Network Working Group A. Barbir
Internet-Draft Nortel Networks
Expires: March 12, 2004 September 12, 2003
OPES processor and end points communications
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).
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. OPES Domain and OPES System . . . . . . . . . . . . . . . . 4
3. OPES Tracing . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1 What is traceable in an OPES Flow? . . . . . . . . . . . . . 6
3.2 Requirements for Information Related to Traceable
Entities? . . . . . . . . . . . . . . . . . . . . . . . . . 7
4. Requirements for OPES processors . . . . . . . . . . . . . . 8
5. Requirements for callout servers . . . . . . . . . . . . . . 9
6. Privacy considerations . . . . . . . . . . . . . . . . . . . 10
6.1 Tracing and Trust Domains . . . . . . . . . . . . . . . . . 10
7. How to Support Tracing . . . . . . . . . . . . . . . . . . . 11
7.1 Tracing and OPES System Granularity . . . . . . . . . . . . 11
7.2 Requirements for In-Band Tracing . . . . . . . . . . . . . . 12
7.2.1 Tracing Information Granularity and Persistence levels
Requirements . . . . . . . . . . . . . . . . . . . . . . . . 12
7.3 Protocol Binding . . . . . . . . . . . . . . . . . . . . . . 13
7.4 Tracing scenarios and examples . . . . . . . . . . . . . . . 13
8. Optional Notification . . . . . . . . . . . . . . . . . . . 14
9. IANA considerations . . . . . . . . . . . . . . . . . . . . 16
10. Security Considerations . . . . . . . . . . . . . . . . . . 17
Normative References . . . . . . . . . . . . . . . . . . . . 18
Informative References . . . . . . . . . . . . . . . . . . . 19
Author's Address . . . . . . . . . . . . . . . . . . . . . . 19
A. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20
Intellectual Property and Copyright Statements . . . . . . . 21
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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: Section 2 defines OPES Domain
and OPES System. Section 3 discusses entities that are traceable in
an OPES 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.
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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 is traceable in an
OPES Flow [8].
An OPES domain describes the collection of OPES entities that a
single provider operates. OPES domains can be based on trust or other
operational boundaries. All elements of an "OPES Domain" MUST be in
the same trust domain. This would be independent of any specific OPES
flow.
An OPES system consists of a limited set of OPES entities, parts of a
single or of multiple OPES operators domains, organized by (or on
behalf) of either a data provider application or a data consumer
application to perform authorized services on a given application
message. Each OPES entity in an OPES system MUST be directly
addressable on IP level by a data consumer application.
An OPES system can be formed in a recursive manner. An OPES 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 is
already in the OPES system. The trust and authority delegation is
viewed in the context of the given application message.
As implied by the above definition, some OPES entities in the system
may not participate in the processing of a given message.
An OPES domain MUST not be an OPES sub-system. An OPES domain MUST
require external resources to provide services. An OPES domain is a
part of an OPES system belonging to a given operator. OPES domains
have no incidence on the 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 OPES Flow is shown that traverses across various OPES
Domains. A data consumer application MUST be able to recive tracing
information on per message basis that enable it to determine the set
of transformations that were perfomed on the data for a particular
OPES Flow. The formation of an OPES flow can be static or dynamic,
meaning that the determination of which OPES Domains will participate
in a given OPES Flow (per message basis) can be a function of
business arrangements.
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+------------------------------------------+
| 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
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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 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 in an OPES System before its delivery
to an end point (the data consumer application).
o OPES trace: application message information about OPES entities in
an OPES System that adapted that message.
o OPES tracing: the process of including, manipulating, and
interpreting an OPES trace 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. The architecture document requires [8]
that 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 be hesitant to reveal information about their
internal network infrastructure.
o Within a service provider network, OPES processors may 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 Flow?
This section focuses on identifying the traceable entities in an OPES
Flow. Tracing information MUST be able to provide a data consumer
application with useful information without tracing the exact OPES
Processor or callout servers that adapted the data. It is up to the
OPES service provider to have maintained appropriate internal
detailed traces to find the answer to the data consumer applications
inquiry.
At the implementation level, for a given trace, an OPES entity
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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 add its entry to the trace.
o An OPES processor SHOULD add its entry to the trace.
o An OPES service SHOULD add its entry to the trace.
o An OPES entity MAY manage trace information from entities that are
under its control. For example, an OPES processor may add or
remove callout service entries in order to manage the size of a
trace. Other considerations include:
* The OPES processor may have a fixed configuration that enable
it to respond to tracing inquires.
* The OPES processor may insert a summary of the services that it
controls. The summary can be used to respond to tracing
inquiries.
* The OPES processor may package tracing information related to
the entities that it control based on the policy of a given
OPES System.
From an OPES context, a good tracing approach is similar to a trouble
ticket ready for submission to a known address. The trace in itself
is not necessarily a detailed description of what has happened. It is
the resposibility of the operator to resolve the problems.
3.2 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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4. Requirements for OPES processors
In order to facilitate compliance, the concept of an "OPES system"
being traceable, requires that each OPES processor MUST support
tracing. Policy can be set that defines which domain has
authorization to turn on tracing and its granularity. An OPES
provider can have its private policy for trace information, but it
MUST support tracing mechanisms and it MUST reveal it's policy.
The requirements for OPES processors that are applicatble to tracing
are:
o Each OPES processor MUST belong to a single OPES Domain.
o Each OPES processor MUST have a Unique Identity in that Domain.
o Each OPES processor MUST support tracing, policy can be used to
turn tracing on and.to determine granuality.
o 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 it's own invocation and
service(s) execution since they 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. Optional Notification
This section examines IAB [2] considerations (3.1) and (3.2)
regarding notification in an OPES architecture.
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 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 an expensive approach for
providing tracing information. However, the current work does not
prevent an OPES System from publishing policy and specifications that
allow Optional Notification. For example, an OPES System can adopt a
mechanism that uses a flag that would allow a data consumer and a
data provider application to signal to each other that they are
interested to receive an explicit notification if an OPES service is
applied to a specific message. The value of this optional flag/field
can be a URI that identifies notification method plus parameters. If
a processor understands the method, it would be able to further
decode the field and send a notification. The specification of the
field name and format for an application protocol can be stated in
the associated binding document. The details of the notification
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protocol is beyond the scope of this Working Group.
For example, the following HTTP header:
o OPES-Notify: URI *(pname=pvalue)
Or,
o My-OPES-Notify: foo=bar q=0.5
can be used.
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9. IANA considerations
TBD
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10. Security Considerations
TBD
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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.
[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.
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Informative References
[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.
[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.
[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
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Appendix A. Acknowledgements
TBD
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