or dynamically discovered using caller
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preferences [4]. (For more information on usage with caller
preferences, see Section 4.2)
3. Event Package Formal Definition
3.1 Event Package Name
This document defines a SIP Event Package as defined in SIP Events
[2]. The event-package token name for this package is:
"message-summary"
3.2 Event Package Parameters
This package does not define any event package parameters.
3.3 SUBSCRIBE Bodies
This package does not define any SUBSCRIBE bodies.
3.4 Subscription Duration
Subscriptions to this event package MAY range from minutes to weeks.
Subscriptions in hours or days are more typical and are RECOMMENDED.
3.5 NOTIFY Bodies
A simple text-based format is proposed to prevent an undue burden on
low-end user agents, for example, inexpensive IP phones with no
display. Although this format is text-based, it is intended for
machine consumption only.
A future extension MAY define other NOTIFY bodies. If no "Accept"
header is present in the SUBSCRIBE, the body type defined in this
document MUST be assumed.
The format specified in this proposal attempts to separate orthogonal
attributes of messages as much as possible. Messages are separated
by media type (audio, text, image, and video); by message status (new
and old); and by urgent and non-urgent type.
The text format begins with a simple status line, and optionally a
summary line per media type. Valid media types are Voicemail
(audio), Email (text), Fax (image), and Video (video). For each
media type the total number of new and old messages is reported in
the new and old fields.
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In some cases, detailed message summaries are not available. The
status line allows messaging systems or messaging gateways to provide
the traditional boolean message waiting notification.
Messages-Waiting: yes
In the example that follows, more functionality is available to the
User Agent. There are one new and three old voice messages.
Voicemail: 1/3
After the summary, the format can optionally list a summary count of
urgent messages. Of the one new and three old voice messages, none
of the new messages are urgent, but one of the old messages is. All
counters have a maximum value of 4,294,967,295 ((2^32) - 1).
Notifiers MUST NOT generate a request with a larger value.
Subscribers MUST ignore a larger value.
Voicemail: 1/3 (0/1)
Optionally, after the summary counts, the messaging systems MAY
append RFC 2822 [9]-style message headers, which further describe
newly added messages. A messaging system which includes message
headers in a NOTIFY, MUST provide an administrator configurable
mechanism for selecting which headers are sent. Likely headers for
inclusion include To, From, Date, Subject, Message-ID, and Priority.
Note that the syntax for these headers is more restrictive than for
RFC 2822 and SIP. For example, line folding is prohibited.
Implementations which generate large notifications are reminded to
follow the message size restrictions for unreliable transports
articulated in Section 18.1.1 of SIP.
Mapping local message state to new/old message status and urgency is
an implementation issue of the messaging server.
Messaging systems MAY use any algorithm for determining the
approporiate media type for a message. Such algorithms are out of
scope of this document. Systems which use Internet Mail SHOULD use
the Message-Context header [6] if present as a hint to make a media
type determination.
3.6 Subscriber generation of SUBSCRIBE requests
Subscriber User Agents will typically SUBSCRIBE to message summary
information for a period of hours or days, and automatically attempt
to re-SUBSCRIBE well before the subscription is completely expired.
If re-subscription fails, the Subscriber SHOULD periodically retry
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again until a subscription is successful, taking care to backoff to
avoid network congestion. If a subscription has expired, new re-
subscriptions MUST use a new Call-ID.
The Subscriber SHOULD SUBSCRIBE to that user's message summaries
whenever a new user becomes associated with the device (a new login).
The Subscriber MAY also explicitly fetch the current status at any
time. The subscriber SHOULD renew its subscription immediately after
a reboot, or when the subscriber's network connectivity has just been
re-established.
The Subscriber MUST be prepared to receive and process a NOTIFY with
new state immediately after sending a new SUBSCRIBE, a SUBSCRIBE,
renewal, an unSUBSCRIBE or a fetch; or at any time during the
subscription.
When a user de-registers from a device (logoff, power down of a
mobile device, etc.), subscribers SHOULD unsubscribe by sending a
SUBSCRIBE message with an Expires header of zero.
3.7 Notifier processing of SUBSCRIBE requests
When a SIP Messaging System receives SUBSCRIBE messages with the
message-summary event-type, it SHOULD authenticate the subscription
request. If authentication is successful, the Notifier MAY limit the
duration of the subscription to an administrator defined amount of
time as described in SIP Events.
3.8 Notifier generation of NOTIFY requests
Immediately after a subscription is accepted, the Notifier MUST send
a NOTIFY with the current message summary information. This allows
the Subscriber to resynchronize its state. This initial
synchronization NOTIFY MUST NOT include the optional message headers.
When the status of the messages changes sufficiently for a messaging
account to change the number of new or old messages, the Notifier
SHOULD send a NOTIFY message to all active subscribers to that
account. NOTIFY messages sent to subscribers of a group or alias,
MUST place the account name in the user part of the Contact header
URL.
A Messaging System MAY send a NOTIFY with an "Expires" header of "0"
and a "Subscription-State" header of "terminated" before a graceful
shutdown.
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3.9 Subscriber processing of NOTIFY requests
Upon receipt of a valid NOTIFY request, the subscriber SHOULD
immediately render the message status and summary information to the
end user in an implementation specific way.
The Subscriber MUST be prepared to receive NOTIFYs from different
Contacts corresponding to the same SUBSCRIBE. (the SUBSCRIBE may
have been forked).
3.10 Handling of Forked Requests
Forked requests are allowed for this event type and may install
multiple subscriptions. The Subscriber MAY render multiple summaries
to the user, or MAY merge them as described below.
If any of the "Messages-Waiting" status lines report "yes", then the
merged state is "yes"; otherwise the merged state is "no".
status-line = "Messages-Waiting: " status CRLF
status = "yes" / "no"
The Subscriber MAY merge summary lines in an implementation-specific
way if all notifications contain at least one summary line.
summary-line = media-type ":" SP new "/" old [ SP urgent ] CRLF
urgent = "(" new-urgent "/" old-urgent ")"
A Subscriber MAY use an "alias" or "group" in the To header and/or
Request-URI if that name is significant to the messaging system.
3.11 Rate of notifications
A Notifier MAY choose to buffer NOTIFY responses for a short
administrator-defined period (seconds or minutes) when the message
status is changing rapidly. This buffering behavior is RECOMMENDED.
Note that timely notification of a newly added message is probably
more significant to the end user than notifications of newly deleted
messages which do not affect the overall message waiting state.
Notifiers SHOULD NOT generate NOTIFY requests more frequently than
once per second.
3.12 State Agents
Implementers MAY create a service which consolidates and summarizes
NOTIFYs from many Contacts. This document does not preclude
implementations from building state agents which support this event
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package.
3.13 Behavior of a Proxy Server
There are no additional requirements on a SIP Proxy, other than to
transparently forward the SUBSCRIBE and NOTIFY methods as required in
SIP. However, Proxies SHOULD allow non-SIP URLs. Proxies and
Redirect servers SHOULD be able to direct the SUBSCRIBE request to an
appropriate messaging server User Agent. Proxies are encouraged to
support routing to Contacts based on the existence of
methods="SUBSCRIBE" and feature="voice-mail" parameters in an Accept-
Contact header (as specified in the caller preferences
specification).
4. Examples of Usage
4.1 Example Message Flow
The examples shown below are for informational purposes only. For a
normative description of the event package, please see sections 4 and
6 of this document.
In the example call flow below, Rohan's IP phone subscribes to the
status of Rohan's messages. Via headers are omitted for clarity.
Subscriber Notifier
| |
| A1: SUBSCRIBE (new) |
|---------------------->|
| A2: 200 OK |
|<----------------------|
| |
| A3: NOTIFY (sync) |
|<----------------------|
| A4: 200 OK |
|---------------------->|
| |
| |
| A5: NOTIFY (change) |
|<----------------------|
| A6: 200 OK |
|---------------------->|
| |
| |
| A7: (re)SUBSCRIBE |
|---------------------->|
| A8: 200 OK |
|<----------------------|
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| |
| A9: NOTIFY (sync) |
|<----------------------|
| A10: 200 OK |
|---------------------->|
| |
| |
| A11: (un)SUBSCRIBE |
|---------------------->|
| A12: 200 OK |
|<----------------------|
| |
| A13: NOTIFY (sync) |
|<----------------------|
| A14: 200 OK |
|---------------------->|
A1: Subscriber (Rohan's phone) ->
Notifier (Rohan's voicemail gateway)
Subscribe to Rohan's message summary status for 1 day.
SUBSCRIBE sip:rohan@vmail.cisco.com SIP/2.0
To: <sip:rohan@cisco.com>
From: <sip:rohan@cisco.com>;tag=78923
Date: Mon, 10 Jul 2000 03:55:06 GMT
Call-Id: 1349882@rmahy-phone.cisco.com
CSeq: 4 SUBSCRIBE
Contact: <sip:rohan@rmahy-phone.cisco.com>
Event: message-summary
Expires: 86400
Accept: application/simple-message-summary
Content-Length: 0
A2: Notifier -> Subscriber
SIP/2.0 200 OK
To: <sip:rohan@cisco.com>;tag=4442
From: <sip:rohan@cisco.com>;tag=78923
Date: Mon, 10 Jul 2000 03:55:07 GMT
Call-Id: 1349882@rmahy-phone.cisco.com
CSeq: 4 SUBSCRIBE
Expires: 86400
Content-Length: 0
A3: Notifier -> Subscriber
(immediate synchronization of current state:
2 new and 8 old [2 urgent] messages)
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NOTIFY sip:rohan@rmahy-phone.cisco.com SIP/2.0
To: <sip:rohan@cisco.com>;tag=78923
From: <sip:rohan@cisco.com>;tag=4442
Date: Mon, 10 Jul 2000 03:55:07 GMT
Call-Id: 1349882@rmahy-phone.cisco.com
CSeq: 20 NOTIFY
Contact: <sip:rohan@vmail.cisco.com>
Event: message-summary
Subscription-State: active
Content-Type: application/simple-message-summary
Content-Length: 45
Messages-Waiting: yes
Voicemail: 2/8 (0/2)
A4: Subscriber -> Notifier
SIP/2.0 200 OK
To: <sip:rohan@cisco.com>;tag=78923
From: <sip:rohan@cisco.com>;tag=4442
Date: Mon, 10 Jul 2000 03:55:08 GMT
Call-Id: 1349882@rmahy-phone.cisco.com
CSeq: 20 NOTIFY
Content-Length: 0
A5: Notifier -> Subscriber
This is a notification of new messages.
Some headers from the new messages are appended.
NOTIFY sip:rohan@rmahy-phone.cisco.com SIP/2.0
To: <sip:rohan@cisco.com>;tag=78923
From: <sip:rohan@cisco.com>;tag=4442
Date: Mon, 10 Jul 2000 04:28:53 GMT
Contact: <sip:rohan@vmail.cisco.com>
Call-ID: 1349882@rmahy-phone.cisco.com
CSeq: 31 NOTIFY
Event: message-summary
Subscription-State: active
Content-Type: application/simple-message-summary
Content-Length: 420
Messages-Waiting: yes
Voicemail: 4/8 (1/2)
To: <rohan@work.com>
From: <friend@home.com>
Subject: carpool tomorrow?
Date: Sun, 09 Jul 2000 21:23:01 -0700
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Priority: normal
Message-ID: 13784434989@vmail.cisco.com
To: <rohan@work.com>
From: <the-boss@work.com>
Subject: HELP! at home ill, present for me please
Date: Sun, 09 Jul 2000 21:25:12 -0700
Priority: urgent
Message-ID: 13684434990@vmail.cisco.com
A6: Subscriber -> Notifier
SIP/2.0 200 OK
To: <sip:rohan@cisco.com>;tag=78923
From: <sip:rohan@cisco.com>;tag=4442
Date: Mon, 10 Jul 2000 04:28:53 GMT
Call-ID: 1349882@rmahy-phone.cisco.com
CSeq: 31 NOTIFY
Content-Length: 0
A7: Subscriber -> Notifier
Refresh subscription.
SUBSCRIBE sip:rohan@vmail.cisco.com SIP/2.0
To: <sip:rohan@cisco.com>;tag=4442
From: <sip:rohan@cisco.com>;tag=78923
Date: Mon, 10 Jul 2000 15:55:06 GMT
Call-Id: 1349882@rmahy-phone.cisco.com
CSeq: 8 SUBSCRIBE
Contact: <sip:rohan@rmahy-phone.cisco.com>
Event: message-summary
Expires: 86400
Accept: application/simple-message-summary
Content-Length: 0
A8: Notifier -> Subscriber
SIP/2.0 200 OK
To: <sip:rohan@cisco.com>;tag=4442
From: <sip:rohan@cisco.com>;tag=78923
Date: Mon, 10 Jul 2000 15:55:07 GMT
Call-Id: 1349882@rmahy-phone.cisco.com
CSeq: 8 SUBSCRIBE
Contact: <sip:rohan@rmahy-phone.cisco.com>
Expires: 86400
Content-Length: 0
A9: Notifier -> Subscriber
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(immediate synchronization of current state)
NOTIFY sip:rohan@rmahy-phone.cisco.com SIP/2.0
To: <sip:rohan@cisco.com>;tag=78923
From: <sip:rohan@cisco.com>;tag=4442
Date: Mon, 10 Jul 2000 15:55:07 GMT
Call-Id: 1349882@rmahy-phone.cisco.com
CSeq: 47 NOTIFY
Contact: <sip:rohan@vmail.cisco.com>
Event: message-summary
Subscription-State: active
Content-Type: application/simple-message-summary
Content-Length: 45
Messages-Waiting: yes
Voicemail: 4/8 (1/2)
A10: Subscriber -> Notifier
SIP/2.0 200 OK
To: <sip:rohan@cisco.com>;tag=78923
From: <sip:rohan@cisco.com>;tag=4442
Date: Mon, 10 Jul 2000 15:55:08 GMT
Call-Id: 1349882@rmahy-phone.cisco.com
CSeq: 47 NOTIFY
Contact: <sip:rohan@vmail.cisco.com>
A11: Subscriber -> Notifier
Un-subscribe after "rohan" logs out.
SUBSCRIBE sip:rohan@vmail.cisco.com SIP/2.0
To: <sip:rohan@cisco.com>;tag=4442
From: <sip:rohan@cisco.com>;tag=78923
Date: Mon, 10 Jul 2000 19:35:06 GMT
Call-Id: 1349882@rmahy-phone.cisco.com
CSeq: 17 SUBSCRIBE
Contact: <sip:rohan@rmahy-phone.cisco.com>
Event: message-summary
Expires: 0
Accept: application/simple-message-summary
Content-Length: 0
A12: Notifier -> Subscriber
SIP/2.0 200 OK
To: <sip:rohan@cisco.com>;tag=4442
From: <sip:rohan@cisco.com>;tag=78923
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Date: Mon, 10 Jul 2000 19:35:07 GMT
Call-Id: 1349882@rmahy-phone.cisco.com
CSeq: 17 SUBSCRIBE
Contact: <sip:rohan@rmahy-phone.cisco.com>
Expires: 0
Content-Length: 0
A13: Notifier -> Subscriber
(immediate synchronization of current state,
which the subscriber can now ignore)
NOTIFY sip:rohan@rmahy-phone.cisco.com SIP/2.0
To: <sip:rohan@cisco.com>;tag=78923
From: <sip:rohan@cisco.com>;tag=4442
Date: Mon, 10 Jul 2000 19:35:07 GMT
Call-Id: 1349882@rmahy-phone.cisco.com
CSeq: 56 NOTIFY
Contact: <sip:rohan@vmail.cisco.com>
Event: message-summary
Subscription-State: active
Content-Type: application/simple-message-summary
Content-Length: 45
Messages-Waiting: yes
Voicemail: 4/8 (1/2)
A10: Subscriber -> Notifier
SIP/2.0 200 OK
To: <sip:rohan@cisco.com>;tag=78923
From: <sip:rohan@cisco.com>;tag=4442
Date: Mon, 10 Jul 2000 19:35:08 GMT
Call-Id: 1349882@rmahy-phone.cisco.com
CSeq: 56 NOTIFY
Event: message-summary
Content-Length: 0
4.2 Example Usage with Caller Preferences
The use of caller preferences is optional but encouraged. If caller
preferences is used, a messaging server MAY REGISTER a Contact with a
"SUBSCRIBE" methods tag. If SUBSCRIBE is used by other services, the
messaging server MAY also REGISTER as a Contact with the
feature="voice-mail" tag. An example of this kind of registration
follows below.
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REGISTER sip:sip3-sj.cisco.com SIP/2.0
To: <sip:rohan@cisco.com>
From: <sip:rohan@cisco.com>;tag=4442
...
Contact: <sip:rohan@vm13-sj.cisco.com>
;feature="voice-mail";methods="SUBSCRIBE"
The following SUBSCRIBE message would find the Contact which
registered in the example above.
SUSBCRIBE sip:rohan@cisco.com SIP/2.0
...
Accept: application/simple-message-summary
Accept-Contact: *;feature="voice-mail";methods="SUBSCRIBE"
5. Formal Syntax
The following syntax specification uses the augmented Backus-Naur
Form (BNF) as described in RFC-2234 [5].
5.1 New event-package definition
This document defines a new event-package with the package name:
message-summary
5.2 Body Format Syntax
The formal syntax for application/simple-message-summary is below:
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messsage-summary = status-line [*(summary-line)] [ *msg ]
status-line = "Messages-Waiting:" SP status CRLF
status = "yes" / "no"
summary-line = media-type ":" SP new "/" old [ SP urgent ] CRLF
urgent = "(" new-urgent "/" old-urgent ")"
media-type = "Voicemail" / "Email" / "Fax" / "Video"
msg = CRLF 1*(mheader)
mheader = mhname ":" SP mhvalue CRLF
mhname = alphanum 1*( alphanum / "-" / "_" )
mhvalue = *( HTAB / %x20-7E / UTF8-NONASCII )
new = 1*DIGIT
old = 1*DIGIT
new-urgent = 1*DIGIT
old-urgent = 1*DIGIT
6. IANA Considerations
6.1 SIP Event Package Registration for message-summary
Package name: message-summary
Type: package
Contact: [Mahy]
Published Specification: This document.
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6.2 MIME Registration for application/simple-message-summary
MIME media type name: application
MIME subtype name: simple-message-summary
Required parameters: none.
Optional parameters: none.
Encoding considerations: This type is only defined for transfer
via SIP [1].
Security considerations: See the "Security Considerations"
section in this document.
Interoperability considerations: none
Published specification: This document.
Applications which use this media: The simple-message-summary
application subtype supports the exchange of message waiting and
message summary information in SIP networks.
Additional information:
1. Magic number(s): N/A
2. File extension(s): N/A
3. Macintosh file type code: N/A
7. Security Considerations
Message Summaries and optional message bodies contain information
which is typically very privacy sensitive. At minimum, subscriptions
to this event package SHOULD be authenticated; and notifications
SHOULD be encrypted and integrity protected using either end-to-end
mechanisms, or the hop-by-hop protection afforded messages sent to
SIPS URIs.
Additional security considerations are covered in SIP [1] and SIP
Events [2].
8. Revision history
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8.1 Open Issues
1. Should the "media types" concept be replaced entirely with
message contexts? This would be a non-backwards compatible
change, but appears to be a better semantic match than what is in
the draft now. This would also add extensibility and change
control in a single document. The list of valid message-context-
classes are voice-message, fax-message, pager-message,
multimedia-message, text-message, and none.
2. Should the syntax follow that of SIP instead of the restrictive
syntax now in place? A SIP syntax would add line folding, for
example. The optional message-headers would borrow the
"extension-header" syntax from SIP and the per-media (or per-
message-context) summary lines would use the explicit whitespace
separators defined in SIP (ex: HCOLON, SLASH).
3. If forking or state agents are supported, and the subscriber
subscribes to a group alias, how is the specific messaging
account specified in the corresponding notifies.
8.2 Changes from draft-mahy-sipping-mwi-00
1. Updated references and split into normative and informational
2. Removed normative behavior now specified in Events
3. Updated to address the event package sections now specified in
Events.
4. Added the Subscription-State header field to the examples and
removed the Event header field from responses.
5. Removed redundant BNF
6. Simplified text on how to choose the media type. For Internet
Mail, this now references the Message-Context header.
8.3 Changes from draft-mahy-sip-mwi-01
1. This document is now formatted as a SIP Event Package as defined
in Section 4 of SIP Events [2].
2. The event-package name is now "message-summary", to allow for
other bodies to extend the package.
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3. The "urgent" token was missing from the BNF.
8.4 Changes from draft-mahy-sip-mwi-00
This draft greatly simplifies and shortens the -00 version.
1. The generic behavior of SUBSCRIBE/NOTIFY is now greatly clarified
in SIP Events [2] and made consistent with PINT and SIP for
presence. This message waiting draft is now consistent with SIP
Events [2].
2. The XML format has been removed due to lack of immediate
interest. At a future date, similar functionality may be added
as another body definition with an appropriate MIME type.
3. An IANA Considerations section was added to register the new
"application/simple-message-summary" MIME type and the "simple-
message-summary" SIP event package.
4. The "flag-list" was removed due to lack of interest and to
encourage simplicity.
5. Due to synchronization issues, and the recommendation of the VPIM
Working Group, support for message count "deltas" was removed.
6. The Messages-Waiting line in the body is now mandatory.
7. This version of the draft clarifies the role of caller
preferences as optional but encouraged.
8. A set of SMTP-like headers from the triggering messages may now
optionally follow the message summaries, provided that the
resulting NOTIFY on UDP fits in a single datagram.
9. Contributors
Ilya Slain came up with the initial format of the text body contained
in this document. He was previously listed as a co-author, however,
he is no longer reachable.
10. Acknowledgments
Thanks to Dave Oran, Bill Foster, Steve Levy, Denise Caballero-
McCann, Jeff Michel, Priti Patil, Satyender Khatter, Bich Nguyen,
Manoj Bhatia, David Williams, and Bryan Byerly of Cisco; and Jonathan
Rosenberg and Adam Roach of Dynamicsoft.
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Normative References
[1] Rosenberg, J. and H. Schulzrinne, "SIP: Session Initiation
Protocol", draft-ietf-sip-rfc2543bis-09 (work in progress),
February 2002.
[2] Roach, A., "SIP-Specific Event Notification", draft-ietf-sip-
events-05 (work in progress), March 2002.
[3] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[4] Rosenberg, J. and H. Schulzrinne, "SIP Caller Preferences and
Callee Capabilities", draft-ietf-sip-callerprefs-05 (work in
progress), November 2001.
[5] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, November 1997.
[6] Klyne, G., Burger, E., Candell, E. and C. Eliot, "Message
Context for Internet Mail", draft-ietf-vpim-hint-08 (work in
progress), June 2002.
Informational References
[7] Parsons, G. and G. Vaudreuil, "Voice Profile for Internet Mail
- version 2", RFC 2421, September 1998.
[8] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046, November
1996.
[9] Resnick, P., "Internet Message Format", RFC 2822, April 2001.
[10] Telcordia, "GR-506: Signaling for Analog Interfaces, Issue 1,
Revision 1", Nov 1996.
Author's Address
Rohan Mahy
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134
USA
EMail: rohan@cisco.com
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Full Copyright Statement
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