PMP Mail Archive: PMP> RE: IPP> RE: Media Names, case sen

PMP Mail Archive: PMP> RE: IPP> RE: Media Names, case sen

PMP> RE: IPP> RE: Media Names, case sensitivity

From: Harry Lewis (harryl@us.ibm.com)
Date: Tue Apr 03 2001 - 17:04:49 EDT

  • Next message: Hastings, Tom N: "PMP> RE: IPP> RE: Media Names, case sensitivity"

    If we want to insist on all lower case then why don't we just say so? I
    just want a short, clear, concise definition.
    ----------------------------------------------
    Harry Lewis
    IBM Printing Systems
    ----------------------------------------------

    "Hastings, Tom N" <hastings@cp10.es.xerox.com>
    Sent by: owner-ipp@pwg.org
    04/03/2001 02:50 PM

     
            To: "Bergman, Ron" <Ron.Bergman@Hitachi-hkis.com>, "'Harry Lewis'"
    <harryl@us.ibm.com>
            cc: "'ipp@pwg.org'" <ipp@pwg.org>, owner-ipp@pwg.org, "pmp (E-mail)"
    <pmp@pwg.org>, "'upd@pwg.org'" <upd@pwg.org>, "'RoBergman@aol.com'"
    <RoBergman@aol.com>, "pmp (E-mail)" <pmp@pwg.org>
            Subject: RE: IPP> RE: Media Names, case sensitivity

     

    I'd like to express an objection to Harry's proposal for case
    insensitiveness in media names. As I understand case insensitiveness, any
    mixture of upper and lower case characters match and must be treated as
    equivalent. Therefore, a recipient (client or Printer) has to convert to
    some internal case convention before comparing for a match. But to be
    user
    friendly, such a recipient (Printer) should remember the case that was
    originally sent by the client, so that the user when querying the same
    attributes subsequently, sees the original case that the user submitted.
    To
    me, such implementation does not lead to "interoperability and
    implementation efficiency", but just the opposite.

    That is why IPP specifically uses all lower case for keyword attribute
    values and so does UPnP. So do other protocols that use IPP semantics.
    Even prtInputMediaType object in the Printer MIB (RFC 1759) has all lower
    case values defined. Now that we have general agreement in the current
    print protocols to use all lower case, why not at least RECOMMEND all
    lower
    case be used by such referencing standards? So I'd like to see something
    like Harry's approach, but RECOMMEND that values be all lower case. After
    all, keywords are really tokens for programs, not people. Having to deal
    with case conversion in a protocol for no benefit, seems a waste.

    Also once keyword names are all lower case, then they are also "case
    sensitive", allowing for more efficient matching. So if a client supplies
    a
    keyword name with some uppercase characters, they won't match the
    supported
    values that the Printer has (since they are all lower case).

    BTW, IPP does RECOMMEND case insensitive matching for attributes with
    'name'
    data type, but the 'keyword' data type MUST be all lower case (and hence
    case sensitive matching for keywords is simpler and correct).

    Also I'd like to see the statement moved from the Media Size Self
    Describing
    Names section to the general conformance section for all three kinds of
    names, as suggested by Ron.

    So using Harry's approach, but making it apply for Media Type Names, Media
    Color Names, and Media Size Self Describing Names, the following two
    paragraphs would be added to section 6 Conformance Requirements:

    " Letters in the names defined in this standard use all lower case. For
    interoperability and implementation efficiency, this standard RECOMMENDS
    that other referencing standards also use these names in their
    all-lower-case form. Then case sensitive matching can be used. However,
    other referencing standards MAY allow substitution of any lower case
    letter
    with its corresponding uppercase letter in the names defined in this
    standard. Such standards MUST require that such substituted letters be
    treated as equivalent to their corresponding lower case letters, i.e.,
    case-insensitive matching.

    For example, if a referencing standard allows uppercase letters in the
    names
    defined in this standard, then the following examples MUST be equivalent:
    'na-letter.8500-11000', 'NA-LETTER.8500-11000, 'NA-Letter.8500-11000',
    'Na-LeTtEr.8500-11000'. "

    Comments?

    Tom

    -----Original Message-----
    From: Bergman, Ron [mailto:Ron.Bergman@Hitachi-hkis.com]
    Sent: Tuesday, April 03, 2001 07:54
    To: 'Harry Lewis'; Hastings, Tom N
    Cc: 'ipp@pwg.org'; owner-ipp@pwg.org; pmp (E-mail); Bergman, Ron;
    'upd@pwg.org'; 'RoBergman@aol.com'
    Subject: RE: IPP> RE: Media Names, case sensitivity

    Harry,

    I like your proposal and unless others express an objection
    will add this to the document.

                     Ron

    -----Original Message-----
    From: Harry Lewis [mailto:harryl@us.ibm.com]
    Sent: Tuesday, April 03, 2001 7:32 AM
    To: Hastings, Tom N
    Cc: 'ipp@pwg.org'; owner-ipp@pwg.org; pmp (E-mail); Bergman, Ron;
    'upd@pwg.org'
    Subject: Re: IPP> RE: Media Names, case sensitivity

    I suggest something more compact like -

    "Media Size Self Describing Names are not case sensitive. As a convention,

    they
    are presented here using lower case characters. Other referencing
    standards
    may impose case sensitive rules across their own interface. For
    interoperability and implementation
    efficiency, imposing case sensitivity is not recommended. "
    ----------------------------------------------
    Harry Lewis
    IBM Printing Systems
    ----------------------------------------------

    -----Original Message-----
    From: Bergman, Ron [mailto:Ron.Bergman@Hitachi-hkis.com]
    Sent: Monday, April 02, 2001 18:16
    To: 'Hastings, Tom N'; Bergman, Ron
    Cc: 'ipp@pwg.org'; 'upd@pwg.org'; 'RonBergman@aol.com'; pmp (E-mail)
    Subject: RE: Media Names, case sensitivity

    Tom,

    See my comments below

                     Ron

    -----Original Message-----
    From: Hastings, Tom N [mailto:hastings@cp10.es.xerox.com]
    Sent: Monday, April 02, 2001 4:52 PM
    To: Bergman, Ron
    Cc: 'ipp@pwg.org'; 'upd@pwg.org'; 'RonBergman@aol.com'; pmp (E-mail)
    Subject: RE: Media Names, case sensitivity

    Ron,

    About case sensitivity in names in the Media standard:

    Draft 0.3 had:

    Media Size Self Describing Names are not case sensitive but will always be
    presented in this standard using lower case characters.

    What I changed it to was:

    While Media Size Self Describing Names are presented in this standard
    using
    lower case characters, other standards that use these names, MUST indicate
    the case sensitivity for their conformance. Such other standards MAY:

    a) also require only lower case as in this standard
    b) allow lower, upper case, and mixed case to be used with
    the same
    meaning as the names in this standard, i.e., case insensitive matching
    c) require all uppercase letters to be used with the same
    meaning as
    the corresponding names in this standard.

    Discussion:

    The important question is what interface is the media standard defining
    conformance requirements for? I had assumed that the media standard was
    NOT
    trying to define an interface that the Printer would implement or that a
    client would implement, but rather was giving a set of names and their
    semantics that other standards would reference.

    RB >> I agree!

      It would be up to these
    other standards to say whether or not case was important. For example,
    IPP
    says that keywords are all lower case, so that both client and Printer can
    count on having all lower case and not having to worry about case
    conversion. Other protocol, such as the Printer MIB use of MediaType and
    UPnP use of MediaType and MediaSize would have to say whether or not case
    was important. We might want the Media standard to RECOMMEND that these
    other standards only use all lower case. That would lower the burden on a
    Printer that is supporting, say, IPP, UPnP, and Printer MIB, if all three
    standards REQUIRED that the values be all lower case.

    RB >> If IPP requires lower case and UpNP requires upper case, then
    responses
    from the printer that contain media names have to be converted for one
    client
    or the other, depending upon the printer table. Existing IPP printers
    most
    likely have the table implemented as lower case. So, I would recommend
    that

    to be compatible we should really REQUIRE lower case. Then it would be
    compatible with current IPP clients and servers. The problem is not
    always
    on the printer (server) side, since the client can also send media names
    to
    the server.

    RB >> I would prefer to specify "not case sensitive" but I see now that
    for
    IPP compatibility it is best to require lower case.

    RB >> A good design will always convert received characters to a specific
    case and send any characters in the specified case. It would be best if
    all protocols specified and then the sender could use common code for all.

    BTW, I have seen some IANA Registries where the tokens are all upper case.
    That is why I included alternative c) above as well.

    Bottom line: The Media standard is writing conformance for other standards
    that reference the Media standard (like the IPP Notification Standard
    placed
    requirements on Delivery Method documents), not conformance for Printers
    or
    clients.

    RB >> I agree, and lower case would be the best choice for conformance.

    See my replies to your message below preceded by TH>

    Comments?

    Tom

    -----Original Message-----
    From: Bergman, Ron [mailto:Ron.Bergman@Hitachi-hkis.com]
    Sent: Monday, April 02, 2001 08:57
    To: Hastings, Tom N
    Cc: 'ipp@pwg.org'; 'upd@pwg.org'; 'RonBergman@aol.com'
    Subject: Media Names, case sensitivity

    Tom,

    I am curious as to why you changed my original statement that the names
    are
    not case sensitive to the the complicated set of requirements that, in
    effect,
    states "do whatever you want, but explicitly state what you want."

    TH> The draft is stating that other standards that use these names do what
    they want, but those standards (such as IPP, UPnP, Printer MIB, etc.) MUST
    say what they require.

    Your specification puts a larger burden on the Printer, since the printer
    will
    have to conform to the applications. (The printer may have to do a case
    conversion for some applications and not others.) So the printer (or
    other
    device) must know the exact format required by the application.

    TH> The Printer will have to conform to whatever standards the Printer
    chooses to support, i.e., IPP, UPnP, Printer MIB, ...

    Just stating the names are not case sensitive, puts the burden on the
    client.

    TH> I disagree. It depends on what the other standards say about case
    sensitivity. Perhaps the Media standard can RECOMMEND that other
    standards
    REQUIRE all lower case, as I suggested above. Wouldn't that help?

    RB >> Do any other standards, besides IPP exist?

    But the client simply has to do a conversion on all names received to
    whatever
    case he has chosen for his tables. The client does not need to know what
    the printer is sending.

    Whatever we conclude,, this text needs will be moved from section 5 to
    section 10, since it applies to all the names in the specification.

    TH> I agree it should be moved to a section that is common for all the
    names. However, section 10 is the authors section.

    RB >> I should have said the conformance section.

        Ron



    This archive was generated by hypermail 2b29 : Tue Apr 03 2001 - 17:07:17 EDT