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Versions: 00 01 02 03 04                                                
INTERNET-DRAFT
<draft-ietf-ipp-install-02.txt>
[Target category:  standards track]                           Hugo Parra
                                                            Novell, Inc.
                                                             Ted Tronson
                                                            Novell, Inc.
                                                            Tom Hastings
                                                             Xerox Corp.
                                                       February 28, 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
   areas, and its working groups.  Note that other groups may also
   distribute working documents as Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress".

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt

   The list of Internet-Draft Shadow Directories can be accessed as
   http://www.ietf.org/shadow.html.

Abstract

   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 the support files varies
   depending on the specific client platform, from simple configuration
   files to highly sophisticated printer drivers.  This document refers
   to these support files as "Client Print Support Files".
   Traditionally, the selection and installation of the correct Client
   Print Support Files has been error prone.  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, document-

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   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. This document describes the IPP extensions that
   enable workstations to obtain the information needed to perform a
   proper printer driver installation using IPP, including security for
   downloading executable code and data.












































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   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 [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.  A few OPTIONAL operator operations have
   been added to IPP/1.1.

   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.

   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 a new scheme named 'ipp'
   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.






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Table of Contents

   1  Introduction....................................................6


   2  Terminology.....................................................6


   3  Model Extensions................................................7

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

            ..........................................................7
   3.1.1 Use of Keyword Values in fields.............................12

   3.1.2 Use of the Special Keyword Value: 'unknown'.................12

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

              values.................................................12

   3.2   Get-Printer-Attributes Operation Extension..................13

   3.2.1 Get-Printer-Attributes Request..............................13

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

                operation attribute..................................13

   3.2.1.1.1   Filter matching rules.................................15

   3.2.2 Get-Printer-Attributes Response.............................16

   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  Conformance....................................................19


   5  Encoding of the Operation Layer................................20


   6  Encoding of Transport Layer....................................20



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   7  IANA Considerations............................................20

   7.1   Attribute Registrations.....................................21

   7.2   Operation Registrations.....................................22


   8  Internationalization Considerations............................22


   9  Security Considerations........................................22


   10 References.....................................................23


   11 Author's Addresses.............................................24


   12 Full Copyright Statement.......................................25



Tables

   Table 1 - "client-print-support-files-supported" attribute fields..9

   Table 2 - "client-print-support-files-filter" attribute fields....14

   Table 3 - REQUIRED "client-print-support-files-filter" fields.....14





















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1  Introduction

   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.  With a
   few extensions, IPP provides a simple and reliable vehicle for
   printers to convey this information to interested workstations.  The
   IPP extensions described in this document enable 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

   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.

   This document uses terms such as "attributes", "keywords", and
   "support".  These terms have special meaning and are defined in the
   model terminology [RFC2911] section 12.2.  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.  These terms are defined in [RFC2911] section 12.1 on
   conformance terminology, most of which is taken from RFC 2119
   [RFC2119].

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

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      REQUIRED: if an implementation supports the extensions described
        in this document, it MUST support a REQUIRED feature.
      OPTIONAL: if an implementation supports the extensions described
        in this document, it MAY support an OPTIONAL feature.

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:

   "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]).

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   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].

   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      Field value
   name


   "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.  Valid keyword values are:  'x86-16',
              'x86-32', 'x86-64', 'dec-vax', 'alpha', 'power-pc', 'm-
              68000, 'sparc', 'itantium', 'mips', 'arm' and will be


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   Field      Field value
   name


              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.  Valid keyword values are:
              'printer-driver', 'ppd', 'updf', 'gpd'.

   "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


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   Field      Field value
   name


              that identifies this printer driver in an .inf file.

   "policy"   One OPTIONAL LOWER-CASE 'keyword' string indicating the
              policy for automatic loading.  Valid 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.  Valid 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.


   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).


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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<

      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.





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   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.

   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:










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      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.

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


      uri-scheme

      os-type

      cpu-type

      document-format

      natural-language



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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).

   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

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   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.  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<

   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.





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   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<

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
        regime 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

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        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.


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-

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        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.  All
     necessary files MUST be compressed into a single transferred file.


4  Conformance

   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 the downloading of Client Print Support Files
       that have been digitally signed as described in section 9.

   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.

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     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.


5  Encoding of the Operation Layer

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


6  Encoding of Transport Layer

   This specification uses the transport layer encoding described in
   [RFC2910] with the following extensions.

   New Error codes:

     0x0417    client-error-client-print-support-file-not-found

   New Operation code

     0x0021    Get-Client-Print-Support-Files


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.

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




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     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 attributes and fields defined in this document will be published
   by IANA according to the procedures in RFC 2911 [RFC2911] section 6.2
   with the following path:

     ftp.isi.edu/iana/assignments/ipp/attributes/

   The registry entry will contain the following information:

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

   For purposes of IANA attribute registration, the following fields of
   the "client-print-support-files-supported" and the "client-print-
   support-files-filter" attributes are registered following the
   procedures for IPP attribute registration:
                                                       Ref:  Section:
   uri (uri)                                           RFC NNNN   3.1
   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

   uri-scheme (uriScheme)                              RFC NNNN   3.2

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








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7.2 Operation Registrations

   The operations defined in this document will be published by IANA
   according to the procedures in RFC 2911 [RFC2911] section 6.4 with
   the following path:

       ftp.isi.edu/iana/assignments/ipp/operations/

   The registry entry will contain the following information:

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


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.



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   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.

   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 References


   [cpu-names]
     IANA Registry of CPU Names at ftp://ftp.isi.edu/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-02.txt>, February 14,
     2001.

   [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.

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   [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.

   [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.

   [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.


11 Author's Addresses

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

   Phone: 801-861-3307
   Fax:   801-861-4025
   e-mail: hparra@novell.com

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

   Phone: 801-861-3338
   Fax:   801-861-4025
   e-mail: ttronson@novell.com

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

   Phone: 310-333-6413
   Fax:   310-333-5514
   e-mail: hastings@cp10.es.xerox.com



12 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
   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.







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