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INTERNET-DRAFT                                   Robert Herriot (editor)
                                                  Sun Microsystems, Inc.
draft-ietf-ipp-lpd-ipp-map-05.txt                           Tom Hastings
                                                       Xerox Corporation
                                                             Norm Jacobs
                                                  Sun Microsystems, Inc.
                                                              Jay Martin
                                                        Underscore, Inc.
                                                       November 16, 1998

                 Mapping between LPD and IPP Protocols

Status of this Memo

This document is an Internet-Draft.  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."

To learn the current status of any Internet-Draft, please check the
"1id-abstracts.txt" listing contained in the Internet-Drafts Shadow
Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe),
munnari.oz.au (Pacific Rim), ftp.ietf.org (US East Coast), or
ftp.isi.edu (US West Coast).

     Copyright (C)The Internet Society (1998). All Rights Reserved.

Abstract

This document is one of a set of documents, which together describe all
aspects of a new Internet Printing Protocol (IPP). IPP is an application
level protocol that can be used for distributed printing using Internet
tools and technologies. This document gives some advice to implementers
of gateways between IPP and LPD (Line Printer Daemon). This document
describes the mapping between (1) the commands and operands of the 'Line
Printer Daemon (LPD) Protocol' specified in RFC 1179 and (2) the
operations, operation attributes and job template attributes of the
Internet Printing Protocol/1.0  (IPP).  One of the purposes of this
document is to compare the functionality of the two protocols.  Another
purpose is to facilitate implementation of gateways between LPD and IPP.

WARNING:  RFC 1179 was not on the IETF standards track.  While RFC 1179
was intended to record existing practice, it fell short in some areas.
However, this specification maps between (1) the actual current practice
of RFC 1179 and (2) IPP.  This document does not attempt to map the
numerous divergent extensions to the LPD protocol that have been made by
many implementers.



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The full set of IPP documents includes:

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

The document, 'Design Goals for an Internet Printing Protocol', 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. Operator and administrator requirements are out of
scope for version 1.0.

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

The document, 'Internet Printing Protocol/1.0: Model and Semantics',
describes a simplified model with abstract objects, their attributes,
and their operations. It introduces a Printer and a Job object. The Job
object supports multiple documents per Job. It also addresses security,
internationalization, and directory issues.

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

This document 'Internet Printing Protocol/1.0: Implementer's Guide',
gives advice to implementers of IPP clients and IPP objects.

















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                           TABLE OF CONTENTS

1.   Introduction......................................................4
2.   Terminology.......................................................4
3.   Mapping from LPD Commands to IPP Operations.......................5
 3.1 Print any waiting jobs..........................................5
 3.2 Receive a printer job...........................................5
   3.2.1 Abort job....................................................6
   3.2.2 Receive control file.........................................7
   3.2.3 Receive data file............................................7
 3.3 Send queue state (short)........................................8
 3.4 Send queue state (long).........................................9
 3.5 Remove jobs....................................................11
4.   Mapping of LPD Control File Lines to IPP Operation and Job Template
Attributes............................................................11
 4.1 Required Job Functions.........................................12
 4.2 Optional Job Functions.........................................13
 4.3 Required Document Functions....................................13
 4.4 Recommended Document Functions.................................14
5.   Mapping from IPP operations to LPD commands......................14
 5.1 Print-Job......................................................15
 5.2 Print-URI......................................................16
 5.3 Validate-Job...................................................16
 5.4 Create-Job.....................................................16
 5.5 Send-Document..................................................17
 5.6 Send-URI.......................................................17
 5.7 Cancel-Job.....................................................17
 5.8 Get-Printer-Attributes.........................................17
 5.9 Get-Job-Attributes.............................................18
 5.10  Get-Jobs.....................................................19
6.   Mapping of IPP Attributes to LPD Control File Lines..............19
 6.1 Required Job Functions.........................................20
 6.2 Optional Job Functions.........................................20
 6.3 Required Document Functions....................................20
7.   Security Considerations..........................................21
8.   References.......................................................21
9.   Author's Addresses...............................................23
10.  Appendix A: ABNF Syntax for response of Send-queue-state (short).23
11.  Appendix B: ABNF Syntax for response of Send-queue-state (long)..24
12.  Appendix C: Unsupported LPD functions............................24
13.  Appendix D: Full Copyright Statement.............................25













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               Mapping between the LPD and IPP Protocols



1. Introduction

The reader of this specification is expected to be familiar with the IPP
Model and Semantics specification [ipp-mod], the IPP Encoding and
Transport [ipp-pro], and the Line Printer Daemon (LPD) protocol
specification [rfc1179] as described in RFC 1179.

RFC 1179 was written in 1990 in an attempt to document existing LPD
protocol implementations.  Since then, a number of undocumented
extensions have been made by vendors to support functionality specific
to their printing solutions.  All of these extensions consist of
additional control file commands.  This document does not address any of
these vendor extensions.  Rather it addresses existing practice within
the context of the features described by RFC 1179.  Deviations of
existing practice from RFC 1179 are so indicated.

Other LPD control file commands in RFC 1179 are obsolete. They are
intended to work on "text" only formats and are inappropriate for many
contemporary document formats that completely specify each page. This
document does not address the support of these obsolete features.

In the area of document formats, also known as page description
languages (PDL), RFC 1179 defines a fixed set with no capability for
extension.  Consequently, some new PDL's are not supported, and some of
those that are supported are sufficiently unimportant now that they have
not been registered for use with the Printer MIB[rfc1759] and IPP[ipp-
mod] [ipp-pro], though they could be registered if desired.  See the
Printer MIB specification [rfc1759] and/or the IPP Model specification
[ipp-mod] for instructions for registration of document-formats with
IANA.  IANA lists the registered document-formats as "printer
languages".

This document addresses the protocol mapping for both directions:
mapping of the LPD protocol to the IPP protocol and mapping of the IPP
protocol to the LPD protocol. The former is called the "LPD-to-IPP
mapper" and the latter is called the "IPP-to-LPD mapper".

This document is an informational document that is not on the standards
track.  It is intended to help implementers of gateways between IPP and
LPD.  It also provides an example, which gives additional insight into
IPP.



2. Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and  "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [rfc2119].




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RFC 1179 uses the word "command" in two contexts: for over-the-wire
operations and for command file functions. This document SHALL use the
word "command" for the former and the phrase "functions" for the latter.
The syntax of the LPD commands is given using ABNF [rfc2234].

The following tokens are used in order to make the syntax more readable:

    LF stands for %x0A (linefeed)
    SP stands for %x20.  (space)
    DIGIT stands for %x30-39 ("0" to "9")


3. Mapping from LPD Commands to IPP Operations

This section describes the mapping from LPD commands  to IPP operations.
Each of the following sub-sections appear as sub-sections of section 5
of RFC 1179.

The following table summarizes the IPP operation that the mapper uses
when it receives an LPD command. Each section below gives more detail:

LPD command                IPP operation


print-any-waiting-jobs     ignore
receive-a-printer-job      Print-Job or Create-Job/Send-Document
send queue state  (short   Get-Printer-Attributes and Get-Jobs
or long)
remove-jobs                Cancel-Job


3.1 Print any waiting jobs

Command syntax:

  print-waiting-jobs = %x01 printer-name LF

This command causes the LPD daemon check its queue and print any waiting
jobs. An IPP printer handles waiting jobs without such a nudge.

If the  mapper receives this LPD command, it SHALL ignore it and send no
IPP operation.



3.2 Receive a printer job

Command syntax:

  receive-job = %x02 printer-name LF

The control file and data files mentioned in the following paragraphs
are received via LPD sub-commands that follow this command. Their
mapping to IPP commands and attributes is described later in this
section.

The mapper maps the 'Receive a printer job' command to either:


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  @ the Print-Job operation which includes a single data file or
  @ the  Create-Job  operation  followed  by  one  Send-Document
     operation for each data file.

If the IPP printer supports both Create-Job and Send-Document, and if a
job consists of:

  @ a single data file, the mapper SHOULD use the Print-Job
     operation,  but  MAY  use  the  Create-Job  and  Send-Document
     operations.
  @ more than one data file, the mapper SHALL use Create-Job
     followed by one Send-Document for each received LPD data file.

If the IPP printer does not support both Create-Job and Send-Document,
and if a job consists of:

  @ a  single  data  file,  the  mapper  SHALL  use  the  PrintJob
     operation.
  @ more than one data file, the mapper SHALL submit each received
     LPD data file as a separate Print-Job operation (thereby
     converting a single LPD job into multiple IPP jobs).

If the mapper uses Create-Job and Send-Document, it MUST send the
Create-Job operation before it sends any Send-Document operations
whether the LPD control file, which supplies attributes for Create-Job,
arrives before or after all LPD data files.

NOTE:  This specification does not specify how the mapper maps: the LPD
Printer-name operand to the IPP "printer-uri" operation attribute.

The following three sub-sections gives further details about the mapping
from LPD receive-a-printer-job sub-commands.  Each of the following sub-
sections appear as sub-sections of section 6 of RFC 1179.



3.2.1 Abort job

Sub-command syntax:

  abort-job = %x1 LF

This sub-command of receive-a-printer-job is intended to abort any job
transfer in process.

If the mapper receives this sub-command, it SHALL cancel the job that it
is in the process of transmitting.

If the mapper is in the process of sending a Print-Job or Create-Job
operation, it terminates the job either by closing the connection, or
performing the Cancel-Job operation with the job-uri that it received
from the Print-Job or Create-Job operation.




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NOTE: This sub-command is implied if at any time the connection between
the LPD client and server is terminated before an entire print job has
been transferred via an LPD Receive-a-printer-job request.



3.2.2 Receive control file

Sub-command syntax:

  receive-control-file = %x2 number-of-bytes SP name-of-control-file LF
  number-of-bytes = 1*DIGIT
  name-of-control-file = "cfA" job-number client-host-name
                          ; e.g. "cfA123woden"
  job-number = 3DIGIT
  client-host-name = <a host name>

This sub-command is roughly equivalent to the IPP Create-Job operation.

The mapper SHALL use the contents of the received LPD control file to
create IPP operation attribute and job template attribute values to
transmit with the Print-Job or Create-Job operation.



3.2.3 Receive data file

Sub-command syntax:  %x3 number-of-bytes-in-data-file Name-of-data-file

  receive-data-file = %x03 number-of-bytes SP name-of-data-file LF
  number-of-bytes = 1*DIGIT
  name-of-data-file = "df" letter job-number client-host-name
              ; e.g. "dfA123woden for the first file
  letter = %x41-5A /  %x61-7A    ;  "A" to "Z", "a" to "z"
                                 ;  first file is "A",
                                 ; second "B", and  52nd file is "z"
  job-number = 3DIGIT
  client-host-name = <a host name>

This sub-command is roughly equivalent to the IPP Send-Document
operation.

The mapper SHALL use the contents of the received LPD data file as the
data to transmit with the IPP Print-Job or Send-Document operation.

Although  RFC-1179 alludes to a method for passing an unspecified
length data file by using an octet-count of zero, no implementations
support this feature. The mapper SHALL reject a job that has a value of
0 in the number-of-bytes field.








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3.3 Send queue state (short)

Command syntax:

  send-queue-short  = %x03 printer-name *(SP(user-name / job-number)) LF

The mapper's response to this command includes information about the
printer and its jobs. RFC 1179 specifies neither the information nor the
format of its response. This document requires the mapper to follow
existing practice as specified in this document.

The mapper SHALL produce a response in the following format which
consists of a printer-status line optionally followed by a heading line,
and a list of jobs. This format is defined by examples below. Appendix A
contains the ABNF syntax.

For an printer with no jobs, the response starts in column 1 and is:

  no entries

For a printer with jobs, an example of the response is:

  killtree is ready and printing
  Rank   Owner      Job          Files             Total Size
  active fred       123          stuff             1204 bytes
  1st    smith      124          resume, foo       34576 bytes
  2nd    fred       125          more              99 bytes
  3rd    mary       126          mydoc             378 bytes
  4th    jones      127          statistics.ps     4567 bytes
  5th    fred       128          data.txt          9 bytes

The column numbers of above headings and job entries are:

  |      |          |            |                 |
  01     08         19           35                63

The mapper SHALL produce each field above from the following IPP
attribute:


   LPD field IPP attribute          special conversion details

   printer-  printer-state and      For a printer-state of idle or
   status    printer-state-reasons  processing, the mapper SHALL use
                                     the formats above.  For stopped,
                                     the mapper SHALL use printer-
                                     state-reasons to produce an
                                     unspecified format for the error.
   rank      number-of-             the mapper SHALL the format above
             intervening-jobs
   owner     job-originating-user-  unspecified conversion; job-
             name                   originating-user-name may be the
                                     mapper's user-name
   job       job-id                 the mapper shall use the job-id


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   LPD field IPP attribute          special conversion details

   files     document-name          the mapper shall create a comma
                                     separated list of the document-
                                     names and then truncate this list
                                     to the first 24 characters
   total-    job-k-                 the mapper shall multiple the
   size      octets*copies*1024     value of job-k-octets by 1024 and
                                     by the value of the "copies"
                                     attribute.


A mapper SHOULD use the job attribute number-of-intervening-jobs rather
than the job's position in a list of jobs to determine 'rank' because a
Printer may omit jobs that it wants to keep secret. If a printer doesn't
support the job attribute number-of-intervening-jobs, a mapper MAY use
the job's position.

Note: a Printer may set the value of job-originating-user-name to the
authenticated user or to the value of "requesting-user-name", depending
on the implementation and configuration. For a gateway, the
authenticated user is the user-id of the gateway, but the "requesting-
user-name" may contain the name of the user who is the gateway's client.

In order to obtain the information specified above, The LPD-to-IPP
mapper SHALL use the Get-Printer-Attributes operation to get printer-
status and SHOULD use the Get-Jobs operation to get information about
all of the jobs. If the LPD command contains job-numbers or user-names,
the mapper MAY handle the filtering of the response. If the LPD command
contains job-numbers but no user-names, the mapper MAY use Get-Job-
Attributes on each converted job-number rather than Get-Jobs. If the LPD
command contains a single user-name but no job-numbers, the mapper MAY
use Get-Jobs with the my-jobs option if the server supports this option
and if the server allows the client to be a proxy for the LPD user.

NOTE:  This specification does not define how the mapper maps the LPD
Printer-name operand to the IPP "printer-uri" operation attribute.



3.4 Send queue state (long)

Command syntax:

  send-queue-long = %x04 printer-name *(SP(user-name / job-number)) LF

The mapper's response to this command includes information about the
printer and its jobs. RFC 1179 specifies neither the information nor the
format of its response. This document requires the mapper to follow
existing practice as specified in this document.

The mapper SHALL produce a response in the following format which
consists of a printer-status line optionally followed a list of jobs,
where each job consists of a blank line, a description line, and one


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line for each file. The description line contains the user-name, rank,
job-number and host. This format is defined by examples below. Appendix
B contain the ABNF syntax.

For an printer with no jobs the response is:

no entries

For a printer with jobs, an example of the response is:

killtree is ready and printing

fred: active                        [job 123 tiger]
        2 copies of stuff           602 bytes

smith: 1st                          [job 124 snail]
        2 copies of resume          7088 bytes
        2 copies of foo             10200 bytes

fred: 2nd                           [job 125 tiger]
        more                        99 bytes

The column numbers of above headings and job entries are:

|       |                           |
01      09                          41

Although the format of the long form is different from the format of the
short form, their fields are identical except for a) the copies and host
fields which are only in the long form, and b)  the "size" field
contains the single copy size of each file.  Thus the sum of the file
sizes in the "size" field  times the value of the "copies" field
produces the value for the "Total Size" field in the short form. For
fields other than the host and copies fields, see the preceding section.
For the host field see the table below.


   LPD field IPP attribute        special conversion details

   host                            unspecified conversion; job-
                                   originating-host may be the
                                   mapper's host
   copies    copies               the mapper shall assume the
                                   value of copies precedes the
                                   string "copies of "; otherwise,
                                   the value of copies is 1.


NOTE:  This specification does not define how the mapper maps the LPD
Printer-name operand to the IPP printer-uri operation attribute.






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3.5 Remove jobs

Command syntax:

  remove-jobs = %x05 printer-name SP agent
                      *(SP(user-name / job-number)) LF

The agent operand is the user-name of the user initiating the remove-
jobs command. The special user-name 'root' indicates a privileged user
who can remove jobs whose user-name differs from the agent..

The mapper SHALL issue one Cancel-Job operation for each job referenced
by the remove-jobs command. Each job-number in the remove-jobs command
references a single job. Each user-name in the remove-jobs command
implicitly references all jobs owned by the specified user. The active
job is implicitly referenced when the remove-jobs command contains
neither job-numbers nor user-names. The mapper MAY use Get-Jobs to
determine the job-uri of implicitly referenced jobs.

The mapper SHALL not use the agent name of 'root' when end-users cancel
their own jobs.  Violation of this rule creates a potential security
violation, and it may cause the printer to issue a notification that
misleads a user into thinking that some other person canceled the job.

If the agent of a remove-jobs command for a job J is the same as the
user name specified with the 'P' function in the control file for job J,
then the mapper SHALL ensure that the initiator of the Cancel-Job
command for job J is the same as  job-originating-user for job J.

Note: This requirement means that a mapper must be consistent in who the
receiver perceives as the initiator of IPP operations. The mapper either
acts as itself or acts on behalf of another user. The latter is
preferable if it is possible. This consistency is necessary between
Print-Job/Create-Job and Cancel-Job in order for Cancel-Job to work, but
it is also desirable for other operations. For example, Get-Jobs may
give more information about job submitted by the initiator of this
operation.

NOTE: This specification does not define  how the mapper maps: (1) the
LPD printer-name to the IPP "printer-uri" or (2) the LPD job-number to
the IPP "job-uri".

NOTE: This specification does not specify how the mapper maps the LPD
user-name to the IPP job-originating-user because the mapper may use its
own user-name with jobs.



4. Mapping of LPD Control File Lines to IPP Operation and Job Template
Attributes

This section describes the mapping from LPD control file lines (called
'functions') to IPP operation attributes and job template attributes.
The mapper receives the control file lines via the LPD receive-control-


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file sub-command..  Each of the LPD functions  appear as sub-sections of
section 7 of RFC 1179.

In LPD control file lines, the text operands have a maximum length of 31
or 99 while IPP operation attribute and job template attribute values
have a maximum of 255 or 1023 octets, depending on the attribute syntax.
Therefore, no data is lost.

The mapper converts each supported LPD function to its corresponding IPP
operation or job template attribute as defined by tables in the
subsections that follow. These subsections group functions according to
whether they are:

  @ required with a job,
  @ optional with a job
  @ required with each document.

In the tables below, each LPD value is given a name, such as 'h'. If an
IPP value uses the LPD value, then the IPP value column contains the LPD
name, such as 'h' to denote this.  Otherwise, the IPP value column
specifies the literal value.



4.1 Required Job Functions

The following LPD functions MUST be in a received LPD job. The mapper
SHALL receive each of the following LPD functions and SHALL include the
information as a operation or job template attribute with each IPP job.
The functions SHOULD be in the order 'H', 'P' and they SHOULD be the
first two functions in the control file, but they MAY be anywhere in the
control file and in any order:


LPD function                      IPP
name value   description         name          value

H    h       Originating Host                  h (in security layer)
P    u       User identification requesting-   u (and in security
                                  user-name     layer)
             none                ipp-          'true'
                                  attribute-
                                  fidelity

A mapper MAY sen. its own host rather than the client's host, and a
mapper MAY send its own user-name as user identification rather than the
client user. But in any case, the values sent SHALL be compatible with
the Cancel-Job operation. The IPP operation MAY have no way to specify
an originating host-name.

The mapper SHALL include ipp-attribute-fidelity = true so that it
doesn't have to determine which attributes a printer supports.





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4.2 Optional Job Functions

The following LPD functions MAY be present in a received job. These
function SHOULD follow the required job functions and precede the
document functions, but they MAY be anywhere in the control file.

If the mapper receives such an LPD function, the mapper SHALL include
the corresponding IPP attribute with the value converted as specified in
the table below.  If the mapper does not receive such an LPD attribute,
the mapper SHALL NOT include the corresponding IPP attribute, except the
'L' LPD function whose absence has a special meaning as noted in the
table.


LPD function                    IPP
name value  description       name           value

J    j      Job name for      job-name       j
             banner page
L    l      Print banner page job-sheets     'standard' if 'L' is
                                               present
                                               'none' if 'L' is present
M    m      Mail When Printed                IPP has no notification
                                               mechanism. To support
                                               this LPD feature, the
                                               gateway must poll using
                                               the Get-Job-Attributes
                                               operation.
.



4.3 Required Document Functions

The mapper SHALL receive one set of the required document functions with
each copy of a document, and SHALL include the converted information as
operation or job template attributes with each IPP document.

If the control file contains required and recommended document
functions, the required functions SHOULD precede the recommended ones
and if the job contains multiple documents, all the functions for each
document are grouped together as shown in the example of section 6.3
"Required Document Functions". However, the document functions MAY be in
any order.




LPD function                    IPP
name  valu description         name             value
      e

f     fff  Print formatted     document-format  'application/octet-
            file                                 stream'
l     fff  Print file leaving  document-format  'application/octet-
            control characters                   stream'


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LPD function (cont.)            IPP
o     fff  Print Postscript    document-format  'application/PostScri
            output file                          pt'
                                copies           see note


Note: In practice, the 'f' LPD function is often overloaded. It is often
used with any format of document data including PostScript and PCL data.

Note: In practice, the 'l' LPD function is often used as a rough
equivalent to the 'f' function.

Note: When RFC 1179 was written, no implementation supported the 'o'
function; instead 'f' was used for PostScript. Windows NT now sends 'o'
function for a PostScript file.

Note: the value 'fff' of the 'f', 'l' and 'o' functions is the name of
the data file as transferred, e.g. "dfA123woden".

If the mapper receives any other lower case letter, the mapper SHALL
reject the job because the document contains a format that the mapper
does not support.

The mapper determines the number of copies by counting the number of
occurrences of each 'fff' file with one of the lower-case functions
above. For example, if 'f dfA123woden' occurs 4 times, then copies has a
value of 4. Although the LPD protocol allows the value of copies to be
different for each document, the commands and the receiving print
systems don't support this.



4.4 Recommended Document Functions

The mapper SHOULD receive one set of the recommended document functions
with each document, and SHOULD include the converted information as an
operation or job template attribute with each IPP document. The
functions SHOULD be received in the order 'U' and 'N', but they MAY
arrive in any order.


LPD function                        IPP
name  value   description          name              value

U     fff                           ignored
N     n       Name of source file  document-name     n

Note: the value 'fff' of the 'U' function is the name of the data file
as transferred, e.g. "dfA123woden".



5. Mapping from IPP operations to LPD commands

If the IPP-to-LPD mapper receives an IPP operation, the following table
summarizes the LPD command that it uses. Each section below gives the


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detail. Each of the following sub-sections appear as sub-sections of
section 3 in the document "Internet Printing Protocol/1.0: Model and
Semantics" [ipp-mod].


IPP operation                     LPD command

Print-Job or Print-URI or         receive-a-printer-job
Create-Job/Send-Document/Send-URI and then print-any-waiting-jobs
Validate-Job                      implemented by the mapper
Cancel-Job                        remove-jobs
Get-Printer-Attributes, Get-Job-  send queue state (short or long)
Attributes or Get-Jobs


5.1 Print-Job

The mapper SHALL send the following commands in the order listed below:

  @ receive-a-printer-job command
  @ both receive-control-file sub-command and receive-data-file
     sub-command
     (unspecified order, see Note below)
  @ print-any-waiting-jobs command,
     except that if the mapper is sending a sequence of receive-a-
     printer-job commands, it MAY omit sending print-any-waiting-
     jobs after any receive-a printer-job command that is neither
     the first nor last command in this sequence

Note: it is recommended that the order of the receive-control-file sub-
command and the receive-data-file sub-command be configurable because
either order fails for some print systems. Some print systems assume
that the control file follows all data files and start printing
immediately on receipt of the control file. When such a print system
tries to print a data file that has not arrived, it produces an error.
Other print systems assume that the control file arrives before the data
files and start printing when the first data file arrives. Such a system
ignores the control information, such as banner page or copies.

NOTE: This specification does not define the mapping between the IPP
printer-uri and the LPD printer-name.

The mapper SHALL send the IPP operation attributes and job template
attributes received from the operation to the LPD printer by using the
LPD receive-control-file sub-command. The mapper SHALL create the LPD
job-number for use in the control file name, but the receiving printer
MAY, in some circumstances, assign a different job-number to the job.
The mapper SHALL create the IPP job-id and IPP job-uri returned in the
Print-Job response.

NOTE: This specification does not specify how the mapper determines the
LPD job-number, the IPP job-id or the IPP job-uri of a job that it
creates nor does it specify the relationship between the IPP job-uri,
IPP the job-id and the LPD job-number, both of which the mapper creates.
However, it is likely that the mapper will use the same integer value


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for both the LPD job-number and the IPP job-id, and that the IPP Job-uri
is the printer's URI with the job-id concatenated on the end.

The mapper SHALL send data received in the IPP operation to the LPD
printer by using the LPD receive-data-file sub-command. The mapper SHALL
specify the exact number of bytes being transmitted in the number-of-
bytes field of the receive-data-file sub-command. It SHALL NOT use a
value of 0 in this field.

If the mapper, while it is transmitting a receive-a-printer-job command
or sub-command, either detects that its IPP connection has closed or
receives a Cancel-Job operation,  the mapper SHALL terminate the LPD job
either with the abort sub-command or the remove-jobs command.

This document does not address error code conversion.



5.2 Print-URI

The mapper SHALL handle this operation in the same way as a Print-Job
operation except that it SHALL obtain data referenced by the "document-
uri" operation attribute and SHALL then treat that data as if it had
been received via a Print-Job operation.



5.3 Validate-Job

The mapper SHALL perform this operation directly. Because LPD supports
very few attributes, this operation doesn't have much to check.



5.4 Create-Job

The mapper SHALL handle this operation like Print-Job, except:

  @ the mapper SHALL send the control file after it has received
     the last Send-Document or Send-URI operation because the
     control file contains all the document-name and document-
     format values specified in the Send-Document and Send-URI
     operations.
  @ the mapper SHALL perform one receive-data-file sub-command for
     each Send-Document or Send-URI operation received and in the
     same order received.
  @ the mapper SHALL send the control file either before all data
     files or after all data files.
     (See the note in the section on Print-Job about the dilemma of
     sending the control file either before or after the data
     files.







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5.5 Send-Document

The mapper performs a receive-data-file sub-command on the received
data. See the preceding section 5.4 "Create-Job" for the details.



5.6 Send-URI

The mapper SHALL obtain the data referenced by the "document-uri"
operation attribute, and SHALL then treat that data as if it had been
received via a Send-Document operation. See the preceding section 5.5
"Send-Document" for the details.



5.7 Cancel-Job

The mapper SHALL perform a remove-jobs command with the following
operation attributes:

  @ the printer is the one to which the job was submitted, that is
     the IPP printer-uri is mapped to an LPD printer-name by the
     same mechanism as for all commands
  @ the agent is the authenticated user-name of the IPP client
  @ the  job-number  is  the  job-id  returned  by  the  Print-Job
     command, that is, the LPD job-number has the same value as the
     IPP job-id for likely implementations



5.8 Get-Printer-Attributes

LPD severely limits the set of attributes that the mapper is able to
return in its response for this operation. The mapper SHALL support, at
most, the following printer attributes:

  @ printer-state
  @ printer-state-reasons

The mapper uses either the long or short form of the "send queue state"
command.

The mapper SHALL assume that the LPD response that it receives has the
format and information specified in section 3.3 "













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Send queue state (short)"  and section 3.4 "Send queue state (long)".
The mapper SHALL determine the value of each requested attribute by
using the inverse of the mapping specified in the two aforementioned
sections.

Note: the mapper can determine the response from the printer-status line
without examining the rest of the LPD response.



5.9 Get-Job-Attributes

LPD severely limits the set of attributes that the mapper is able to
return in its response for this operation. The mapper SHALL support, at
most, the following job attributes:

  @ number-of-intervening-jobs
  @ job-originating-user-name
  @ job-id
  @ document-name
  @ job-k-octets
  @ copies

The mapper uses either the long or short form of the "send queue state"
command. If it receives a request for the "job-k-octets" or  "copies"
and supports the attribute it SHALL use the long form; otherwise, it
SHALL use the short form.

Note: the value of job-k-octets is the value in the short form divided
by the number of "copies" which is on the long form only. Its value can
also be determined by adding the "size" field values for each document
in the job in the long form.

The mapper SHALL assume that the LPD response that it receives has the
format and information specified in section 3.3 "





















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Send queue state (short)"  and section 3.4 "Send queue state (long)".
The mapper SHALL determine the value of each requested attribute by
using the inverse of the mapping specified in the two aforementioned
sections.

Note: when the mapper uses the LPD short form, it can determine the
response from the single LPD line that pertains to the job specified by
the Get-Job-Attributes operation.

Note: the mapper can use its correspondence between the IPP job-id, job-
uri and the LPD job-number.



5.10 Get-Jobs

The mapper SHALL perform this operation in the same way as Get-Job-
Attributes except that the mapper converts all the LPD job-lines, and
the IPP response contains one job object for each job-line in the LPD
response.



6. Mapping of IPP Attributes to LPD Control File Lines

This section describes the mapping from IPP operation attributes and job
template attributes to LPD control file lines (called 'functions'). The
mapper receives the IPP operation attributes and job template atributes
via the IPP operation.  Each of the IPP operation attributes and job
template attributes appear as sub-sections of section 3 and 4.2 in the
IPP model document [ipp-mod].

In the context of LPD control file lines, the text operands have a
maximum length of 31 or 99 while IPP operation attributes and job
template attributes have a maximum of 255 or 1023 octets, depending on
the attribute syntax.  Therefore, there may be some data loss if the IPP
operation attribute and job template attribute values exceed the maximum
length of the LPD equivalent operands.

The mapper converts each supported IPP operation attribute and job
template attribute to its corresponding LPD function as defined by
tables in the subsections that follow. These subsections group functions
according to whether they are:

  @ required with a job,
  @ optional with a job
  @ required with each document.

In the tables below, each IPP value is given a name, such as 'h'. If an
LPD value uses the IPP value, then the LPD value column contains the IPP
name, such as 'h' to denote this.  Otherwise, the LPD value column
specifies the literal value.





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6.1 Required Job Functions

The mapper SHALL include the following LPD functions with each job, and
they SHALL have the specified value. They SHALL be the first functions
in the control file and they SHALL be in the order "H" and then "P".


IPP                           LPD function
name                  value   name  value         description

(perhaps in security  h       H     gateway host  Originating Host
layer)
requesting-user-name  u       P     u             User identification
and in the security
layer

A mapper SHALL sends its own host rather than the client's host, because
some LPD systems require that it be the same as the host from which the
remove-jobs command comes.  A mapper MAY send its own user name as user
identification rather than the client user. But in any case, the values
sent SHALL be compatible with the LPD remove-jobs operation.



6.2 Optional Job Functions

The mapper MAY include the following LPD functions with each job. They
SHALL have the specified value if they are sent. These functions, if
present, SHALL follow the require job functions, and they SHALL precede
the required document functions.




IPP attribute                      LPD function
name           value               nam  value  description
                                   e

job-name       j                   J    j      Job name for banner
                                                page
job-sheets     'standard'          L    u      Print banner page
job-sheets     'none'                          omit 'L' function
Note: 'L' has special meaning when it is omitted. If 'J' is omitted,
some undefined behavior occurs with respect to the banner page.



6.3 Required Document Functions

The mapper SHALL include one set of  the following LPD functions with
each document, and they SHALL have the specified values. For each
document, the order of the functions SHALL be 'f', 'U' and then 'N',
where 'f' is replicated once for each copy.


IPP attribute                       LPD function




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name        value                  name value  description

document-   'application/octet-    f    fff    Print formatted file
format      stream' or
            'application/PostScrip
            t'
copies      c                                   replicate 'f' 'c'
                                                 times
none                                U    fff    Unlink data file
document-   n                      N    n      Name of source file
name


Note: the value 'fff' of the 'f' and 'U' functions is the name of the
data file as transferred, e.g. "dfA123woden".

Note: the mapper SHALL not send the 'o' function

ISSUE: should we register DVI, troff or ditroff?

If the mapper receives no "ipp-attribute-fidelitybest-effort" or it has
a value of false, then the mapper SHALL reject the job if it specifies
attributes or attribute values that are not among those supported in the
above tables.

Below is an example of the minimal control file for a job with three
copies of two files 'foo' and 'bar':

  H tiger
  P jones
  f dfA123woden
  f dfA123woden
  f dfA123woden
  U dfA123woden
  N foo
  f dfB123woden
  f dfB123woden
  f dfB123woden
  U dfB123woden
  N bar


7. Security Considerations

There are no security issues beyond those covered in the IPP Encoding
and Transport document [ipp-pro], the IPP model document [ipp-mod] and
the LPD document [rfc1179].



8. References

[ipp-iig] Hasting, Tom, et al., "Internet Printing Protocol/1.0:
       Implementer's Guide", draft-ietf-ipp-implementers-guide-00.txt,
       November 1998


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[ipp-mod]   R. deBry, T. Hastings, R. Herriot, S. Isaacson, P. Powell,
       "Internet Printing Protocol/1.0: Model and Semantics", <draft-
       ietf-ipp-model-11.txt>, November, 1998.

[ipp-pro] Herriot, R., Butler, S., Moore, P., Tuner, R., "Internet
       Printing Protocol/1.0: Encoding and Transport", draft-ietf-ipp-
       pro-07.txt, November 1998.

[ipp-rat]   Zilles, S., "Rationale for the Structure and Model and
       Protocol for the Internet Printing Protocol", draft-ietf-ipp-
       rat-04.txt, November 1998.

[ipp-req]   Wright, D., "Design Goals for an Internet Printing
       Protocol", draft-ietf-ipp-req-03.txt, November, 1998.

[rfc1179]   L. McLaughlin, "Line Printer Daemon Protocol", RFC 1179,
       August 1990.

[rfc1759]   Smith, R., Wright, F., Hastings, T., Zilles, S., and
       Gyllenskog, J., "Printer MIB", RFC 1759, March 1995.

[rfc2119]   S. Bradner, "Key words for use in RFCs to Indicate
       Requirement Levels", RFC 2119, March 1997

[rec2234] D. Crocker et al., "Augmented BNF for Syntax Specifications:
       ABNF", RFC 2234, November 1997.





























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9. Author's Addresses

Robert Herriot (editor)              Norm Jacobs
Sun Microsystems Inc.                Sun Microsystems Inc.
901 San Antonio.Road., MPK-17        1430 Owl Ridge Rd.
Mountain View, CA 94043              Colorado Springs, CO 80919

Phone:  650-786-8995                 Phone:  719-532-9927
Fax: 650-786-7077                    Fax:   719-535-0956
Email:  robert.herriot@eng.sun.com   Email:
                                     Norm.Jacobs@Central.sun.com

Thomas N. Hastings                   Jay Martin
Xerox Corporation                    Underscore, Inc.
701 S. Aviation Blvd., ESAE-231      41-C Sagamore Park Road
El Segundo, CA 90245                 Hudson, NH 03051-4915

Phone: 310-333-6413                  Phone:  603-889-7000
Fax:   310-333-5514                  Fax:  603-889-2699
EMail: hastings@cp10.es.xerox.com    Email:  jkm@underscore.com



10. Appendix A: ABNF Syntax for response of Send-queue-state (short)

The syntax in ABNF for the response to the LPD command 'send-queue-state
(long)' is:

  status-response = empty-queue / nonempty-queue
  empty-queue = "no-entries" LF
  nonempty-queue = printer-status LF heading LF *(job LF)
  printer-status =  OK-status / error-status
  OK-status = printer-name SP "ready and printing" LF
  error-status = < implementation dependent status information >
  heading = "Rank" 3SP "Owner" 6SP "Job" 13SP "Files"
                  23SP "Total Size" LF
                     ; the column headings and their values below begin
  at the columns
                     ; 1, 8, 19, 35 and 63
  job = rank *SP owner *SP job *SP files *SP total-size "bytes"
                    ; jobs are in order of oldest to newest
  rank = "active" / "1st" / "2nd" / "3rd" / integer "th"
                    ; job that is printing is "active"
                    ; other values show position in the queue
  owner = <user name of person who submitted the job>
  job = 1*3DIGIT   ; job-number
  files = <file name> *( "," <file name>) ; truncated to 24 characters
  total-size = 1*DIGIT  ; combined size in bytes of all documents








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11. Appendix B: ABNF Syntax for response of Send-queue-state (long)

The syntax in ABNF for the response to the LPD command 'send-queue-state
(long)' is:

  status-response = empty-queue / nonempty-queue
  empty-queue = "no-entries" LF
  nonempty-queue = printer-status LF  *job
  printer-status =  OK-status / error-status
  OK-status = printer-name SP "ready and printing" LF
  error-status = < implementation dependent status information >
  job = LF line-1 LF line-2 LF
  line-1 = owner ":" SP rank 1*SP "[job" job SP host "]"
  line-2 =  file-name 1*SP document-size "bytes"
        ; jobs are in order of oldest to newest
  rank = "active" / "1st" / "2nd" / "3rd" / integer "th"
          ; job that is printing is "active"
          ; other values show position in the queue
  owner = <user name of person who submitted the job>
  job = 1*3DIGIT
  file-name = [ 1*DIGIT  "copies of" SP ] <file name>
                ; truncated to 24 characters
  document-size = 1*DIGIT  ;size of single copy of the document.


12. Appendix C: Unsupported LPD functions

The follow LPD functions have no IPP equivalent. The LPD-to-IPP mapper
ignores them and the IPP-to-LPD mapper does not send them.


     LPD command
     name  description

     C     Class for banner page
     I     Indent Printing
     H     Host of client
     M     Mail when printed
     S     Symbolic link data
     T     Title for pr
     W     Width of output
     1     troff R font
     2     troff I font
     3     troff B font
     4     troff S font

The follow LPD functions specify document-formats which have no IPP
equivalent, unless someone registers them. The LPD-to-IPP mapper rejects
jobs that request such a document format, and the IPP-to-LPD mapper does
not send them.







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     LPD command
     name   description

     c      Plot CIF file
     d      Print DVI file
     g      Plot file
     k      reserved for Kerberized clients and servers
     n      Print ditroff output file
     p      Print file with 'pr' format
     r      File to print with FORTRAN carriage control
     t      Print troff output file
     v      Print raster file
     z      reserved for future use with the Palladium
            print system



13. Appendix D: Full Copyright Statement

Copyright (C)The Internet Society (1997). 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.











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