Network Working Group A. Barbir Internet-Draft Nortel Networks Expires: November 2, 2003 May 4, 2003 OPES Tracing draft-ietf-opes-tracing-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 groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http:// www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on November 2, 2003. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract This memo provides a discussion of tracing requirements for OPES as part of addressing the IAB considerations on this issue. Barbir Expires November 2, 2003 [Page 1] Internet-Draft OPES Tracing May 2003 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements for Notification in an OPES Flow . . . . . . . 4 2.1 Notification Concerns . . . . . . . . . . . . . . . . . . . 5 2.2 How to Fulfill Notifications Requirements . . . . . . . . . 6 3. Requirements for Tracing in an OPES Flow . . . . . . . . . . 8 3.1 What is traceable? . . . . . . . . . . . . . . . . . . . . . 8 3.1.1 Requirements for Information Related to Traceable Entities . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3.2 Tracing and Trust Domains . . . . . . . . . . . . . . . . . 9 3.3 Tracing and OPES System Granularity . . . . . . . . . . . . 9 3.4 Requirements for In-Band Tracing . . . . . . . . . . . . . . 10 3.4.1 Tracing Information Granularity andPpersistence levels Requirements . . . . . . . . . . . . . . . . . . . . . . . . 10 3.4.2 Protocol Binding . . . . . . . . . . . . . . . . . . . . . . 10 3.5 Tracing Requirements and Privacy . . . . . . . . . . . . . . 10 3.6 Requirements for OCP Support for Tracing . . . . . . . . . . 10 3.7 How to Support Tracing . . . . . . . . . . . . . . . . . . . 11 3.8 Tracing Examples and Scenarios . . . . . . . . . . . . . . . 12 3.8.1 Tracing as a Callout Service . . . . . . . . . . . . . . . . 12 4. Security Considerations . . . . . . . . . . . . . . . . . . 13 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . 14 Normative References . . . . . . . . . . . . . . . . . . . . 15 Informative References . . . . . . . . . . . . . . . . . . . 16 Author's Address . . . . . . . . . . . . . . . . . . . . . . 16 A. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17 Intellectual Property and Copyright Statements . . . . . . . 18 Barbir Expires November 2, 2003 [Page 2] Internet-Draft OPES Tracing May 2003 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. In [2] the IAB has required OPES solutions to address end user and content provider notification concerns. IAB, considerations regarding notification 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, and that the overall OPES framework should assist end users in detecting the behavior of OPES intermediaries, potentially allowing them to identify imperfect or compromised intermediaries. This document specifies tracing mechanisms that address those concerns. The work focus on developing tracing requirements that can be used to fulfil the notification and Non-Blocking suggestions from the IAB. The appropriate design of tracing mechanisms can properly address the notification requirements without introducing added complexity to the OPES architecture. 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. Furthermore, the work addresses IAB consideration (3.3) (Non-blocking) that suggests that the OPES architecture must not prevent the end consumer application from accessing a non OPES version of the content if that version is avilable. The document is organized as follows: Section 2 considers ? Section 3? etc. Barbir Expires November 2, 2003 [Page 3] Internet-Draft OPES Tracing May 2003 2. Requirements for Notification in an OPES Flow 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. (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. (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. Before discussing notification, 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). Tracing SHOULD be performed on per message basis. The format is dependent on the application level protocol that is used by the OPES system. The architecture requires that tracing be supported in-band. Furthermore, tracing can be used as a tool by the end user data application to infer the actions that has been performed by the OPES system. On the otherhand, 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. Barbir Expires November 2, 2003 [Page 4] Internet-Draft OPES Tracing May 2003 Notification +----------------------------------------------- | | | V +---------------+ +-------+ +---------------+ | | | | | Data Provider | | Data Consumer | Tracing | OPES |<----->| Application | | Application |<-----------| | +---------------+ +---------------+ +-------+ ^ |OCP | V +---------+ | Callout | | Server | +---------+ Figure 1: Notification Flow 2.1 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 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. Barbir Expires November 2, 2003 [Page 5] Internet-Draft OPES Tracing May 2003 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. 2.2 How to Fulfill Notifications Requirements 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. In other words, the 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). 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: Barbir Expires November 2, 2003 [Page 6] Internet-Draft OPES Tracing May 2003 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). 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. Barbir Expires November 2, 2003 [Page 7] Internet-Draft OPES Tracing May 2003 3. Requirements for Tracing in an OPES Flow In [2], the IAB has required that the OPES architecture provide tracing and debugging facilities. From [8], the OPES architecture SHOULD assist consumer application in detecting the behavior of OPES processors and callout servers to potentially allow them to identify imperfect or compromised operations. The OPES architecture document [8] has addressed these concerns at a higher level. The architecture requires that tracing be feasible on an OPES flow per OPES processor using in-band annotation. This requirement provides a participant with the ability to detect OPES intermediaries in the course of normal interaction. 3.1 What is traceable? Tracing should provide information to end points in an OPES flow that enable it to identify the various entities that are involved. The main focus of this work is the data consumer application end point. The following entities SHOULD be identified in a trace by a data consumer application end point: 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. 3.1.1 Requirements for Information Related to Traceable Entities 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 message From a architectural standpoint, every OPES processor MUST be a traceable entity but callout servers MAY be traceable entities. Barbir Expires November 2, 2003 [Page 8] Internet-Draft OPES Tracing May 2003 3.2 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. 3.3 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 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. Barbir Expires November 2, 2003 [Page 9] Internet-Draft OPES Tracing May 2003 3.4 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. 3.4.1 Tracing Information Granularity andPpersistence 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 profile details? Where to set preferences? o TBD 3.4.2 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. 3.5 Tracing Requirements and Privacy 3.6 Requirements for OCP Support for Tracing If it is the task of an OPES processor to add trace records to Barbir Expires November 2, 2003 [Page 10] Internet-Draft OPES Tracing May 2003 application messages, then the OCP protocol is 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 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 3.7 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". Barbir Expires November 2, 2003 [Page 11] Internet-Draft OPES Tracing May 2003 3.8 Tracing Examples and Scenarios TBD 3.8.1 Tracing as a Callout Service TBD Barbir Expires November 2, 2003 [Page 12] Internet-Draft OPES Tracing May 2003 4. Security Considerations Barbir Expires November 2, 2003 [Page 13] Internet-Draft OPES Tracing May 2003 5. 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. Barbir Expires November 2, 2003 [Page 14] Internet-Draft OPES Tracing May 2003 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. Barbir Expires November 2, 2003 [Page 15] Internet-Draft OPES Tracing May 2003 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(_at_)nortelnetworks(_dot_)com Barbir Expires November 2, 2003 [Page 16] Internet-Draft OPES Tracing May 2003 Appendix A. Acknowledgements This document is the product of OPES WG. Oskar Batuner (Independent consultant) and Andre Beck (Lucent) are additional authors that have contributed to this current document. Earlier versions of this work was done by Gary Tomlinson (The Tomlinson Group) and Michael Condry (Intel). The authors gratefully acknowledge the contributions of: John Morris, Mark Baker, Ian Cooper and Marshall T. Rose. 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