each Operation attribute value:
a) that the length of each Operation attribute value is correct
for the attribute syntax tag supplied by the client according
to [RFC2911] Section 4.1,
b) that the attribute syntax tag is correct for that Operation
attribute according to [RFC2911] Section 3,
c) that the value is in the range specified for that Operation
attribute according to [RFC2911] Section 3,
d) that multiple values are supplied by the client only for
operation attributes that are multi-valued, i.e., that are
1setOf X according to [RFC2911] Section 3.
If any of these checks fail, the IPP object REJECTS the request and
RETURNS the 'client-error-bad-request' or the 'client-error-request-
value-too-long' status code. Since such an error is most likely to
be an error detected by a client developer, rather than by an end-
user, the IPP object NEED NOT return an indication of which attribute
had the error in either the Unsupported Attributes Group or the
Status Message. The description for each of these syntactic checks
is explicitly expressed in the first IF statement in the following
table.
In addition, the IPP object checks each Operation attribute value
against some Printer object attribute or some hard-coded value if
there is no "xxx-supported" Printer object attribute defined. If its
value is not among those supported or is not in the range supported,
then the IPP object REJECTS the request and RETURNS the error status
code indicated in the table by the second IF statement. If the value
of the Printer object's "xxx-supported" attribute is 'no-value'
(because the system administrator hasn't configured a value), the
check always fails.
-----------------------------------------------
attributes-charset (charset)
IF NOT a single non-empty 'charset' value, REJECT/RETURN 'client-
error-bad-request'.
IF the value length is greater than 63 octets, REJECT/RETURN
'client-error-request-value-too-long'.
IF NOT in the Printer object's "charset-supported" attribute,
REJECT/RETURN "client-error-charset-not-supported".
attributes-natural-language(naturalLanguage)
IF NOT a single non-empty 'naturalLanguage' value, REJECT/RETURN
'client-error-bad-request'.
IF the value length is greater than 63 octets, REJECT/RETURN
'client-error-request-value-too-long'.
ACCEPT the request even if not a member of the set in the Printer
object's "generated-natural-language-supported" attribute. If the
supplied value is not a member of the Printer object's
"generated-natural-language-supported" attribute, use the Printer
object's "natural-language- configured" value.
requesting-user-name
IF NOT a single 'name' value, REJECT/RETURN 'client-error-bad-
request'.
IF the value length is greater than 255 octets, REJECT/RETURN
'client-error-request-value-too-long'.
IF the IPP object can obtain a better-authenticated name, use it
instead.
job-name(name)
IF NOT a single 'name' value, REJECT/RETURN 'client-error-bad-
request'.
IF the value length is greater than 255 octets, REJECT/RETURN
'client-error-request-value-too-long'.
IF NOT supplied by the client, the Printer object creates a name
from the document-name or document-uri.
document-name (name)
IF NOT a single 'name' value, REJECT/RETURN 'client-error-bad-
request'.
IF the value length is greater than 255 octets, REJECT/RETURN
'client-error-request-value-too-long'.
ipp-attribute-fidelity (boolean)
IF NEITHER a single 'true' NOR a single 'false' 'boolean' value,
REJECT/RETURN 'client-error-bad-request'.
IF the value length is NOT equal to 1 octet, REJECT/RETURN
'client-error-request-value-too-long'
IF NOT supplied by the client, the IPP object assumes the value
'false'.
document-format (mimeMediaType)
IF NOT a single non-empty 'mimeMediaType' value, REJECT/RETURN
'client-error-bad-request'.
IF the value length is greater than 255 octets, REJECT/RETURN
'client-error-request-value-too-long'.
IF NOT in the Printer object's "document-format-supported"
attribute, REJECT/RETURN 'client-error-document-format-not-
supported'
IF NOT supplied by the client, the IPP object assumes the value of
the Printer object's "document-format-default" attribute.
document-uri (uri)
IF NOT a single non-empty 'uri' value, REJECT/RETURN 'client-
error-bad-request'.
IF the value length is greater than 1023 octets, REJECT/RETURN
'client-error-request-value-too-long'.
IF the URI syntax is not valid, REJECT/RETURN 'client-error-bad-
request'.
If the client-supplied URI scheme is not supported, i.e., the
value is not in the Printer object's referenced-uri-scheme-
supported" attribute, the Printer object MUST reject the request
and return the 'client-error-uri-scheme-not-supported' status
code. The Printer object MAY check to see if the document exists
and is accessible. If the document is not found or is not
accessible, REJECT/RETURN 'client-error-not found'.
last-document (boolean)
IF NEITHER a single 'true' NOR a single 'false' 'boolean' value,
REJECT/RETURN 'client-error-bad-request'.
IF the value length is NOT equal to 1 octet, REJECT/RETURN
'client-error-request-value-too-long'
job-id (integer(1:MAX))
IF NOT an single 'integer' value equal to 4 octets AND in the
range 1 to MAX, REJECT/RETURN 'client-error-bad-request'.
IF NOT a job-id of an existing Job object, REJECT/RETURN 'client-
error-not-found' or 'client-error-gone' status code, if keep track
of recently deleted jobs.
requested-attributes (1setOf keyword)
IF NOT one or more 'keyword' values, REJECT/RETURN 'client-
error-bad-request'.
IF the value length is greater than 255 octets, REJECT/RETURN
'client-error-request-value-too-long'.
Ignore unsupported values, which are the keyword names of
unsupported attributes. Don't bother to copy such requested
(unsupported) attributes to the Unsupported Attribute response
group since the response will not return them.
which-jobs (type2 keyword)
IF NOT a single 'keyword' value, REJECT/RETURN 'client-error-bad-
request'.
IF the value length is greater than 255 octets, REJECT/RETURN
'client-error-request-value-too-long'.
IF NEITHER 'completed' NOR 'not-completed', copy the attribute and
the unsupported value to the Unsupported Attributes response group
and REJECT/RETURN 'client-error-attributes-or-values-not-
supported'.
Note: a Printer still supports the 'completed' value even if it
keeps no completed/canceled/aborted jobs: by returning no jobs
when so queried.
IF NOT supplied by the client, the IPP object assumes the 'not-
completed' value.
my-jobs (boolean)
IF NEITHER a single 'true' NOR a single 'false' 'boolean' value,
REJECT/RETURN 'client-error-bad-request'.
IF the value length is NOT equal to 1 octet, REJECT/RETURN
'client-error-request-value-too-long'
IF NOT supplied by the client, the IPP object assumes the 'false'
value.
limit (integer(1:MAX))
IF NOT a single 'integer' value equal to 4 octets AND in the range
1 to MAX, REJECT/RETURN 'client-error-bad-request'.
IF NOT supplied by the client, the IPP object returns all jobs, no
matter how many.
-----------------------------------------------
3.1.2.1.6 Validate the values of the OPTIONAL Operation attributes
OPTIONAL Operation attributes are those that an IPP object MAY
support. An IPP object validates the values of the OPTIONAL
attributes supplied by the client. The IPP object performs the same
syntactic validation checks for each OPTIONAL attribute value as in
Section 3.1.2.1.5. As in Section 3.1.2.1.5, if any fail, the IPP
object REJECTS the request and RETURNS the 'client-error-bad-request'
or the 'client-error-request-value-too-long' status code.
In addition, the IPP object checks each Operation attribute value
against some Printer attribute or some hard-coded value if there is
no "xxx-supported" Printer attribute defined. If its value is not
among those supported or is not in the range supported, then the IPP
object REJECTS the request and RETURNS the error status code
indicated in the table. If the value of the Printer object's "xxx-
supported" attribute is 'no-value' (because the system administrator
hasn't configured a value), the check always fails.
If the IPP object doesn't recognize/support an attribute, the IPP
object treats the attribute as an unknown or unsupported attribute
(see the last row in the table below).
-----------------------------------------------
document-natural-language (naturalLanguage)
IF NOT a single non-empty 'naturalLanguage' value, REJECT/RETURN
'client-error-bad-request'.
IF the value length is greater than 63 octets, REJECT/RETURN
'client-error-request-value-too-long'.
IF NOT a value that the Printer object supports in document
formats, (no corresponding "xxx-supported" Printer attribute),
REJECT/RETURN 'client-error-natural-language-not-supported'.
compression (type3 keyword)
IF NOT a single 'keyword' value, REJECT/RETURN 'client-error-bad-
request'.
IF the value length is greater than 255 octets, REJECT/RETURN
'client-error-request-value-too-long'.
IF NOT in the Printer object's "compression-supported" attribute,
REJECT/RETURN 'client-error-compression-not-supported'.
Note to IPP/1.0 implementers: Support for the "compression"
attribute was optional in IPP/1.0 and was changed to REQUIRED in
IPP/1.1. However, an IPP/1.0 object SHOULD at least check for the
"compression" attribute being present and reject the create
request, if they don't support "compression". Not checking is a
bug, since the data will be unintelligible.
job-k-octets (integer(0:MAX))
IF NOT a single 'integer' value equal to 4 octets, REJECT/RETURN
'client-error-bad-request'.
IF NOT in the range of the Printer object's "job-k-octets-
supported" attribute, copy the attribute and the unsupported value
to the Unsupported Attributes response group and REJECT/RETURN
'client-error-attributes-or-values-not-supported'.
job-impressions (integer(0:MAX))
IF NOT a single 'integer' value equal to 4 octets, REJECT/RETURN
'client-error-bad-request'.
IF NOT in the range of the Printer object's "job-impressions-
supported" attribute, copy the attribute and the unsupported value
to the Unsupported Attributes response group and REJECT/RETURN
'client-error-attributes-or-values-not-supported'.
job-media-sheets (integer(0:MAX))
IF NOT a single 'integer' value equal to 4 octets, REJECT/RETURN
'client-error-bad-request'.
IF NOT in the range of the Printer object's "job-media-sheets-
supported" attribute, copy the attribute and the unsupported value
to the Unsupported Attributes response group and REJECT/RETURN
'client-error-attributes-or-values-not-supported'.
message (text(127))
IF NOT a single 'text' value, REJECT/RETURN 'client-error-bad-
request'.
IF the value length is greater than 127 octets, REJECT/RETURN
'client-error-request-value-too-long'.
unknown or unsupported attribute
IF the attribute syntax supplied by the client is supported but
the length is not legal for that attribute syntax, REJECT/RETURN
'client-error-request-value-too-long'.
ELSE copy the attribute and value to the Unsupported Attributes
response group and change the attribute value to the "out-of-band"
'unsupported' value, but otherwise ignore the attribute.
Note: Future Operation attributes may be added to the protocol
specification that may occur anywhere in the specified group. When
the operation is otherwise successful, the IPP object returns the
'successful-ok-ignored-or-substituted-attributes' status code.
Ignoring unsupported Operation attributes in all operations is
analogous to the handling of unsupported Job Template attributes in
the create and Validate-Job operations when the client supplies the
"ipp-attribute-fidelity" Operation attribute with the 'false' value.
This last rule is so that we can add OPTIONAL Operation attributes to
future versions of IPP so that older clients can inter-work with new
IPP objects and newer clients can inter-work with older IPP objects.
(If the new attribute cannot be ignored without performing
unexpectedly, the major version number would have been increased in
the protocol document and in the request). This rule for Operation
attributes is independent of the value of the "ipp-attribute-
fidelity" attribute. For example, if an IPP object doesn't support
the OPTIONAL "job-k-octets" attribute', the IPP object treats "job-
k-octets" as an unknown attribute and only checks the length for the
'integer' attribute syntax supplied by the client. If it is not four
octets, the IPP object REJECTS the request and RETURNS the 'client-
error-bad-request' status code, else the IPP object copies the
attribute to the Unsupported Attribute response group, setting the
value to the "out-of-band" 'unsupported' value, but otherwise ignores
the attribute.
3.1.2.2 Suggested Additional Processing Steps for Operations that
Create/Validate Jobs and Add Documents
This section in combination with the previous section recommends the
processing steps for the Print-Job, Validate-Job, Print-URI, Create-
Job, Send-Document, and Send-URI operations that IPP objects SHOULD
use. These are the operations that create jobs, validate a Print-Job
request, and add documents to a job.
IIG Sect # Flow IPP error status codes
---------- ---- ----------------------
|
v No
3.1.2.2.1 <ipp-attribute-fidelity> ------------------+
<supplied?> |
Yes| |
| ipp-attribute-fidelity = no |
|<------------------------------+
v No
3.1.2.2.2 <Printer is> --> server-error-not-accepting-jobs
<accepting jobs?>
Yes|
v err
3.1.2.3 <Validate values of> --> client-error-bad-request
<Job template attributes> client-error-request-value-too-
long
<(length, tag, range,>
<multi-value)>
ok|
v err
3.1.2.3 <Validate values with> --> client-error-bad-request
<supported values> client-error-attributes-or-
| values-not-supported
v err
3.1.2.3.1 <Any conflicting> --> client-error-conflicting-
attributes
<Job Template attr values> client-error-attributes-or-
values-not-supported
v
3.1.2.2.1 Default "ipp-attribute-fidelity" if not supplied
The Printer object checks to see if the client supplied an "ipp-
attribute-fidelity" Operation attribute. If the attribute is not
supplied by the client, the IPP object assumes that the value is
'false'.
3.1.2.2.2 Check that the Printer object is accepting jobs
If the value of the Printer objects "printer-is-accepting-jobs" is
'false', the Printer object REJECTS the request and RETURNS the
'server-error-not-accepting-jobs' status code.
3.1.2.2.3 Validate the values of the Job Template attributes
An IPP object validates the values of all Job Template attribute
supplied by the client. The IPP object performs the analogous
syntactic validation checks of each Job Template attribute value that
it performs for Operation attributes (see Section 3.1.2.1.5.):
a) that the length of each value is correct for the attribute
syntax tag supplied by the client according to [RFC2911]
Section 4.1.
b) that the attribute syntax tag is correct for that attribute
according to [RFC2911] Sections 4.2 to 4.4.
c) that multiple values are supplied only for multi-valued
attributes, i.e., that are 1setOf X according to [RFC2911]
Sections 4.2 to 4.4.
As in Section 3.1.2.1.5, if any of these syntactic checks fail, the
IPP object REJECTS the request and RETURNS the 'client-error-bad-
request' or 'client-error-request-value-too-long' status code as
appropriate, independent of the value of the "ipp-attribute-
fidelity". Since such an error is most likely to be an error
detected by a client developer, rather than by an end-user, the IPP
object NEED NOT return an indication of which attribute had the error
in either the Unsupported Attributes Group or the Status Message.
The description for each of these syntactic checks is explicitly
expressed in the first IF statement in the following table.
Each Job Template attribute MUST occur no more than once. If an IPP
Printer receives a create request with multiple occurrences of a Job
Template attribute, it MAY:
1. reject the operation and return the 'client-error-bad-request'
error status code
2. accept the operation and use the first occurrence of the
attribute
3. accept the operation and use the last occurrence of the
attribute
depending on implementation. Therefore, clients MUST NOT supply
multiple occurrences of the same Job Template attribute in the Job
Attributes group in the request.
3.1.2.3 Algorithm for job validation
The process of validating a Job-Template attribute "xxx" against a
Printer attribute "xxx-supported" can use the following validation
algorithm (see section 3.2.1.2 in [RFC2911]).
To validate the value U of Job-Template attribute "xxx" against the
value V of Printer "xxx-supported", perform the following algorithm:
1. If U is multi-valued, validate each value X of U by performing the
algorithm in Table 7 with each value X. Each validation is
separate from the standpoint of returning unsupported values.
Example: If U is "finishings" that the client supplies with
'staple', 'bind' values, then X takes on the successive values:
'staple', then 'bind'
2. If V is multi-valued, validate X against each Z of V by performing
the algorithm in Table 7 with each value Z. If a value Z
validates, the validation for the attribute value X succeeds. If
it fails, the algorithm is applied to the next value Z of V. If
there are no more values Z of V, validation fails. Example" If V
is "sides-supported" with values: 'one- sided', 'two-sided-long',
and 'two-sided-short', then Z takes on the successive values:
'one-sided', 'two-sided-long', and 'two-sided-short'. If the
client supplies "sides" with 'two-sided- long', the first
comparison fails ('one-sided' is not equal to 'two-sided-long'),
the second comparison succeeds ('two-sided-long' is equal to
'two-sided-long"), and the third comparison ('two-sided-short'
with 'two-sided-long') is not even performed.
3. If both U and V are single-valued, let X be U and Z be V and use
the validation rules in Table 7.
Table 7 - Rules for validating single values X against Z
Attribute syntax attribute syntax validated if:
of X of Z
integer rangeOfInteger X is within the range of Z
uri uriScheme the uri scheme in X is equal to
Z
any boolean the value of Z is TRUE
any any X and Z are of the same type
and are equal.
If the value of the Printer object's "xxx-supported" attribute is
'no-value' (because the system administrator hasn't configured a
value), the check always fails. If the check fails, the IPP object
copies the attribute to the Unsupported Attributes response group
with its unsupported value. If the attribute contains more than one
value, each value is checked and each unsupported value is separately
copied, while supported values are not copied. If an IPP object
doesn't recognize/support a Job Template attribute, i.e., there is no
corresponding Printer object "xxx-supported" attribute, the IPP
object treats the attribute as an unknown or unsupported attribute
(see the last row in the table below).
If some Job Template attributes are supported for some document
formats and not for others or the values are different for different
document formats, the IPP object SHOULD take that into account in
this validation using the value of the "document-format" supplied by
the client (or defaulted to the value of the Printer's "document-
format-default" attribute, if not supplied by the client). For
example, if "number-up" is supported for the 'text/plain' document
format, but not for the 'application/postscript' document format, the
check SHOULD (though it NEED NOT) depend on the value of the
"document-format" operation attribute. See "document-format" in
[RFC2911] section 3.2.1.1 and 3.2.5.1.
Note: whether the request is accepted or rejected is determined by
the value of the "ipp-attribute-fidelity" attribute in a subsequent
step, so that all Job Template attribute supplied are examined and
all unsupported attributes and/or values are copied to the
Unsupported Attributes response group.
-----------------------------------------------
job-priority (integer(1:100))
IF NOT a single 'integer' value with a length equal to 4 octets,
REJECT/RETURN 'client-error-bad-request'.
IF NOT supplied by the client, use the value of the Printer
object's "job-priority-default" attribute at job submission time.
IF NOT in the range 1 to 100, inclusive, copy the attribute and
the unsupported value to the Unsupported Attributes response
group.
Map the value to the nearest supported value in the range 1:100 as
specified by the number of discrete values indicated by the value
of the Printer's "job-priority-supported" attribute. See the
formula in [RFC2911] Section 4.2.1.
job-hold-until (type3 keyword | name)
IF NOT a single 'keyword' or 'name' value, REJECT/RETURN 'client-
error-bad-request'.
IF the value length is greater than 255 octets, REJECT/RETURN
'client-error-request-value-too-long'.
IF NOT supplied by the client, use the value of the Printer
object's "job-hold-until" attribute at job submission time.
IF NOT in the Printer object's "job-hold-until-supported"
attribute, copy the attribute and the unsupported value to the
Unsupported Attributes response group.
job-sheets (type3 keyword | name)
IF NOT a single 'keyword' or 'name' value, REJECT/RETURN 'client-
error-bad-request'.
IF the value length is greater than 255 octets, REJECT/RETURN
'client-error-request-value-too-long'.
IF NOT in the Printer object's "job-sheets-supported" attribute,
copy the attribute and the unsupported value to the Unsupported
Attributes response group.
multiple-document-handling (type2 keyword)
IF NOT a single 'keyword' value, REJECT/RETURN 'client-error-bad-
request'.
IF the value length is greater than 255 octets, REJECT/RETURN
'client-error-request-value-too-long'.
IF NOT in the Printer object's "multiple-document-handling-
supported" attribute, copy the attribute and the unsupported value
to the Unsupported Attributes response group.
copies (integer(1:MAX))
IF NOT a single 'integer' value with a length equal to 4 octets,
REJECT/RETURN 'client-error-bad-request'.
IF NOT in range of the Printer object's "copies-supported"
attribute
copy the attribute and the unsupported value to the Unsupported
Attributes response group.
finishings (1setOf type2 enum)
IF NOT an 'enum' value(s) each with a length equal to 4 octets,
REJECT/RETURN 'client-error-bad-request'.
IF NOT in the Printer object's "finishings-supported" attribute,
copy the attribute and the unsupported value(s), but not any
supported values, to the Unsupported Attributes response group.
page-ranges (1setOf rangeOfInteger(1:MAX))
IF NOT a 'rangeOfInteger' value(s) each with a length equal to 8
octets, REJECT/RETURN 'client-error-bad-request'.
IF first value is greater than second value in any range, the
ranges are not in ascending order, or ranges overlap,
REJECT/RETURN 'client-error-bad-request'.
IF the value of the Printer object's "page-ranges-supported"
attribute is 'false', copy the attribute to the Unsupported
Attributes response group and set the value to the "out-of-band"
'unsupported' value.
sides (type2 keyword)
IF NOT a single 'keyword' value, REJECT/RETURN 'client-error-bad-
request'.
IF the value length is greater than 255 octets, REJECT/RETURN
'client-error-request-value-too-long'.
IF NOT in the Printer object's "sides-supported" attribute, copy
the attribute and the unsupported value to the Unsupported
Attributes response group.
number-up (integer(1:MAX))
IF NOT a single 'integer' value with a length equal to 4 octets,
REJECT/RETURN 'client-error-bad-request'.
IF NOT a value or in the range of one of the values of the Printer
object's "number-up-supported" attribute, copy the attribute and
value to the Unsupported Attribute response group.
orientation-requested (type2 enum)
IF NOT a single 'enum' value with a length equal to 4 octets,
REJECT/RETURN 'client-error-bad-request'.
IF NOT in the Printer object's "orientation-requested-supported"
attribute, copy the attribute and the unsupported value to the
Unsupported Attributes response group.
media (type3 keyword | name)
IF NOT a single 'keyword' or 'name' value, REJECT/RETURN 'client-
error-bad-request'.
IF the value length is greater than 255 octets, REJECT/RETURN
'client-error-request-value-too-long'.
IF NOT in the Printer object's "media-supported" attribute, copy
the attribute and the unsupported value to the Unsupported
Attributes response group.
printer-resolution (resolution)
IF NOT a single 'resolution' value with a length equal to 9
octets, REJECT/RETURN 'client-error-bad-request'.
IF NOT in the Printer object's "printer-resolution-supported"
attribute, copy the attribute and the unsupported value to the
Unsupported Attributes response group.
print-quality (type2 enum)
IF NOT a single 'enum' value with a length equal to 4 octets,
REJECT/RETURN 'client-error-bad-request'.
IF NOT in the Printer object's "print-quality-supported"
attribute, copy the attribute and the unsupported value to the
Unsupported Attributes response group.
unknown or unsupported attribute (i.e., there is no corresponding
Printer object "xxx-supported" attribute)
IF the attribute syntax supplied by the client is supported but
the length is not legal for that attribute syntax,
REJECT/RETURN 'client-error-bad-request' if the length of the
attribute syntax is fixed or 'client-error-request-value-too-long'
if the length of the attribute syntax is variable.
ELSE copy the attribute and value to the Unsupported Attributes
response group and change the attribute value to the "out-of-band"
'unsupported' value. Any remaining Job Template Attributes are
either unknown or unsupported Job Template attributes and are
validated algorithmically according to their attribute syntax for
proper length (see below).
-----------------------------------------------
If the attribute syntax is supported AND the length check fails,
the IPP object REJECTS the request and RETURNS the 'client-error-
bad-request' if the length of the attribute syntax is fixed or the
'client-error-request-value-too-long' status code if the length of
the attribute syntax is variable. Otherwise, the IPP object copies
the unsupported Job Template attribute to the Unsupported
Attributes response group and changes the attribute value to the
"out-of-band" 'unsupported' value. The following table shows the
length checks for all attribute syntaxes. In the following table:
"<=" means less than or equal, "=" means equal to:
Name Octet length check for read-write attributes
---------- ---------------------------------------------
'textWithLanguage <= 1023 AND 'naturalLanguage' <= 63
'textWithoutLanguage' <= 1023
'nameWithLanguage' <= 255 AND 'naturalLanguage' <= 63
'nameWithoutLanguage' <= 255
'keyword' <= 255
'enum' = 4
'uri' <= 1023
'uriScheme' <= 63
'charset' <= 63
'naturalLanguage' <= 63
'mimeMediaType' <= 255
'octetString' <= 1023
'boolean' = 1
'integer' = 4
'rangeOfInteger' = 8
'dateTime' = 11
'resolution' = 9
'1setOf X'
Note: It's possible for a Printer to receive a zero length keyword
in a request. Since this is a keyword, its value needs to be
compared with the supported values. Assuming that the printer
doesn't have any values in its corresponding "xxx-supported"
attribute that are keywords of zero length, the comparison will fail.
Then the request will be accepted or rejected depending on the value
of "ipp-attributes-fidelity" being 'false' or 'true', respectively.
No special handling is required for
3.1.2.3.1 Check for conflicting Job Template attributes values
Once all the Operation and Job Template attributes have been checked
individually, the Printer object SHOULD check for any conflicting
values among all the supported values supplied by the client. For
example, a Printer object might be able to staple and to print on
transparencies, however due to physical stapling constraints, the
Printer object might not be able to staple transparencies. The IPP
object copies the supported attributes and their conflicting
attribute values to the Unsupported Attributes response group. The
Printer object only copies over those attributes that the Printer
object either ignores or substitutes in order to resolve the
conflict, and it returns the original values which were supplied by
the client. For example suppose the client supplies "finishings"
equals 'staple' and "media" equals 'transparency', but the Printer
object does not support stapling transparencies. If the Printer
chooses to ignore the stapling request in order to resolve the
conflict, the Printer objects returns "finishings" equal to 'staple'
in the Unsupported Attributes response group. If any attributes are
multi-valued, only the conflicting values of the attributes are
copied.
Note: The decisions made to resolve the conflict (if there is a
choice) is implementation dependent.
3.1.2.3.2 Decide whether to REJECT the request
If there were any unsupported Job Template attributes or
unsupported/conflicting Job Template attribute values and the client
supplied the "ipp-attribute-fidelity" attribute with the 'true'
value, the Printer object REJECTS the request and return the status
code:
1.'client-error-conflicting-attributes' status code, if there were
any conflicts between attributes supplied by the client.
2.'client-error-attributes-or-values-not-supported' status code,
otherwise.
Note: Unsupported Operation attributes or values that are returned
do not affect the status returned in this step. If the unsupported
Operation attribute was a serious error, the above already rejected
the request in a previous step. If control gets to this step with
unsupported Operation attributes being returned, they are not serious
errors.
In general, the final results of Job processing are unknown at Job
submission time. The client has to rely on notifications or polling
to find out what happens at Job processing time. However, there are
cases in which some Printers can determine at Job submission time
that Job processing is going to fail. As an optimization, we'd like
to have the Printer reject the Job in these cases.
There are three types of "processing" errors that might be detectable
at Job submission time:
1. 'client-error-document-format-not-supported' : For the Print-
Job, Send-Document, Print-URI, and Send-URI operations, if all these
conditions are true:
- the Printer supports auto-sensing,
- the request "document-format" operation attribute is
'application/octet-stream',
- the Printer receives document data before responding,
- the Printer auto-senses the document format before responding,
- the sensed document format is not supported by the Printer
then the Printer should respond with 'client-error-document-format-
not-supported' status.
2. 'client-error-compression-error': For the Print-Job, Send-
Document, Print-URI, and Send-URI operations, if all these
conditions are true:
- the client supplies a supported value for the "compression"
operation attribute in the request
- the Printer receives document data before responding,
- the Printer attempts to decompress the document data before
responding,
- the document data cannot be decompressed using the algorithm
specified by the "compression" operation attribute
then the Printer should respond with 'client-error-compression-error'
status.
3. 'client-error-document-access-error': For the Print-URI, and
Send-URI operations, if the Printer attempts and fails to pull the
referenced document data before responding, it should respond with
'client-error-document-access-error' status.
Some Printers are not able to detect these errors until Job
processing time. In that case, the errors are recorded in the
corresponding job-state and job-state reason attributes. (There is
no standard way for a client to determine whether a Printer can
detect these errors at Job submission time.) For example, if auto-
sensing happens AFTER the job is accepted (as opposed to auto-sensing
at submit time before returning the response), the implementation
aborts the job, puts the job in the 'aborted' state and sets the
'unsupported-document-format' value in the job's "job-state-reasons".
A client should always provide a valid "document-format" operation
attribute whenever practical. In the absence of other information, a
client itself may sniff the document data to determine document
format.
Auto sensing at Job submission time may be more difficult for the
Printer when combined with compression. For auto-sensed Jobs, a
client may be better off deferring compression to the transfer
protocol layer, e.g.; by using the HTTP Content-Encoding header.
3.1.2.3.3 For the Validate-Job operation, RETURN one of the success
status codes
If the requested operation is the Validate-Job operation, the Printer
object returns:
1. the "successful-ok" status code, if there are no unsupported or
conflicting Job Template attributes or values.
2. the "successful-ok-conflicting-attributes, if there are any
conflicting Job Template attribute or values.
3. the "successful-ok-ignored-or-substituted-attributes, if there
are only unsupported Job Template attributes or values.
Note: Unsupported Operation attributes or values that are returned
do not affect the status returned in this step. If the unsupported
Operation attribute was a serious error, the above already rejected
the request in a previous step. If control gets to this step with
unsupported Operation attributes being returned, they are not serious
errors.
3.1.2.3.4 Create the Job object with attributes to support
If "ipp-attribute-fidelity" is set to 'false' (or it was not supplied
by the client), the Printer object:
1. creates a Job object, assigns a unique value to the job's
"job-uri" and "job-id" attributes, and initializes all of the
job's other supported Job Description attributes.
2. removes all unsupported attributes from the Job object.
3. for each unsupported value, removes either the unsupported
value or substitutes the unsupported attribute value with some
supported value. If an attribute has no values after removing
unsupported values from it, the attribute is removed from the
Job object (so that the normal default behavior at job
processing time will take place for that attribute).
4. for each conflicting value, removes either the conflicting
value or substitutes the conflicting attribute value with some
other supported value. If an attribute has no values after
removing conflicting values from it, the attribute is removed
from the Job object (so that the normal default behavior at job
processing time will take place for that attribute).
If there were no attributes or values flagged as unsupported, or the
value of 'ipp-attribute-fidelity" was 'false', the Printer object is
able to accept the create request and create a new Job object. If
the "ipp-attribute-fidelity" attribute is set to 'true', the Job
Template attributes that populate the new Job object are necessarily
all the Job Template attributes supplied in the create request. If
the "ipp-attribute-fidelity" attribute is set to 'false', the Job
Template attributes that populate the new Job object are all the
client supplied Job Template attributes that are supported or that
have value substitution. Thus, some of the requested Job Template
attributes will not appear in the Job object because the Printer
object did not support those attributes. The attributes that
populate the Job object are persistently stored with the Job object
for that Job. A Get-Job-Attributes operation on that Job object will
return only those attributes that are persistently stored with the
Job object.
Note: All Job Template attributes that are persistently stored with
the Job object are intended to be "override values"; that is, they
that take precedence over whatever other embedded instructions might
be in the document data itself. However, it is not possible for all
Printer objects to realize the semantics of "override". End users
may query the Printer's "pdl-override-supported" attribute to
determine if the Printer either attempts or does not attempt to
override document data instructions with IPP attributes.
There are some cases, where a Printer supports a Job Template
attribute and has an associated default value set for that attribute.
In the case where a client does not supply the corresponding
attribute, the Printer does not use its default values to populate
Job attributes when creating the new Job object; only Job Template
attributes actually in the create request are used to populate the
Job object. The Printer's default values are only used later at Job
processing time if no other IPP attribute or instruction embedded in
the document data is present.
Note: If the default values associated with Job Template attributes
that the client did not supply were to be used to populate the Job
object, then these values would become "override values" rather than
defaults. If the Printer supports the 'attempted' value of the
"pdl-override-supported" attribute, then these override values could
replace values specified within the document data. This is not the
intent of the default value mechanism. A default value for an
attribute is used only if the create request did not specify that
attribute (or it was ignored when allowed by "ipp-attribute-fidelity"
being 'false') and no value was provided within the content of the
document data.
If the client does not supply a value for some Job Template
attribute, and the Printer does not support that attribute, as far as
IPP is concerned, the result of processing that Job (with respect to
the missing attribute) is undefined.
3.1.2.3.5 Return one of the success status codes
Once the Job object has been created, the Printer object accepts the
request and returns to the client:
1. the 'successful-ok' status code, if there are no unsupported or
conflicting Job Template attributes or values.
2. the 'successful-ok-conflicting-attributes' status code, if
there are any conflicting Job Template attribute or values.
3. the 'successful-ok-ignored-or-substituted-attributes' status
code, if there are only unsupported Job Template attributes or
values.
Note: Unsupported Operation attributes or values that are returned
do not affect the status returned in this step. If the unsupported
Operation attribute was a serious error, the above already rejected
the request in a previous step. If control gets to this step with
unsupported Operation attributes being returned, they are not serious
errors.
The Printer object also returns Job status attributes that indicate
the initial state of the Job ('pending', 'pending-held',
'processing', etc.), etc. See Print-Job Response, [RFC2911] section
3.2.1.2.
3.1.2.3.6 Accept appended Document Content
The Printer object accepts the appended Document Content data and
either starts it printing, or spools it for later processing.
3.1.2.3.7 Scheduling and Starting to Process the Job
The Printer object uses its own configuration and implementation
specific algorithms for scheduling the Job in the correct processing
order. Once the Printer object begins processing the Job, the
Printer changes the Job's state to 'processing'. If the Printer
object supports PDL override (the "pdl-override-supported" attribute
set to 'attempted'), the implementation does its best to see that IPP
attributes take precedence over embedded instructions in the document
data.
3.1.2.3.8 Completing the Job
The Printer object continues to process the Job until it can move the
Job into the 'completed' state. If an Cancel-Job operation is
received, the implementation eventually moves the Job into the
'canceled' state. If the system encounters errors during processing
that do not allow it to progress the Job into a completed state, the
implementation halts all processing, cleans up any resources, and
moves the Job into the 'aborted' state.
3.1.2.3.9 Destroying the Job after completion
Once the Job moves to the 'completed', 'aborted', or 'canceled'
state, it is an implementation decision as to when to destroy the Job
object and release all associated resources. Once the Job has been
destroyed, the Printer would return either the "client-error-not-
found" or "client-error-gone" status codes for operations directed at
that Job.
Note: the Printer object SHOULD NOT re-use a "job-uri" or "job-id"
value for a sufficiently long time after a job has been destroyed, so
that stale references kept by clients are less likely to access the
wrong (newer) job.
3.1.2.3.10 Interaction with "ipp-attribute-fidelity"
Some Printer object implementations may support "ipp-attribute-
fidelity" set to 'true' and "pdl-override-supported" set to
'attempted' and yet still not be able to realize exactly what the
client specifies in the create request. This is due to legacy
decisions and assumptions that have been made about the role of job
instructions embedded within the document data and external job
instructions that accompany the document data and how to handle
conflicts between such instructions. The inability to be 100%
precise about how a given implementation will behave is also
compounded by the fact that the two special attributes, "ipp-
attribute-fidelity" and "pdl-"override-supported", apply to the whole
job rather than specific values for each attribute. For example, some
implementations may be able to override almost all Job Template
attributes except for "number-up". Character Sets, natural
languages, and internationalization
This section discusses character set support, natural language
support and internationalization.
3.1.2.3.11 Character set code conversion support
IPP clients and IPP objects are REQUIRED to support UTF-8. They MAY
support additional charsets. It is RECOMMENDED that an IPP object
also support US-ASCII, since many clients support US-ASCII, and
indicate that UTF-8 and US-ASCII are supported by populating the
Printer's "charset-supported" with 'utf-8' and 'us-ascii' values. An
IPP object is required to code covert with as little loss as possible
between the charsets that it supports, as indicated in the Printer's
"charsets-supported" attribute.
How should the server handle the situation where the "attributes-
charset" of the response itself is "us-ascii", but one or more
attributes in that response is in the "utf-8" format?
Example: Consider a case where a client sends a Print-Job request
with "utf-8" as the value of "attributes-charset" and with the "job-
name" attribute supplied. Later another client submits a Get-Job-
Attribute or Get-Jobs request. This second request contains the
"attributes-charset" with value "us-ascii" and "requested-attributes"
attribute with exactly one value "job-name".
According to the RFC2911 document (section 3.1.4.2), the value of the
"attributes-charset" for the response of the second request must be
"us-ascii" since that is the charset specified in the request. The
"job-name" value, however, is in "utf-8" format. Should the request
be rejected even though both "utf-8" and "us-ascii" charsets are
supported by the server? or should the "job-name" value be converted
to "us-ascii" and return "successful-ok-conflicting-attributes"
(0x0002) as the status code?
Answer: An IPP object that supports both utf-8 (REQUIRED) and us-
ascii, the second paragraph of section 3.1.4.2 applies so that the
IPP object MUST accept the request, perform code set conversion
between these two charsets with "the highest fidelity possible" and
return 'successful-ok', rather than a warning 'successful-ok-
conflicting-attributes, or an error. The printer will do the best it
can to convert between each of the character sets that it supports --
even if that means providing a string of question marks because none
of the characters are representable in US ASCII. If it can't perform
such conversion, it MUST NOT advertise us-ascii as a value of its
"attributes-charset-supported" and MUST reject any request that
requests 'us-ascii'.
One IPP object implementation strategy is to convert all request text
and name values to a Unicode internal representation. This is 16-bit
and virtually universal. Then convert to the specified operation
attributes-charset on output.
Also it would be smarter for a client to ask for 'utf-8', rather than
'us-ascii' and throw away characters that it doesn't understand,
rather than depending on the code conversion of the IPP object.
3.1.2.3.12 What charset to return when an unsupported charset is
requested (Issue 1.19)?
Section 3.1.4.1 Request Operation attributes was clarified in
November 1998 as follows:
All clients and IPP objects MUST support the 'utf-8' charset
[RFC2044] and MAY support additional charsets provided that they are
registered with IANA [IANA-CS]. If the Printer object does not
support the client supplied charset value, the Printer object MUST
reject the request, set the "attributes-charset" to 'utf-8' in the
response, and return the 'client-error-charset-not-supported' status
code and any 'text' or 'name' attributes using the 'utf-8' charset.
Since the client and IPP object MUST support UTF-8, returning any
text or name attributes in UTF-8 when the client requests a charset
that is not supported should allow the client to display the text or
name.
Since such an error is a client error, rather than a user error, the
client should check the status code first so that it can avoid
displaying any other returned 'text' and 'name' attributes that are
not in the charset requested.
Furthermore, [RFC2911] section 14.1.4.14 client-error-charset-not-
supported (0x040D) was clarified in November 1998 as follows:
For any operation, if the IPP Printer does not support the charset
supplied by the client in the "attributes-charset" operation
attribute, the Printer MUST reject the operation and return this
status and any 'text' or 'name' attributes using the 'utf-8' charset