\
Network Working Group                                          A. Barbir
Internet-Draft                                           Nortel Networks
Expires: December 10, 2003                                 June 11, 2003


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

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups. Note that other
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   This Internet-Draft will expire on December 10, 2003.

Copyright Notice

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

Abstract

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














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Table of Contents

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





















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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: .......


















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2. OPES Tracing

   Before discussing what is traceable in an OPES flow, it is beneficial
   to define what tracing means. Tracing is defined as the inclusion of
   necessary information within a message in an OPES flow that could be
   used to identify the set 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  OPES tracing: the process of including, manipulating, and
      interpreting an OPES trace

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

2.1 What is traceable in an OPES Flow?

   o  The data consumer application end point MUST be able to identify
      the OPES processors that have acted on an application message.

   o  The data consumer application end point SHOULD be able to identify
      OPES 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 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 OPES system MUST be traceable

   o  An OPES processor SHOULD be traceable

   o  An OPES service MAY be traceable

   o  Editor Note: Need to define an OPES System properly




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2.2 Requirements for Information Related to Traceable Entities?

   The requirements for information as related to entities that are
   terceable in an OPES flow are:

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

   o  Identification 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, the OPES
      processors involved in processing the messag

   o  TBD



































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3. Requirements for OPES systems

   Editor Note: Need to define OPES System and state requirements
















































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4. Requirements for OPES processors

   TBD
















































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5. Requirements for callout servers

   If it is the task of an OPES processor to add trace records to
   application messages, then callout servers that uses the OCP protocol
   are not affected by tracing requirements.In order for an OCP protocol
   to be tracing neutral, the OPES server SHOULD be able to meet the
   following requirements:

   o  Callout services adapt payload regardless of the application
      protocol in use and leave header adjustment to OPES processor.

   o  OPES processor SHOULD be able  to trace its own invocation and
      service(s) execution because OPES processor understand the
      application protocol.

   o  Callout servers  MAY be able to add their own OPES trace records
      to application level messages.

   o  TBD
































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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 one trace entry
   per system. Entities outside of that 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. If an OPES system is working inside
   end-user domain, the origin server is not guaranteed any traces
   related to user requests.






































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7. How to Support Tracing

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

   o  There MUST be a System Identifier that identify a domain that is
      employing an OPES system.

   o  An OPES processor MUST be able to be uniquely identified (MUST
      have an Identifier) within a system.

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

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

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

   o  An OPES processor MAY group the above information 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  An OPES processor MAY delegate trace management to  a callout
      service within the same "system/entity".

   TBD

7.1 Tracing and OPES System Granularity

   There are two distinct uses of 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 able to see a trace
   entry, but does not need to be able to interpret it beyond
   identification of the trust domain(s).

   Second, the domain administrator SHOULD be able to take a trace entry
   (possibly supplied by an "end? as an opaque string) and interpret it.
   The administrator must be able to identify OPES processor(s) involved
   and may be able to identify applied adaptation services along with
   other message-specific information. That information SHOULD help to
   explain what OPES agent(s) were 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 to an
   exhaustive audit.

   Since the administrators of various trust domains can have various



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   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 to extend beyond basic OPES requirements. Trace
   management algorithms should treat trace records as 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 an end-user suspects that a served is corrupted by a
   callout service, there is no guarantee that the use will be able 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 it is impossible, in general, to know the
   contact person for an application on an origin server that generates
   corrupted HTML; and even if the person is known, one should not
   expect that person to respond to 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 type of application protocols that
   OPES can support. The details of what a trace record can convey is
   also dependent on the choice of the application level protocol.

   For these reasons, the work will document requirements for
   application protocols that need to support OPES traces. However, the
   architecture does not prevent implementers of 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 able to trace entities that have acted on an
   application message in an OPES flow, there may be requirements to
   keep information that is related to the following:

   o  Message-related informatio: All data that describes specific
      actions performed on the message SHOULD be provided with that
      message, as there is no other way to find message level details
      later.

   o  Session related information: Session level data MUST be preserved
      for the duration of the session. OPES processor is responsible for
      inserting notifications if session-level information changes.

   o  End-point related data: What profile is activated? Where to get



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      profile details? Where 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





































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8. IAB considerations

   This section examines IAB [2] considerations (3.1) and (3.2)
   regarding notification in an OPES architecture. The IAB
   considerations are reiterated here for ease of reference.

   Notification propagates in opposite direction of tracing and cannot
   be attached to application messages that it notifies about.
   Notification can be done out-band and may require the development of
   a new protocol. The direction of data flow for tracing and
   notification are deoicted in Figure 1.



                                      Notification
                +-----------------------------------------------
                |                                               |
                |                                               V
          +---------------+            +-------+       +---------------+
          |               |            |       |       | Data Provider |
          | Data Consumer | Tracing    | 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 be preferable to consider mechanisms
   that allow for the  explicit request of notification. Hence, a
   mechanism for explicit request of notification May be required.

   Furthermore, end point privacy is a concern. An end user may consider
   information about OPES services applied on their behalf as private.
   For example, if translation for braille device has been applied, it
   can be concluded that the user is having eyesight problems; such



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   information may be misused if the user is applying 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 that have
   not been publicly announced yet. Another example of privacy, include
   situations where a user may not want to reveal to any content
   provider all the OPES services that have been applied on their
   behalf. For example, why should every content provider know what
   exact virus scanner a user is using?

   Security is also a concern. An attacker may benefit from knowledge
   of internal OPES services layout, execution order, software versions
   and other information that are likely to be present in  automated
   notifications.

   The level 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 to be interested in notifications at
   all. For example, Hit Metering protocol [11] has been designed to
   supply content providers with proxy cache hit counts, in an effort to
   reduce cache busting behavior which was caused by content providers
   desire to get accurate site "access counts". However, the Hit
   Metering protocol is currently not widely deployed. This is because
   the protocol does not supply  content providers with information such
   as client IP addresses, browser versions, or cookies.

   The Hit  Metering experience is relevant because Hit Metering
   protocol was  designed to do for HTTP caching intermediaries what
   OPES notifications are meant to do for OPES intermediaries. Thus, it
   is important to have the right balance when specifying the
   notofication requirements for OPES.

   In this document,  IAB choice of "Notification" label is interpreted
   as "Notification assistance" (i.e. making notifications meaningful)
   and is not be interpreted as a "Notification protocol".  Therefore,
   the work treats IAB considerations (3.1 and 3.2) as informative (not
   normative).

8.1.1 Addressing IAB Consideration 3.1

   The consideration is restated below for ease of reference.

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




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   IAB consideration (3.1) suggests that the overall OPES framework
   needs to assist content providers in detecting 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 to application messages and have
   to travel in 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 of band protocol to
   support notification, since requiring the OPES architecture to having
   a  tracing facility can fulfil the objectives of notification. In
   this regard, it is recommended that tracing MUST be always-on, just
   like HTTP Via headers. This should eliminate notification as a
   separate requirement.

8.1.2 Addressing IAB Consideration 3.2

   The consideration is restated below for ease of reference.

   (3.2) Notification: The overall OPES framework should assist end
   users in detecting the behavior of OPES intermediaries, potentially
   allowing them to identify imperfect or compromised intermediaries.

   TBD

   If the OPES end points cooperate then notification can be supported
   by tracing. Content providers 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
      to assume that OPES intermediaries are involved until proven
      otherwise.

   o  If OPES intermediaries are suspected, request OPES traces from
      potentially affected user(s). The trace will be a part of the
      application message received by the user software. If users
      cooperate, the provider(s) have all the information they need. If
      users do not cooperate, the provider(s) cannot do much about it
      (they might be able to deny service  to uncooperative users in
      some cases).




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   o  Some traces may indicate that more information is available by
      accessing certain resources on the specified OPES intermediary or
      elsewhere. Content providers may query for more information in
      that case.

   o  If everything else fails, providers can enforce no-adaptation
      policy using appropriate OPES bypass mechanisms and/or end-to-end
      mechanisms.











































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9. Security considerations

   TBD
















































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10. IANA 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.














































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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.





















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Informative References

   [9]   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]  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]  "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



























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Appendix A. Acknowledgements

   TBD
















































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   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
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Acknowledgment

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











































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