IPP Mail Archive: Re: IPP> OPS - Ok that the 'any-value' out

IPP Mail Archive: Re: IPP> OPS - Ok that the 'any-value' out

Re: IPP> OPS - Ok that the 'any-value' out-of-band value hasan attribute value?

From: Ron Bergman (rbergma@hitachi-hkis.com)
Date: Thu Mar 09 2000 - 13:07:43 EST

  • Next message: Hastings, Tom N: "RE: IPP> OPS - Ok that the 'any-value' out-of-band value has an a ttribute value?"

    All,

    In the IPP 1.1 Protocol document, the paragraph cited
    by Hugo goes on to read...

    "However, the definitions of additional "out-of-band"
    values in future documents are able to explicitly use the value field
    and have a value-length that is non-zero, if there is a need for
    additional information to be associated with the out-of-band value.
    Unless the definition of an "out-of-band" value explicitly allows for a
    value, the value-length MUST be 0 and the value empty."

    So a 1.1 implemetation must not break, but a 1.0 might.

        Ron Bergman
        Hitachi Koki Imaging Solutions

    Hugo Parra wrote:

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



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