Network Working Group                                        S. Chisholm
Internet-Draft                                                    Nortel
Intended status: Standards Track                              H. Trevino
Expires: January 9, March 13, 2008                                            Cisco
                                                            July 8,
                                                      September 10, 2007

                      NETCONF Event Notifications
           draft-ietf-netconf-notification-08.txt.pre-release
                 draft-ietf-netconf-notification-09.txt

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Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   This document defines mechanisms which that provide an asynchronous message
   notification delivery service for the NETCONF protocol.  This is an
   optional capability built on top of the base NETCONF definition.
   This document defines the capabilities and operations necessary to
   support this service.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  Definition of Terms  . . . . . . . . . . . . . . . . . . .  4
     1.2.  Motivation . . . . . . . . . . . . . . . . . . . . . . . .  5
     1.3.  Event Notifications in NETCONF . . . . . . . . . . . . . .  5
     1.4.  Requirements . . . . . . . . . . . . . . . . . . . . . . .  6
   2.  Notification-Related Operations  . . . . . . . . . . . . . . .  7
     2.1.  Subscribing to Receive Event Notifications . . . . . . . .  7
       2.1.1.  <create-subscription>  . . . . . . . . . . . . . . . .  7
     2.2.  Sending Event Notifications  . . . . . . . . . . . . . . .  9
       2.2.1.  <notification> . . . . . . . . . . . . . . . . . . . .  9
     2.3.  Terminating the Subscription . . . . . . . . . . . . . . . 10
   3.  Supporting Concepts  . . . . . . . . . . . . . . . . . . . . . 11
     3.1.  Capabilities Exchange  . . . . . . . . . . . . . . . . . . 11
       3.1.1.  Capability Identifier  . . . . . . . . . . . . . . . . 11
       3.1.2.  Capability Example . . . . . . . . . . . . . . . . . . 11
     3.2.  Event Streams  . . . . . . . . . . . . . . . . . . . . . . 11
       3.2.1.  Event Stream Definition  . . . . . . . . . . . . . . . 12 13
       3.2.2.  Event Stream Content Format  . . . . . . . . . . . . . 13
       3.2.3.  Default Event Stream . . . . . . . . . . . . . . . . . 13
       3.2.4.  Event Stream Sources . . . . . . . . . . . . . . . . . 13
       3.2.5.  Event Stream Discovery . . . . . . . . . . . . . . . . 13
     3.3.  Notification Replay  . . . . . . . . . . . . . . . . . . . 15 16
       3.3.1.  Overview . . . . . . . . . . . . . . . . . . . . . . . 15 16
       3.3.2.  Creating a Subscription with Replay  . . . . . . . . . 16
       3.3.3.  Replay Complete Notification . . . . . . . . . . . . . 16 17
     3.4.  Notification Management Schema . . . . . . . . . . . . . . 16 17
     3.5.  Subscriptions Data . . . . . . . . . . . . . . . . . . . . 19 21
     3.6.  Filter Mechanics . . . . . . . . . . . . . . . . . . . . . 19 21
       3.6.1.  Filtering  . . . . . . . . . . . . . . . . . . . . . . 19 21
     3.7.  Message Flow . . . . . . . . . . . . . . . . . . . . . . . 19 21
   4.  XML Schema for Event Notifications . . . . . . . . . . . . . . 21 24
   5.  Filtering Examples . . . . . . . . . . . . . . . . . . . . . . 25 28
     5.1.  Subtree Filtering  . . . . . . . . . . . . . . . . . . . . 25 32
     5.2.  XPATH filters  . . . . . . . . . . . . . . . . . . . . . . 28 33
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 30 35
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 31 36
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 32 37
   9.  Normative References . . . . . . . . . . . . . . . . . . . . . 33 38
   Appendix A.  Change Log  . . . . . . . . . . . . . . . . . . . . . 34 39
     A.1.  Version -08  . . . . . . . . . . . . . . . . . . . . . . . 34 39
     A.2.  Version -09  . . . . . . . . . . . . . . . . . . . . . . . 41
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 37 44
   Intellectual Property and Copyright Statements . . . . . . . . . . 38 45

1.  Introduction

   [NETCONF] can be conceptually partitioned into four layers:

   Layer                      Example
    +-------------+      +----------------------------------------+
    |   Content   |      |     Configuration data                 |
    +-------------+      +----------------------------------------+
              |                           |
    +-------------+      +-------------------------------------------+
    | Operations  |      | <get-config>, <edit-config> <notification>|
    +-------------+      +-------------------------------------------+
              |                           |                    |
    +-------------+      +-----------------------------+       |
    |     RPC     |      |    <rpc>, <rpc-reply>       |       |
    +-------------+      +-----------------------------+       |
             |                           |                     |
    +-------------+      +------------------------------------------+
    | Transport   |      |   BEEP, SSH, SSL, console                |
    |   Protocol  |      |                                          |
    +-------------+      +------------------------------------------+

                                 Figure 1

   This document defines mechanisms which provide an asynchronous
   message notification delivery service for the [NETCONF] protocol.
   This is an optional capability built on top of the base NETCONF
   definition.  This memo defines the capabilities and operations
   necessary to support this service.

1.1.  Definition of Terms

   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].

   Element:  An [XML] Element.

   Subscription:  An agreement and method to receive event notifications
      over a NETCONF session.  A concept related to the delivery of
      notifications (if there are any to send) involving destination and
      selection of notifications.  It is bound to the lifetime of a
      session.

   Operation:  This term is used to refer to NETCONF protocol operations
      [NETCONF].  Specifically within  Within this document, operation refers to NETCONF
      protocol operations defined in support of NETCONF notifications.

   Event:  An event is something that happens which may be of interest -
      a configuration change, a fault, a change in status, crossing a
      threshold, or an external input to the system, for example.  Often
      this results in an asynchronous message, sometimes referred to as
      a notification or event notification, being sent to interested
      parties to notify them that this event has occurred.

   Replay:  The ability to send/re-send previously logged notifications
      upon request.  These notifications are sent asynchronously.  This
      feature is implemented by the NETCONF server and invoked by the
      NETCONF client.

   Stream:  An event stream is a set of event notifications matching
      some forwarding criteria and it is available to NETCONF clients for
      subscription.

   Filter:  A parameter that indicates which subset of all possible
      events are of interest.  A filter is defined as one or more filter
      element [NETCONF], which each identifies a portion of the overall
      filter.

1.2.  Motivation

   The motivation for this work is to enable the sending of asynchronous
   messages that are consistent with the data model (content) and
   security model used within a NETCONF implementation.

1.3.  Event Notifications in NETCONF

   This memo defines a mechanism whereby

   The scope of the NETCONF client indicates
   interest work aims meeting the following operational needs:

   o  Initial release should ensure it supports notifications in receiving event support
      of configuration operations.

   o  It should be possible to use the same data model for notifications from
      as for configuration operations.

   o  Solution should support a NETCONF server by
   creating reasonable message size limit (i.e., not
      too short)

   o  The notifications should be carried over a connection-oriented
      delivery mechanism.

   o  A subscription to receive event notifications.  The mechanism for notifications should be provided.
      This takes into account that a NETCONF server replies to indicate whether the subscription request was
   successful and, if it was successful, begins sending the event does not send
      notifications before being asked to do so and that it is the
      NETCONF client as the events occur within who initiates the
   system.  These event notifications will continue to be sent flow of notifications.

   o  A filtering mechanism for sending notifications should be put in
      place within the NETCONF server.

   o  The information contained in a notification should be sufficient
      so that it can be analyzed independent of the transport mechanism.
      In other words the data content fully describes a notification;
      protocol information is not needed to understand a notification.

   o  The server should have the capability to replay locally logged
      notifications.

1.3.  Event Notifications in NETCONF

   This memo defines a mechanism whereby the NETCONF client indicates
   interest in receiving event notifications from a NETCONF server by
   creating a subscription to receive event notifications.  The NETCONF
   server replies to indicate whether the subscription request was
   successful and, if it was successful, begins sending the event
   notifications to the NETCONF client as the events occur within the
   system.  These event notifications will continue to be sent until
   either the NETCONF session is terminated or the subscription
   terminates for some other reason.  The event notification
   subscription allows a number of options to enable the NETCONF client
   to specify which events are of interest.  These are specified when
   the subscription is created.

   A

   The NETCONF server is will not read RPC requests, by default, on the
   session associated with MUST accept and process the subscription until close-session
   operation, even while the notification subscription is done.  A capability may be advertised to announce
   that a active.  The
   NETCONF server is able to MAY accept and process RPCs while a notification stream is
   active on other commands, otherwise they
   will be rejected and the server MUST send a session.  The behaviour 'resource-denied' error.
   An example of such when other commands would be processed is if a separate
   capability is outside
   the scope was advertised indicating support of this document.

1.4.  Requirements functionality.

2.  Notification-Related Operations

2.1.  Subscribing to Receive Event Notifications

   The following requirements have been addressed event notification subscription is initiated by the solution:

   o  Initial release should ensure it supports notification in support
      of configuration operations

   o  Data content must not preclude the use of the same data model as
      used in configuration

   o  Solution should support a reasonable message size limit (ie, not
      too short)

   o  Solution should provide reliable delivery of notifications

   o  Solution should provide a subscription mechanism (A NETCONF server
      does not send notifications before being asked to do so and the
      NETCONF client initiates the flow of notifications)

   o  Solution should provide a filtering mechanism within NETCONF
   client and responded to by the NETCONF
      server

   o  Solution should send sufficient information in a notification so
      that it can be analyzed independent of the transport mechanism
      (data content fully describes a notification; protocol information server.  A subscription is not needed
   bound to understand a notification)

   o  Solution should support replay of locally logged notifications

2.  Notification-Related Operations

2.1.  Subscribing to Receive Event Notifications

   The event notification subscription is initiated by single stream for the NETCONF
   client and responded to by lifetime of the NETCONF server. subscription.  When
   the event notification subscription is created, the events of
   interest are specified.

   Content for an event notification subscription can be selected by
   applying user-specified filters.

2.1.1.  <create-subscription>

   Description:

      This operation initiates an event notification subscription which
      will send asynchronous event notifications to the initiator of the
      command until the subscription terminates.

   Parameters:

      Stream:

         An optional parameter parameter, <stream>, that indicates which stream of
         events is of interest.  If not present, then events in the default
         NETCONF stream will be sent.

      Filter:

         An optional parameter parameter, <filter>, that indicates which subset of
         all possible events are is of interest.  The format of this
         parameter is the same as that of the filter parameter in the
         NETCONF protocol operations.  If not present, all events not
         precluded by other parameters will be sent.  See section 3.6
         for more information on filters.

      Start Time:

         A parameter parameter, <startTime>, used to trigger the replay feature
         and indicate that the replay should start at the time
         specified.  If
         startTime <startTime> is not present, this is not a replay
         subscription.  It is not valid to specify start times that are
         later than the current time.  If the startTime <startTime> specified is
         earlier than the log can support, the replay will begin with
         the earliest available notification.  This parameter is of type
         dateTime.

      Stop Time:

         An optional parameter parameter, <stopTime>, used with the optional
         replay feature to indicate the newest notifications of
         interest.  If stop time is not present, the notifications will
         continue until the subscription is terminated.  Must be used
         with and be later than 'startTime'.  It is valid to specify <startTime>.  A stop times that are is later
         than the current time. time, will be interpreted as being the time of
         the subscription creation (current time).  This parameter is of
         type dateTime.

   Positive Response:

      If the NETCONF server can satisfy the request, the server sends an
      <ok> element.

   Negative Response:

      An <rpc-error> element is included within the <rpc-reply> if the
      request cannot be completed for any reason.  Subscription requests
      will fail if a filter with invalid syntax is provided or if the
      name of a non-existent profile or stream is provided.

      If a stopTime <stopTime> is specified in a request without having specified
      a
      startTime <startTime>, the following error is returned:

         Tag: missing-element

         Error-type: protocol

         Severity: error

         Error-info: <badElement>: <bad-element>: startTime

         Description: An expected element is missing.

      If the optional replay feature is requested but it is not
      supported by the NETCONF server, the following error is returned:

         Tag: operation-failed

         Error-type: protocol

         Severity: error
         Error-info: none

         Description: Request could not be completed because the
         requested operation failed for some reason not covered by any
         other error condition

2.1.1.1.  Usage Example

   The following demonstrates creating a simple subscription.  More
   complex examples can be found in section 5.

   <netconf:rpc message-id="101"
         xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
         xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0"/>
       <create-subscription
           xmlns="urn:ietf:params:netconf:capability:notification:1.0">
       </create-subscription>
   </netconf:rpc>

                                 Figure 2

2.2.  Sending Event Notifications

   Once the subscription has been set up, the NETCONF server sends the
   event notifications asynchronously over the connection.

2.2.1.  <notification>

   Description:

      An event notification is sent to the client who initiated a
      <create-subscription> command asynchronously when an event of
      interest (i.e., meeting the specified filtering criteria) to them has
      occurred.  An event notification is a complete and well-formed XML
      document.  Note that <notification> is not an RPC method but
      rather the top level element identifying the one way one-way message as a
      notification.

   Parameters:

         Contains

      eventTime

         The time the event was generated by the event source

      Also contains notification-specific tagged content.  The content, if any.  With
      the exception of <eventTime>, the content of the data tag notification is
      beyond the scope of this document.

   Response:

      No response.  Not applicable.

2.3.  Terminating the Subscription

   Closing of the event notification subscription can be done by
   terminating the NETCONF session ( <kill-session> ) or the underlying
   transport session.  If a stop time is provided when the subscription
   is created, then the subscription will terminate after the stop time is
   reached.  In this case, the NETCONF session will still be an active
   session.

3.  Supporting Concepts

3.1.  Capabilities Exchange

   The ability to process and send event notifications is advertised
   during the capability exchange between the NETCONF client and server.

3.1.1.  Capability Identifier

   "urn:ietf:params:netconf:capability:notification:1.0"

3.1.2.  Capability Example

   <hello xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <capabilities>
        <capability>
            urn:ietf:params:xml:ns:netconf:base:1.0
          </capability>
          <capability>
            urn:ietf:params:netconf:capability:startup:1.0
          </capability>
          <capability>
            urn:ietf:params:netconf:capability:notification:1.0
          </capability>
       </capabilities>
     <session-id>4</session-id>
   </hello>

                                 Figure 3

3.2.  Event Streams

   An event stream is defined as a set of event notifications matching
   some forwarding criteria.

   The diagram depicted in

   Figure 2 illustrates the notification flow and concepts identified in
   this document.  The following is observed from the diagram below:
   System components (c1..cn) generate event notifications which are
   passed to a central component for classification and distribution.
   The central component inspects each event notification and matches
   the event notification against the set of stream definitions.  When a
   match occurs, the event notification is considered to be a member of
   that event stream (stream 1..stream n).  An event notification may be
   part of multiple event streams.

   When a

   At some point after the NETCONF client subscribes to a given server receives the internal event
   from a stream, user-
   defined filters, if applicable, are applied it is converted to an appropriate XML encoding by the event stream
   server, and
   matching event notifications are forwarded to the a <notification> element is ready to send to all NETCONF
   sessions subscribed to that stream.

   After generation of the <notification> element, access control is
   applied by the server.  If a session does not have permission to
   receive the <notification>, then it is discarded for that session,
   and processing of the internal event is completed for that session.

   When a NETCONF client subscribes to a given event stream, user-
   defined filter elements, if applicable, are applied to the event
   stream and matching event notifications are forwarded to the NETCONF
   server for distribution to subscribed NETCONF clients.  A filter is
   transferred from the client to the server during the <create-
   subscription> operation and applied against each <notification>
   element generated by the stream.  For more information on
   filters, filtering,
   see section 3.6.

   A notification logging service may also be available, in which case,
   the central component logs notifications.  The NETCONF server may
   later retrieve logged notifications via the optional replay feature.
   For more information on replay, see section 3.3.

   +----+
   | c1 |----+             available streams
   +----+    |    +---------+
   +----+    |    |central  |-> stream 1
   | c2 |    +--->|event    |-> stream 2     filter  +-------+
   +----+    |    |processor|-> NETCONF stream ----->|netconf| ----->|NETCONF|
    ...      |    |         |-> stream n             |server |
   System    |    +---------+                        +-------+
   Components|        |                                 /\
    ...      |        |                                 ||
   +----+    |        |       (------------)            ||
   | cn |----+        |       (notification)            ||
   +----+             +-----> (  logging   )            ||
                              (  service   )            ||
                              (------------)            ||
                                                        ||
                                                        ||
                                                        \/
                                                    +-------+
                                                    |netconf|
                                                    |NETCONF|
                                                    |client |
                                                    +-------+

                                 Figure 4 2

3.2.1.  Event Stream Definition

   Event streams are predefined on the managed device.  The
   configuration of event streams is outside the scope of this document.
   However, it is envisioned that event streams are either pre-
   established by the vendor (pre-configured) or (pre-configured), user configurable (e.g.,
   part of the device's configuration) or both.  Device vendors may
   allow event stream configuration via the NETCONF protocol (i.e.,
   edit-config operation).

3.2.2.  Event Stream Content Format

   The contents of all event streams made available to a NETCONF client
   (i.e., the notification sent by the NETCONF server) must be encoded
   in XML.

3.2.3.  Default Event Stream

   A NETCONF server implementation supporting the notification
   capability must support the "NETCONF" notification event stream.
   This stream contains all NETCONF XML event notifications supported by
   the NETCONF server.  The definition exact string "NETCONF" is used during
   advertisement of stream support during the <get> operation on
   <streams> and during the <create-subscription> operation.  Definition
   of the event notifications and their contents contents, beyond the inclusion
   of <eventTime>, for this event stream is outside the scope of this
   document.

3.2.4.  Event Stream Sources

   With the exception of the default event stream (NETCONF
   notifications) (NETCONF),
   specification of additional event stream sources (e.g., SNMP, syslog, etc.) syslog)
   is outside the scope of this document.  NETCONF server
   implementations may leverage any desired event stream source in the
   creation of supported event streams.

3.2.5.  Event Stream Discovery

   A NETCONF client retrieves the list of supported event streams from a
   NETCONF server using the <get> RPC request. operation.

3.2.5.1.  Name Retrieval using <get> operation

   The list of available event streams is retrieved by requesting the
   <eventStreams>
   <streams> subtree via a <get> operation.  Available event streams for
   the requesting session are returned in the reply containing the
   <name> and <description> elements, where the <name> element is mandatory
   mandatory, and its value is unique within the scope of a NETCONF
   server.  The returned list must only include the names of
   those event streams for which the NETCONF session has sufficient
   privileges.  The NETCONF session privileges are determined via access
   control mechanisms which are beyond the scope of this document.  An empty reply is returned if there are no available event
   streams.  The

   Additional information available about a stream include whether
   notification replay is retrieved by requesting available and if so, the <eventStreams> subtree via
   a <get> operation.

   Example: Retrieving timestamp of the
   earliest possible notification to replay.

   The following example shows retrieving the list of available event
   stream list using the <get>
   operation: operation.

   <rpc message-id="101"
      xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <get>
      <filter type="subtree">
      <eventStreams xmlns="urn:ietf:params:xml:ns:netmod:notification"/>
        <netconf xmlns="urn:ietf:params:xml:ns:netmod:notification">
           <streams/>
         <netconf>
      </filter>
     </get>
   </rpc>

                                 Figure 5
   The NETCONF server returns a list of event streams available for
   subscription: NETCONF, SNMP, and syslog-critical in this example.

   <rpc-reply message-id="101"
                    xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <data>
     <eventStreams
       <netconf  xmlns="urn:ietf:params:xml:ns:netmod:notification">
        <streams>
           <stream>
              <name>NETCONF</name>
           <description>Default netconf
              <description>default NETCONF event stream
              </description>
              <replaySupport>true</replaySupport>
           <replayLogStartTime>2007-07-08T00:00:00Z</replayLogStartTime>
              <replayLogCreationTime>
                2007-07-08T00:00:00Z
              </replayLogCreationTime>
           </stream>
           <stream>
              <name>SNMP</name>
              <description>SNMP notifications</description>
              <replaySupport>false</replaySupport>
           </stream>
           <stream>
             <name>syslog-critical</name>
             <description>Critical and higher severity
             </description>
             <replaySupport>true</replaySupport>
          <replayLogStartTime>2007-07-01T00:00:00Z</replayLogStartTime>
             <replayLogCreationTime>
               2007-07-01T00:00:00Z
             </replayLogCreationTime>
            </stream>
      </eventStreams>
           </streams>
         </netconf>
     </data>
   </rpc-reply>
                                 Figure 6

3.2.5.2.  Event Stream Subscription

   A NETCONF client may request from the NETCONF server the list of
   event streams available to this session and then issue a <create-
   subscription> request with the desired event stream name.  Omitting
   the event stream name from the <create-subscription> request results
   in subscription to the default NETCONF event stream.

3.2.5.2.1.  Filtering Event Stream Contents

   The set of event notifications delivered in an event stream may be
   further refined by applying a user-specified filter supplied at
   subscription creation time ( <create-subscription> ).  This is a
   transient filter associated with the event notification subscription
   and does not modify the event stream configuration.  The filter
   element is applied against the contents of the <notification> wrapper
   and not the wrapper itself.  See section 5 for examples.  Either
   subtree or XPATH filtering can be used.

   XPATH support for the Notification capability is advertised as part
   of the normal XPATH capability advertisement.  If XPATH support is
   advertised via the XPATH capability then XPATH is supported for
   notification filtering and if this capability is not advertised, then
   XPATH is not supported for notification filtering.

3.3.   Notification Replay

3.3.1.  Overview

   Replay is the ability to create an event subscription that will
   resend recently generated notifications, or in some cases send them
   for the first time to a particular NETCONF client.  These
   notifications are sent the same way as normal notifications.

   A replay of notifications is specified by including an the optional
   <startTime> parameter to the subscription command that command, which indicates
   the start time of the replay.  The end time is specified using the
   optional stopTime <stopTime> parameter.  If not present, notifications will
   continue to be sent until the subscription is terminated.

   A notification stream that supports replay is not expected to have an
   unlimited supply of saved notifications available to accommodate any
   replay request.

   The actual number of stored notifications available for retrieval at
   any given time is a NETCONF server implementation specific matter.
   Control parameters for this aspect of the feature are outside the
   scope of the current this document.

   Replay is dependent on a notification stream supporting some form of
   notification logging, although it puts no restrictions on the size or
   form of the log, nor or where it resides within the device.  Whether or
   not a stream supports replay can be discovered by doing a <get>
   operation on the eventStreams <streams> element of the Notification Management
   Schema.  This schema also provides
   Schema and looking at the replayLogStartTime value of the <replaySupport> object.  This
   schema also provides the <replayLogCreationTime> element to indicate
   the earliest available logged notification.

3.3.2.  Creating a Subscription with Replay

   This feature uses optional parameters to the <create-subscription>
   command called 'startTime' <startTime> and 'stopTime'. 'startTime' <stopTime>. <startTime> identifies the
   earliest date and time of interest for event notifications being
   replayed and also indicates that a subscription will be providing
   replay of notifications.  Events generated before this time are not
   matched. 'stopTime' <stopTime> specifies the latest date and time of interest
   for event notifications being replayed.  If it is not present, then
   notifications will continue to be sent until the subscription is
   terminated.

   Note that startTime <startTime> and stopTime <stopTime> are associated with the time an
   event was generated by the system. event source.

   A replayComplete <replayComplete> notification is sent to indicate that all of the
   replay notifications have been sent.  If this subscription has a stop
   time, then this session becomes a normal NETCONF session again.  When
   a <stopTime> has been specified, <notificationComplete> notification
   is the last notification sent on the subscription before it
   terminates and the NETCONF session returns to being a normal NETCONF
   session.  The NETCONF server will then accept <rpc> operations.  In
   the case of a subscription without a stop time, after the
   replayComplete
   <replayComplete> notification has been sent, it can be expected that
   any notifications generated since the start of the subscription
   creation will be sent sent, followed by notifications as they arise
   naturally within the system.

3.3.3.  Replay Complete Notification

   The replayComplete notification is the last notification sent over a
   replay subscription.  It indicates that replay is complete.  After
   this notification is received the subscription is terminated <replayComplete> and the
   session becomes normal command-response NETCONF session.

   The replayComplete can not <notificationComplete> notifications cannot
   be filtered out.  It  They will always be sent on a relay replay subscription
   that specified a stop time. startTime and stopTime respectively.

3.4.  Notification Management Schema

   This Schema is used to learn about the event streams supported on the
   system.  It also contains the definition of the replayComplete, <replayComplete> and
   <notificationComplete> notifications, which
   is are sent to indicate that
   an event replay has sent all applicable
   notifications." notifications and that the
   subscription has terminated, respectively.

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
    xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0"
    xmlns:ncEvent="urn:ietf:params:netconf:capability:notification:1.0"
    xmlns:manageEvent="urn:ietf:params:xml:ns:netmod:notification"
    targetNamespace="urn:ietf:params:xml:ns:netmod:notification"
    elementFormDefault="qualified"
    attributeFormDefault="unqualified">
    attributeFormDefault="unqualified"
    xml:lang="en" version="1.0">
    <xs:annotation>
        <xs:documentation xml:lang="en">
            A schema that can be used to learn about current
            event streams. It also contains the replayComplete
            and notificationComplete  notification.
        </xs:documentation>
    </xs:annotation>

<xs:import namespace="http://www.w3.org/XML/1998/namespace"
        schemaLocation="http://www.w3.org/2001/xml.xsd"/>
<xs:import namespace="urn:ietf:params:xml:ns:netconf:base:1.0"
    schemaLocation=
     "http://www.iana.org/assignments/xml-registry/schema/netconf.xsd"/>
<xs:import namespace=
    "urn:ietf:params:netconf:capability:notification:1.0"
      schemaLocation=
"http://www.iana.org/assignments/xml-registry/schema/notification.xsd"/>
<!-- The above  schemaLocation value is a placeholder and the actual
                                      value will be assigned by IANA -->

<xs:element name="netconf" type="manageEvent:Netconf"/>

<xs:complexType name="Netconf">
  <xs:sequence>
      <xs:element name="eventStreams" name="streams" >
        <xs:annotation>
           <xs:documentation>
             The list of event streams supported by the
             system. When a query is issued, the returned
             set of streams is determined based on user
             privileges.
           </xs:documentation>
         </xs:annotation>
         <xs:complexType>
           <xs:sequence minOccurs="0" minOccurs="1" maxOccurs="unbounded">
             <xs:element name="stream">
                <xs:annotation>
                  <xs:documentation>
                    Stream name name, description and description. other information.
                  </xs:documentation>
                </xs:annotation>
                <xs:complexType>
                  <xs:sequence>
                    <xs:element name="name" type="xs:string"/>
                            type="ncEvent:streamNameType">
                       <xs:annotation>
                         <xs:documentation>
                           The name of the event stream. If this is
                           the default NETCONF stream, this must have
                           the value "NETCONF".
                         </xs:documentation>
                       </xs:annotation>
                    </xs:element>
                    <xs:element name="description"
                                        type="xs:string"/>
                                        type="xs:string">
                       <xs:annotation>
                         <xs:documentation>
                           A description of the event stream, including
                           such information as the type of events that
                           are sent over this stream.
                         </xs:documentation>
                       </xs:annotation>
                    </xs:element>
                    <xs:element name="replaySupport"
                                        type="xs:boolean"/>
                                        type="xs:boolean">
                     <xs:annotation>
                         <xs:documentation>
                           An indication of whether or not event replay
                           is available on this stream.
                         </xs:documentation>
                       </xs:annotation>
                    </xs:element>
                    <xs:element name="replayLogStartTime" name="replayLogCreationTime"
                                   type="xs:dateTime" minOccurs="0">
                      <xs:annotation>
                        <xs:documentation>
                       The start time timestamp of the creation of the log
                       used to support the replay function. function on
                       this stream.
                       Note that this might be earlier then
                       the earliest available
                       notification in the log. This object
                       is updated if the log resets
                       for some reason. This
                       object MUST be present if replay is
                       supported.
                         </xs:documentation>
                       </xs:annotation>
                     </xs:element>
                   </xs:sequence>
                 </xs:complexType>
               </xs:element>
             </xs:sequence>
           </xs:complexType>
         </xs:element>
    </xs:sequence>
    </xs:complexType>

    <xs:complexType name="ReplayCompleteNotificationType">
        <xs:complexContent>
            <xs:extension base="ncEvent:NotificationContentType"/>
        </xs:complexContent>
    </xs:complexType>
                     <xs:element name="replayComplete"
        type="manageEvent:ReplayCompleteNotificationType"
        substitutionGroup="ncEvent:notificationContent"> name="replayLogAgedTime"
                            type="xs:dateTime" minOccurs="0">
                       <xs:annotation>
                         <xs:documentation>
            This notification is sent to signal
                           The timestamp of the last notification
                           aged out of the log. This
                           object MUST be present if replay is
                           supported and any notifications
                           have been aged out of the log.
                         </xs:documentation>
                       </xs:annotation>
                     </xs:element>
                   </xs:sequence>
                 </xs:complexType>
               </xs:element>
             </xs:sequence>
           </xs:complexType>
         </xs:element>
    </xs:sequence>
    </xs:complexType>

    <xs:complexType name="ReplayCompleteNotificationType">
        <xs:complexContent>
            <xs:extension base="ncEvent:NotificationContentType"/>
        </xs:complexContent>
    </xs:complexType>

    <xs:element name="replayComplete"
        type="manageEvent:ReplayCompleteNotificationType"
        substitutionGroup="ncEvent:notificationContent">
                <xs:annotation>
          <xs:documentation>
            This notification is sent to signal the end of a replay
            portion of a subscription.
          </xs:documentation>
        </xs:annotation>
        </xs:element>

    <xs:complexType name="NotificationCompleteNotificationType">
        <xs:complexContent>
            <xs:extension base="ncEvent:NotificationContentType"/>
        </xs:complexContent>
    </xs:complexType>

    <xs:element name="notificationComplete"
        type="manageEvent:NotificationCompleteNotificationType"
        substitutionGroup="ncEvent:notificationContent">
                <xs:annotation>
          <xs:documentation>
            This notification is sent to signal the end of a
            notification subscription. It is sent in the case
            that stopTime was specified during the creation of
            the subscription.
          </xs:documentation>
        </xs:annotation>
        </xs:element>

</xs:schema>

                                 Figure 7

3.5.  Subscriptions Data

   While it may be possible to retrieve information about subscriptions
   via a get operation, subscriptions are not stored configuration.
   They

   Subscriptions are non-persistent state information and their lifetime
   is defined by their session. session or by the <stopTime> paramter.

3.6.  Filter Mechanics

   When multiple filter elements are specified, they are applied
   collectively, so event notifications need to pass all specified
   filters
   filter elements in order to be sent to the subscriber.  If a filter
   element is specified to look for data of a particular value, and the
   data item is not present within a particular event notification for
   its value to be checked against, the notification will be filtered
   out.  For example, if one were to check for 'severity=critical' in a
   configuration event notification where this field was not supported,
   then the notification would be filtered out.

   The order

   For subtree filtering, a non-empty node set means that filter elements are applied does not matter since the
   resulting set of notifications is filter
   matches.  For XPath filtering, the intersection of mechanisms defined in [XPATH]
   should be used to convert the set of
   notifications that pass each filtering criteria. returned value to boolean.

3.6.1.  Filtering

   Filtering is explicitly stated when the event notification
   subscription is created.  This is specified via the 'filter'
   parameter.  Filters  A Filter only exist as parameters a parameter to the subscription.

3.7.  Message Flow
   The following figure depicts message flow between a NETCONF client
   (C) and NETCONF server (S) in order to create a subscription and
   begin the flow of notifications.  This subscription specified a
   <startTime>, so the server starts by replaying logged notifications.
   It is possible that many rpc/rpc-reply sequences occur before the
   subscription is created or after a
   stopTime in a replay subscription, created, but this is not depicted in the figure.

                        C                           S
                        |                           |
                        |  capability exchange      |
                        |-------------------------->|
                        |<------------------------->|
                        |                           |
                        |  <create-subscription>    |
                        |-------------------------->|
                        |<--------------------------|
                        |     <rpc-reply>           |
                        |                           |
                        |     <notification>        |
                        |<--------------------------|
                        |                           |
                        |     <notification>        |
                        |<--------------------------|
                        |      <notification>       | (replayComplete)
                        |<--------------------------|
                        |                           |
                        |                           |
                        |                           |
                        |     <notification>        |
                        |<--------------------------|
                        |                           |
                        |                           |
                        |     <notification>        |
                        |<--------------------------|
                        |                           |
                        |                           |

                                 Figure 8

4.  XML Schema for Event Notifications 3
   The following [XML Schema] defines figure depicts message flow between a NETCONF Event Notifications.

<?xml version="1.0" encoding="UTF-8"?>
  <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
        xmlns="urn:ietf:params:netconf:capability:notification:1.0"
        xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0"
        targetNamespace=
          "urn:ietf:params:netconf:capability:notification:1.0"
        elementFormDefault="qualified"
        attributeFormDefault="unqualified"
            xml:lang="en">

    <!-- import standard XML definitions -->

     <xs:import namespace="http://www.w3.org/XML/1998/namespace"
                schemaLocation="http://www.w3.org/2001/xml.xsd">
       <xs:annotation>
         <xs:documentation>
           This import accesses the xml: attribute groups for the
           xml:lang as declared on the error-message client
   (C) and NETCONF server (S) in order to create a subscription and
   begin the flow of notifications.  This subscription specified a
   <startTime> and <stopTime> so it starts by replaying logged
   notifications and then returns to be a normal command-response
   NETCONF session after the <replayComplete> and <notificationComplete>
   notifications are sent and it is available to process <rpc> requests.
   It is possible that many rpc/rpc-reply sequences occur before the
   subscription is created, but this is not depicted in the figure.

                     C                           S
                     |                           |
                     |  capability exchange      |
                     |-------------------------->|
                     |<------------------------->|
                     |                           |
                     |  <create-subscription>    |
                     |-------------------------->|
                     |<--------------------------|
                     |     <rpc-reply>           |
                     |                           |
                     |     <notification>        |
                     |<--------------------------|
                     |                           |
                     |     <notification>        |
                     |<--------------------------|
                     |      <notification>       | (replayComplete)
                     |<--------------------------|
                     |      <notification>       |(notificationComplete)
                     |<--------------------------|
                     |                           |
                     |                           |
                     |                           |
                     |          <rpc>            |
                     |-------------------------->|
                     |<--------------------------|
                     |       <rpc-reply>         |
                     |                           |

                                 Figure 4

4.  XML Schema for Event Notifications

   The following [XML Schema] defines NETCONF Event Notifications.

<?xml version="1.0" encoding="UTF-8"?>
  <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
     xmlns="urn:ietf:params:netconf:capability:notification:1.0"
     xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0"
     targetNamespace=
        "urn:ietf:params:netconf:capability:notification:1.0"
     elementFormDefault="qualified"
     attributeFormDefault="unqualified"
       xml:lang="en">

    <!-- import standard XML definitions -->

     <xs:import namespace="http://www.w3.org/XML/1998/namespace"
                schemaLocation="http://www.w3.org/2001/xml.xsd">
       <xs:annotation>
         <xs:documentation>
           This import accesses the xml: attribute groups for the
           xml:lang as declared on the error-message element.
         </xs:documentation>
       </xs:annotation>
     </xs:import>

     <!-- import base netconf definitions -->
     <xs:import namespace="urn:ietf:params:xml:ns:netconf:base:1.0"
       schemaLocation=
     "http://www.iana.org/assignments/xml-registry/schema/netconf.xsd"/>

<!-- ************** Symmetrical Operations  ********************-->

     <!-- <create-subscription> operation -->

    <xs:complexType name="createSubscriptionType">
        <xs:complexContent>
            <xs:extension base="netconf:rpcOperationType">
                <xs:sequence>
                    <xs:element name="stream"
                        type="streamNameType" minOccurs="0">
                        <xs:annotation>
                            <xs:documentation>
                               An optional parameter that indicates
                               which stream of events is of interest. If
                               not present, then events in the default
                               NETCONF stream will be sent.
                            </xs:documentation>
                        </xs:annotation>
                    </xs:element>
                        <xs:element name="filter"
                            type="netconf:filterInlineType"
                            minOccurs="0">
                            <xs:annotation>
                                <xs:documentation>
                                    An optional parameter that indicates
                                    which subset of all possible events
                                    are
                                    is of interest. The format of this
                                    parameter is the same as that of the
                                    filter parameter in the NETCONF
                                    protocol operations. If not present,
                                    all events not precluded by other
                                    parameters will be sent.
                                </xs:documentation>
                            </xs:annotation>
                        </xs:element>
                    <xs:element name="startTime" type="xs:dateTime"
                        minOccurs="0" >
                        <xs:annotation>
                            <xs:documentation>
                                A parameter used to trigger the replay
                                feature and indicates that the replay
                                should start at the time specified. If
                                start time is not present, this is not a
                                replay subscription.
                            </xs:documentation>
                        </xs:annotation>
                    </xs:element>
                    <xs:element name="stopTime" type="xs:dateTime"
                        minOccurs="0" >
                        <xs:annotation>
                            <xs:documentation>
                                An optional parameter used with the
                                optional replay feature to indicate the
                                newest notifications of interest. If
                                stop time is not present, the
                                notifications will continue until the
                                subscription is terminated. Must be used
                                with 'startTime'. startTime.
                            </xs:documentation>
                        </xs:annotation>
                    </xs:element>
                </xs:sequence>
            </xs:extension>
        </xs:complexContent>
    </xs:complexType>

    <xs:simpleType name="streamNameType">
        <xs:annotation>
            <xs:documentation>
                The name of an event stream.
            </xs:documentation>
        </xs:annotation>
        <xs:restriction base="xs:string"/>
    </xs:simpleType>

    <xs:element name="create-subscription"
        type="createSubscriptionType"
        substitutionGroup="netconf:rpcOperation">
        <xs:annotation>
            <xs:documentation>
                The command to create a notification subscription. It
                takes as argument the name of the notification stream
                and  filter or profile information. All filter. Both of those options
                limit the content of the subscription. In addition,
                there are two time-related parameters parameters, startTime and
                stopTime
                stopTime, which can be used to select the time interval
                of interest. interest to the notification replay feature.
            </xs:documentation>
        </xs:annotation>
    </xs:element>

<!-- ************** One-way Operations  ******************-->

     <!-- <Notification> operation -->
     <xs:complexType name="NotificationContentType"/>

    <xs:element name="notificationContent"
        type="NotificationContentType" abstract="true"/>

    <xs:complexType name="NotificationType">
        <xs:sequence>
            <xs:element name="eventTime" type="xs:dateTime">
              <xs:annotation>
                <xs:documentation>
                The time the event was generated by the event source
                </xs:documentation>
              </xs:annotation>
            </xs:element>
            <xs:element ref="notificationContent"/>
        </xs:sequence>
    </xs:complexType>

    <xs:element name="notification" type="NotificationType"/>

  </xs:schema>

                                 Figure 9

5.  Filtering Examples

   The following section provides examples to illustrate the various
   methods of filtering content on an event notification subscription.

5.1.  Subtree Filtering

   XML subtree filtering is not well suited for creating elaborate

   In order to illustrate the use of filter definitions given that expressions, it only supports equality comparisons
   and logical OR operations (e.g., in an event subtree give me all
   event notifications which have severity=critical or severity=major or
   severity=minor).  Nevertheless, it may be used for defining simple
   event notification forwarding filters as shown below.

   In order to illustrate the use of filter expressions it is necessary
   to assume some of the is necessary
   to assume some of the event notification content.  The examples
   herein below
   assume that the event notification schema definition has an
   <events> <event>
   element at the top level that contains one or more child
   elements <eventEntry> consisting of the event class (e.g., fault,
   state, config, etc.) config), reporting entity and either severity or operational
   state.

   Sample event list

   Examples in this section are generated from the following fictional
   Schema.

 <?xml version="1.0" encoding="UTF-8"?>
<xs:schema targetNamespace="http://example.com/event/1.0"
    xmlns="http://example.com/event/1.0"
    elementFormDefault="qualified"
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    xmlns:ncEvent="urn:ietf:params:netconf:capability:notification:1.0">

    <xs:import namespace=
        "urn:ietf:params:netconf:capability:notification:1.0"
        schemaLocation=
"http://www.iana.org/assignments/xml-registry/schema/notification.xsd"/>

    <xs:complexType name="eventType">
        <xs:complexContent>
            <xs:extension base="ncEvent:NotificationContentType">
                <xs:sequence>
                    <xs:element name="eventClass" />
                    <xs:element name="reportingEntity">
                        <xs:complexType>
                            <xs:sequence>
                                <xs:any namespace="##any"
                                processContents="lax"/>
                            </xs:sequence>
                        </xs:complexType>
                    </xs:element>
                    <xs:choice>
                        <xs:element name="severity"/>
                        <xs:element name="operState"/>
                    </xs:choice>
                </xs:sequence>
            </xs:extension>
        </xs:complexContent>
    </xs:complexType>

    <xs:element name="event"
        type="eventType"
        substitutionGroup="ncEvent:notificationContent"/>

</xs:schema>

   The above fictional notification definition could result in the
   following is a sample notification list, whihc is used in the
   examples in this section.

   <notification
      xmlns="urn:ietf:params:netconf:capability:notification:1.0">
      <eventTime>2007-07-08T00:01:00Z</eventTime>
      <event xmlns="http://example.com/event/1.0">
         <eventClass>fault</eventClass>
         <reportingEntity>
             <card>Ethernet0</card>
         </reportingEntity>
         <severity>major</severity>
       </event>
   </notification>

   <notification
     xmlns="urn:ietf:params:netconf:capability:notification:1.0">
      <eventTime>2007-07-08T00:02:00Z</eventTime>
      <event xmlns="http://example.com/event/1.0">
          <eventClass>fault</eventClass>
          <reportingEntity>
              <card>Ethernet2</card>
          </reportingEntity>
          <severity>critical</severity>
       </event>
   </notification>

   <notification
     xmlns="urn:ietf:params:netconf:capability:notification:1.0">
      <eventTime>2007-07-08T00:04:00Z</eventTime>
      <event xmlns="http://example.com/event/1.0">
          <eventClass>fault</eventClass>
          <reportingEntity>
               <card>ATM1</card>
           </reportingEntity>
           <severity>minor</severity>
      </event>
   </notification>

   <notification
     xmlns="urn:ietf:params:netconf:capability:notification:1.0">
     <eventTime>2007-07-08T00:10:00Z</eventTime>
     <event xmlns="http://example.com/event/1.0">
         <eventClass>state</eventClass>
         <reportingEntity>
             <card>Ethernet0</card>
         </reportingEntity>
         <operState>enabled</operState>
      </event>

                                 Figure 10
   </notification>

5.1.  Subtree Filtering

   XML subtree filtering is not well-suited for creating elaborate
   filter definitions given that it only supports equality comparisons
   and application of the logical OR operators (e.g., in an event
   subtree give me all event notifications which have severity=critical
   or severity=major or severity=minor).  Nevertheless, it may be used
   for defining simple event notification forwarding filters as shown
   below.

   The following example illustrates selecting how to select fault events which
   have severities of critical, major, or minor (presumably fault events). minor.  The filtering criteria
   evaluation is as follows:

   ((severity=critical) | (severity=major) | (severity=minor))

      <netconf:rpc netconf:message-id="101"
              xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
        <create-subscription
            xmlns="urn:ietf:params:netconf:capability:notification:1.0">
          <filter netconf:type="subtree">
            <event xmlns="http://example.com/event/1.0">
              <eventClass>fault</eventClass>
              <severity>critical</severity>
            </event>
            <event xmlns="http://example.com/event/1.0">
              <eventClass>fault</eventClass>
              <severity>major</severity>
            </event>
            <event xmlns="http://example.com/event/1.0">
              <eventClass>fault</eventClass>
              <severity>minor</severity>
            </event>
          </filter>
        </create-subscription>
      </netconf:rpc>

                                 Figure 11

   The following example illustrates selecting how to select state or config
   EventClasses or fault events that are related to card Ethernet0.  The
   filtering criteria evaluation is as follows:

   ( state | config | ( fault & card=Ethernet0) ( card=Ethernet0)))

<netconf:rpc netconf:message-id="101"
                xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
      <create-subscription
          xmlns="urn:ietf:params:netconf:capability:notification:1.0">
        <filter netconf:type="subtree">
          <event xmlns="http://example.com/event/1.0">
            <eventClass>fault</eventClass>
          </event>
          <event xmlns="http://example.com/event/1.0">
            <eventClass>state</eventClass>
          </event>
          <event xmlns="http://example.com/event/1.0">
            <eventClass>config</eventClass>
          </event>
          <event xmlns="http://example.com/event/1.0">
            <eventClass>fault</eventClass>
            <reportingElement>
              <card>Ethernet0</card>
            </reportingElement>
          </event>
        </filter>
      </create-subscription>
</netconf:rpc>

5.2.  XPATH filters

   The following [XPATH] example illustrates selecting how to select fault
   EventClass notifications that have severities of critical, major, or
   minor.  The filtering criteria evaluation is as follows:

   ((fault) & ((severity=critical) | (severity=major) | (severity =
   minor)))

    <netconf:rpc netconf:message-id="101"
              xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
      <create-subscription
            xmlns="urn:ietf:params:netconf:capability:notification:1.0">
        <filter netconf:type="xpath"
                xmlns:ex="http://example.com/event/1.0"
           select="/ex:event[ex:eventClass='fault' and
                (ex:severity='minor' or ex:severity='major'
                     or ex:severity='critical')]"/>
      </create-subscription>
    </netconf:rpc>
                                 Figure 13
   The following example illustrates selecting how to select state and config
   EventClasses or fault events that have severities of critical, major,
   or minor or any severity that come from card
   Ethernet0.  The filtering criteria evaluation is as follows:

   (( state | config) & ((fault & severity=critical) | (fault &
   severity=major) | (fault & severity = minor) | (fault &
   card=Ethernet0))) card=Ethernet0))

      <netconf:rpc netconf:message-id="101" message-id="101"
              xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
        <create-subscription
           xmlns="urn:ietf:params:netconf:capability:notification:1.0">
             <filter netconf:type="xpath"
                     xmlns:ex="http://example.com/event/1.0"
                select="/ex:event[
                    ex:eventClass='fault' and ex:severity='minor') or
                    (ex:eventClass='fault' and ex:severity='major')
                   (ex:eventClass='state' or
                    ex:eventClass='fault' ex:eventClass='config') and ex:severity='critical') or
                    (ex:eventClass='fault'
                   ((ex:eventClass='fault' and
                    ex:reportingElement/ex:card='Ethernet0') or
                    ex:eventClass='state' or
                    ex:eventClass='config']"/> ex:card='Ethernet0'))]"/>
       </create-subscription>
     </netconf:rpc>

                                 Figure 14

6.  Security Considerations

   The security considerations from the base [NETCONF] document apply also
   apply to the Notification capability.

   The access control framework and the choice of transport will have a
   major impact on the security of the solution.

   The <notification> elements are never sent before the transport layer
   and the netconf layer (capabilities exchange) NETCONF layer, including capabilities exchange, have been
   established, and the manager has been identified and authenticated.

   It is recommended that care be taken to ensure the secure operation
   of the following commands: execution:

   o  <create-subscription> invocation

   o  <get> on read-only data models

   o  read-write data models

   o  notification  <notification> content

   One potential security issue related to the notifications draft is the transport of data from non-netconf non-
   NETCONF streams, such as syslog and SNMP.  This data may be more
   vulnerable (or is not more less vulnerable) when being transported over netconf NETCONF
   than when being transported using the protocol normally used for
   transporting it, depending on the security credentials of the two
   subsystems.  The NETCONF server is responsible for providing applying access
   control to stream content.

   If a

   The contents of notifications as well as the name of event streams
   may contain sensitive information and care should be taken to ensure
   that it is viewed only by authorized users.  If a user does not have
   permission to view content via other NETCONF
   operations operations, it does not
   have permission to access that content via Notifications.  If a user
   is not permitted to view one element in the content of the
   notification, the notification is not sent to that user.

   If a subscription is created with a stopTime, <stopTime>, the NETCONF session
   will return to being a normal command-response NETCONF session when
   the replay is completed.  It is the responsibility of the NETCONF
   client to close off this session when it is no longer of use.

7.  IANA Considerations

   This document registers two three URIs for the NETCONF XML namespace in
   the IETF XML registry [RFC3688].

   Following the format in RFC 3688, IANA has made the following
   registration.

   URI: urn:ietf:params:netconf:capability:notification:1.0

   URI: urn:ietf:params:xml:ns:netmod:notification

   URI: urn:ietf:params:xml:ns:netconf:notification

   Registrant Contact: The IESG.

   XML: N/A, the requested URI is an XML namespace.

8.  Acknowledgements

   Thanks to Gilbert Gagnon, Greg Wilbur and Kim Curran for providing
   their input into the early work on this document.  In addition, the
   editors would like to acknowledge input at the Vancouver editing
   session from the following people: Orly Nicklass, James Balestriere,
   Yoshifumi Atarashi, Glenn Waters, Alexander Clemm, Dave Harrington,
   Dave Partain, Ray Atarashi and Dave David Perkins and the following
   additional people from the Montreal editing session: Balazs Lengyel,
   Phil Shafer, Rob Enns, Andy Bierman, Dan Romascanu, Bert Wijnen,
   Simon Leinen, Juergen Schoenwaelder, Hideki Okita, Vincent Cridlig,
   Martin Bjorklund, Olivier Festor, Radu State, Brian Trammell, William
   Chow.  We would also like to thank Li Yan for his numerous reviews.

9.  Normative References

   [NETCONF]  Enns, R., "NETCONF Configuration Protocol", RFC 4741,
              December 2006.

   [RFC2026]  Bradner, S., "The Internet Standards Process -- Revision
              3", RFC 2026, BCP 9, October 1996.

   [RFC2119]  Bradner, s., "Key words for RFCs to Indicate Requirements
              Levels", RFC 2119, March 1997.

   [RFC2223]  Postel, J. and J. Reynolds, "Instructions to RFC Authors",
              RFC 2223, October 1997.

   [RFC3688]  Bradner, s., "The IETF XML Registry", RFC 3688, January
               2004.

   [XML]      World Wide Web Consortium, "Extensible Markup Language
              (XML) 1.0", W3C XML, February 1998,
              <http://www.w3.org/TR/1998/REC-xml-19980210>.

   [XML Schema]
              Fallside, D. and P. Walmsley, "XML Schema Part 0: Primer
              Second Edition", W3C XML Schema, October 2004.

   [XPATH]    Clark, J. and S. DeRose, "XML Path Language (XPath)
              Version 1.0",
              W3C http://www.w3.org/TR/1999/REC-xpath-19991116,
              November 1999.

Appendix A.  Change Log

A.1.  Version -08

   1.   Removed named profiles

   2.   Removed eventClass that was accidentally included in the
        definition of the replayComplete notification

   3.   Deleted data wrapper from notification

   4.   Changed replayLogStartTime to have a minOccurs of 0.  It will
        only be there when replay is supported.  Verify examples in
        section 3.2.5.1 are correct with respect to this element.

   5.   Error codes in section 2.1.1, fixed formatting issue

   6.   Moved replayComplete to not be under <netconf>

   7.   Section 2.1, fixed capitalization

   8.   In figure 4, the line was pushed out by 'system components',
        fixed this.

   9.   On page 8, replaced "If the startTime specified is earlier then
        the" with 'If the startTime specified is earlier than the"

   10.  Updated some name spaces and schemaLocations as per Andy's June
        3rd email.

   11.  Added discussion of replayLogStartTime to draft in section 3.3.1
        as follows "Whether or not a stream supports replay can be
        discovered by doing a <get> operation on the eventStreams <streams> elements
        of the Notification Management Schema.  This schema also
        provides the replayLogStartTime element to indicate the earliest
        available logged notification."

   12.  Removed most of the uses of the phrase 'Note that'.  I kept two
        uses that prevent sentences from starting with either a lower
        case letter or an angle bracket.

   13.  In section 3.6 replaced "it will be filtered out" with "the
        notification will be filtered out"

   14.  In section 3.4, replaced "and the query" with "and to query"

   15.  Replaced 3 instances of "replay complete notification" with
        "replayComplete notification"
   16.  In section 3.3.2, replaced "normal NETCONF session" with "normal
        command-response NETCONF session"

   17.  In section 3.3.1, replaced "create an event subscription that
        will resend recently generated notification" with "create an
        event subscription that will resend recently generated
        notification, or is some cases send them for the first time to a
        particular NETCONF client."

   18.  In section 3.2.5.2, s/available event streams to/event streams
        available to/

   19.  In one spot, changed snmp to SNMP (the other gets deleted)

   20.  In section 3.2.5.1 s/where <name> element is/where the <name>
        element is/

   21.  In section 3.2.5.1, clarified that "value is unique" - within
        the scope of a NETCONF server.

   22.  In section 2.1.1, clarified that stopTime cannot preceded start
        time.

   23.  In section 2.1.1, in Start Time s/indicates/indicate/

   24.  In section 2.1.1, in Filter: s/This is mutually exclusive/The
        filter parameter is mutually exclusive/ ("this" could refer to
        the behavior described in the previous sentence.)

   25.  In section 1.4, third bullet, replaced "syslog and SNMP are
        rather constrained in terms of message sizes)" with (ie, not too
        short)

   26.  In section 1.4, made all bullets start with capital leters.

   27.  Added definition of Filter to section 1.1

   28.  In section 1.1, improved the definition of subscription with "An
        agreement and method to receive event notifications over a
        NETCONF session."

   29.  In section 1.1, in the definition of operation, added a
        reference to [NETCONF].

   30.  Created a change log section

   31.  Fixed reference to IETF XML Registry in IANA Considerations
        section.

   32.  In section 3.3.3, deleted "This notification will only be sent
        if a 'stopTime' was specified when the replay subscription was
        created."

   33.  Added text to the security considerations section that says "If
        a subscription is created with a stopTime, the NETCONF session
        will return to being a normal command-response NETCONF session
        when the replay is completed.  It is the responsibility of the
        NETCONF client to close off this session when it is no longer of
        use".

   34.  Update examples in section 5 to get rid of extra wrapper tag.

   35.  In section 2.1, replace "A NETCONF server is not required to
        process RPC requests on the session associated with the
        subscription until the notification subscription is done and may
        silently discard these requests." with "A NETCONF server is will
        not read RPC requests, by default, on the session associated
        with the subscription until the notification subscription is
        done.

   36.  Updated the notification definition and the replyComplete
        notification definition to use a substitution group.

A.2.  Version -09

   1.   In section 5.1 "logical OR operation" -> "application of the
        logical OR operator"

   2.   In section 6 "ensure the secure operation of the following
        commands" -> "secure execution"

   3.   Removed a couple remaining references to named profiles.

   4.   Updated name datatype in eventStreams element.

   5.   Modified the cardinality of eventStreams to reflect that there
        will always be at least one event stream.

   6.   Fixed description of examples to remove reference to eventEntry,
        which is no longer part of the actual example.

   7.   In examples, for consistency changed some references to
        reportingElement to be reportingEntity

   8.   Fixed section 3.2, third pararaph to talk about filter elements
        instead of filters.

   9.   Merge section 3.3.2 and section 3.3.3.  Delete the first
        paragraph in (old) section 3.3.3 since it both duplicates and
        contradicts text in section 3.3.2

   10.  In section 3.2.5.2.1, added clarification to first paragraph
        that "Either subtree or XPATH filtering can be used.  "

   11.  Removed discussion of not allowing the return of stream names
        for which the user does not have permissions from the body of
        the document to the security considerations section.

   12.  Fixed typos and did wordsmithing in various parts of the
        document.

   13.  In section 2.1, explicitly stated that a subscription is bound
        to a single stream for the lifetime of the subscription.

   14.  removed single quotes around some instances of stopTime and
        startTime for consistency.  When appropriate, put between angle
        brackets.

   15.  In section 2.1.1, changed "Error-info: <badElement>: startTime"
        to use bad-element.

   16.  In section 2.2.1, under the parameter tag, replaced "Contains
        notification-specific tagged content." with "Contains
        notification-specific tagged content, if any.  "

   17.  Clarified some text in section 3.2, paragraph 3 around sending
        of filters from client and the fitlers later being applied to
        the notifications.

   18.  Fixed target namespace in section 4.

   19.  Added missing lang and version information to schema in section
        3.4

   20.  Clarified that the examples in section 5 all used the same
        example event list.

   21.  Cleaned up security considerations section.

   22.  In section 3.4, clarified the definition of replayLogStart time
        to be the timestamp of the earliest available notification in
        the log used to support the replay function in the description
        tag for the object definition.

   23.  In section 3.3.2, clarified that the time an event was generated
        by the system means time an event was generated by the event
        source.

   24.  In section 3.5, deleted discussion about possibly defining
        subscriptions in XML Schema.

   25.  In section 3.6, deleted discussion about filter element
        execution order not mattering.

   26.  Fixed examples in section 5 to add <netconf> tag and to make
        other corrections

   27.  Added XML Schema definition for examples in section 5 and showed
        the event list with <notification> wrappers.

   28.  Added <notificationComplete> notification

   29.  Removed support of startTime and stopTime in the future.

   30.  Replaced replayLogStartTime with replayLogCreationTime and
        replayLogAgedTime.

Authors' Addresses

   Sharon Chisholm
   Nortel
   3500 Carling Ave
   Nepean, Ontario  K2H 8E9
   Canada

   Email: schishol@nortel.com

   Hector Trevino
   Cisco
   Suite 400
   9155 E. Nichols Ave
   Englewood, CO  80112
   USA

   Email: htrevino@cisco.com

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