Open Pluggable Edge Services (OPES) Use Cases and Deployment Scenarios
RFC 3752

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Network Working Group                                          A. Barbir
Request for Comments: 3752                               Nortel Networks
Category: Informational                                        E. Burger
                                             Brooktrout Technology, Inc.
                                                                 R. Chen
                                                               AT&T Labs
                                                              S. McHenry
                                                  Individual Contributor
                                                                H. Orman
                                               Purple Streak Development
                                                                R. Penno
                                                         Nortel Networks
                                                              April 2004

                  Open Pluggable Edge Services (OPES)
                   Use Cases and Deployment Scenarios

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2004).  All Rights Reserved.

Abstract

   This memo provides a discussion of use cases and deployment scenarios
   for Open Pluggable Edge Services (OPES).  The work examines services
   that could be performed to requests and/or responses.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Types of OPES services . . . . . . . . . . . . . . . . . . . .  3
       2.1.  Services performed on requests . . . . . . . . . . . . .  3
             2.1.1.  Services intending to modify requests  . . . . .  3
             2.1.2.  Services *not* intending to modify requests  . .  4
       2.2.  Services performed on responses. . . . . . . . . . . . .  4
             2.2.1.  Services intending to modify responses . . . . .  4
             2.2.2.  Services *not* intending to modify responses . .  5
       2.3.  Services creating responses. . . . . . . . . . . . . . .  5
   3.  OPES deployment scenarios  . . . . . . . . . . . . . . . . . .  5
       3.1.  Surrogate Overlays . . . . . . . . . . . . . . . . . . .  6
       3.2.  Delegate Overlays  . . . . . . . . . . . . . . . . . . .  7

Barbir, et al.               Informational                      [Page 1]
RFC 3752                     OPES Scenarios                   April 2004

       3.3.  Enterprise environment . . . . . . . . . . . . . . . . .  8
       3.4.  Callout Servers  . . . . . . . . . . . . . . . . . . . .  9
       3.5.  Chaining of OPES data filters and callout servers  . . .  9
             3.5.1.  Chaining along the content path. . . . . . . . .  9
             3.5.2.  Chaining along the callout path. . . . . . . . .  9
   4.  Failure cases and service notification . . . . . . . . . . . . 10
   5.  Security Considerations. . . . . . . . . . . . . . . . . . . . 11
   6.  Informative References . . . . . . . . . . . . . . . . . . . . 11
   7.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
   8.  Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 12
   9.  Full Copyright Statement . . . . . . . . . . . . . . . . . . . 14

1.  Introduction

   The Open Pluggable Edge Services (OPES) [1] architecture 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 filtering 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 [6]
   servers.

   The document presents examples of services in which Open Pluggable
   Edge Services (OPES) would be useful.  There are different types of
   OPES services: services that modify requests, services that modify
   responses, and a special case of the latter, services that create
   responses.

   The work also examines various deployment scenarios of OPES services.
   The two main deployment scenarios, as described by the OPES
   architecture [1], are surrogate overlays and delegate overlays.
   Surrogate overlays act on behalf of data provider applications, while
   delegate overlays act on behalf of data consumer applications.  The
   document also describes combined surrogate and delegate overlays, as
   one might find within an enterprise deployment.

   The document is organized as follows: Section 2 discusses the various