Rationale for the Structure of the Model and Protocol for the Internet Printing Protocol
Network Working Group S. Zilles
Request for Comments: 2568 Adobe Systems Inc.
Category: Experimental April 1999
Rationale for the Structure of the Model and Protocol
for the Internet Printing Protocol
Status of this Memo
This memo defines an Experimental Protocol for the Internet
community. It does not specify an Internet standard of any kind.
Discussion and suggestions for improvement are requested.
Distribution of this memo is unlimited.
Copyright (C) The Internet Society (1999). All Rights Reserved.
This document defines an Experimental protocol for the Internet
community. The IESG expects that a revised version of this protocol
will be published as Proposed Standard protocol. The Proposed
Standard, when published, is expected to change from the protocol
defined in this memo. In particular, it is expected that the
standards-track version of the protocol will incorporate strong
authentication and privacy features, and that an "ipp:" URL type will
be defined which supports those security measures. Other changes to
the protocol are also possible. Implementors are warned that future
versions of this protocol may not interoperate with the version of
IPP defined in this document, or if they do interoperate, that some
protocol features may not be available.
The IESG encourages experimentation with this protocol, especially in
combination with Transport Layer Security (TLS) [RFC2246], to help
determine how TLS may effectively be used as a security layer for
This document is one of a set of documents, which together describe
all aspects of a new Internet Printing Protocol (IPP). IPP is an
application level protocol that can be used for distributed printing
using Internet tools and technologies. This document describes IPP
from a high level view, defines a roadmap for the various documents
that form the suite of IPP specifications, and gives background and
rationale for the IETF working group's major decisions.
Zilles Experimental [Page 1]
RFC 2568 Rationale for IPP April 1999
The full set of IPP documents includes:
Design Goals for an Internet Printing Protocol [RFC2567]
Rationale for the Structure and Model and Protocol for the
Internet Printing Protocol (this document)
Internet Printing Protocol/1.0: Model and Semantics [RFC2566]
Internet Printing Protocol/1.0: Encoding and Transport [RFC2565]
Internet Printing Protocol/1.0: Implementer's Guide [ipp-iig]
Mapping between LPD and IPP Protocols [RFC2569]
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
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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