RFC 2568 (rfc2568) - Page 2 of 10

Rationale for the Structure of the Model and Protocol for the Internet Printing Protocol

RFC 2568                   Rationale for IPP                  April 1999


   The full set of IPP documents includes:

      Design Goals for an Internet Printing Protocol [RFC 2567]
      Rationale for the Structure and Model and Protocol for the
      Internet Printing Protocol (this document)
      Internet Printing Protocol/1.0: Model and Semantics [RFC 2566]
      Internet Printing Protocol/1.0: Encoding and Transport [RFC 2565]
      Internet Printing Protocol/1.0: Implementer's Guide [ipp-iig]
      Mapping between LPD and IPP Protocols [RFC 2569]

   The "Design Goals for an Internet Printing Protocol" document takes a
   broad look at distributed printing functionality, and it enumerates
   real-life scenarios that help to clarify the features that need to be
   included in a printing protocol for the Internet.  It identifies
   requirements for three types of users: end users, operators, and
   administrators.  The Design Goals document calls out a subset of end
   user requirements that are satisfied in IPP/1.0. Operator and
   administrator requirements are out of scope for version 1.0.

   The "Internet Printing Protocol/1.0: Model and Semantics" document
   describes a simplified model consisting of abstract objects, their
   attributes, and their operations that is independent of encoding and
   transport.  The model consists of a Printer and a Job object.  The
   Job optionally supports multiple documents.  This document also
   addresses security, internationalization, and directory issues.

   The "Internet Printing Protocol/1.0: Encoding and Transport" document
   is a formal mapping of the abstract operations and attributes defined
   in the model document onto HTTP/1.1.  It defines the encoding rules
   for a new Internet media type called "application/ipp".

   The "Internet Printing Protocol/1.0: Implementer's Guide" document
   gives insight and advice to implementers of IPP clients and IPP
   objects.  It is intended to help them understand IPP/1.0 and some of
   the considerations that may assist them in the design of their client
   and/or IPP object implementations.  For example, a typical order of
   processing requests is given, including error checking.  Motivation
   for some of the specification decisions is also included.

   The "Mapping between LPD and IPP Protocols" document gives some
   advice to implementers of gateways between IPP and LPD (Line Printer
   Daemon) implementations.

1.   ARCHITECTURAL OVERVIEW

   The Internet Printing Protocol (IPP) is an application level protocol
   that can be used for distributed printing on the Internet.  This
   protocol defines interactions between a client and a server.  The



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