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INTERNET-DRAFT                                   Robert Herriot (editor)
                                                        Sun Microsystems
<draft-ietf-ipp-protocol-07.txt>                           Sylvan Butler
                                                         Hewlett-Packard
                                                              Paul Moore
                                                               Microsoft
                                                            Randy Turner
                                                              Sharp Labs
                                                       November 16, 1998


         Internet Printing Protocol/1.0: Encoding and Transport

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 Notice

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 defines the rules for encoding IPP
operations and IPP attributes into a new Internet mime media type called
"application/ipp".  This document also defines the rules for
transporting over HTTP a message body whose Content-Type is
"application/ipp".








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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 (this
   document)
   Internet Printing Protocol/1.0: Implementer's Guide [ipp-iig]
   Mapping between LPD and IPP Protocols [ipp-lpd]

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 that are independent of encoding and transport. It
introduces a Printer and a Job object. The Job object optionally
supports multiple documents per Job. It also addresses security,
internationalization, and directory issues.

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

The document "Mapping between LPD and IPP Protocols" gives some advice
to implementers of gateways between IPP and LPD (Line Printer Daemon)
implementations.
















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                           Table of Contents

1. Introduction.......................................................4
2. Conformance Terminology............................................4
3. Encoding of  the Operation Layer...................................4
   3.1  Picture of the Encoding.......................................5
   3.2  Syntax of Encoding............................................7
   3.3  Version-number................................................8
   3.4  Operation-id..................................................8
   3.5  Status-code...................................................9
   3.6  Request-id....................................................9
   3.7  Tags..........................................................9
      3.7.1 Delimiter Tags.............................................9
      3.7.2 Value Tags................................................10
   3.8  Name-Length..................................................12
   3.9  (Attribute) Name.............................................12
   3.10 Value Length.................................................14
   3.11 (Attribute) Value............................................15
   3.12 Data.........................................................16
4. Encoding of Transport Layer.......................................16
5. Security Considerations...........................................17
   5.1  Using IPP with SSL3..........................................18
6. References........................................................18
7. Author's Address..................................................20
8. Other Participants:...............................................20
9. Appendix A: Protocol Examples.....................................21
   9.1  Print-Job Request............................................21
   9.2  Print-Job Response (successful)..............................22
   9.3  Print-Job Response (failure).................................23
   9.4  Print-Job Response (success with attributes ignored).........24
   9.5  Print-URI Request............................................25
   9.6  Create-Job Request...........................................26
   9.7  Get-Jobs Request.............................................27
   9.8  Get-Jobs Response............................................28
10.Appendix C: Registration of MIME Media Type Information for
"application/ipp".....................................................29
11.Appendix D: Full Copyright Statement..............................31


















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1. Introduction

This document contains the rules for encoding IPP operations and
describes two layers: the transport layer and the operation layer.

The transport layer consists of an  HTTP/1.1 request or response. RFC
2068 [rfc2068] describes HTTP/1.1. This document specifies the HTTP
headers that an IPP implementation supports.

The operation layer consists of  a message body in an HTTP request or
response.  The document "Internet Printing Protocol/1.0: Model and
Semantics" [ipp-mod] defines the semantics of such a message body and
the supported values. This document specifies the encoding of an IPP
operation. The aforementioned document [ipp-mod] is henceforth referred
to as the "IPP model document"


2. Conformance Terminology

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


3. Encoding of  the Operation Layer

The operation layer MUST contain a single operation request or operation
response.  Each request or response consists of a sequence of values and
attribute groups. Attribute groups consist of a sequence of attributes
each of which is a name and value.  Names and values are ultimately
sequences of octets

The encoding consists of octets as the most primitive type. There are
several types built from octets, but three important  types are
integers,  character strings and octet strings, on which most  other
data types are built. Every character string in this encoding MUST be a
sequence of characters where the characters are associated with some
charset and some natural language. A character string MUST be in
"reading  order" with the first character in the value (according to
reading order) being the first character in the encoding. A character
string whose associated charset is US-ASCII whose associated natural
language is US English is henceforth called a US-ASCII-STRING. A
character string whose associated charset and natural language are
specified in a request or response as described in the model document is
henceforth called a LOCALIZED-STRING. An octet string MUST be in "IPP
model document order" with the first octet in the value (according to
the IPP model document  order) being the first octet in the encoding
Every integer in this encoding MUST be encoded as a signed integer using
two's-complement binary encoding with big-endian format (also known as
"network order" and "most significant byte first"). The number of octets
for an integer MUST be 1, 2 or 4, depending on usage in the protocol.
Such one-octet integers, henceforth called SIGNED-BYTE, are used for the
version-number and tag fields. Such two-byte integers, henceforth called
SIGNED-SHORT are used for the operation-id, status-code and length

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fields. Four byte integers, henceforth called SIGNED-INTEGER, are used
for values fields and the sequence number.

The following two sections present the operation layer in two ways

  @ informally through pictures and description
  @ formally through Augmented Backus-Naur Form (ABNF), as specified by
     RFC 2234 [rfc2234]


3.1 Picture of the Encoding

The encoding for an operation request or response consists of:

  -----------------------------------------------
  |                  version-number             |   2 bytes  - required
  -----------------------------------------------
  |               operation-id (request)        |
  |                      or                     |   2 bytes  - required
  |               status-code (response)        |
  -----------------------------------------------
  |                   request-id                |   4 bytes  - required
  -----------------------------------------------------------
  |               xxx-attributes-tag            |   1 byte  |
  -----------------------------------------------           |-0 or more
  |             xxx-attribute-sequence          |   n bytes |
  -----------------------------------------------------------
  |              end-of-attributes-tag          |   1 byte   - required
  -----------------------------------------------
  |                     data                    |   q bytes  - optional
  -----------------------------------------------

The xxx-attributes-tag and xxx-attribute-sequence represents four
different values of "xxx", namely, operation, job, printer and
unsupported. The xxx-attributes-tag and an xxx-attribute-sequence
represent attribute groups in the model document. The xxx-attributes-tag
identifies the attribute group and the xxx-attribute-sequence contains
the attributes.

The expected sequence of  xxx-attributes-tag and xxx-attribute-sequence
is specified in the IPP model document for each operation request and
operation response.

A request or response SHOULD contain each xxx-attributes-tag defined for
that request or response even if there are no attributes except for the
unsupported-attributes-tag which SHOULD be present only if the
unsupported-attribute-sequence is non-empty. A receiver of a request
MUST be able to process as equivalent empty attribute groups:

  a) an xxx-attributes-tag with an empty xxx-attribute-sequence,

  b) an expected but missing xxx-attributes-tag.

The data is omitted from some operations, but the end-of-attributes-tag
is present even when the data is omitted. Note, the xxx-attributes-tags

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and end-of-attributes-tag are called 'delimiter-tags'. Note: the xxx-
attribute-sequence, shown above may consist of 0 bytes, according to the
rule below.

An xxx-attributes-sequence consists of zero or more compound-attributes.

  -----------------------------------------------
  |              compound-attribute             |   s bytes - 0 or more
  -----------------------------------------------

A compound-attribute consists of an attribute with a single value
followed by zero or more additional values.

Note: a 'compound-attribute' represents a single attribute in the model
document.  The 'additional value' syntax is for attributes with 2 or
more values.

Each attribute consists of:

  -----------------------------------------------
  |                   value-tag                 |   1 byte
  -----------------------------------------------
  |               name-length  (value is u)     |   2 bytes
  -----------------------------------------------
  |                     name                    |   u bytes
  -----------------------------------------------
  |              value-length  (value is v)     |   2 bytes
  -----------------------------------------------
  |                     value                   |   v bytes
  -----------------------------------------------

An additional value consists of:

  -----------------------------------------------------------
  |                   value-tag                 |   1 byte  |
  -----------------------------------------------           |
  |            name-length  (value is 0x0000)   |   2 bytes |
  -----------------------------------------------           |-0 or more
  |              value-length (value is w)      |   2 bytes |
  -----------------------------------------------           |
  |                     value                   |   w bytes |
  -----------------------------------------------------------

Note: an additional value is like an attribute whose name-length is 0.

>From the standpoint of a parsing loop, the encoding consists of:









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  -----------------------------------------------
  |                  version-number             |   2 bytes  - required
  -----------------------------------------------
  |               operation-id (request)        |
  |                      or                     |   2 bytes  - required
  |               status-code (response)        |
  -----------------------------------------------
  |                   request-id                |   4 bytes  - required
  -----------------------------------------------------------
  |        tag (delimiter-tag or value-tag)     |   1 byte  |
  -----------------------------------------------           |-0 or more
  |           empty or rest of attribute        |   x bytes |
  -----------------------------------------------------------
  |              end-of-attributes-tag          |   2 bytes  - required
  -----------------------------------------------
  |                     data                    |   y bytes  - optional
  -----------------------------------------------


The value of the tag determines whether the bytes following the tag are:

  @ attributes
  @ data
  @ the remainder of a single attribute where the tag specifies the
     type of the value.

3.2 Syntax of Encoding

The syntax below is ABNF [rfc2234] except 'strings of literals' MUST be
case sensitive. For example 'a' means lower case  'a' and not upper case
'A'.   In addition, SIGNED-BYTE and SIGNED-SHORT fields are represented
as '%x' values which show their range of values.


  ipp-message = ipp-request / ipp-response
  ipp-request = version-number operation-id request-id
           *(xxx-attributes-tag  xxx-attribute-sequence) end-of-
  attributes-tag data
  ipp-response = version-number status-code request-id
           *(xxx-attributes-tag xxx-attribute-sequence)  end-of-
  attributes-tag  data
  xxx-attribute-sequence = *compound-attribute

  xxx-attributes-tag = operation-attributes-tag / job-attributes-tag /
        printer-attributes-tag / unsupported-attributes-tag

  version-number = major-version-number minor-version-number
  major-version-number = SIGNED-BYTE  ; initially %d1
  minor-version-number = SIGNED-BYTE  ; initially %d0

  operation-id = SIGNED-SHORT    ; mapping from model defined below
  status-code = SIGNED-SHORT  ; mapping from model defined below
  request-id = SIGNED-INTEGER ; whose value is > 0

  compound-attribute = attribute *additional-values

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  attribute = value-tag name-length name value-length value
  additional-values = value-tag zero-name-length value-length value

  name-length = SIGNED-SHORT    ; number of octets of 'name'
  name = LALPHA *( LALPHA / DIGIT / "-" / "_" / "." )
  value-length = SIGNED-SHORT  ; number of octets of 'value'
  value = OCTET-STRING

  data = OCTET-STRING

  zero-name-length = %x00.00           ; name-length of 0
  operation-attributes-tag =  %x01             ; tag of 1
  job-attributes-tag   =  %x02                 ; tag of 2
  printer-attributes-tag =  %x04               ; tag of 4
  unsupported- attributes-tag =  %x05          ; tag of 5
  end-of-attributes-tag = %x03                 ; tag of 3
  value-tag = %x10-FF

  SIGNED-BYTE = BYTE
  SIGNED-SHORT = 2BYTE
  SIGNED-INTEGER = 4BYTE
  DIGIT = %x30-39    ;  "0" to "9"
  LALPHA = %x61-7A   ;  "a" to "z"
  BYTE = %x00-FF
  OCTET-STRING = *BYTE

The syntax allows an xxx-attributes-tag to be present when the xxx-
attribute-sequence that follows is empty. The syntax is defined this way
to allow for the response of Get-Jobs where no attributes are returned
for some job-objects.  Although it is RECOMMENDED that the sender not
send an xxx-attributes-tag if there are no attributes (except in the
Get-Jobs response just mentioned), the receiver MUST be able to decode
such syntax.


3.3 Version-number

The version-number MUST consist of a major and minor version-number,
each of which MUST be represented by a SIGNED-BYTE. The protocol
described in this document MUST have a major version-number of 1 (0x01)
and a minor version-number of  0 (0x00).  The ABNF for these two bytes
MUST be %x01.00.


3.4 Operation-id

Operation-ids are defined as enums in the model document. An operation-
ids enum value MUST be encoded as a SIGNED-SHORT.

Note: the values 0x4000 to 0xFFFF are reserved for private extensions.




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3.5 Status-code

Status-codes are defined as enums in the model document. A status-code
enum value MUST be encoded as a SIGNED-SHORT.

The status-code is an operation attribute in the model document. In the
protocol, the status-code is in a special position, outside of the
operation attributes.

If an IPP status-code is returned, then the HTTP Status-Code MUST be 200
(successful-ok). With any other HTTP Status-Code value, the HTTP
response MUST NOT contain an IPP message-body, and thus no IPP status-
code is returned.


3.6 Request-id

The request-id allows a client to match a response with a request.  This
mechanism is unnecessary in HTTP, but may be useful when application/ipp
entity bodies are used in another context.

The request-id in a response MUST be the value of the request-id
received in the corresponding request.  A client can set the request-id
in each request to a unique value or a constant value, such as 1,
depending on what the client does with the request-id returned in the
response. The value of the request-id MUST be greater than zero.


3.7 Tags

There are two kinds of tags:

  @ delimiter tags: delimit major sections of the protocol, namely
     attributes and data
  @ value tags: specify the type of each attribute value

3.7.1 Delimiter Tags


The following table specifies the values for the delimiter tags:


   Tag Value (Hex)   Delimiter

   0x00              reserved
   0x01              operation-attributes-tag
   0x02              job-attributes-tag
   0x03              end-of-attributes-tag
   0x04              printer-attributes-tag
   0x05              unsupported-attributes-tag
   0x06-0x0e         reserved for future delimiters
   0x0F              reserved for future chunking-end-of-attributes-
                      tag



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When an xxx-attributes-tag occurs in the protocol, it MUST mean that
zero or more following attributes up to the next delimiter tag are
attributes belonging to group xxx as defined in the model document,
where xxx is operation, job, printer, unsupported.

Doing substitution for xxx in the above paragraph, this means the
following. When an operation-attributes-tag occurs in the protocol, it
MUST mean that the zero or more following attributes up to the next
delimiter tag are operation attributes as defined in the model document.
When an job-attributes-tag occurs in the protocol, it MUST mean that the
zero or more following attributes up to the next delimiter tag are job
attributes or job template attributes as defined in the model document.
When a printer-attributes-tag occurs in the protocol, it MUST mean that
the zero or more following attributes up to the next delimiter tag are
printer attributes as defined in the model document. When an
unsupported-attributes-tag occurs in the protocol, it MUST mean that the
zero or more following attributes up to the next delimiter tag are
unsupported attributes as defined in the model document.

The operation-attributes-tag and end-of-attributes-tag MUST each occur
exactly once in an operation. The operation-attributes-tag MUST be the
first tag delimiter, and  the end-of-attributes-tag MUST be the last tag
delimiter. If the operation has a document-content group, the document
data in that group MUST follow the end-of-attributes-tag.

Each of the  other three  xxx-attributes-tags defined above is OPTIONAL
in an operation and each MUST occur at most once in an operation, except
for job-attributes-tag in a Get-Jobs response which may occur zero or
more times.

The order and presence of delimiter tags for each operation request and
each operation response MUST be that defined in the model document. For
further details, see section 3.9 "(Attribute) Name" and section 9
"Appendix A: Protocol Examples".

A Printer MUST treat the reserved delimiter tags differently from
reserved value tags so that the Printer knows that there is an entire
attribute group that it doesn't understand as opposed to a single value
that it doesn't understand.


3.7.2 Value Tags

The remaining tables show values for the value-tag, which is the first
octet of  an attribute. The value-tag specifies the type of the value of
the attribute. The following table specifies the "out-of-band" values
for the value-tag.


   Tag Value (Hex) Meaning

   0x10            unsupported
   0x11            reserved for future 'default'
   0x12            unknown
   0x13            no-value

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   Tag Value (Hex) Meaning

   0x14-0x1F       reserved for future "out-of-band" values.

The "unsupported" value MUST be used in the attribute-sequence of an
error response for those attributes which the printer does not support.
The "default" value is reserved for future use of setting value back to
their default value. The "unknown" value is used for the value of a
supported attribute when its value is temporarily unknown. The "no-
value" value is used for a supported attribute to which no value has
been assigned, e.g. "job-k-octets-supported" has no value if an
implementation supports this attribute, but an administrator has not
configured the printer to have a limit.

The following table specifies the integer values for the value-tag:


   Tag Value (Hex)  Meaning

   0x20             reserved
   0x21             integer
   0x22             boolean
   0x23             enum
   0x24-0x2F        reserved for future integer types

NOTE: 0x20 is reserved for "generic integer" if it should ever be
needed.

The following table specifies the octetString values for the value-tag:


   Tag Value (Hex)  Meaning

   0x30             octetString with an  unspecified format
   0x31             dateTime
   0x32             resolution
   0x33             rangeOfInteger
   0x34             reserved for collection (in the future)
   0x35             textWithLanguage
   0x36             nameWithLanguage
   0x37-0x3F        reserved for future octetString types

The following table specifies the character-string values for the value-
tag:


   Tag Value (Hex)  Meaning

   0x40             reserved
   0x41             textWithoutLanguage
   0x42             nameWithoutLanguage
   0x43             reserved
   0x44             keyword
   0x45             uri
   0x46             uriScheme
   0x47             charset
   0x48             naturalLanguage

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   Tag Value (Hex)  Meaning

   0x49             mimeMediaType
   0x4A-0x5F        reserved for future character string types

NOTE: 0x40 is reserved for "generic character-string" if it should ever
be needed.

NOTE:  an attribute value always has a type, which is explicitly
specified by its tag; one such tag value is "nameWithoutLanguage".   An
attribute's name has an implicit type, which is keyword.

The values 0x60-0xFF are reserved for future types. There are no values
allocated for private extensions. A new type MUST be registered via the
type 2 registration process [ipp-mod].

The tag 0x7F is reserved for extending types beyond the 255 values
available with a single byte. A tag value of 0x7F MUST signify that the
first 4 bytes of the value field are interpreted as the tag value.
Note, this future extension doesn't affect parsers that  are unaware of
this special tag. The tag is like any other unknown tag, and the value
length specifies the length of a value which contains a value that the
parser treats atomically.  All these 4 byte tag values are currently
unallocated except that the values 0x40000000-0x7FFFFFFF are reserved
for experimental use.


3.8 Name-Length

The name-length field MUST consist of a SIGNED-SHORT. This field MUST
specify the number of octets in the name field which follows the name-
length field, excluding the two bytes of the name-length field.

If a name-length field has a value of zero, the following name field
MUST be empty, and the following value MUST be treated as an additional
value for the preceding attribute. Within an attribute-sequence, if two
attributes have the same name, the first occurrence MUST be ignored. The
zero-length name is the only mechanism for multi-valued attributes.


3.9 (Attribute) Name

Some operation elements are called parameters in the model document
[ipp-mod]. They MUST be encoded in a special position and they MUST NOT
appear as an operation attributes.  These parameters are:

  @ "version-number": The parameter  named "version-number" in the IPP
     model document MUST become the "version-number" field in the
     operation layer request or response.
  @ "operation-id": The parameter named "operation-id" in the IPP model
     document MUST become the "operation-id" field in the operation
     layer request.



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  @ "status-code": The parameter named "status-code" in the IPP model
     document MUST become the "status-code" field in the operation layer
     response.
  @  "request-id": The parameter named "request-id" in the IPP model
     document MUST become the "request-id" field in the operation layer
     request or response.

All Printer and Job objects are identified by a Uniform Resource
Identifier (URI) [rfc2396] so that they can be persistently and
unambiguously referenced.  The notion of a URI is a useful concept,
however, until the notion of URI is more stable (i.e.,  defined more
completely and deployed more widely), it is expected that the URIs used
for IPP objects will actually be URLs [rfc1738]  [rfc1808].  Since every
URL is a specialized form of a URI, even though the more generic term
URI is used throughout the rest of this document, its usage is intended
to cover the more specific notion of URL as well.

Some operation elements are encoded twice, once as the request-URI on
the HTTP Request-Line and a second time as a REQUIRED operation
attribute in the application/ipp entity.  These attributes are the
target URI for the operation:

  @ "printer-uri": When the target is a printer and the transport is
     HTTP or HTTPS (for SSL3 [ssl]), the target printer-uri defined in
     each operation in the IPP model document MUST be an operation
     attribute called "printer-uri" and it MUST also be specified
     outside of  the operation layer as the request-URI on the Request-
     Line at the HTTP level.
  @ "job-uri": When the target is a job and the transport is HTTP or
     HTTPS (for SSL3), the target job-uri of each operation in the IPP
     model document MUST be an operation attribute called "job-uri" and
     it MUST also be specified outside of  the operation layer as the
     request-URI on the Request-Line at the HTTP level.

Note: The target URI is included twice in an operation referencing the
same IPP object, but the two URIs NEED NOT be literally identical. One
can be a relative URI and the other can be an absolute URI.  HTTP/1.1
allows clients to generate and send a relative URI rather than an
absolute URI.  A relative URI identifies a resource with the scope of
the HTTP server, but does not include scheme, host or port.  The
following statements characterize how URLs should be used in the mapping
of IPP onto HTTP/1.1:

  1. Although potentially redundant, a client MUST supply the target of
     the operation both as an operation attribute and as a URI at the
     HTTP layer.  The rationale for this decision is to maintain a
     consistent set of rules for mapping application/ipp to possibly
     many communication layers, even where URLs are not used as the
     addressing mechanism in the transport layer.
  2. Even though these two URLs might not be literally identical (one
     being relative and the other being absolute), they MUST both
     reference the same IPP object.
  3. The URI in the HTTP layer is either relative or absolute and is
     used by the HTTP server to route the HTTP request to the correct

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     resource relative to that HTTP server.  The HTTP server need not be
     aware of the URI within the operation request.
  4. Once the HTTP server resource begins to process the HTTP request,
     it might get the reference to the appropriate IPP Printer object
     from either the HTTP URI (using to the context of the HTTP server
     for relative URLs) or from the URI within the operation request;
     the choice is up to the implementation.
  5. HTTP URIs can be relative or absolute, but the target URI in the
     operation MUST be an absolute URI.

The model document arranges the remaining attributes into groups for
each operation request and response. Each such group MUST be represented
in the protocol by an xxx-attribute-sequence preceded by the appropriate
xxx-attributes-tag (See the table below and section 9 "Appendix A:
Protocol Examples"). In addition, the order of these xxx-attributes-tags
and xxx-attribute-sequences in the protocol MUST be the same as in the
model document, but the order of attributes within each xxx-attribute-
sequence MUST be unspecified. The table below maps the model document
group name to xxx-attributes-sequence:


Model Document Group           xxx-attributes-sequence

Operation Attributes           operations-attributes-sequence
Job Template Attributes        job-attributes-sequence
Job Object Attributes          job-attributes-sequence
Unsupported Attributes         unsupported- attributes-sequence
Requested Attributes (Get-     job-attributes-sequence
Job-Attributes)
Requested Attributes (Get-     printer-attributes-sequence
Printer-Attributes)
Document Content               in a special position as described above

If an operation contains attributes from more than one job object (e.g.
Get-Jobs response), the attributes from each job object MUST be in a
separate job-attribute-sequence, such that the attributes from the ith
job object are in the ith job-attribute-sequence. See  Section 9
"Appendix A: Protocol Examples" for table showing the application of the
rules above.


3.10 Value Length

Each attribute value MUST be preceded by a SIGNED-SHORT, which MUST
specify the number of octets in the value which follows this length,
exclusive of the two bytes specifying the length.

For any of the types represented by binary signed integers, the sender
MUST encode the value in exactly four octets.

For any of the types represented by character-strings, the sender MUST
encode the value with all the characters of the string and without any
padding characters.



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If a value-tag contains an "out-of-band" value, such as "unsupported",
the value-length MUST be 0 and the value empty . the value has no
meaning when the value-tag has an "out-of-band" value. If a client
receives a response with a nonzero value-length in this case, it MUST
ignore the value field. If a printer receives a request with a nonzero
value-length in this case, it MUST reject the request.


3.11 (Attribute) Value

The syntax types and most of the details of their representation are
defined in the IPP model document. The table below augments the
information in the model document, and defines the syntax types from the
model document in terms of the 5 basic types defined in section 3
"Encoding of  the Operation Layer". The 5 types are US-ASCII-STRING,
LOCALIZED-STRING, SIGNED-INTEGER, SIGNED-SHORT, SIGNED-BYTE, and OCTET-
STRING.


Syntax of Attribute  Encoding
Value

textWithoutLanguage, LOCALIZED-STRING.
nameWithoutLanguage

textWithLanguage     OCTET_STRING consisting of 4 fields:
                       a) a SIGNED-SHORT which is the number of octets
                          in the following field
                       b) a value of type natural-language,
                       c) a SIGNED-SHORT which is the number of octets
                          in the following field,
                       d) a value of type textWithoutLanguage.

                      The length of a textWithLanguage value MUST be 4
                      + the value of field a + the value of field c.

nameWithLanguage     OCTET_STRING consisting of 4 fields:
                       a) a SIGNED-SHORT which is the number of octets
                          in the following field
                       b) a value of type natural-language,
                       c) a SIGNED-SHORT which is the number of octets
                          in the following field
                       d) a value of type nameWithoutLanguage.

                      The length of a nameWithLanguage value MUST be 4
                      + the value of field a + the value of field c.

charset,             US-ASCII-STRING.
naturalLanguage,
mimeMediaType,
keyword, uri, and
uriScheme

boolean              SIGNED-BYTE  where 0x00 is 'false' and 0x01 is
                      'true'.

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Syntax of Attribute  Encoding
Value


integer and enum     a SIGNED-INTEGER.

dateTime             OCTET-STRING consisting of eleven octets whose
                      contents are defined by "DateAndTime" in RFC
                      1903 [rfc1903].

resolution           OCTET_STRING consisting of nine octets of  2
                      SIGNED-INTEGERs followed by a SIGNED-BYTE. The
                      first SIGNED-INTEGER contains the value of cross
                      feed direction resolution. The second SIGNED-
                      INTEGER contains the value of feed direction
                      resolution. The SIGNED-BYTE contains the units
                      value.

rangeOfInteger       Eight octets consisting of 2 SIGNED-INTEGERs.
                      The first SIGNED-INTEGER contains the lower
                      bound and the second SIGNED-INTEGER contains the
                      upper  bound.

1setOf  X            Encoding according to the rules for an attribute
                      with more than 1 value.  Each value X is encoded
                      according to the rules for encoding its type.

octetString          OCTET-STRING


The type of the value in the model document determines the encoding in
the value and the value of the value-tag.


3.12 Data

The data part MUST include any data required by the operation


4. Encoding of Transport Layer

HTTP/1.1 [rfc2068] is the transport layer for this protocol.

The operation layer has been designed with the assumption that the
transport layer contains the following information:

  @ the URI of the target job or printer operation
  @ the total length of the data in the operation layer, either as a
     single length or as a sequence of chunks each with a length.

It is REQUIRED that a printer implementation support HTTP over the IANA
assigned Well Known Port 631 (the IPP default port), though a printer
implementation may support HTTP over some other port as well.  In


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addition, a printer may have to support another port for privacy (See
Section 5 "Security Considerations").

Note: even though port 631 is the IPP default, port 80 remains the
default for an HTTP URI.  Thus a URI for a printer using port 631 MUST
contain an explicit port, e.g. "http://forest:631/pinetree".  An HTTP
URI for IPP with no explicit port implicitly reference port 80, which is
consistent with the rules for HTTP/1.1. Each HTTP operation MUST use the
POST method where the request-URI is the object target of the operation,
and where the "Content-Type" of the message-body in each request and
response MUST be "application/ipp". The message-body MUST contain the
operation layer and MUST have the syntax described in section 3.2
"Syntax of Encoding". A client implementation MUST adhere to the rules
for a client described for HTTP1.1 [rfc2068] . A printer (server)
implementation MUST adhere the rules for an origin server described for
HTTP1.1 [rfc2068]  .

An IPP server sends a response for each request that it receives.  If an
IPP server detects an error, it MAY send a response before it has read
the entire request.  If the HTTP layer of the IPP server completes
processing the HTTP headers successfully, it MAY send an intermediate
response, such as "100 Continue", with no IPP data before sending the
IPP response.  A client MUST expect such a variety of responses from an
IPP server. For further information on HTTP/1.1, consult the HTTP
documents [rfc2068].


5. Security Considerations

The IPP Model document defines an IPP implementation with "privacy" as
one that implements Secure Socket Layer Version 3 (SSL3).  Note:  SSL3
is not an IETF standards track specification. SSL3 meets the
requirements for IPP security with regards to features such as mutual
authentication and privacy (via encryption). The IPP Model document also
outlines IPP-specific security considerations and should be the primary
reference for security implications with regards to the IPP protocol
itself.

The IPP Model document defines an IPP implementation with
"authentication" as one that implements the standard way for
transporting IPP messages within HTTP 1.1. These include the security
considerations outlined in the HTTP 1.1 standard document [rfc2068] and
Digest Access Authentication extension [rfc2069].

The current HTTP infrastructure supports HTTP over TCP port 80. IPP
server implementations MUST offer IPP services using HTTP over the IANA
assigned Well Known Port 631 (the IPP default port). IPP server
implementations may support other ports, in addition to this port.

See further discussion of IPP security concepts in the model document
[ipp-mod].




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5.1 Using IPP with SSL3

An assumption is that the URI for a secure IPP Printer object has been
found by means outside the IPP printing protocol, via a directory
service, web site or other means.

IPP provides a transparent connection to SSL by calling the
corresponding URL (a https URI connects by default to port 443).
However, the following functions can be provided to ease the integration
of IPP with SSL during implementation:

  connect (URI), returns a status

     "connect" makes an https call and returns the immediate status of
     the connection as returned by SSL to the user. The status values
     are explained in section 5.4.2 of the SSL document [ssl].

     A session-id may also be retained to later resume a session.  The
     SSL handshake protocol may also require the cipher specifications
     supported by the client, key length of the ciphers, compression
     methods, certificates, etc. These should  be sent to the server and
     hence should be available to the IPP client (although as part of
     administration features).

  disconnect (session)

     to disconnect a particular session.

     The session-id available from the "connect" could be used.

  resume (session)

     to reconnect using a previous session-id.

The availability of this information as administration features are left
for implementers, and need not be specified at this time.


6. References

[char] N. Freed, J. Postel:  IANA Charset Registration Procedures, Work
       in Progress (draft-freed-charset-reg-02.txt).

[dpa]  ISO/IEC 10175 Document Printing Application (DPA), June 1996.

[iana] IANA Registry of Coded Character Sets: ftp://ftp.isi.edu/in-
       notes/iana/assignments/character-sets.

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




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[ipp-lpd]       Herriot, R., Hastings, T., Jacobs, N., Martin, J.,
       "Mapping between LPD and IPP Protocols", draft-ietf-ipp-lpd-ipp-
       map-05.txt, November 1998.

[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.

[rfc822]                Crocker, D., "Standard for the Format of ARPA
     Internet Text Messages", RFC 822, August 1982.

[rfc1123]       Braden, S., "Requirements for Internet Hosts -
     Application and Support", RFC 1123, October, 1989.

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

[rfc1543]       Postel, J., "Instructions to RFC Authors", RFC 1543,
       October 1993.

[rfc1738]       Berners-Lee, T., Masinter, L., McCahill, M. , "Uniform
     Resource Locators (URL)", RFC 1738, December, 1994.

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

[rfc1766]       H. Alvestrand, " Tags for the Identification of
       Languages", RFC 1766, March 1995.

[rfc1808]       R. Fielding, "Relative Uniform Resource Locators",
       RFC1808, June 1995.

[rfc1903]       J. Case, et al. "Textual Conventions for Version 2 of
       the Simple Network Management Protocol (SNMPv2)", RFC 1903,
       January 1996.

[rfc2046]       N. Freed & N. Borenstein, Multipurpose Internet Mail
       Extensions (MIME) Part Two: Media Types. November 1996, RFC 2046.

[rfc2048]       N. Freed, J. Klensin & J. Postel.  Multipurpose Internet
       Mail Extension (MIME) Part Four: Registration Procedures.
       November 1996 (Also BCP0013), RFC 2048.


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[rfc2068]       R Fielding, et al, "Hypertext Transfer Protocol .
       HTTP/1.1" RFC 2068, January 1997.

[rfc2069]       J. Franks, et al, "An Extension to HTTP: Digest Access
       Authentication" RFC 2069, January 1997.

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

[rfc2184]       N. Freed, K. Moore, "MIME Parameter Value and Encoded
       Word Extensions: Character Sets, Languages, and Continuations",
       RFC 2184, August 1997.

[rfc2234]       D. Crocker et al., "Augmented BNF for Syntax
       Specifications: ABNF", RFC 2234. November 1997.

[rfc2396]       Berners-Lee, T., Fielding, R., Masinter, L., "Uniform
      Resource Identifiers (URI): Generic Syntax", RFC 2396, August
      1998.


7. Author's Address


                                    Paul Moore
Robert Herriot (editor)
                                    Microsoft
Sun Microsystems Inc.
                                    One Microsoft Way
901 San Antonio Road, MPK-17
                                    Redmond, WA 98053
Palo Alto, CA 94303

                                    Phone: 425-936-0908
Phone: 650-786-8995
                                    Fax: 425-93MS-FAX
Fax:  650-786-7077
                                    Email: paulmo@microsoft.com
Email: robert.herriot@eng.sun.com

                                    Randy Turner
Sylvan Butler
                                    Sharp Laboratories
Hewlett-Packard
                                    5750 NW Pacific Rim Blvd
11311 Chinden Blvd.
                                    Camas, WA 98607
Boise, ID 83714

                                    Phone: 360-817-8456
Phone: 208-396-6000
                                    Fax: : 360-817-8436
Fax: 208-396-3457
                                    Email: rturner@sharplabs.com
Email: sbutler@boi.hp.com


IPP Mailing List:  ipp@pwg.org
IPP Mailing List Subscription:  ipp-request@pwg.org
IPP Web Page:  http://www.pwg.org/ipp/


8. Other Participants:


Chuck Adams - Tektronix             Harry Lewis - IBM
Ron Bergman - Dataproducts          Tony Liao - Vivid Image
Keith Carter - IBM                  David Manchala - Xerox
Angelo Caruso - Xerox               Carl-Uno Manros - Xerox

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Jeff Copeland - QMS                 Jay Martin - Underscore
Roger deBry - IBM                   Larry Masinter - Xerox
Lee Farrell - Canon                 Ira McDonald - High North Inc.
Sue Gleeson - Digital               Bob Pentecost - Hewlett-Packard
Charles Gordon - Osicom             Patrick Powell - Astart
                                    Technologies
Brian Grimshaw - Apple              Jeff Rackowitz - Intermec
Jerry Hadsell - IBM                 Xavier Riley - Xerox
Richard Hart - Digital              Gary Roberts - Ricoh
Tom Hastings - Xerox                Stuart Rowley - Kyocera
Stephen Holmstead                   Richard Schneider - Epson
Zhi-Hong Huang - Zenographics       Shigern Ueda - Canon
Scott Isaacson - Novell             Bob Von Andel - Allegro Software
Rich Lomicka - Digital              William Wagner - Digital Products
David Kellerman - Northlake         Jasper Wong - Xionics
Software
Robert Kline - TrueSpectra          Don Wright - Lexmark
Dave Kuntz - Hewlett-Packard        Rick Yardumian - Xerox
Takami Kurono - Brother             Lloyd Young - Lexmark
Rich Landau - Digital               Peter Zehler - Xerox
Greg LeClair - Epson                Frank Zhao - Panasonic
                                    Steve Zilles - Adobe

9. Appendix A: Protocol Examples


9.1 Print-Job Request

The following is an example of a Print-Job request with job-name,
copies, and sides specified. The "ipp-attribute-fidelity" attribute is
set to 'true' so that the print request will fail if the "copies" or the
"sides" attribute are not supported or their values are not supported.


Octets          Symbolic Value                Protocol field

0x0100          1.0                           version-number
0x0002          Print-Job                     operation-id
0x00000001      1                             request-id
0x01            start operation-attributes    operation-attributes-tag
0x47            charset type                  value-tag
0x0012                                        name-length
attributes-     attributes-charset            name
charset
0x0008                                        value-length
us-ascii        US-ASCII                      value
0x48            natural-language type         value-tag
0x001B                                        name-length
attributes-     attributes-natural-language   name
natural-
language
0x0005                                        value-length
en-us           en-US                         value
0x45            uri type                      value-tag
0x000B                                        name-length

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Octets          Symbolic Value                Protocol field

printer-uri     printer-uri                   name
0x001A                                        value-length
http://forest:  printer pinetree              value
631/pinetree
0x42            nameWithoutLanguage type      value-tag
0x0008                                        name-length
job-name        job-name                      name
0x0006                                        value-length
foobar          foobar                        value
0x22            boolean type                  value-tag
0x16                                          name-length
ipp-attribute-  ipp-attribute-fidelity        name
fidelity
0x01                                          value-length
0x01            true                          value
0x02            start job-attributes          job-attributes-tag
0x21            integer type                  value-tag
0x0006                                        name-length
copies          copies                        name
0x0004                                        value-length
0x00000014      20                            value
0x44            keyword type                  value-tag
0x0005                                        name-length
sides           sides                         name
0x0013                                        value-length
two-sided-      two-sided-long-edge           value
long-edge
0x03            end-of-attributes             end-of-attributes-tag
%!PS...         <PostScript>                  data

9.2 Print-Job Response (successful)

Here is an example of a successful Print-Job response to the previous
Print-Job request.  The printer supported the "copies" and "sides"
attributes and their supplied values.  The status code returned is
'successful-ok'.


Octets            Symbolic Value              Protocol field

0x0100            1.0                         version-number
0x0000            successful-ok               status-code
0x00000001        1                           request-id
0x01              start operation-attributes  operation-attributes-tag
0x47              charset type                value-tag
0x0012                                        name-length
attributes-       attributes-charset          name
charset
0x0008                                        value-length
us-ascii          US-ASCII                    value
0x48              natural-language type       value-tag
0x001B                                        name-length
attributes-       attributes-natural-         name

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Octets            Symbolic Value              Protocol field

natural-language  language
0x0005                                        value-length
en-us             en-US                       value
0x41              textWithoutLanguage type    value-tag
0x000E                                        name-length
status-message    status-message              name
0x000D                                        value-length
successful-ok     successful-ok               value
0x02              start job-attributes        job-attributes-tag
0x21              integer                     value-tag
0x0006                                        name-length
job-id            job-id                      name
0x0004                                        value-length
147               147                         value
0x45              uri type                    value-tag
0x0007                                        name-length
job-uri           job-uri                     name
0x001E                                        value-length
http://forest:63  job 123 on pinetree         value
1/pinetree/123
0x42              nameWithoutLanguage type    value-tag
0x0009                                        name-length
job-state         job-state                   name
0x0004                                        value-length
0x0003            pending                     value
0x03              end-of-attributes           end-of-attributes-tag

9.3 Print-Job Response (failure)

Here is an example of an unsuccessful Print-Job response to the previous
Print-Job request. It fails because, in this case, the printer does not
support the "sides" attribute and because the value '20' for the
"copies" attribute is not supported. Therefore, no job is created, and
neither a "job-id" nor a "job-uri" operation attribute is returned. The
error code returned is 'client-error-attributes-or-values-not-supported'
(0x040B).


Octets        Symbolic Value                Protocol field

0x0100        1.0                           version-number
0x040B        client-error-attributes-or-   status-code
              values-not-supported
0x00000001    1                             request-id
0x01          start operation-attributes    operation-attribute tag
0x47          charset type                  value-tag
0x0012                                      name-length
attributes-   attributes-charset            name
charset
0x0008                                      value-length
us-ascii      US-ASCII                      value
0x48          natural-language type         value-tag
0x001B                                      name-length

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Octets        Symbolic Value                Protocol field

attributes-   attributes-natural-language   name
natural-
language
0x0005                                      value-length
en-us         en-US                         value
0x41          textWithoutLanguage type      value-tag
0x000E                                      name-length
status-       status-message                name
message
0x002F                                      value-length
client-error- client-error-attributes-or-   value
attributes-   values-not-supported
or-values-
not-supported
0x05          start unsupported-attributes  unsupported-attributes tag
0x21          integer type                  value-tag
0x0006                                      name-length
copies        copies                        name
0x0004                                      value-length
0x00000014    20                            value
0x10          unsupported  (type)           value-tag
0x0005                                      name-length
sides         sides                         name
0x0000                                      value-length
0x03          end-of-attributes             end-of-attributes-tag

9.4 Print-Job Response (success with attributes ignored)

Here is an example of a successful Print-Job response to a Print-Job
request like the previous Print-Job request, except that the value of
'ipp-attribute-fidelity' is false. The print request succeeds, even
though, in this case, the printer supports neither the "sides" attribute
nor the value '20' for the "copies" attribute. Therefore, a job is
created, and both a "job-id" and a "job-uri" operation attribute are
returned. The unsupported attributes are also returned in an Unsupported
Attributes Group. The error code returned is 'successful-ok-ignored-or-
substituted-attributes' (0x0001).


Octets            Symbolic Value              Protocol field

0x0100            1.0                         version-number
0x0001            successful-ok-ignored-or-   status-code
                  substituted-attributes
0x00000001        1                           request-id
0x01              start operation-attributes  operation-attributes-tag
0x47              charset type                value-tag
0x0012                                        name-length
attributes-       attributes-charset          name
charset
0x0008                                        value-length
us-ascii          US-ASCII                    value
0x48              natural-language type       value-tag

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Octets            Symbolic Value              Protocol field

0x001B                                        name-length
attributes-       attributes-natural-         name
natural-language  language
0x0005                                        value-length
en-us             en-US                       value
0x41              textWithoutLanguage type    value-tag
0x000E                                        name-length
status-message    status-message              name
0x002F                                        value-length
successful-ok-    successful-ok-ignored-or-   value
ignored-or-       substituted-attributes
substituted-
attributes
0x05              start unsupported-          unsupported-attributes
                  attributes                  tag
0x21              integer type                value-tag
0x0006                                        name-length
copies            copies                      name
0x0004                                        value-length
0x00000014        20                          value
0x10              unsupported  (type)         value-tag
0x0005                                        name-length
sides             sides                       name
0x0000                                        value-length
0x02              start job-attributes        job-attributes-tag
0x21              integer                     value-tag
0x0006                                        name-length
job-id            job-id                      name
0x0004                                        value-length
147               147                         value
0x45              uri type                    value-tag
0x0007                                        name-length
job-uri           job-uri                     name
0x001E                                        value-length
http://forest:63  job 123 on pinetree         value
1/pinetree/123
0x42              nameWithoutLanguage type    value-tag
0x0009                                        name-length
job-state         job-state                   name
0x0004                                        value-length
0x0003            pending                     value
0x03              end-of-attributes           end-of-attributes-tag



9.5 Print-URI Request

The following is an example of Print-URI request with copies and job-
name parameters:


Octets         Symbolic Value               Protocol field
0x0100         1.0                          version-number

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Octets         Symbolic Value               Protocol field
0x0003         Print-URI                    operation-id
0x00000001     1                            request-id
0x01           start operation-attributes   operation-attributes-tag
0x47           charset type                 value-tag
0x0012                                      name-length
attributes-    attributes-charset           name
charset
0x0008                                      value-length
us-ascii       US-ASCII                     value
0x48           natural-language type        value-tag
0x001B                                      name-length
attributes-    attributes-natural-language  name
natural-
language
0x0005                                      value-length
en-us          en-US                        value
0x45           uri type                     value-tag
0x000B                                      name-length
printer-uri    printer-uri                  name
0x001A                                      value-length
http://forest  printer pinetree             value
:631/pinetree
0x45           uri type                     value-tag
0x000C                                      name-length
document-uri   document-uri                 name
0x11                                        value-length
ftp://foo.com  ftp://foo.com/foo            value
/foo
0x42           nameWithoutLanguage type     value-tag
0x0008                                      name-length
job-name       job-name                     name
0x0006                                      value-length
foobar         foobar                       value
0x02           start job-attributes         job-attributes-tag
0x21           integer type                 value-tag
0x0006                                      name-length
copies         copies                       name
0x0004                                      value-length
0x00000001     1                            value
0x03           end-of-attributes            end-of-attributes-tag

9.6 Create-Job Request

The following is an example of Create-Job request with no parameters and
no attributes:


Octets         Symbolic Value              Protocol field
0x0100         1.0                         version-number
0x0005         Create-Job                  operation-id
0x00000001     1                           request-id
0x01           start operation-attributes  operation-attributes-tag
0x47           charset type                value-tag
0x0012                                      name-length

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Octets         Symbolic Value              Protocol field
attributes-    attributes-charset          name
charset
0x0008                                      value-length
us-ascii       US-ASCII                    value
0x48           natural-language type       value-tag
0x001B                                      name-length
attributes-    attributes-natural-language name
natural-
language
0x0005                                      value-length
en-us          en-US                       value
0x45           uri type                    value-tag
0x000B                                      name-length
printer-uri    printer-uri                 name
0x001A                                      value-length
http://forest: printer pinetree            value
631/pinetree
0x03           end-of-attributes           end-of-attributes-tag

9.7 Get-Jobs Request

The following is an example of Get-Jobs request with parameters but no
attributes:


Octets           Symbolic Value               Protocol field
0x0100           1.0                          version-number
0x000A           Get-Jobs                     operation-id
0x00000123       0x123                        request-id
0x01             start operation-attributes   operation-attributes-tag
0x47             charset type                 value-tag
0x0012                                        name-length
attributes-      attributes-charset           name
charset
0x0008                                        value-length
us-ascii         US-ASCII                     value
0x48             natural-language type        value-tag
0x001B                                        name-length
attributes-      attributes-natural-language  name
natural-
language
0x0005                                        value-length
en-us            en-US                        value
0x45             uri type                     value-tag
0x000B                                        name-length
printer-uri      printer-uri                  name
0x001A                                        value-length
http://forest:6  printer pinetree             value
31/pinetree
0x21             integer type                 value-tag
0x0005                                        name-length
limit            limit                        name
0x0004                                        value-length
0x00000032       50                           value

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Octets           Symbolic Value               Protocol field
0x44             keyword type                 value-tag
0x0014                                        name-length
requested-       requested-attributes         name
attributes
0x0006                                        value-length
job-id           job-id                       value
0x44             keyword type                 value-tag
0x0000           additional value             name-length
0x0008                                        value-length
job-name         job-name                     value
0x44             keyword type                 value-tag
0x0000           additional value             name-length
0x000F                                        value-length
document-format  document-format              value
0x03             end-of-attributes            end-of-attributes-tag

9.8 Get-Jobs Response

The following is an of Get-Jobs response from previous request with 3
jobs. The Printer returns no information about the second job (because
of security reasons):


Octets           Symbolic Value                Protocol field
0x0100           1.0                           version-number
0x0000           successful-ok                 status-code
0x00000123       0x123                         request-id (echoed
                                               back)
0x01             start operation-attributes    operation-attribute-tag
0x47             charset type                  value-tag
0x0012                                         name-length
attributes-      attributes-charset            name
charset
0x000A                                         value-length
ISO-8859-1       ISO-8859-1                    value
0x48             natural-language type         value-tag
0x001B                                         name-length
attributes-      attributes-natural-language   name
natural-
language
0x0005                                         value-length
en-us            en-US                         value
0x41             textWithoutLanguage type      value-tag
0x000E                                         name-length
status-message   status-message                name
0x000D                                         value-length
successful-ok    successful-ok                 value
0x02             start job-attributes (1st     job-attributes-tag
                 object)
0x21             integer type                  value-tag
0x0006                                         name-length
job-id           job-id                        name
0x0004                                         value-length
147              147                           value

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Octets           Symbolic Value                Protocol field
0x36             nameWithLanguage              value-tag
0x0008                                         name-length
job-name         job-name                      name
0x000C                                         value-length
0x0005                                         sub-value-length
fr-ca            fr-CA                         value
0x0003                                         sub-value-length
fou              fou                           name
0x02             start job-attributes (2nd     job-attributes-tag
                 object)
0x02             start job-attributes (3rd     job-attributes-tag
                 object)
0x21             integer type                  value-tag
0x0006                                         name-length
job-id           job-id                        name
0x0004                                         value-length
148              148                           value
0x36             nameWithLanguage              value-tag
0x0008                                         name-length
job-name         job-name                      name
0x0012                                         value-length
0x0005                                         sub-value-length
de-CH            de-CH                         value
0x0009                                         sub-value-length
isch guet        isch guet                     name
0x03             end-of-attributes             end-of-attributes-tag

10. Appendix C: Registration of MIME Media Type Information for
"application/ipp"

This appendix contains the information that IANA requires for
registering a MIME media type.  The information following this paragraph
will be forwarded to IANA to register application/ipp whose contents are
defined in Section 3 "Encoding of  the Operation Layer"  in this
document:

MIME type name: application

MIME subtype name: ipp

A Content-Type of "application/ipp" indicates an Internet Printing
Protocol message body (request or response). Currently there is one
version: IPP/1.0, whose syntax is described in Section 3 "Encoding of
the Operation Layer"  of [ipp-pro], and whose semantics are described in
[ipp-mod].

Required parameters:  none

Optional parameters:  none

Encoding considerations:



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IPP/1.0 protocol requests/responses MAY contain long lines and ALWAYS
contain binary data (for example attribute value lengths).

Security considerations:

IPP/1.0 protocol requests/responses do not introduce any security risks
not already inherent in the underlying transport protocols. Protocol
mixed-version interworking rules in [ipp-mod] as well as protocol
encoding rules in [ipp-pro] are complete and unambiguous.

Interoperability considerations:

IPP/1.0 requests (generated by clients) and responses (generated by
servers) MUST comply with all conformance requirements imposed by the
normative specifications [ipp-mod] and [ipp-pro]. Protocol encoding
rules specified in [ipp-pro] are comprehensive, so that interoperability
between conforming implementations is guaranteed (although support for
specific optional features is not ensured). Both the "charset" and
"natural-language" of all IPP/1.0 attribute values which are a
LOCALIZED-STRING  are explicit within IPP protocol requests/responses
(without recourse to any external information in HTTP, SMTP, or other
message transport headers).

Published specification:

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

Applications which use this media type:

Internet Printing Protocol (IPP) print clients and print servers,
communicating using HTTP/1.1 (see [IPP-PRO]), SMTP/ESMTP, FTP, or other
transport protocol. Messages of type "application/ipp" are self-
contained and transport-independent, including "charset" and "natural-
language" context for any LOCALIZED-STRING value.

Person & email address to contact for further information:

Scott A. Isaacson
Novell, Inc.
122 E 1700 S
Provo, UT 84606

Phone: 801-861-7366
Fax: 801-861-4025
Email: sisaacson@novell.com

or


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Robert Herriot
Sun Microsystems Inc.
901 San Antonio Road, MPK-17
Palo Alto, CA 94303

Phone: 650-786-8995
Fax: 650-786-7077
Email: robert.herriot@eng.sun.com

Intended usage:

COMMON


11. Appendix D: Full Copyright Statement

Copyright (C)The Internet Society (1998). 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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