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Versions: 00 draft-ietf-simple-winfo-filter-reqs

Network Working Group                                       K. Kiss
Internet-Draft                                          E. Leppanen
Expires: August 25, 2003                               H. Khartabil
                                                              Nokia
                                                  February 24, 2003




            Requirements for Filtering of Watcher Information
                 draft-kiss-simple-winfo-filter-reqs-00




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
   Task Force (IETF), its areas, and its working groups.  Note that
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Copyright Notice

   Copyright (C) The Internet Society (2003).  All Rights Reserved.


Abstract

   This document defines a set of structured requirements whereby a
   watcher information subscriber (client) may select specific
   information to be received in the watcherinfo notification sent by
   the notifier (server). The purpose is to limit the content so that
   only essential information is delivered by the server.

   Also the preference for full or partial state information is
   considered in requirements.







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Table of Contents

      1 Introduction                                                 3
      2 Conventions used in this document                            3
      3.1 Common syntax                                              3
      3.2 Package Identification                                     3
      3.3 Target URI                                                 3
      3.4 Notification Content Limiting                              3
         3.4.1 Logical Expressions                                   4
         3.4.2 Status                                                4
         3.4.3 Event causing the transition                          4
         3.4.4 Expiration                                            4
         3.4.5 Duration of subscription                              4
         3.4.6 Selected watchers                                     4
         3.4.7 Partial or full state                                 4
      4.1 SUBSCRIBE method                                           4
         4.1.1 Retention of filter settings                          5
         4.1.2 Changing filter settings                              5
      4.2 Server does not support filters                            5
      4.3 Server does not support filter settings                    5
      4.4 Server can no longer support filter settings               5
      5    Security considerations                                   5
      6    Example Applications for Notification Filtering           5
      7    Acknowledgements                                          6
      8    Normative References                                      6
      9    Informative References                                    6
      10   Author's Addresses                                        6

1    Introduction

   SIP event notification is described in [2]. It defines a general
   framework for subscriptions and notifications for SIP event packages.
   Concrete applications of the general event framework to a specific
   group of events are described in [3] (user presence) and [4] (watcher
   information).

   The watcher information refers to the set of users subscribed to a
   particular resource within a particular event package. Watcher
   information changes dynamically as users subscribe, unsubscribe, are
   approved, or rejected. A client can subscribe to this information.

   As the inherent usage of event packages grows, the client needs some
   mechanisms for controlling the event notifications at the source.
   Evidence of this need is found in [6].

   The Internet Draft describing the watcher information template
   package [4] mentions the possibility for filtering. Accordingly, the
   SUBSCRIBE request may contain a body for filtering the watcher
   information subscription. However, the definition of filtering has
   been left out of the scope of the Internet Draft. As an example, the
   body of the SUBSCRIBE request may include an indication whether the
   notifications should contain partial or full state information.




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   These mechanisms are expected to be particularly valuable to users of
   wireless devices. The characteristics of these devices typically
   include low bandwidth, low data processing capabilities, small
   display and limited battery power. Such devices can benefit from the
   ability to filter the amount of information generated at the source
   of the event notification.

   However, it is expected that the control mechanisms for event
   notifications add value for all users irrespectively of their device
   or network access characteristics.

   Sections 3 and 4 of this draft propose a set of requirements whereby
   a client may specify which notifications it is interested in. That
   is, a means to specify filtering rules to be executed by the server.
   Section 6 provides a few example applications of notification
   filtering.

2    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 [5].

3     Requirements for Specification of Filters

   The following requirements relate to the creation of filters (rules).

3.1  Common syntax

   A common set of constructs MUST be defined for the creation of rules.
   There MUST be a common set of operations that follow a common syntax.
   The client MUST be possible to define different rules for different
   purposes using a common filtering mechanism.

3.2  Package Identification

   A means is REQUIRED whereby the client may specify the package the
   rules apply to.

3.3  Target URI

   It MUST be possible for the client to indicate the target user to
   which a certain filter criteria is applied.

3.4  Notification Content Limiting

   This chapter presents requirements for specifying the content to be
   sent in the notifications.

   It MUST be possible for the client to specify the watcher XML
   elements [5] to be delivered in the notification.




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3.4.1     Logical Expressions

   It MUST be possible to specify logical expressions based on the value
   of elements defined in the template-package for the purpose of
   determining what to send in the notification.

   It MUST be possible to construct expressions that combine multiple
   tests.

3.4.2     Status

   The client MUST be able to indicate to the server to include only
   those watchers in the notifications which are in a specific status.

3.4.3     Event causing the transition

   The client MUST be able to indicate to the server to include only
   those watchers in the notifications which are transitioned in their
   current status because of a specific event.

3.4.4     Expiration

   The client MUST be able to indicate to the server to include only
   those watchers in the notifications which have subscription lifetime
   higher than (less than) a specific amount of seconds.

3.4.5     Duration of subscription

   The client MUST be able to indicate to the server to include only
   those watchers in the notifications which are subscribed for a
   duration higher than (less than) a specific amount of seconds.

3.4.6     Selected watchers

   The client MUST be able to indicate to the server to include only
   certain watchers (e.g. watchers from a particular domain, specific
   watchers defined by the filters) in the notifications.

3.4.7     Partial or full state

   It MUST be possible for the client to be able to select whether full
   or partial state of the watcher information is delivered.

4    Requirements for uploading rules (Operational Rules)

   It MUST be possible for the client to upload the rules to the server
   and know the status - accepted or rejected.

4.1  SUBSCRIBE method

   Placing filtering rules in the body of the subscription MUST be
   supported.



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4.1.1     Retention of filter settings

   The server MUST retain the uploaded filter setting for the duration
   of the subscription.

4.1.2     Changing filter settings

   It MUST be possible to change the filter settings during a
   subscription.

   It MUST be possible for the client to reset the filter settings to
   the service (server) defined default.

4.2  Server does not support filters

   If the server does not support filters (the content type) then it
   MUST be able to indicate so in a response.

4.3  Server does not support filter settings

   If the server does not support or understand the filter settings, it
   MUST explicitly indicate so in a response to the SUBSCRIBE request
   or in the NOTIFY request.

   The server MAY indicate the general reason the request is not
   supported or understood, e.g. by returning a specific reason value
   for the event.

4.4  Server can no longer support filter settings

   The server MUST be able to terminate the subscription if the active
   filter is no longer applicable due to a policy in the server.


5    Security considerations

   Further security requirements over [3] have not yet been identified.


6    Example Applications for Notification Filtering

     *    A presentity wishes to see who has subscribed to their presence.
        The presentity only wishes to see information for subscribers who
        are co-workers.

     *    A presentity makes subscription to get information about active
        watchers.

     *    A presentity makes subscription to get information about
        defined, new or unauthorised watchers.

     *    A presentity requests history information of watchers.

     *    A user requests full state information every time something
        changes.


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7    Acknowledgements

   The authors would like to thank Jonathan Rosenberg, Tim Moran and
   Juha Kalliokulju for their valuable input.


8    Normative References

   [1]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
      Levels", BCP 14, RFC 2119, March 1997


9    Informative References

   [2]  Roach, A., "Session Initiation Protocol (SIP)-Specific Event
      Notification", RFC 3265, June 2002

   [3]  Rosenberg, J., "A Presence Event package for the Session
      Initiation Protocol (SIP)", draft-ietf-simple-presence-10, Internet
      Draft, January 2003, work in progress

   [4]  Rosenberg, J., "A Watcher Information Event Template-Package for
      the Session Initiation Protocol (SIP)",
      draft-ietf-simple-winfo-package-05, Internet Draft, January 2003,
      work in progress

   [5]  Rosenberg, J., "An Extensible Markup Language (XML) Based Format
      for Watcher Information", draft-ietf-simple-winfo-format-04,
      Internet Draft, January 2003, work in progress

   [6]  Kiss, K., "Requirements for Presence Service in 3GPP Wireless
      Systems", draft-kiss-simple-presence-wireless-reqs-02.txt,
      February 2003


10   Author's Addresses

      Krisztian Kiss
      Nokia
      P.O. Box 100
      FIN-33721 Tampere
      FINLAND
      Tel: +358 50 4835363
      E-mail: krisztian.kiss@nokia.com

      Eva Leppanen
      Nokia
      P.O Box 785
      FIN-33101 Tampere
      FINLAND
      Tel: +358 7180 77066
      E-mail: eva-maria.leppanen@nokia.com




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      Hisham Khartabil
      Nokia
      P.O. Box 321
      FIN-00045 NOKIA GROUP
      FINLAND
      Tel: + 358 7180 76161
      E-mail: hisham.khartabil@nokia.com


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Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.













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