Network Working Group                                          A. Barbir
Internet-Draft                                           Nortel Networks
Expires: December 10, 2003                                 June 11, March 12, 2004                               September 12, 2003

              OPES processor and end points communications
                      draft-ietf-opes-end-comm-00
                      draft-ietf-opes-end-comm-01

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Copyright Notice

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

Abstract

   This memo documents tracing requirements for Open Pluggable Edge
   Services (OPES).

Table of Contents

   1.    Introduction . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.    OPES Tracing Domain and OPES System  . . . . . . . . . . . . . . . .  4
   3.    OPES Tracing . . . . . . . .  4
   2.1   What is traceable in an OPES Flow? . . . . . . . . . . . . .  4
   2.2   Requirements for Information Related to Traceable
         Entities? . . .  6
   3.1   What is traceable in an OPES Flow? . . . . . . . . . . . . .  6
   3.2   Requirements for Information Related to Traceable
         Entities?  . . . . . . . . . .  5
   3.    Requirements for OPES systems . . . . . . . . . . . . . . .  6  7
   4.    Requirements for OPES processors . . . . . . . . . . . . . .  7  8
   5.    Requirements for callout servers . . . . . . . . . . . . . .  8  9
   6.    Privacy considerations . . . . . . . . . . . . . . . . . . .  9 10
   6.1   Tracing and Trust Domains  . . . . . . . . . . . . . . . . .  9 10
   7.    How to Support Tracing . . . . . . . . . . . . . . . . . . . 10 11
   7.1   Tracing and OPES System Granularity  . . . . . . . . . . . . 10 11
   7.2   Requirements for In-Band Tracing . . . . . . . . . . . . . . 11 12
   7.2.1 Tracing Information Granularity and Persistence levels
         Requirements . . . . . . . . . . . . . . . . . . . . . . . . 11 12
   7.3   Protocol Binding . . . . . . . . . . . . . . . . . . . . . . 12 13
   7.4   Tracing scenarios and examples . . . . . . . . . . . . . . . 12
   8.    IAB considerations . . . . . . . . . . . . . . . . . . . . . 13
   8.1
   8.    Optional Notification Concerns  . . . . . . . . . . . . .  . . . . . . 13
   8.1.1 Addressing IAB Consideration 3.1 . . . . . . . . . . . . . . 14
   8.1.2 Addressing IAB Consideration 3.2 . . . . . . . . . . . . . . 15
   9.    Security    IANA considerations  . . . . . . . . . . . . . . . . . . 17
   10.   IANA Considerations . . 16
   10.   Security Considerations  . . . . . . . . . . . . . . . . . . 18 17
         Normative References . . . . . . . . . . . . . . . . . . . . 19 18
         Informative References . . . . . . . . . . . . . . . . . . . 20 19
         Author's Address . . . . . . . . . . . . . . . . . . . . . . 20 19
   A.    Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21 20
         Intellectual Property and Copyright Statements . . . . . . . 22 21

1. Introduction

   The Open Pluggable Edge Services (OPES) architecture [8] enables
   cooperative application services (OPES services) between a data
   provider, a data consumer, and zero or more OPES processors.  The
   application services under consideration analyze and possibly
   transform application-level messages exchanged between the data
   provider and the data consumer.

   The execution of such services is governed by a set of rules
   installed on the OPES processor.  The rules enforcement can trigger
   the execution of service applications local to the OPES processor.
   Alternatively, the OPES processor can distribute the responsibility
   of service execution by communicating and collaborating with one or
   more remote callout servers. As described in [8], an OPES processor
   communicates with and invokes services on a callout server by using a
   callout protocol.

   The work specify the requirements for providing tracing functionality
   for the OPES architecture [8]. This document specifies tracing
   mechanisms that the OPES architecture could provide that enable data
   provider application to detect inappropriate clinet centric actions
   by OPES entities. The work focus on developing tracing requirements
   that can be used to fulfil the notification and Non-Blocking
   requirements [2].

   In the OPES architecture document [8], there is a requirement of
   relaying tracing information in-band. This work investigates this
   possibility and discusses possible methods that could be used to
   detect faulty OPES processors or callout servers by end points in an
   OPES flow.

   The document is organized as follows: .......

2. Section 2 defines OPES Tracing

   Before discussing what is Domain
   and OPES System. Section 3 discusses entities that are traceable in
   an OPES flow, it is beneficial Flow. Sections 4 and 5 discuss tracing requirements for OPES
   systems and callout servers. Section 6 focus on Tracing and Trust
   Domains. Section 7 discusses how to support tracing and provides uses
   cases. Section 8 examines Optional Notofication.  Section 9 looks
   into IANA considerations. Section 10 examines security
   considerations.

2. OPES Domain and OPES System

   This sections clarifies the terms OPES system and OPES Domain [8].
   These terms are needed in order to define what tracing means. Tracing is defined as the inclusion of
   necessary information within a message traceable in an
   OPES flow that could be
   used to identify Flow [8].

   An OPES domain describes the set collection of transformations or adpatations that have
   been performed on its content before its delivery to an end point
   (the data consumer application).

   o  OPES trace:	application message information about OPES entities that adapted that message

   o a
   single provider operates. OPES tracing: the process domains can be based on trust or other
   operational boundaries. All elements of including, manipulating, and
      interpreting an OPES trace

   To emphasize, the above definition means that OPES tracing SHOULD "OPES Domain" MUST be
   performed on per  message basis. Trace format is dependent on in
   the
   application protocol being adapted by OPES. Data consumer application
   can use same trust domain. This would be independent of any specific OPES trace to infer the actions that have been performed by
   flow.

   An OPES system(s). The architecture document requires [8] that tracing
   be supported in-band.

2.1 What is traceable in an system consists of a limited set of OPES Flow?

   o  The data consumer application end point MUST be able to identify
      the entities, parts of a
   single or of multiple OPES processors that have acted operators domains, organized by (or on an
   behalf) of either a data provider application message.

   o  The or a data consumer
   application end point SHOULD be able to identify
      OPES perform authorized services (including callout services) that were performed on
      request/responses that are part of an application message.

   o  TBD

   o  TBD

   For a given trace, an application
   message. Each OPES entity involved in handling the
   corresponding application message is "traceable" or "traced" if
   information about it appears in that trace. OPES entities have
   different levels of traceability requirements. Specifically,

   o  An an OPES system MUST be traceable

   o directly
   addressable on IP level by a data consumer application.

   An OPES processor SHOULD system can be traceable

   o formed in a recursive manner. An OPES service MAY be traceable

   o  Editor Note: Need to define an OPES System properly

2.2 Requirements for Information Related to Traceable Entities?

   The requirements for information as related to entities system
   can start with either a data provider application or a data consumer
   application (for a given message). The OPES system then includes any
   OPES entity trusted by (accepting authority from) an entity that are
   terceable is
   already in an the OPES flow are:

   o system. The privacy policy at the time it dealt with trust and authority delegation is
   viewed in the message

   o  Identification context of the party responsible for setting and  enforcing
      that policy

   o  Information pointing to a technical contact

   o  Information that identifies, to the technical contact, given application message.

   As implied by the above definition, some OPES
      processors involved entities in processing the messag

   o  TBD

3. Requirements for system
   may not participate in the processing of a given message.

   An OPES systems

   Editor Note: Need to define domain MUST not be an OPES System and state requirements

4. Requirements for sub-system. An OPES processors

   TBD

5. Requirements for callout servers

   If it domain MUST
   require external resources to provide services. An OPES domain is the task a
   part of an OPES processor to add trace records system belonging to
   application messages, then callout servers that uses a given operator. OPES domains
   have no incidence on the OCP protocol
   are not affected by tracing requirements.In order structure of an OPES system, but they may
   influence its organization for different reasons such as security,
   payment, quality of service, delivery parameters among others.

   In Figure 1 an OCP protocol
   to be tracing neutral, the OPES server SHOULD Flow is shown that traverses across various OPES
   Domains. A data consumer application MUST be able to meet recive tracing
   information on per message basis that enable it to determine the
   following requirements:

   o  Callout services adapt payload regardless set
   of transformations that were perfomed on the application
      protocol in use and leave header adjustment to data for a particular
   OPES processor.

   o Flow. The formation of an OPES processor SHOULD flow can be able  to trace its own invocation and
      service(s) execution because static or dynamic,
   meaning that the determination of which OPES processor understand Domains will participate
   in a given OPES Flow (per message basis) can be a function of
   business arrangements.

               +------------------------------------------+
               |             Data Consumer Application    |
               +------------------------------------------+
                                                     ^
                                                     |
               +-------------------------------------------+
               |                OPES System          | O   |
               |                                     |     |
               |     +-------------------------+     | P   |
               |     |        OPES Domain      |     |     |
               |     |      +---------------+  |     | E   |
               |     |      | OPES Entity   |  |     |     |
               |     |      +---------------+  |     | S   |
               |     |           .             |     |     |
               |     |           .             |     |     |
               |     |      +---------------+  |     | F   |
               |     |      |Callout Server |  |     |     |
               |     |      +---------------+  |     | L   |
               |     |                         |     |     |
               |     +-------------------------+     | O   |
               |                   .                 |     |
               |                   .                 | W   |
               |     +-------------------------+     |     |
               |     |        OPES Domain      |     |     |
               |     |      +---------------+  |     |     |
               |     |      | OPES Entity   |  |     |     |
               |     |      +---------------+  |     |     |
               |     |           .             |     |     |
               |     |           .             |     |     |
               |     |      +---------------+  |     |     |
               |     |      | OPES Entity   |  |     |     |
               |     |      +---------------+  |     |     |
               |     +-------------------------+     |     |
               |                                     v     |
               |    +-----------------------------------+  |
               |    |   Data Provider Application       |  |
               |    +-----------------------------------+  |
               |                                           |
               +-------------------------------------------+

                         Figure 1: OPES System

3. OPES Tracing

   Before discussing what is traceable in an OPES flow, it is beneficial
   to define what tracing means. Tracing is defined as the
      application protocol.

   o  Callout servers  MAY inclusion of
   necessary information within a message in an OPES flow that could be able
   used to add their own identify the set of transformations or adpatations that have
   been performed on its content in an OPES trace records System before its delivery
   to an end point (the data consumer application).

   o  OPES trace: application level messages. message information about OPES entities in
      an OPES System that adapted that message.

   o  TBD

6. Privacy considerations

6.1 Tracing and Trust Domains

   A trust domain may include several  OPES systems tracing: the process of including, manipulating, and entities. Within
   a trust domain, there MUST be at least support for one
      interpreting an OPES trace entry in an OPES System.

   To emphasize, the above definition means that OPES tracing SHOULD be
   performed on per message basis. Trace format is dependent on the
   application protocol that is being adapted by OPES. Data consumer
   application can use OPES trace to infer the actions that have been
   performed by the OPES system. Entities outside of  The architecture document requires [8]
   that system tracing be supported in-band.

   In an OPES System the task of providing tracing information, must
   take into account the following considerations:

   o  Providers may or be hesitant to reveal information about their
      internal network infrastructure.

   o  Within a service provider network, OPES processors may not see any
   traces, depending on domain policies or configuration. For example,
   if be
      configured to use non-routable, private IP addresses.

   o  A Data consumer applications would prefer to have a single point
      of contact regarding the trace information.

   o  TBD

3.1 What is traceable in an OPES system is Flow?

   This section focuses on identifying the content provider "side", end-users are
   not guaranteed any traces. If traceable entities in an OPES system is working inside
   end-user domain,
   Flow.  Tracing information MUST be able to provide a data consumer
   application with useful information without tracing the origin server exact OPES
   Processor or callout servers that adapted the data. It is not guaranteed any traces
   related up to user requests.

7. How the
   OPES service provider to Support Tracing

   In order have maintained appropriate internal
   detailed traces to support tracing, find the following aspects must be addressed:

   o  There MUST be a System Identifier that identify answer to the data consumer applications
   inquiry.

   At the implementation level, for a domain that is
      employing given trace, an OPES system.

   o  An entity
   involved in handling the corresponding application message is
   "traceable" or "traced" if information about it appears in that
   trace. OPES processor MUST be able to be uniquely identified (MUST entities have an Identifier) within a system. different levels of traceability
   requirements. Specifically,

   o  An OPES processor system MUST add its identification entry to the trace.

   o  An OPES processor SHOULD add its entry to the trace  identification of every
      callout service that received the application message. trace.

   o  An OPES processor MUST service SHOULD add its entry to the trace identification  of the
      "system/entity" it belongs to. "System" ID MUST make it possible
      to access "system" privacy  policy. trace.

   o  An OPES processor entity MAY group the above information for sequential
      trace entries having  the same "system/entity" ID. In other words, manage trace information from entities that are
      under its control. For example, an OPES processor may add or
      remove callout service entries produced within in order to manage the same "system/entity"  MAY be
      merged/aggregated into size of a single less detailed trace entry.

   o  An
      trace. Other considerations include:

      *  The OPES processor may have a fixed configuration that enable
         it to respond to tracing inquires.

      *  The OPES processor MAY delegate trace management to may insert a callout
      service within the same "system/entity".

   TBD

7.1 Tracing and OPES System Granularity

   There are two distinct uses summary of traces. First, is to SHOULD enable the
   "end (content producer or consumer) services that it
         controls. The summary can be used to detect respond to tracing
         inquiries.

      *  The OPES processor presence
   within end's trust domain. Such "end" should be able may package tracing information related to see
         the entities that it control based on the policy of a trace
   entry, but does not need given
         OPES System.

   From an OPES context, a good tracing approach is similar to be able a trouble
   ticket ready for submission to interpret it beyond
   identification a known address. The trace in itself
   is not necessarily a detailed description of what has happened. It is
   the trust domain(s).

   Second, resposibility of the domain administrator SHOULD be able operator to take a trace entry
   (possibly supplied by an "end? as an opaque string) and interpret it. resolve the problems.

3.2 Requirements for Information Related to Traceable Entities?

   The administrator must be able requirements for information as related to identify entities that are
   terceable in an OPES processor(s) involved flow are:

   o  The privacy policy at the time it dealt with the message

   o  Identification of the party responsible for setting and may be able  enforcing
      that policy

   o  Information pointing to identify applied adaptation services along with
   other message-specific information. That information SHOULD help a technical contact

   o  Information that identifies, to
   explain what the technical contact, the OPES agent(s) were
      processors involved and what they did. It may be
   impractical to provide all the required information in all cases.
   This document view a trace record as a hint, as opposed processing the messag

   o  TBD

4. Requirements for OPES processors

   In order to an
   exhaustive audit.

   Since facilitate compliance, the administrators concept of various trust domains an "OPES system"
   being traceable, requires that each OPES processor MUST support
   tracing.  Policy can have various
   ways of looking into tracing, they MAY require the choice of freedom
   in what to put in trace records and how to format them. Trace records
   should be easy set that defines which domain has
   authorization to extend beyond basic turn on tracing and its granularity.  An OPES requirements. Trace
   management algorithms should treat
   provider can have its private policy for trace records as opaque data to
   the extent possible.

   It is not expected information, but it
   MUST support tracing mechanisms and it MUST reveal it's policy.

   The requirements for OPES processors that entities in one trust domain are applicatble to be able tracing
   are:

   o  Each OPES processor MUST belong to
   get all OPES-related feedback from entities in other trust domains.
   For example, if an end-user suspects that a served is corrupted by single OPES Domain.

   o  Each OPES processor MUST have a
   callout service, there is no guarantee Unique Identity in that the use will Domain.

   o  Each OPES processor MUST support tracing, policy can be able used to
   identify that service, contact its owner, or debug it _unless_ the
   service is within my trust domain. This is no different from the
   current situation where
      turn tracing on and.to determine granuality.

   o  TBD

5. Requirements for callout servers

   If it is impossible, in general, to know the
   contact person for an application on task of an origin server that generates
   corrupted HTML; and even if the person is known, one should not
   expect that person OPES processor to respond add trace records to end-user queries.

7.2 Requirements
   application messages, then callout servers that uses the OCP protocol
   are not affected by tracing requirements. In order for In-Band Tracing

   The an OCP
   protocol to be tracing neutral, the OPES architecture [8] states that traces must server SHOULD be in-band. The
   support of this design specification is dependent on able to
   meet the specifics following requirements:

   o  Callout services adapt payload regardless of the message application level
      protocol that is being used in an use and leave header adjustment to OPES
   flow. In-band tracing limits processor.

   o  OPES processor SHOULD be able  to trace it's own invocation and
      service(s) execution since they understand the type of application protocols that
      protocol.

   o  Callout servers  MAY be able to add their own OPES can support. The details of what a trace record can convey is
   also dependent on the choice of the records
      to application level protocol.

   For these reasons, the work will document requirements messages.

   o  TBD

6. Privacy considerations

6.1 Tracing and Trust Domains

   A trust domain may include several OPES systems and entities. Within
   a trust domain, there MUST be at least support for
   application protocols one trace entry
   per system. Entities outside of that need to support system may or may not see any
   traces, depending on domain policies or configuration. For example,
   if an OPES system is on the content provider "side", end-users are
   not guaranteed any traces. However, If an OPES system is working inside
   end-user domain, the
   architecture does origin server is not prevent implementers of developing out-of-band
   protocols and techniques guaranteed any traces
   related to address the above limitation.

7.2.1 user requests.

7. How to Support Tracing Information Granularity and Persistence levels
      Requirements

   In order to support tracing, the following aspects must be addressed:

   o  There MUST be able to trace entities a System Identifier that have acted on an
   application message in identify a domain that is
      employing an OPES flow, there may system.

   o  An OPES processor MUST be requirements able to
   keep information that is related be uniquely identified (MUST
      have an Identifier) within a system.

   o  An OPES processor MUST add its identification  to the following: trace.

   o  Message-related informatio: All data that describes specific
      actions performed on the message  An OPES processor SHOULD be provided with that
      message, as there is no other way add to find message level details
      later. the trace  identification of every
      callout service that received the application message.

   o  Session related information: Session level data  An OPES processor MUST be preserved
      for add to the duration trace identification  of the session.
      "system/entity" it belongs to. "System" ID MUST make it possible
      to access "system" privacy  policy.

   o  An OPES processor is responsible for
      inserting notifications if session-level MAY group the above information changes. for sequential
      trace entries having  the same "system/entity" ID. In other words,
      trace  entries produced within the same "system/entity"  MAY be
      merged/aggregated into a single less detailed trace entry.

   o  End-point related data: What profile is activated? Where to get
      profile details? Where  An OPES processor MAY delegate trace management to set preferences?

   o  TBD

7.3 Protocol Binding

   How tracing is added is application protocol-specific and will be
   documented in separate drafts. This work documents what tracing
   information is required and some common tracing elements.

7.4 Tracing scenarios and examples

   TBD

8. IAB considerations

   This section examines IAB [2] considerations (3.1)  a callout
      service within the same "system/entity".

   TBD

7.1 Tracing and (3.2)
   regarding notification in an OPES architecture. The IAB
   considerations System Granularity

   There are reiterated here for ease of reference.

   Notification propagates in opposite direction two distinct uses of tracing and cannot traces. First, is to SHOULD enable the
   "end (content producer or consumer) to detect OPES processor presence
   within end's trust domain. Such "end" should be attached able to see a trace
   entry, but does not need to application messages that it notifies about.
   Notification can be done out-band and may require the development able to interpret it beyond
   identification of the trust domain(s).

   Second, the domain administrator SHOULD be able to take a new protocol. trace entry
   (possibly supplied by an "end? as an opaque string) and interpret it.
   The direction of data flow for tracing administrator must be able to identify OPES processor(s) involved
   and
   notification are deoicted in Figure 1.

                                      Notification
                +-----------------------------------------------
                |                                               |
                |                                               V
          +---------------+            +-------+       +---------------+
          |               |            |       |       | Data Provider |
          | Data Consumer | Tracing    | may be able to identify applied adaptation services along with
   other message-specific information. That information SHOULD help to
   explain what OPES  |<----->|  Application  |
          |  Application  |<-----------|       |       +---------------+
          +---------------+            +-------+
                                           ^
                                           |OCP
                                           |
                                           V
                                       +---------+
                                       | Callout |
                                       | Server  |
                                       +---------+

                      Figure 1: Notification Flow

8.1 Notification Concerns

   Notifications for every HTTP request can burden some content
   providers. Therefore, it might agent(s) were involved and what they did. It may be preferable
   impractical to consider mechanisms
   that allow for provide all the  explicit request required information in all cases.
   This document view a trace record as a hint, as opposed to an
   exhaustive audit.

   Since the administrators of various trust domains can have various
   ways of notification. Hence, a
   mechanism for explicit request looking into tracing, they MAY require the choice of notification May freedom
   in what to put in trace records and how to format them. Trace records
   should be required.

   Furthermore, end point privacy is a concern. An end user may consider
   information about easy to extend beyond basic OPES services applied on their behalf requirements. Trace
   management algorithms should treat trace records as private. opaque data to
   the extent possible.

   It is not expected that entities in one trust domain to be able to
   get all OPES-related feedback from entities in other trust domains.
   For example, if translation for braille device has been applied, it
   can an end-user suspects that a served is corrupted by a
   callout service, there is no guarantee that the use will be concluded able to
   identify that service, contact its owner, or debug it _unless_ the user
   service is having eyesight problems; such
   information may be misused if within my trust domain. This is no different from the user
   current situation where it is applying impossible, in general, to know the
   contact person for a job online.
   Similarly, a content provider may consider information about its OPES
   services private. For example, use of a specific OPES intermediary by
   a high traffic volume site may indicate business alliances an application on an origin server that have
   not been publicly announced yet. Another example of privacy, include
   situations where a user may generates
   corrupted HTML; and even if the person is known, one should not want
   expect that person to reveal respond to any content
   provider all end-user queries.

7.2 Requirements for In-Band Tracing

   The OPES architecture [8] states that traces must be in-band. The
   support of this design specification is dependent on the specifics of
   the message application level protocol that is being used in an OPES
   flow. In-band tracing limits the OPES services type of application protocols that have been applied on their
   behalf. For example, why should every content provider know
   OPES can support. The details of what
   exact virus scanner a user is using?

   Security trace record can convey is
   also a concern. An attacker may benefit from knowledge dependent on the choice of internal OPES services layout, execution order, software versions
   and other information the application level protocol.

   For these reasons, the work will document requirements for
   application protocols that are likely need to be present in  automated
   notifications.

   The level support OPES traces. However, the
   architecture does not prevent implementers of available details in notifications versus content
   provider interest in supporting notification is a concern.
   Experience shows that content providers often require very detailed
   information  about user actions developing out-of-band
   protocols and techniques to address the above limitation.

7.2.1 Tracing Information Granularity and Persistence levels
      Requirements

   In order to be interested in notifications at
   all. For example, Hit Metering protocol [11] has been designed able to
   supply content providers with proxy cache hit counts, trace entities that have acted on an
   application message in an effort OPES flow, there may be requirements to
   reduce cache busting behavior which was caused by content providers
   desire
   keep information that is related to get accurate site "access counts". However, the Hit
   Metering protocol is currently not widely deployed. This is because following:

   o  Message-related informatio: All data that describes specific
      actions performed on the protocol does not supply  content providers message SHOULD be provided with information such that
      message, as client IP addresses, browser versions, or cookies.

   The Hit  Metering experience is relevant because Hit Metering
   protocol was  designed there is no other way to do find message level details
      later.

   o  Session related information: Session level data MUST be preserved
      for HTTP caching intermediaries what the duration of the session. OPES notifications are meant to do processor is responsible for OPES intermediaries. Thus, it
      inserting notifications if session-level information changes.

   o  End-point related data: What profile is important activated? Where to have the right balance when specifying the
   notofication requirements for OPES.

   In this document,  IAB choice of "Notification" label get
      profile details? Where to set preferences?

   o  TBD

7.3 Protocol Binding

   How tracing is interpreted
   as "Notification assistance" (i.e. making notifications meaningful)
   and added is not application protocol-specific and will be interpreted as a "Notification protocol".  Therefore,
   the
   documented in separate drafts. This work treats IAB considerations (3.1 and 3.2) as informative (not
   normative).

8.1.1 Addressing IAB Consideration 3.1

   The consideration documents what tracing
   information is restated below for ease of reference.

   (3.1) Notification: The overall OPES framework needs to assist
   content providers in detecting required and responding to client-centric
   actions by OPES intermediaries that are deemed inappropriate by the
   content provider. some common tracing elements.

7.4 Tracing scenarios and examples

   TBD

8. Optional Notification

   This section examines IAB consideration [2] considerations (3.1) suggests that the overall and (3.2)
   regarding notification in an OPES framework
   needs to assist content providers architecture.

   Notification propagates in detecting opposite direction of tracing and responding to
   client-centric actions by OPES intermediaries that are deemed
   inappropriate by the content provider.

   It is important to note that most client-centric actions happen after
   the application message has left the content provider(s). Thus,
   notifications cannot
   be piggy-backed attached to application messages that it notifies about.
   Notification can be done out-band and have
   to travel in may require the opposite direction of traces, see Figure 1. To
   address this requirement directly, one would have to develop an out
   of band protocol to support notification.

   At this stage, there is no need to develop an out development of band protocol to
   support notification, since requiring the OPES architecture to having
   a  tracing facility can fulfil the objectives new protocol. The direction of notification. In
   this regard, it is recommended that data flow for tracing MUST be always-on, just
   like HTTP Via headers. This should eliminate and
   notification as a
   separate requirement.

8.1.2 Addressing IAB Consideration 3.2

   The consideration are depicted in Figure 2.

                                      Notification
                +-----------------------------------------------
                |                                               |
                |                                               V
          +---------------+            +-------+       +---------------+
          |               |            |       |       | Data Provider |
          | Data Consumer | Tracing    | OPES  |<----->|  Application  |
          |  Application  |<-----------|       |       +---------------+
          +---------------+            +-------+
                                           ^
                                           |OCP
                                           |
                                           V
                                       +---------+
                                       | Callout |
                                       | Server  |
                                       +---------+

                      Figure 2: Notification Flow

   In [9] it was argued that Notification is restated below an expensive approach for ease of reference.

   (3.2) Notification: The overall OPES framework should assist end
   users in detecting
   providing tracing information. However, the behavior of current work does not
   prevent an OPES intermediaries, potentially
   allowing them to identify imperfect or compromised intermediaries.

   TBD

   If the System from publishing policy and specifications that
   allow Optional Notification. For example, an OPES end points cooperate then notification System can be supported
   by tracing. Content providers adopt a
   mechanism that uses a flag that suspect or experience difficulties
   can do any of the following:

   o  Check whether requests they receive pass through OPES
      intermediaries. Presence of OPES tracing info will determine that.
      This check is only possible for request/response protocols. For
      other protocols (e.g., broadcast or push), the provider would have allow a data consumer and a
   data provider application to assume signal to each other that OPES intermediaries are involved until proven
      otherwise.

   o  If OPES intermediaries they are suspected, request
   interested to receive an explicit notification if an  OPES traces from
      potentially affected user(s). service is
   applied to a specific message. The trace will value of this optional flag/field
   can be a part of the
      application message received by the user software. If users
      cooperate, the provider(s) have all the information they need. URI that identifies notification method plus parameters. If
      users do not cooperate,
   a processor understands the provider(s) cannot do much about method, it
      (they might would be able to deny service  to uncooperative users in
      some cases).

   o  Some traces may indicate that more information is available by
      accessing certain resources on further
   decode the specified OPES intermediary or
      elsewhere. Content providers may query field and send a notification. The specification of  the
   field name and format for more information an  application protocol can be stated in
      that case.
   the associated binding document. The details of the notification
   protocol is beyond the scope of this Working Group.

   For example, the following HTTP header:

   o  If everything else fails, providers  OPES-Notify: URI *(pname=pvalue)

   Or,

   o  My-OPES-Notify: foo=bar q=0.5

   can enforce no-adaptation
      policy using appropriate OPES bypass mechanisms and/or end-to-end
      mechanisms. be used.

9. Security IANA considerations

   TBD

10. IANA Security Considerations

   The proposed work will evaluate current protocols for OCP. If the
   work determines that a new protocol need to be developed, then there
   may be a need to request new numbers from IANA.

   TBD

Normative References

   [1]  McHenry, S., et. al, "OPES Scenarios and Use Cases",
        Internet-Draft TBD, May 2002.

   [2]  Floyd, S. and L. Daigle, "IAB Architectural and Policy
        Considerations for Open Pluggable Edge Services", RFC 3238,
        January 2002.

   [3]  Fielding, R., Gettys, J., Mogul, J., Nielsen, H., Masinter, L.,
        Leach, P. and T. Berners-Lee, "Hypertext Transfer Protocol --
        HTTP/1.1", RFC 2616, June 1999.

   [4]  OPES working group, "OPES Service Authorization and Enforcement
        Requirements", Internet-Draft TBD, May 2002.

   [5]  OPES working group, "OPES Ruleset Schema", Internet-Draft TBD,
        May 2002.

   [6]  A. Beck et al., "Requirements for OPES Callout Protocols",
        Internet-Draft http://www.ietf.org/internet-drafts/
        draft-ietf-opes-protocol-reqs-03.txt, December 2002.

   [7]  A. Barbir et al., "Security Threats and Risks for Open Pluggable
        Edge Services", Internet-Draft http://www.ietf.org/
        internet-drafts/draft-ietf-opes-threats-00.txt, October  2002.

   [8]  A. Barbir et al., "An Architecture for Open Pluggable Edge
        Services (OPES)", Internet-Draft http://www.ietf.org/
        internet-drafts/draft-ietf-opes-architecture-04, December  2002.

   [9]  A. Barbir et al., "OPES Treatment of IAB Considerations",
        Internet-Draft http://www.ietf.org/internet-drafts/
        draft-ietf-opes-iab-01.txt, February  2004.

Informative References

   [9]

   [10]  Westerinen, A., Schnizlein, J., Strassner, J., Scherling, M.,
         Quinn, B., Herzog, S., Huynh, A., Carlson, M., Perry, J. and S.
         Waldbusser, "Terminology for Policy-Based Management", RFC
         3198, November 2001.

   [10]

   [11]  L. Cranor,  et. al, "The Platform for Privacy Preferences 1.0
         (P3P1.0) Specification", W3C Recommendation 16 http://
         www.w3.org/TR/2002/REC-P3P-20020416/ , April  2002.

   [11]

   [12]  "Hit Metering", RFC .

Author's Address

   Abbie Barbir
   Nortel Networks
   3500 Carling Avenue
   Nepean, Ontario  K2H 8E9
   Canada

   Phone: +1 613 763 5229
   EMail: abbieb@nortelnetworks.com

Appendix A. Acknowledgements

   TBD

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