[Search] [txt|pdf|bibtex] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03 04 05 rfc2569                                     
INTERNET-DRAFT


                                                 Robert Herriot (editor)
                                                  Sun Microsystems, Inc.
                                                            Tom Hastings
                                                       Xerox Corporation
                                                             Norm Jacobs
                                                  Sun Microsystems, Inc.
                                                              Jay Martin
                                                        Underscore, Inc.
                                                       November 20, 1997

                 Mapping between LPD and IPP Protocols
                   draft-ietf-ipp-lpd-ipp-map-02.txt
     Copyright c The Internet Society (date). All Rights Reserved.


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), ds.internic.net (US East Coast), or
     ftp.isi.edu (US West Coast).

                                Abstract

     This Internet-Draft specifies the mapping between (1) the commands
     and operands of the ''Line Printer Daemon (LPD) Protocol'' specified
     in RFC 1179 and (2) the operations and parameters of the Internet
     Printing Protocol (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.

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

     WARNING:  RFC 1179 was not on 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.
Herriot, Hastings,         November 20, 1997,                   [Page 1]


Jacobs, Martin            Expires May 20, 1998


INTERNET DRAFT   Mapping between LPD and IPP Protocols  November 20,1997



                           TABLE OF CONTENTS

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















Herriot, Hastings,         November 20, 1997,                   [Page 2]


Jacobs, Martin            Expires May 20, 1998


INTERNET DRAFT   Mapping between LPD and IPP Protocols  November 20,1997


               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 Protocol
specification [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 implementors 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 [abnf].

RFC 1179 uses the word "command" in two contexts: for over-the-wire
operations and for command file functions. This document SHALL use the
Herriot, Hastings,         November 20, 1997,                   [Page 3]


Jacobs, Martin            Expires May 20, 1998


INTERNET DRAFT   Mapping between LPD and IPP Protocols  November 20,1997


word "command" for the former and the phrase "functions" for the latter.
The syntax of the LPD commands is given using ABNF [abnf].

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-Attributes (printer) 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:

  .  the Print-Job operation which includes a single data file or

Herriot, Hastings,         November 20, 1997,                   [Page 4]


Jacobs, Martin            Expires May 20, 1998


INTERNET DRAFT   Mapping between LPD and IPP Protocols  November 20,1997


  .  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" parameter.

The following 3 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.

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.
Herriot, Hastings,         November 20, 1997,                   [Page 5]


Jacobs, Martin            Expires May 20, 1998


INTERNET DRAFT   Mapping between LPD and IPP Protocols  November 20,1997


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 parameter and 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.


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.
Herriot, Hastings,         November 20, 1997,                   [Page 6]


Jacobs, Martin            Expires May 20, 1998


INTERNET DRAFT   Mapping between LPD and IPP Protocols  November 20,1997


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-namemay be the
                                     mapper's user-name
   job       job-id                  the mapper shall use the job-id
   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
Herriot, Hastings,         November 20, 1997,                   [Page 7]


Jacobs, Martin            Expires May 20, 1998


INTERNET DRAFT   Mapping between LPD and IPP Protocols  November 20,1997


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.



ISSUE: the value of job-originating-user-name is still somewhat murky in
IPP especially where the IPP client is a proxy for some user coming from
elsewhere.In order to obtain the information specified above, The LPD-
to-IPP mapper SHALL use the Get-Attributes operation of the printer 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-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-Attributes 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" parameter.


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
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]
Herriot, Hastings,         November 20, 1997,                   [Page 8]


Jacobs, Martin            Expires May 20, 1998


INTERNET DRAFT   Mapping between LPD and IPP Protocols  November 20,1997


        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 parameter.


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.

Herriot, Hastings,         November 20, 1997,                   [Page 9]


Jacobs, Martin            Expires May 20, 1998


INTERNET DRAFT   Mapping between LPD and IPP Protocols  November 20,1997


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 caller 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 caller 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 caller 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 Parameters

This section describes the mapping from LPD control file lines (called
`functions') to IPP operation input parameters. The mapper receives the
control file lines via the LPD receive-control-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 input parameters have a maximum of 255 characters.
Therefore, no data is lost.

The mapper converts each supported LPD function to its corresponding IPP
parameter 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.



Herriot, Hastings,         November 20, 1997,                  [Page 10]


Jacobs, Martin            Expires May 20, 1998


INTERNET DRAFT   Mapping between LPD and IPP Protocols  November 20,1997


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 parameter 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                u (in security layer
                                                and operation
                                                attribute)
             none                 best-effort   `true'

A mapper MAY sends 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.

ISSUE: what do we do about job-orginating-host?

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


4.2 Optional Job Functions

The following LPD functions MAY be 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
Herriot, Hastings,         November 20, 1997,                  [Page 11]


Jacobs, Martin            Expires May 20, 1998


INTERNET DRAFT   Mapping between LPD and IPP Protocols  November 20,1997


                                               gateway must poll
.


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
parameters 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'
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.

Herriot, Hastings,         November 20, 1997,                  [Page 12]


Jacobs, Martin            Expires May 20, 1998


INTERNET DRAFT   Mapping between LPD and IPP Protocols  November 20,1997


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
parameters 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
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-Attributes (printer or job)   send queue state (short or long)
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
Herriot, Hastings,         November 20, 1997,                  [Page 13]


Jacobs, Martin            Expires May 20, 1998


INTERNET DRAFT   Mapping between LPD and IPP Protocols  November 20,1997


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 parameters and 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 relation ship 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
for both theLPD  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.

ISSUE: 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" parameter 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.




Herriot, Hastings,         November 20, 1997,                  [Page 14]


Jacobs, Martin            Expires May 20, 1998


INTERNET DRAFT   Mapping between LPD and IPP Protocols  November 20,1997


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.

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"
parameter, 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
parameters:

  .  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-Attributes

LPD severely limits the set of attributes that the mapper is able to
return in its response for this operation.

When the mapper receives a Get-Attributes operation for a printer
object, it SHALL support, at most, the following printer attributes:

Herriot, Hastings,         November 20, 1997,                  [Page 15]


Jacobs, Martin            Expires May 20, 1998


INTERNET DRAFT   Mapping between LPD and IPP Protocols  November 20,1997


  .  printer-state
  .  printer-state-reasons

When the mapper receives a Get-Attributes operation for a job object, it
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 "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 receives the Get-Attributes operation for a
printer, it can determine the response from the printer-status line
without examining the rest of the LPD response. When the mapper receives
the Get-Attributes operation for a job and uses the LPD short form, it
can determine the response from the single line that pertains to the job
specified by the Get-Attributes operation.

NOTE: for Get-Attributes of a job, the mapper can use its correspondence
between the IPP job-id, job-uri and the LPD job-number.




5.9 Get-Jobs

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


6. Mapping of IPP Parameters to LPD Control File Lines

This section describes the mapping from IPP operation input parameters
to LPD control file lines (called `functions'). The mapper receives the
Herriot, Hastings,         November 20, 1997,                  [Page 16]


Jacobs, Martin            Expires May 20, 1998


INTERNET DRAFT   Mapping between LPD and IPP Protocols  November 20,1997


IPP operation input parameters via the IPP operation.  Each of the IPP
operation input parameters 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 input parameters have a maximum of
255 characters.  Therefore, there may be some data loss if the IPP
parameters exceed the maximum length of the LPD equivalent operands.

The mapper converts each supported IPP parameter 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.


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)
(in security layer)   u       P     u             User identification

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

Herriot, Hastings,         November 20, 1997,                  [Page 17]


Jacobs, Martin            Expires May 20, 1998


INTERNET DRAFT   Mapping between LPD and IPP Protocols  November 20,1997


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
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 "best-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
Herriot, Hastings,         November 20, 1997,                  [Page 18]


Jacobs, Martin            Expires May 20, 1998


INTERNET DRAFT   Mapping between LPD and IPP Protocols  November 20,1997


  f dfB123woden
  f dfB123woden
  U dfB123woden
  N bar

7. Copyright Notice

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.


8. References

[ipp-mod]   R. deBry, T. Hastings, R. Herriot, S. Isaacson, P. Powell,
       "Internet Printing Protocol/1.0: Model and Semantics", <draft-
       ietf-ipp-model-07.txt>, November 1997.

[ipp-pro]   R. Herriot, S. Butler, P. Moore, R. Turner, "Internet
       Printing Protocol/1.0: Protocol specification", <draft-ietf-ipp-
       protocol-03.txt>, November 1997.

[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

[abnf] D.   Crocker et al., "Augmented BNF for Syntax Specifications:
       ABNF", draft-ietf-drums-abnf-05.txt.


Herriot, Hastings,         November 20, 1997,                  [Page 19]


Jacobs, Martin            Expires May 20, 1998


INTERNET DRAFT   Mapping between LPD and IPP Protocols  November 20,1997


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

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:

Herriot, Hastings,         November 20, 1997,                  [Page 20]


Jacobs, Martin            Expires May 20, 1998


INTERNET DRAFT   Mapping between LPD and IPP Protocols  November 20,1997


  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.

     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
Herriot, Hastings,         November 20, 1997,                  [Page 21]


Jacobs, Martin            Expires May 20, 1998


INTERNET DRAFT   Mapping between LPD and IPP Protocols  November 20,1997


     t      Print troff output file
     v      Print raster file
     z      reserved for future use with the Palladium
            print system

ISSUE: we may move some of these to the supported list.
















































Herriot, Hastings,         November 20, 1997,                  [Page 22]

Jacobs, Martin            Expires May 20, 1998