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<DIV>All,</DIV>
<DIV> </DIV>
<DIV>Our current client implementation (Novell's IPP Gateway) checks that all
"out of band" attributes have value lengths of zero. This code
hasn't yet been officially released, so it's still possible to change it, if
needs be. But make no mistake, allowing non-zero values for
"out-of-band" values does break the current IPP rules. Section
3.10 of the "IPP/1.0: Encoding and Transport" document reads:</DIV>
<DIV> </DIV>
<DIV><FONT style="BACKGROUND-COLOR: #ffffff">"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."</FONT></DIV>
<DIV><FONT style="BACKGROUND-COLOR: #ffffff"></FONT> </DIV>
<DIV><FONT style="BACKGROUND-COLOR: #ffffff">-Hugo</FONT><BR><BR>>>>
"Hastings, Tom N" <<A
href="mailto:hastings@cp10.es.xerox.com">hastings@cp10.es.xerox.com</A>>
03/08/00 05:29PM >>><BR>At the IPP telecon today we agreed to remove
the final issue from the "Job<BR>and Printer Set operation" document,
because we didn't see any problems.<BR>However, we also agreed that I should ask
for comments regarding the issue<BR>on the DL. We assume that Printer
parsers aren't checking for out-of-band<BR>values to have a zero length and
rejecting requests if its is non-zero, at<BR>least for the three out-of-band
values defined in IPP/1.1 [ipp-mod and<BR>ipp-pro] which are 'unknown',
'unsupported', and 'no-value'. We are also<BR>assuming that clients won't
crash if they get an out-of-band value with a<BR>non-zero length in a
response. Please send any objections. Silence will be<BR>assumed to be
agreement. <BR><BR>In the [ipp-pro] document, the statement that an
out-of-band value MUST have<BR>a zero length, has been qualified to say for the
out-of-band values "defined<BR>in this [ipp-pro]
document".<BR><BR>Therefore, we are free to define an attribute value for
use with a new<BR>out-of-band value, if that provides some useful
capabilities. We have found<BR>a need for being able to indicate in an
"xxx-supported" attribute in a<BR>Get-Printer-Supported-Valued
response, for the 'any-value' out-of band value<BR>to indicate which attribute
syntax it is to apply. This 'any-value' could<BR>also be used in
"xxx-supported" with Get-Printer-Attributes to indicate that<BR>the
Printer will accept any value for attribute syntaxes that don't have a<BR>way to
indicate any, such as 'name', 'mimeMediaType', 'uriScheme'.<BR><BR>Here is the
definition of the 'any-value' out-of-band value as it appears in<BR>the
"Job and Printer Set operation" document:<BR><BR>8.3
'any-value' out-of-band attribute value<BR>The 'any-value' out-of-band attribute
value MAY be used in combination with<BR>an attribute syntax to represent
"any" attribute value of that attribute<BR>syntax. <BR>See
section 4.3 in this document for an example definition of the usage of<BR>the
'any-value' out-of-band attribute value with the 'name' attribute syntax<BR>in
any "xxx-supported" attribute returned in a
Get-Printer-Supported-Values<BR>response.<BR><BR>8.3.1
Encoding of the 'any-value' out-of-band attribute value<BR>The encoding of the
'any-value' out-of-band attribute value is 0x17 (see<BR>[ipp-pro]). This
out-of-band value REQUIRES a non-zero length and an<BR>attribute value which
identifies an attribute syntax type. The attribute<BR>value is either (1)
a one-octet attribute syntax tag as defined in [ipp-pro]<BR>(value length = 1)
or (2) a 0x7F code followed by a 4-octets of an extended<BR>attribute syntax
type code as allocated in [ipp-pro] (value length = 5).<BR>ISSUE 01 - Ok to
define the 'any-value' out-of-band value to have an actual<BR>value, consisting
of the attribute syntax code?<BR><BR></DIV></BODY></HTML>