Internet Printing Protocol WG Hugo Parra

Internet Printing Protocol WG Hugo Parra
INTERNET-DRAFT Novell, Inc.
<draft-ietf-ipp-install-04.txt> Ted Tronson
Updates: RFC 2911 Novell, Inc.
[Target category: standards track] Tom Hastings
Expires: January 17, 2002 Xerox Corp
July 17, 2001

Internet Printing Protocol (IPP):
Printer Installation Extension

Copyright (C) The Internet Society (2001). All Rights Reserved.

Status of this Memo

This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of [RFC2026]. Internet-Drafts are
working documents of the Internet Engineering Task Force (IETF), its
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Abstract

This document describes an OPTIONAL extension to the Internet
Printing Protocol/1.0 (IPP) [RFC2566, RFC2565] and IPP/1.1 [RFC2911,
RFC2910]. Various client platforms require that some setting up take
place at the workstation before the client can properly submit jobs
to a specific printer. This setup process is sometimes referred to
as printer installation. Most clients need some information about
the printer being installed as well as support files to complete the
printer installation. The nature of these "Client Print Support
Files" varies depending on the specific client platform, from simple
configuration files to highly sophisticated printer drivers. The
selection and installation process can be simplified and even
automated if the workstation can learn some key information about the
printer and which sets of Client Print Support Files are available.
Such key information includes: operating system type, CPU type,

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document-format (PDL), natural language, compression mechanism, file
type, client file name, policy for automatic loading, file size, file
version, file date and time, file information description, and
digital signature.

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Table of Contents

1 Introduction.....................................................5

2 Terminology......................................................5

3 Model Extensions.................................................6
3.1 client-print-support-files-supported (1setOf octetString(MAX)).6
3.1.1 Use of Keyword Values in fields.............................11
3.1.2 Use of the Special Keyword Value: 'unknown'.................11
3.1.3 Examples of "client-print-support-files-supported" attribute
values.................................................11
3.2 Get-Printer-Attributes Operation Extension....................12
3.2.1 Get-Printer-Attributes Request..............................12
3.2.1.1 client-print-support-files-filter (octetString(MAX))
operation attribute..................................12
3.2.1.1.1 Filter matching rules...................................14
3.2.2 Get-Printer-Attributes Response.............................15
3.3 Get-Client-Print-Support-Files................................17
3.3.1 Get-Client-Print-Support-Files Request......................17
3.3.2 Get-Client-Print-Support-Files Response.....................18

4 New Values for Existing Printer Description Attributes..........19

5 Conformance.....................................................19
5.1 Printer Conformance Requirements..............................19
5.2 Client Conformance Requirements...............................20

6 Encoding of the Operation Layer.................................20

7 IANA Considerations.............................................20
7.1 Attribute Registrations.......................................21
7.2 Additional Attribute Value Registrationsfor existing attributes21
7.2.1 Additional values for the "client-print-support-files-xxx"
attributes.............................................21
7.2.2 Additional values for the "operations-supported" Printer
attribute..............................................23
7.3 Operation Registrations.......................................23
7.4 Status Code Registrations.....................................23

8 Internationalization Considerations.............................24

9 Security Considerations.........................................24

10 Status Code Extensions.........................................25
10.1 client-error-client-print-support-file-not-found (0x0417)....25

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11 References.....................................................25

12 Author's Addresses.............................................27

13 Description of the Base IPP Documents..........................28

14 Full Copyright Statement.......................................29

Tables

Table 1 - "client-print-support-files-supported" attribute fields..8
Table 2 - "client-print-support-files-filter" attribute fields....13
Table 3 - REQUIRED "client-print-support-files-filter" fields.....14
Table 4 - Operation-id assignments................................19

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1 Introduction

This IPP notification specification is an OPTIONAL extension to
Internet Printing Protocol/1.0 (IPP) [RFC2566, RFC2565] and IPP/1.1
[RFC2911, RFC2910]. See section 13 for a brief description of the
IPP base documents.

A common configuration for printing from a workstation requires that
some Client Print Support Files (e.g., PPD, printer driver files)
specific to the target printer be installed on that workstation.
Selection and configuration of the appropriate Client Print Support
Files can be simplified and even automated if the workstation can
obtain some key information about the printer and which sets of
Client Print Support Files are available. Such key information
includes: operating system type, CPU type, document-format (PDL),
natural language, compression mechanism, file type, client file name,
policy for automatic loading, file size, file version, file date and
time, file information description, and digital signature.

The OPTIONAL IPP extension defined in this document provides a simple
and reliable vehicle for printers to convey this information to
interested workstations. This extension enables a flexible solution
for installing Client Print Support Files on workstations running
different operating systems and for printers of all makes and models.
It allows Client Print Support Files to be downloaded from
repositories of different sorts. A possible repository for the files
is the printer itself. The extensions necessary for getting Client
Print Support Files from the printer are included in this document,
including security for downloading executable code and data.

2 Terminology

This section defines the following terms that are used throughout
this document:

This document uses the same terminology as [RFC2911], such as
"attribute", "attribute value", "keyword", "operation", "request",
"response", and "support". In addition, the following terms are
defined for use in this document and the Delivery Method Documents:

Client Print Support Files - a set of files, such as a printer
driver, font metric file, printer configuration file (PPD, GPD, etc.)
that support a client printing to a particular Printer. A Printer
MAY have multiple sets of Client Print Support Files that work for
different operating systems, document formats, natural languages,
CPUs, etc.

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This document uses the same terminology as [RFC2911], such as
"client", "Printer", "attribute", "attribute value", "keyword",
"operation", "request", "response", and "support". This document
also uses the terms "IPP Printer", "Printer" and "Printer object"
interchangeably as in [RFC2911] to mean the software entity that
accepts IPP operation requests and returns IPP operation responses
(see [RFC2911] section 2).

Capitalized terms, such as MUST, MUST NOT, REQUIRED, SHOULD,
SHOULD NOT, MAY, NEED NOT, and OPTIONAL, have special meaning
relating to conformance as define in RFC 2119 [RFC2119] and
[RFC2911] section 12.1. If an implementation supports the
extension defined in this document, then these terms apply;
otherwise, they do not. These terms define conformance to this
document only; they do not affect conformance to other
documents, unless explicitly stated otherwise.

3 Model Extensions

To assist workstations in the printer installation process, an IPP
printer needs to provide the workstation with information about the
Client Print Support Files, such as the their name and location/s.
This information needs to match the workstation's specific
environment, such as its operating system, preferred natural
language, and preferred document format.

The following extensions to the IPP model enable assisted or
automated printer installation. This section describes each
extension in detail.

- A new REQUIRED Printer Description attribute: "client-print-
support-files-supported" (1setOf octetString(MAX)).
- A new REQUIRED Get-Printer-Attributes operation attribute:
"client-print-support-files-filter" (octetString(MAX)).
- A new RECOMMENDED printer operation: Get-Client-Print-Support-
Files.

3.1 client-print-support-files-supported (1setOf octetString(MAX))

An IPP Printer uses the REQUIRED Printer Description attribute
"client-print-support-files-supported" to represent relevant
information about all of the Client Print Support Files it supports.
Each value is a composite UTF-8 string with well-defined fields (see
Table 1). Each value string MUST be formatted as follows:

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"uri=val1< field-name2=val21,...,val2p< ... < field-
namen=valn1,...,valnq<"

The first field MUST be the "uri" field. The remaining fields MAY be
in any order.

The string MUST NOT include any control characters (hex 00 to 1F),
even the so-called white space control characters (TAB, CR, and LF)
anywhere. Only zero or more UTF-8 SPACE characters (hex 20) can be
included and they can be included only IMMEDIATELY AFTER the
delimiter character: "<", but NOT anywhere else, including after "="
and ",". However, if the UTF-8 SPACE character is needed in a
client-file-name value, then each occurrence is included directly,
without escaping (see example). On the other hand, if the UTF-8
SPACE character is needed in a URL value, then each occurrence is
escaped as: "%20" (URI conventions - see [RFC2396]).

Table 1 lists the REQUIRED fields that a Printer MUST support and the
OPTIONAL fields that a Printer MAY support in the "client-print-
support-files-supported" (1setOf octetString(MAX)) Printer
Description attribute. A Printer implementation MAY support
additional fields using the same syntax. Values are defined to be
either CASE-SENSITIVE or ALL-LOWER-CASE according to the definitions
for the attribute syntaxes from [RFC2911] (set off by single quotes
in the table). The CASE-SENSITIVE values MAY have upper and lower
case letters as for the corresponding attribute syntaxes in
[RFC2911]. The LOWER-CASE values MUST have all lower case alphabetic
letters. Additional characters, such as digits, hyphen-minus (-),
period (.), and slash (/) are according to the corresponding
attribute syntaxes in [RFC2911]. Additional values for these fields
can be registered with IANA according to the procedures in [RFC2911]
for registering additional values of attributes. Additional fields
can be registered with IANA according to the procedures defined in
[RFC2911] for registering attributes. See section 7.

Clients SHOULD ignore fields they don't recognize in a given value.
This allows for future extensions to the format of the string without
breaking compatibility with earlier clients.

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Table 1 - "client-print-support-files-supported" attribute fields

Field
name Field value

"uri" One REQUIRED CASE-SENSITIVE 'uri' string identifying the
uri where to obtain the support files for each OS
platform, document format, and natural language the
printer supports. This MUST be the first field in each
value. Examples of uri schemes that MAY be found here
are 'ftp', 'http', and 'ipp'. The 'ftp' and 'http'
schemed URIs identify the archive file that contains all
the necessary client support files.

The 'ipp' schemed URIs identify the archive file that
clients MAY obtain from the Printer using the Get-
Client-Print-Support-Files operation (see section 3.3).
The URI MUST be a valid URI to the same Printer object,
i.e., one of the values of the Printer's "printer-uri-
supported" attribute. The 'ipp' URI is used to
distinguish between multiple Client Print Support Files
in an implementation dependent manner using the URL
query syntax (e.g., "?drv-id=xxx") [RFC2396]. The
query part MUST NOT exceed 127 octets, not counting the
"?" character that begins the query part. A Printer
SHOULD support the 'ipp' scheme.

"os-type" One or more REQUIRED comma-separated LOWER-CASE
'keyword' strings identifying the operating system types
supported by this set of Client Print Support Files.
Valid values are the operating system names defined in
the IANA document [os-names] and the special keyword
value: 'unknown'. Although the IANA registry requires
that the names be all upper-case, the values MUST be all
lower case in this field (plus hyphen-minus (-), period
(.), and slash (/)). Examples: 'linux', 'linux-2.2',
'os/2', 'sun-os-4.0', 'unix', 'unix-bsd', 'win32',
'windows-95', 'windows-98', 'windows-ce', 'windows-nt',
'windows-nt-4', 'windows-nt-5', 'unknown'.

"cpu- One or more REQUIRED comma-separated LOWER-CASE
type" 'keyword' strings identifying the CPU types supported by
this set of Client Print Support Files. The values
indicate the CPU family independent of the CPU
manufacturer. Standard keyword values are: 'x86-16',
'x86-32', 'x86-64', 'dec-vax', 'alpha', 'power-pc', 'm-

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Field Field value
name

'x86-32', 'x86-64', 'dec-vax', 'alpha', 'power-pc', 'm-
68000, 'sparc', 'itantium', 'mips', 'arm' and will be
used as the initial value for the "cpu-type" IANA
registry. In addition, the special keyword value:
'unknown' is valid.

"document One or more REQUIRED comma-separated CASE-SENSITIVE
-format" 'mimeMediaType' strings identifying the document formats
supported by this set of Client Print Support Files.
Valid values are the string representation of the IPP
mimeMediaType attribute syntax (see [RFC2911] section
4.1.9), for example 'application/postscript'. In
addition, the special keyword value: 'unknown' is valid.

"natural- One or more REQUIRED comma-separated LOWER-CASE
language" 'naturalLanguage' strings identifying the natural
language used by this set of Client Print Support Files.
Valid values are the string representation of the IPP
'naturalLanguage' attribute syntax (see [RFC2911]
section 4.1.8), for example 'en' and 'en-us'. In
addition, the special keyword value: 'unknown' is valid.

"compress One REQUIRED LOWER-CASE 'keyword' string identifying the
ion" mechanism used to compress this set of Client Print
Support Files. All files needed for the installation of
a printer driver MUST be compressed into a single file.
Valid keyword values are the keywords defined by
[RFC2911] or registered with IANA for use in the IPP
"compression" and "compression-supported" attributes.
See [RFC2911] section 4.4.32), for example 'gzip'. The
'none' value limits the uncompressed Client Print
Support File to a single file. The values for the
"compression" field that a Printer supports NEED NOT be
the same values that the Printer is configured to
support in Job Creation operations as indicated in the
Printer's "compressions-supported" attribute.

"file- One or more REQUIRED comma-separated LOWER-CASE
type" 'keyword' strings identifying the type of the Client
Print Support Files. Standard keyword values are:
'printer-driver', 'ppd', 'updf', 'gpd'.

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Field Field value
name

"client- One REQUIRED CASE-SENSITIVE string identifying the name
file- by which the Client Print Support Files will be
name" installed on the workstation. For Client Print Support
Files of type 'printer-driver', this is also the name
that identifies this printer driver in an .inf file.

"policy" One OPTIONAL LOWER-CASE 'keyword' string indicating the
policy for automatic loading. Standard keyword values
are: 'manufacturer-recommended', 'administrator-
recommended', 'manufacturer-experimental,
'administrator-experimental'. The experimental values
are for beta test.

"file- One OPTIONAL file size in octets represented as ASCII
size" decimal digits.

"file- One OPTIONAL LOWER-CASE version number. Recommended to
version" be of the form "Major.minor[.revision]" where "Major" is
the major version number, "minor" is the minor version
number and "revision" is an optional revision number.

"file- One OPTIONAL File CASE-SENSITIVE creation date and time
date- according to ISO 8601 where all fields are fixed length
time" with leading zeroes (see [RFC2518] Appendix 2).
Examples: 2000-01-01T23:09:05Z and 2000-01-01T02:59:59-
04.00

"file- One OPTIONAL CASE-SENSITIVE human readable 'text' string
info" describing this set of Client Print Support Files. The
natural language for this value MUST be the natural
language indicated by the Printer's "natural-language-
configured" attribute. To avoid exceeding the maximum
limit imposed on IPP attributes and to increase
interoperability with other systems, the length of this
field value MUST not exceed 127 characters.

"digital- One REQUIRED LOWER-CASE 'keyword' string identifying the
signature mechanism used to ensure the integrity and authenticity
" of this set of Client Print Support Files. Standard
values are: 'smime', 'pgp', 'dss', and 'xmldsig' which
are defined in [RFC2634], [RFC1991], [dss], and
[xmldsig], respectively. In addition, the special
keyword value: 'none' is valid.

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Field Field value
name

keyword value: 'none' is valid.

Each value MUST refer to one and only one set of Client Print Support
Files, even if the files are downloadable from various repositories
(i.e., even if they are associated with multiple URIs).

3.1.1 Use of Keyword Values in fields

A number of the fields in Table 1 use keyword strings as values. The
syntax of these keywords is the same as in [RFC2911], including the
use of private keywords. See [RFC2911] sections 4.1.3 and 6.1.
Printer implementers are strongly RECOMMENDED to submit additional
keyword values for registration with IANA according to the procedures
for registering attributes. See section 7 and [RFC2911] section 6.1.

3.1.2 Use of the Special Keyword Value: 'unknown'

A number of REQUIRED 'keyword' value fields have a special keyword
value: 'unknown' defined. This value is intended for use when the
actual value is not known, such as by an administrator automatic
software configuring the IPP Printer object. However, it is strongly
RECOMMENDED that other more meaningful values be used, instead of the
'unknown' value whenever possible.

3.1.3 Examples of "client-print-support-files-supported" attribute
values

The following illustrates what two valid values of the "client-print-
support-files-supported" (1setOf octetString(MAX)) Printer
Description attribute might look like:

uri=ipp://mycompany.com/myprinter?drv-id=ModelY.gz<
os-type=windows-95< cpu-type=x86-32<
document-format=application/postscript<
natural-language=en< compression=gzip<
file-type=printer-driver<
client-file-name=CompanyX-ModelY-driver.gz<
policy=manufacturer-recommended<

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uri=ftp://mycompany.com/root/drivers/win95/CompanyX/ModelY.gz<
os-type=windows-95< cpu-type=x86-32<
document-format=application/postscript,application/vnd.hp-PCL<
natural-language=en,fr< compression=gzip<
file-type=printer-driver<
client-file-name=Company T Model Z driver.gz<
policy=manufacturer-recommended<

The above examples have been broken onto separate lines for
readability in this document. However, there MUST NOT be any line
breaks in the actual values.

The "client-print-support-files-supported" Printer Description
attribute MAY be preset at manufacturing time or through
administrative means outside the scope of this document.

3.2 Get-Printer-Attributes Operation Extension

The "client-print-support-files-supported" Printer Description
attribute defined in section 3.1 contains information, such as
operating system, natural language, and document format, about all of
the sets of Client Print Support Files. This section defines an
extension to the Get-Printer-Attributes operation that allows a
workstation to filter out all but the Client Print Support Files of
interest.

3.2.1 Get-Printer-Attributes Request

A Printer MAY contain information about multiple sets of Client Print
Support Files to match the different operating systems, natural
languages and document formats it supports. A workstation MAY query
this information by including the 'client-print-support-files-
supported' keyword as a value of the "requested-attributes" operation
attribute of the Get-Printer-Attributes operation.

3.2.1.1 client-print-support-files-filter (octetString(MAX)) operation
attribute

The client can request a subset of the values of the "client-print-
support-files-supported" Printer attribute by supplying the "client-
print-support-files-filter" (octetString(MAX)) operation attribute in
the request as a filter. The filter value indicates in which Client
Print Support Files the client is interested. The client MAY supply
this attribute. The Printer MUST support this attribute.

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The filter value of the "client-print-support-files-filter" attribute
is a composite string with the same format as that of "client-print-
support-files-supported" (see Table 1 - "client-print-support-files-
supported" attribute fields in section 3.1) with the following
exceptions:

Table 2 - "client-print-support-files-filter" attribute fields

Field Field Value in the "client-print-support-files-filter"
Name attribute

uri- One or more comma-separated LOWER-CASE 'uriScheme'
scheme string values identifying the uri scheme to be
filtered on. Valid values are the string
representation of the IPP 'uriScheme' attribute syntax
(see [RFC2911] section 4.1.6). Example URI schemes
are: 'ftp', 'http', and 'ipp'. The Printer SHOULD
support the 'ipp' scheme. If supplied by the client,
this field NEED NOT be first. If this field is
omitted by the client, the Printer returns all
schemes.

xxx One or more comma-separated values for any of the
fields defined in Table 1, with the single exception
of the "uri" field which a client MUST NOT supply and
a Printer MUST NOT support.
The Printer MUST support any filter field having more
than one value separated by a COMMA (,), including the
fields that Table 1 indicates MUST BE single valued.

Printer implementations MUST support the "client-print-support-files-
filter" operation attribute in a Get-Printer-Attributes request with
the member fields listed Table 3. Printers MAY support any
additional filter fields listed in Table 2.

Client implementations MAY supply any filter fields listed in Table 2
in the "client-print-support-files-filter" operation attribute of a
Get-Printer-Attributes request.

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Table 3 - REQUIRED "client-print-support-files-filter" fields

uri-scheme

os-type

cpu-type

document-format

natural-language

3.2.1.1.1 Filter matching rules

The Printer returns only the values of the "client-print-support-
files-supported" Printer Description attribute that match the filter
in the "client-print-support-files-filter" operation attribute. The
following filter matching rules are defined:

1. A match occurs if at least one value of each field supplied by
the client in the filter matches a Client Print Support File
value. Printers MUST ignore a filter field supplied by a client
that the Printer does not support and return a match if all
supported fields do match, no matter what value the client
supplied for that unsupported field. Similarly, Printers MUST
ignore a filter field supplied by a client that the Printer does
support, but which the field has not been populated for a Client
Print Support Files and return a match if all supported and
populated fields do match, no matter what value the client
supplied for that unpopulated field.

2. A match for a CASE-INSENSITIVE field occurs independent of the
case of the letters supplied by the client and those stored by
the Printer, while a match for a LOWER-CASE field is a strict
character for character match.

3. A match for a 'keyword' Printer field that is populated with the
'unknown' special keyword value occurs for any value supplied by
the client for that field.

4. If the "client-print-support-files-filter" operation attribute
filter is not supplied by the client, the printer SHOULD behave
as if the attribute had been provided with all fields left empty
(i.e., return an unfiltered list).

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The following are two examples of a "client-print-support-files-
filter" filter value:

os-type=windows-95< cpu-type=x86-32<
document-format=application-postscript< natural-language=en,de<

uri-scheme=ipp< os-type=windows-95< cpu-type=x86-32<
document-format=application-postscript< natural-language=en,de<

See section 3.2.2 for example matching responses.

It is RECOMMENDED that workstations first use the Get-Printer-
Attributes operation in combination with "client-print-support-files-
filter" operation attribute filter to get a list of the potential
Client Print Support Files that meet the workstation's requirements.
The workstation can then choose from the returned list which Client
Print Support Files to use and where to get them. If one of the URIs
returned is an IPP uri, the workstation can retrieve the Client Print
Support Files from an IPP printer via the Get-Client-Print-Support-
Files operation (see section 3.3).

3.2.2 Get-Printer-Attributes Response

A Printer MUST return the "client-print-support-files-supported"
(1setOf octetString(MAX)) attribute in the Printer Object Attributes
group (Group 3) when requested by a client, unless there are no
matches, in which case the attribute is not returned in Group 3.
Each returned attribute value MUST satisfy the criteria specified by
the client in the request.

For example, if the request contains the following "client-print-
support-files-filter" filter:

os-type=windows-95< cpu-type=x86-32<
document-format=application-postscript<
natural-language=en,de<

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A conforming response is the following two octet String values:

uri=ipp://mycompany.com/myprinter?drv-id=ModelY.gz<
os-type=windows-95< cpu-type=x86-32<
document-format=application/postscript<
natural-language=en< compression=gzip<
file-type=printer-driver<
client-file-name=CompanyX-ModelY-driver.gz<
policy=manufacturer-recommended<
digital-signature=smime<

uri=ftp://mycompany.com/root/drivers/win95/CompanyX/ModelY.gz<
os-type=windows-95< cpu-type=x86-32<
document-format=application/postscript,application/vnd.hp-PCL<
natural-language=en,fr< compression=gzip<
file-type=printer-driver<
client-file-name=CompanyX-ModelY-driver.gz<
policy=manufacturer-recommended<
digital-signature=smime<

These examples have been broken onto separate lines for readability
in this document. However, there MUST NOT be any line breaks in the
actual values.

As another example, if the above request had also contained the "uri-
scheme" field in the following "client-print-support-files-filter"
filter:

uri-scheme=ipp< os-type=windows-95< cpu-type=x86-32<
document-format=application-postscript<
natural-language=en,de<

Then only the first value would have been returned as a single
octetString value:

uri=ipp://mycompany.com/myprinter?drv-id=ModelY.gz<
os-type=windows-95< cpu-type=x86-32<
document-format=application/postscript<
natural-language=en< compression=gzip<
file-type=printer-driver<
client-file-name=CompanyX-ModelY-driver.gz<
policy=manufacturer-recommended<
digital-signature=smime<

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3.3 Get-Client-Print-Support-Files

This RECOMMENDED operation allows a client to download Client Print
Support Files from an IPP Printer.

3.3.1 Get-Client-Print-Support-Files Request

The following sets of attributes are part of the Get-Client-Print-
Support-Files request:

Group 1: Operation Attributes

Natural Language and Character Set:
The "attributes-charset" and "attributes-natural-language"
attributes as described in [RFC2911], section 3.1.4.1.

Target:
The "printer-uri" (uri) operation attribute which is the target
for this operation as described in [RFC2911], section 3.1.5.
The client MUST use the URI value as the target of this
operation that the Printer returns in the "uri" field (see Table
1) in the Get-Printer-Attributes response. Furthermore, the
client MUST use the appropriate authorization and security
mechanism for this URI as indicated by the Printer's "printer-
uri-supported", "uri-authentication-supported" and "uri-
security-supported" attributes (see [RFC2911] sections 4.4.1,
4.4.2, and 4.4.3). Only if the URI returned in the "uri" field
matches the URI that the client used for the Get-Printer-
Attributes request MAY the client use the same HTTP connection.
The 'ipp' URL matching rules are defined in [ipp-url] and do not
include the query part.

Requesting User Name:
The "requesting-user-name" (name(MAX)) attribute SHOULD be
supplied by the client as described in [RFC2911], section 8.3.

"client-print-support-files-query" (text(127)):
The client MUST supply this attribute specifying the query part
[RFC2396] of the ipp uri for the desired Client Print Support
Files not including the "?" character that starts the query
part, i.e., the value of the "uri" field following the "?"
character returned by the Get-Printer-Attributes in one of the
values of the "client-print-support-files-supported" (1setOf
octetString(MAX)) Printer attribute (see Table 1) that had an
'ipp' scheme. If the Printer does not find any Client Print

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Support Files which match the query, the Printer MUST reject
this request with a 'client-error-client-print-support-file-not-
found' status code (see section 10.1).

3.3.2 Get-Client-Print-Support-Files Response

The Printer object returns the following sets of attributes as part
of the Get-Client-Print-Support-Files Response:

Group 1: Operation Attributes

Status Message:
In addition to the REQUIRED status code returned in every
response, the response OPTIONALLY includes a "status-message"
(text(255)) operation attribute as described in [RFC2911],
sections 13 and 3.1.6.

Natural Language and Character Set:
The "attributes-charset" and "attributes-natural-language"
attributes as described in [RFC2911], section 3.1.4.2.

Group 2: Unsupported Attributes
See [RFC2911], section 3.1.7 for details on returning Unsupported
Attributes.

Group 3: Printer Object Attributes
"client-print-support-files-supported" (octetString(MAX)).
This attribute identifies the properties of the returned Client
Print Support Files. The Printer object MUST return this
attribute if the response includes Group 4 (i.e., if a set of
Client Print Support Files identified by the supplied "client-
print-support-files-query" operation attribute was found). The
Printer MUST return all configured fields for the selected
Client Print Support Files in the format shown in section 3.1.

Group 4: Client Print Support Files
The printer MUST supply the Client Print Support Files that match
the client's criteria following the "end-of-attributes" tag, same
as for the Print-Job request. All necessary files MUST be
compressed into a single transferred file.

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4 New Values for Existing Printer Description Attributes

The following "operation-id" value is added in order to support the
new operation defined in this document:

Table 4 - Operation-id assignments

Value Operation Name

0x0021 Get-Client-Print-Support-Files

5 Conformance

5.1 Printer Conformance Requirements

A Printer conforming to this specification:

1.MUST support the "client-print-support-files-supported" Printer
Description attribute as defined in section 3.1, including all
of the REQUIRED fields defined in Table 1 and MAY support the
OPTIONAL fields defined in Table 1.

2.MUST support the "client-print-support-files-filter" operation
attribute in the Get-Printer-Attributes request as defined in
section 3.2, including all of the fields listed in Table 3 and
ignoring any fields not recognized.

3.MUST support at least one of the following URI schemes that
identify the support files: 'ftp', 'http', or 'ipp', of which
the 'ipp' scheme is the RECOMMENDED one.

4.SHOULD support the Get-Client-Print-Support-Files operation as
described in section 3.3. If this operation is supported, then
one of the supported schemes MUST be 'ipp'.

5.SHOULD support TLS as described in section 9.

6.SHOULD support at least one method for the downloading of Client
Print Support Files that have been digitally signed as described
in section 9.

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5.2 Client Conformance Requirements

A client conforming to this specification:

1.MUST ignore any fields returned by the Printer in the "client-
print-support-files-supported" Printer Description attribute
that the client does not recognize or support.

2.SHOULD be able to retrieve Client Print Support Files by either
FTP Get or HTTP Get operations.

3.MUST be able to retrieve Client Print Support Files using the
Get-Client-Print-Support-Files operation, i.e., support the
'ipp' scheme.

4.MUST supply the proper URI value for the "printer-uri" operation
attribute as specified in section 3.3.1 under Target:.

5.MUST validate that files that are supposed to be digitally
signed are done with the indicated mechanism as described in
section 9.

6.SHOULD support TLS as described in section 9.

6 Encoding of the Operation Layer

This extension uses the operation layer encoding described in
[RFC2910].

7 IANA Considerations

The IANA-registered operating system names that IANA has registered
[os-names] are required by this spec for use in the "os-type" field
(see Table 1).

Table 1 of this document defines possible 'keyword' values for the
"cpu-type" field. However, the existing IANA machine registration
[cpu-names] is inadequate for two reasons: a) it is really a machine
model number, not a CPU type, and b) it doesn't express whether a
CPU is 16-bit, 32-bit, or 64-bit which needs to be indicated in the
keyword value. Therefore, the "os-type" field will be a new
registration with initial values assigned.

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Implementers may register additional values for the fields defined in
Table 1 with IANA according to the procedures in [RFC2911] for
registering additional values of attributes. Implementers may
register additional fields with IANA according to the procedures
defined in [RFC2911] for registering attribute values, even though
fields are more like attributes (see section 7.2.1).

The rest of this section contains the registration information for
IANA to add to the various IPP Registries according to the procedures
defined in RFC 2911 [RFC2911] section 6 to cover the definitions in
this document.

Note to RFC Editors: Replace RFC NNNN below with the RFC number
for this document, so that it accurately reflects the content of
the information for the IANA Registry.

7.1 Attribute Registrations

The following table lists all attributes and fields defined in this
document. These are to be registered according to the procedures in
RFC 2911 [RFC2911] section 6.2.

Printer Description Attributes: Ref: Section:
client-print-support-files-supported (1setOf octetString(MAX))
RFC NNNN 3.1

Operation Attributes: Ref: Section:
client-print-support-files-filter (octetString(MAX)) RFC NNNN 3.2

The resulting attribute registrations will be published in the
ftp://ftp.iana.org/in-notes/iana/assignments/ipp/attributes/
area.

7.2 Additional Attribute Value Registrationsfor existing attributes

This section lists additional attribute value registrations for use
with existing attributes defined in other documents.

7.2.1 Additional values for the "client-print-support-files-xxx"
attributes

The following table lists the fields defined in this document for use
with the "client-print-support-files-supported" Printer Description
(defined in section ) attribute and the "client-print-support-files-
filter" operation attribute (defined in section ). For purposes of

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IANA registration, the following fields are registered according to
the attribute value procedures in RFC 2911 [RFC2911] section 6.1,
even though they are more like attributes and have an attribute
syntax and string values.

field Attribute Values: Ref: Section:
os-type (type2 keyword) RFC NNNN 3.1
cpu-type (type2 keyword) RFC NNNN 3.1
document-format (mimeMediaType) RFC NNNN 3.1
natural-language (naturalLanguage) RFC NNNN 3.1
compression (type2 keyword) RFC NNNN 3.1
file-type (type2 keyword) RFC NNNN 3.1
client-file-name (name(MAX)) RFC NNNN 3.1
policy (type2 keyword) RFC NNNN 3.1
file-size (integer(0:MAX)) RFC NNNN 3.1
file-version (name(MAX)) RFC NNNN 3.1
file-date-time (text(25)) RFC NNNN 3.1
file-info (text(127)) RFC NNNN 3.1
digital-signature (type2 keyword) RFC NNNN 3.1

The resulting URI scheme attribute value registration will be
published in the
ftp://ftp.iana.org/in-notes/iana/assignments/ipp/attribute-

values/client-print-support-files-supported/
AND

ftp://ftp.iana.org/in-notes/iana/assignments/ipp/attribute-

values/client-print-support-files-filter/
areas.

uri (uri) RFC NNNN 3.1

The resulting URI scheme attribute value registration will be
published in the
ftp://ftp.iana.org/in-notes/iana/assignments/ipp/attribute-

values/client-print-support-files-supported/
area.

uri-scheme (uriScheme) RFC NNNN 3.2

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The resulting URI scheme attribute value registration will be
published in the
ftp://ftp.iana.org/in-notes/iana/assignments/ipp/attribute-

values/client-print-support-files-filter/
area.

7.2.2 Additional values for the "operations-supported" Printer attribute

The following table lists the enum attribute value defined in this
document as an additional type2 enum value for use with the
"operations-supported" Printer attribute defined in [RFC2911]. This
is to be registered according to the procedures in RFC 2911 [RFC2911]
section 6.1.

type2 enum Attribute Values: Value Ref. Section:
Get-Clint-Print-Support-Files 0x0021 RFC NNNN 4

The resulting enum attribute value registration will be published in
the
ftp://ftp.iana.org/in-notes/iana/assignments/ipp/attribute-
values/operations-supported/
area.

7.3 Operation Registrations

The following table lists the operation defined in this document.
This is to be registered according to the procedures in RFC 2911
[RFC2911] section 6.4.

Operations: Ref. Section:
Get-Client-Print-Support-Files RFC NNNN 3.3

The resulting operation registration will be published in the
ftp://ftp.iana.org/in-notes/iana/assignments/ipp/operations/
area.

7.4 Status Code Registrations

The following table lists the status code defined in this document.
This is to be registered according to the procedures in RFC 2911
[RFC2911] section 6.6.

Status codes: Ref. Section:
client-error-client-print-support-file-not-found (0x0417)
RFC NNNN 10.1

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The resulting status code registration will be published in the
ftp://ftp.iana.org/in-notes/iana/assignments/ipp/status-codes/
area.

8 Internationalization Considerations

All text representations introduced by this specification adhere to
the internationalization-friendly representation supported by IPP.
This work is also accommodates the use of Client Print Support Files
of different languages.

9 Security Considerations

The IPP Model and Semantics document [RFC2911] discusses high-level
security requirements (Client Authentication, Server Authentication
and Operation Privacy). Client Authentication is the mechanism by
which the client proves its identity to the server in a secure
manner. Server Authentication is the mechanism by which the server
proves its identity to the client in a secure manner. Operation
Privacy is defined as a mechanism for protecting operations from
eavesdropping.

Only operators of a printer SHOULD be allowed to set the "client-
print-support-files-supported" attribute and only users of the
printer SHOULD be allowed to query that information.

The IPP extension described in this document introduces the potential
for a security threat previously not encountered by IPP. As Client
Print Support Files might exist in the form of executable objects (as
is the case with printer drivers, for example), additional provisions
are needed to prevent the distribution of malicious code through this
mechanism. Digital signatures provide the message level security
commonly used to help consumers of network resources verify the
authenticity and integrity of those resources. Specifically, digital
signatures help defend against security threats such as message
insertion, message deletion, and message modification, and their
combined use into man-in-the-middle attacks.

This document identifies some commonly used signing mechanisms (SMIME
[RFC2634], PGP [RFC1991], DSS [dss], and XML Digital Signatures
[xmldsig]), though any others MAY be used. Of course, it is assumed
that once end-users know the identity of the provider of Client Print
Support Files, they can make the correct determination as to whether
it is safe to use those files.

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Printers that support the Get-Client-Print-Support-Files operation
SHOULD support the downloading of Client Print Support Files that
have been digitally signed. Clients that invoke the Get-Client-
Print-Support-Files operation MUST make sure that Client Print
Support Files that are supposed to be signed (i.e., whose client-
print-support-files-supported attribute value includes the "digital-
signature" field) are indeed signed via the specified mechanism when
downloaded from the printer.

Furthermore, printers that support the Get-Client-Print-Support-Files
operation SHOULD implement TLS to provide application level channel
security and enable users to reliably authenticate the source of the
Client Print Support Files.

10 Status Code Extensions

The following status code is defined as an extension for Notification
and is returned as the value of the "status-code" parameter in the
Operation Attributes Group of a response (see [RFC2911] section
3.1.6.1).

10.1 client-error-client-print-support-file-not-found (0x0417)

The Printer was unable to match the query in the Get-Client-Print-
Support-Files request with any Client Print Support Files. This
status code is not used with the Get-Printer-Attributes operation.

11 References

[cpu-names]
IANA Registry of CPU Names at ftp://ftp.iana.org/in-
notes/iana/assignments/XXX.

[dss]
U.S. Department of Commerce, "Digital Signature Standard (DDS)",
Federal Information Processing Standards Publication 186-1 (FIPS
PUB 186-1), December 15, 1998.

[ipp-url]
Herriot, R., McDonald, I., "Internet Printing Protocol (IPP): IPP
URL Scheme." <draft-ietf-ipp-url-scheme-03.txt>, April 2, 2001.

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[os-names]
IANA Registry of Operating System Names at ftp://ftp.isi.edu/in-
notes/iana/assignments/operating-system-names.

[RFC1991]
D. Atkins, W. Stallings, P. Zimmermann, "PGP Message Exchange
Formats", RFC 1991, August, 1996.

[RFC2026]
S. Bradner, "The Internet Standards Process -- Revision 3", RFC
2026, October 1996.

[RFC2396]
Berners-Lee, T., Fielding, R., Masinter, L., "Uniform Resource
Identifiers (URI): Generic Syntax", RFC 2396, August 1998.

[RFC2518]
Goland, Y., et al, "HTTP Extensions for Distributed Authoring --
WEBDAV", RFC 2518, February 1999.

[RFC2565]
Herriot, R., Butler, S., Moore, P., and R. Turner, "Internet
Printing Protocol/1.0: Encoding and Transport", RFC 2565, April
1999.

[RFC2566]
R. deBry, T. Hastings, R. Herriot, S. Isaacson, and P. Powell,
"Internet Printing Protocol/1.0: Model and Semantics", RFC 2566,
April 1999.

[RFC2567]
Wright, D., "Design Goals for an Internet Printing Protocol", RFC
2567, April 1999.

[RFC2568]
Zilles, S., "Rationale for the Structure and Model and Protocol for
the Internet Printing Protocol", RFC 2568, April 1999.

[RFC2569]
Herriot, R., Hastings, T., Jacobs, N., Martin, J., "Mapping between
LPD and IPP Protocols", RFC 2569, April 1999.

[RFC2616]
R. Fielding, J. Gettys, J. Mogul, H. Frystyk, L. Masinter, P.
Leach, T. Berners-Lee, "Hypertext Transfer Protocol - HTTP/1.1",
RFC 2616, June 1999.

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[RFC2634]
P. Hoffman, "Enhanced Security Services for S/MIME", RFC 2634, June
1999.

[RFC2910]
Herriot, R., Butler, S., Moore, P., Tuner, R., "Internet Printing
Protocol/1.1: Encoding and Transport", RFC 2910, September 2000.

[RFC2911]
R. deBry, T. Hastings, R. Herriot, S. Isaacson, P. Powell,
"Internet Printing Protocol/1.0: Model and Semantics", RFC 2911,
September 2000.

[xmldsig]
D. Eastlake, J. Reagle, D. Solo "XML-Signature Syntax and
Processing", <draft-ietf-xmldsig-core-11.txt>, October 31, 2000.

12 Author's Addresses

Hugo Parra
Novell, Inc.
1800 South Novell Place
Provo, UT 84606

Phone: 801-861-3307
Fax: 801-861-4025
e-mail: [email protected]

Ted Tronson
Novell, Inc.
1800 South Novell Place
Provo, UT 84606

Phone: 801-861-3338
Fax: 801-861-4025
e-mail: [email protected]

Thomas N. Hastings
Xerox Corp.
737 Hawaii St. ESAE 231
El Segundo, CA 90245

Phone: 310-333-6413
Fax: 310-333-5514
e-mail: [email protected]

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IPP Web Page: http://www.pwg.org/ipp/
IPP Mailing List: [email protected]

To subscribe to the ipp mailing list, send the following email:
1) send it to [email protected]
2) leave the subject line blank
3) put the following two lines in the message
body:
subscribe ipp
end

Implementers of this specification document are encouraged to join
the IPP Mailing List in order to participate in any discussions of
clarification issues and review of registration proposals for
additional attributes and values. In order to reduce spam the
mailing list rejects mail from non-subscribers, so you must subscribe
to the mailing list in order to send a question or comment to the
mailing list.

13 Description of the Base IPP Documents

The base 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 [RFC2568]
Internet Printing Protocol/1.1: Model and Semantics [RFC2911]
Internet Printing Protocol/1.1: Encoding and Transport [RFC2910]
Internet Printing Protocol/1.1: 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. It calls out a subset of end user requirements that
are satisfied in IPP/1.0 [RFC2566, RFC2565]. A few OPTIONAL operator
operations have been added to IPP/1.1 [RFC2911, RFC2910].

The "Rationale for the Structure and Model and Protocol for the
Internet Printing Protocol" document describes IPP from a high level
view, defines a roadmap for the various documents that form the suite
of IPP specification documents, and gives background and rationale
for the IETF working group's major decisions.

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The "Internet Printing Protocol/1.1: Encoding and Transport" document
is a formal mapping of the abstract operations and attributes defined
in the model document onto HTTP/1.1 [RFC2616]. It defines the
encoding rules for a new Internet MIME media type called
"application/ipp". This document also defines the rules for
transporting a message body over HTTP whose Content-Type is
"application/ipp". This document defines the 'ipp' scheme for
identifying IPP printers and jobs.

The "Internet Printing Protocol/1.1: Implementer's Guide" document
gives insight and advice to implementers of IPP clients and IPP
objects. It is intended to help them understand IPP/1.1 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.

14 Full Copyright Statement

Copyright (C) The Internet Society (2001). All Rights Reserved.

This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.

The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.

This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION

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HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

Funding for the RFC Editor function is currently provided by the
Internet Society.

Trade Marks

Trademarks within this document are the property of their owners.

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