One document matched: draft-camarillo-sipping-list-state-00.txt
SIPPING G. Camarillo
Internet-Draft Ericsson
Expires: August 29, 2006 February 25, 2006
The Session Initiation Protocol (SIP) List State Event Package
draft-camarillo-sipping-list-state-00.txt
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Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
This document defines the SIP List State event package. This event
package is used by Resource List Servers to inform user agents about
the consent-related status of the entries in one or several resource
lists.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Overview of Operation . . . . . . . . . . . . . . . . . . . . 3
4. List State Event Package Definition . . . . . . . . . . . . . 3
4.1. Event Package Name . . . . . . . . . . . . . . . . . . . . 4
4.1.1. Event Package Parameters . . . . . . . . . . . . . . . 4
4.1.2. SUBSCRIBE Bodies . . . . . . . . . . . . . . . . . . . 4
4.1.3. Subscription Duration . . . . . . . . . . . . . . . . 4
4.1.4. NOTIFY Bodies . . . . . . . . . . . . . . . . . . . . 4
4.1.5. Notifier Processing of SUBSCRIBE Requests . . . . . . 5
4.1.6. Notifier Generation of NOTIFY Requests . . . . . . . . 5
4.1.7. Subscriber Processing of NOTIFY Requests . . . . . . . 5
4.1.8. Handling of Forked Requests . . . . . . . . . . . . . 5
4.1.9. Rate of Notifications . . . . . . . . . . . . . . . . 5
4.1.10. State Agents . . . . . . . . . . . . . . . . . . . . . 5
4.1.11. Example . . . . . . . . . . . . . . . . . . . . . . . 6
5. Usage of the 'list-state' Event Package with the XCAP Diff
Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6. List State RLS Service . . . . . . . . . . . . . . . . . . . . 7
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
8. Security Considerations . . . . . . . . . . . . . . . . . . . 7
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
10.1. Normative References . . . . . . . . . . . . . . . . . . . 8
10.2. Informative References . . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 9
Intellectual Property and Copyright Statements . . . . . . . . . . 10
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1. Introduction
The framework for consent-based communications in SIP [4] identifies
the need for users manipulating the translation logic at a relay
(e.g., adding a new recipient) to be informed about the consent-
related status of the recipients of a given translation. That is,
the user manipulating the translation logic needs to know which
recipients have given the relay permission to send them SIP requests.
This document defines a SIP event package whereby user agents can
subscribe to the state of a resource list that defines a translation.
This state includes the consent related-status of the resources of
the resource list.
2. Terminology
In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT
RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as
described in BCP 14, RFC 2119 [1] and indicate requirement levels for
compliant implementations.
3. Overview of Operation
A user agent subscribes to a resource list server using the 'list-
state' event package. NOTIFY requests within this event package can
carry an XML document in the "application/resource-lists+xml" format
[5] or in the "application/xcap-diff+xml" format [6].
A document in the "application/resource-lists+xml" format provides
the user agent with the whole resource list, including consent-
related state information.
A document in the "application/xcap-diff+xml" format informs the user
agent that the document that described the resource list has changed.
The user agent then downloads the document in the "application/
resource-lists+xml" format from the permission server using XCAP.
4. List State Event Package Definition
This section provides the details for defining a SIP [2] event
notification package, as specified by RFC 3265 [3].
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4.1. Event Package Name
The name of this event package is "list-state". This package name is
carried in the Event and Allow-Events header, as defined in RFC 3265
[3].
4.1.1. Event Package Parameters
This package does not define any event package parameters.
4.1.2. SUBSCRIBE Bodies
A SUBSCRIBE for 'list-state' events MAY contain a body. This body
would serve the purpose of filtering the subscription. The
definition of such a body is outside the scope of this specification.
A SUBSCRIBE for the 'list-state' package MAY be sent without a body.
This implies that the default session policy filtering policy has
been requested. The default policy is that notifications are
generated every time there is any change in the state of a resource
in the list.
4.1.3. Subscription Duration
The default expiration time for a subscription is one hour (3600
seconds).
4.1.4. NOTIFY Bodies
In this event package, the body of the notifications contains a
resource list document. This document describes a resource list and
the consent-related state of its resources. All subscribers and
notifiers MUST support the "application/resource-lists+xml" data
format [5] and its extension to carry consent-related state
information [7]. The subscribe request MAY contain an Accept header
field. If no such header field is present, it has a default value of
"application/resource-lists+xml". If the header field is present, it
MUST include "application/resource-lists+xml", and MAY include any
other types capable of representing translation state.
OPEN ISSUE: do we need to discuss how to use content indirection
here?
Additionally, all subscribers and notifiers SHOULD support the
"application/xcap-diff+xml" format [6]. Section 5 discusses the
usage of the 'list-state' event package with this format.
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4.1.5. Notifier Processing of SUBSCRIBE Requests
The state of a resource list defining a translation can reveal
sensitive information. Therefore, all subscriptions SHOULD be
authenticated and then authorized before approval. Authorization
policy is at the discretion of the administrator.
4.1.6. Notifier Generation of NOTIFY Requests
A notifier for the List State event package SHOULD include the
<consent-status> element [7] when the framework for consent-based
communications in SIP is used. When present, the <consent-status>
element MUST be positioned as an instance of the <any> element within
the <entry> element.
Notifications SHOULD be generated for the List State package whenever
there is a change in the resource-list state.
4.1.7. Subscriber Processing of NOTIFY Requests
NOTIFY requests contain the full resource-list state. The subscriber
does not need to perform any type of information aggregation.
4.1.8. Handling of Forked Requests
The state of a given resource list is normally handled by a server
and stored in a repository. Therefore, there is usually a single
place where the resource-list state is resident. This implies that a
subscription for this information is readily handled by a single
element with access to this repository. There is, therefore, no
compelling need for a subscription to session policy information to
fork. As a result, a subscriber MUST NOT create multiple dialogs as
a result of a single subscription request. The required processing
to guarantee that only a single dialog is established is described in
Section 4.4.9 of RFC 3265 [3].
4.1.9. Rate of Notifications
For reasons of congestion control, it is important that the rate of
notifications not become excessive. As a result, it is RECOMMENDED
that the server doesn't generate notifications for a single
subscriber at a rate faster than once every 5 seconds.
4.1.10. State Agents
State agents have no role in the handling of this package.
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4.1.11. Example
The following is an example of an "application/xcap-diff+xml"
document that carries consent-related state information using
<consent-status> elements:
<?xml version="1.0" encoding="UTF-8"?>
<resource-lists xmlns="urn:ietf:params:xml:ns:resource-lists"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:cs="urn:ietf:params:xml:ns:consent-status">
<list name="friends">
<entry uri="sip:bill@example.com">
<display-name>Bill Doe</display-name>
<cs:consent-status>pending</cs:consent-status>
</entry>
<entry uri="sip:joe@example.com">
<display-name>Joe Smith</display-name>
<cs:consent-status>pending</cs:consent-status>
</entry>
<entry uri="sip:nancy@example.com">
<display-name>Nancy Gross</display-name>
<cs:consent-status>granted</cs:consent-status>
</entry>
</list>
</resource-lists>
5. Usage of the 'list-state' Event Package with the XCAP Diff Format
As discussed in Section 4.1.4, if a client subscribing to the 'list-
state' event package an Accept header field including the MIME type
"application/xcap-diff+xml", the permission server has the option of
returning documents in this format (instead of in the 'application/
list-state+xml' format).
Upon initial subscription, the permission server does not know which
instance of the resource list document for the user (where each
instance is identified by an etag) the client currently posessses, if
any. Indeed, upon startup, the client will not have any documents.
The initial NOTIFY request in this case MUST include a <document>
element for the resource list. The "previous-etag" attribute MUST be
absent, and the "new-etag" attribute MUST be present and contain the
entity tag for the current version of the document. An XCAP diff
document structured this way is called a "reference" XCAP diff
document. It establishes the baseline etag and document URI for the
document covered by the subscription.
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Upon receipt of this document, the client can determine whether its
local instance document, if any, matches the etag in the XCAP diff
document. If they do not match, the client SHOULD perform a
conditional GET for each document. The document URI is constructed
by appending the XCAP root in the "xcap-root" attribute of the <xcap-
diff> element to the escape coded "doc-selector" from the <document>
element. The request is made conditional by including an If-Match
header field, with the value of the etag from the <document> element.
So long as the documents haven't changed between the NOTIFY and the
GET, the client will obtain the reference version that the server
will use for subsequent notifications.
If the conditional GET should fail, the client SHOULD generate a
SUBSCRIBE refresh request to trigger a new NOTIFY. The server will
always generate a "reference" XML diff document on receipt of a
SUBSCRIBE refresh. This establishes a new baseline etag, and the
client can then attempt to do another fetch.
Once the client has obtained the version of the document identified
in the reference XML diff, it can process NOTIFY requests on that
subscription. To process the NOTIFY requests, it makes sure that its
current version matches the version in the "previous-etag" attribute
of the <document> element. If not, the client can then fetch the
updated document from the server. If they do match, the client has
the most current version.
6. List State RLS Service
TBD: Define the 'List State' RLS service [5]. Example:
<packages>
<package>presence</package>
<package>list state</package>
</packages>
7. IANA Considerations
TBD.
8. Security Considerations
TBD.
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9. Acknowledgements
TBD.
10. References
10.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:
Session Initiation Protocol", RFC 3261, June 2002.
[3] Roach, A., "Session Initiation Protocol (SIP)-Specific Event
Notification", RFC 3265, June 2002.
[4] Rosenberg, J., "A Framework for Consent-Based Communications in
the Session Initiation Protocol (SIP)",
draft-ietf-sipping-consent-framework-03 (work in progress),
October 2005.
[5] Rosenberg, J., "Extensible Markup Language (XML) Formats for
Representing Resource Lists",
draft-ietf-simple-xcap-list-usage-05 (work in progress),
February 2005.
[6] Rosenberg, J., "An Extensible Markup Language (XML) Document
Format for Indicating A Change in XML Configuration Access
Protocol (XCAP) Resources", draft-ietf-simple-xcap-diff-02 (work
in progress), October 2005.
[7] Camarillo, G., "Session Initiation Protocol (SIP) Registration
Event Package Extension for Consent-Based Communications",
draft-camarillo-sipping-consent-reg-event-00 (work in progress),
February 2006.
10.2. Informative References
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Author's Address
Gonzalo Camarillo
Ericsson
Hirsalantie 11
Jorvas 02420
Finland
Email: Gonzalo.Camarillo@ericsson.com
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