Open Pluggable Edge Services (OPES) Callout Protocol (OCP) Core
RFC 4037

Network Working Group                                        A. Rousskov
Request for Comments: 4037                       The Measurement Factory
Category: Standards Track                                     March 2005

    Open Pluggable Edge Services (OPES) Callout Protocol (OCP) Core

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   This document specifies the core of the Open Pluggable Edge Services
   (OPES) Callout Protocol (OCP).  OCP marshals application messages
   from other communication protocols: An OPES intermediary sends
   original application messages to a callout server; the callout server
   sends adapted application messages back to the processor.  OCP is
   designed with typical adaptation tasks in mind (e.g., virus and spam
   management, language and format translation, message anonymization,
   or advertisement manipulation).  As defined in this document, the OCP
   Core consists of application-agnostic mechanisms essential for
   efficient support of typical adaptations.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
       1.1.  Scope  . . . . . . . . . . . . . . . . . . . . . . . . .  4
       1.2.  OPES Document Map  . . . . . . . . . . . . . . . . . . .  5
       1.3.  Terminology  . . . . . . . . . . . . . . . . . . . . . .  6
   2.  Overall Operation  . . . . . . . . . . . . . . . . . . . . . .  7
       2.1.  Initialization . . . . . . . . . . . . . . . . . . . . .  7
       2.2.  Original Dataflow  . . . . . . . . . . . . . . . . . . .  8
       2.3.  Adapted Dataflow . . . . . . . . . . . . . . . . . . . .  8
       2.4.  Multiple Application Messages  . . . . . . . . . . . . .  9
       2.5.  Termination  . . . . . . . . . . . . . . . . . . . . . .  9
       2.6.  Message Exchange Patterns  . . . . . . . . . . . . . . .  9
       2.7.  Timeouts . . . . . . . . . . . . . . . . . . . . . . . . 10
       2.8.  Environment  . . . . . . . . . . . . . . . . . . . . . . 11
   3.  Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Rousskov                    Standards Track                     [Page 1]
RFC 4037               OPES Callout Protocol Core             March 2005

       3.1.  Message Format . . . . . . . . . . . . . . . . . . . . . 12
       3.2.  Message Rendering  . . . . . . . . . . . . . . . . . . . 13
       3.3.  Message Examples . . . . . . . . . . . . . . . . . . . . 14
       3.4.  Message Names  . . . . . . . . . . . . . . . . . . . . . 15
   4.  Transactions . . . . . . . . . . . . . . . . . . . . . . . . . 15
   5.  Invalid Input  . . . . . . . . . . . . . . . . . . . . . . . . 16
   6.  Negotiation  . . . . . . . . . . . . . . . . . . . . . . . . . 16
       6.1.  Negotiation Phase  . . . . . . . . . . . . . . . . . . . 17
       6.2.  Negotiation Examples . . . . . . . . . . . . . . . . . . 18
   7.  'Data Preservation' Optimization . . . . . . . . . . . . . . . 20
   8.  'Premature Dataflow Termination' Optimizations . . . . . . . . 21
       8.1.  Original Dataflow  . . . . . . . . . . . . . . . . . . . 22
       8.2.  Adapted Dataflow . . . . . . . . . . . . . . . . . . . . 23
       8.3.  Getting Out of the Loop  . . . . . . . . . . . . . . . . 24
   9.  Protocol Element Type Declaration Mnemonic (PETDM) . . . . . . 25
       9.1     Optional Parameters  . . . . . . . . . . . . . . . . . 27
   10. Message Parameter Types  . . . . . . . . . . . . . . . . . . . 28
       10.1.   uri. . . . . . . . . . . . . . . . . . . . . . . . . . 28
       10.2.   uni. . . . . . . . . . . . . . . . . . . . . . . . . . 28
       10.3.   size . . . . . . . . . . . . . . . . . . . . . . . . . 29
       10.4.   offset . . . . . . . . . . . . . . . . . . . . . . . . 29
       10.5.   percent  . . . . . . . . . . . . . . . . . . . . . . . 29
       10.6.   boolean. . . . . . . . . . . . . . . . . . . . . . . . 30
       10.7.   xid .  . . . . . . . . . . . . . . . . . . . . . . . . 30
       10.8.   sg-id. . . . . . . . . . . . . . . . . . . . . . . . . 30
       10.9.   modp. . . . . . . . . . . . . . . . . . . . . . . . .  30
       10.10.  result. . . . . . . . . . . . . . . . . . . . . . . .  30
       10.11.  feature . . . . . . . . . . . . . . . . . . . . . . .  32
       10.12.  features. . . . . . . . . . . . . . . . . . . . . . .  32
       10.13.  service . . . . . . . . . . . . . . . . . . . . . . .  32
       10.14.  services. . . . . . . . . . . . . . . . . . . . . . .  33