prtChannelInformation specification, 30oct telecon revisions

prtChannelInformation specification, 30oct telecon revisions

prtChannelInformation specification, 30oct telecon revisions

David_Kellerman at nls.com David_Kellerman at nls.com
Sat Nov 2 19:12:03 EST 1996


Here is the latest revision of the prtChannelInformation object
definition.  I've tried to incorporated all the decisions reached at the
October 30th conference call.  


I took the liberty of changing "human-readable" to "textual" in the
description.  We seem to keep tripping over the implications of
"human-readable."  "Textual" seems more neutral, more appropriate, and
is in keeping with the description of the DisplayString textual
convention. 


Question: UTF-8 apparently uses eight-bit codes, which causes problems
if we're saying data values are coded with only NVT ASCII graphic
characters (32-126).  There's an RFC 1642 that describes UTF-7, a
seven-bit representation of Unicode, but I have no idea of whether it is
generally accepted.  Suggestions from anyone? 


Following the object definition are the specific semantics for the
handful of enum values I volunteered for, also updated.  


Please let me know if anything is missing or mis-stated, or if you have
suggestions on clarifying the language. 


::  David Kellerman         Northlake Software      503-228-3383
::  david_kellerman at nls.com Portland, Oregon        fax 503-228-5662




prtChannelInformation OBJECT-TYPE
    SYNTAX      DisplayString (SIZE(0..255))
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
        "Auxiliary information to allow a printing application to use
        the channel for data submission to the printer.  An application
        capable of using a specific PrtChannelType should be able to use
        the combined information from the prtChannelInformation and
        other channel and interface group objects to 'bootstrap' its use
        of the channel.  prtChannelInformation is not intended to
        provide a general channel description, nor to provide
        information that is available once the channel is in use. 


        The encoding and interpretation of the prtChannelInformation
        object is specific to channel type.  The description of each
        PrtChannelType enum value for which prtChannelInformation is
        defined specifies the appropriate encoding and interpretation,
        including interaction with other objects.  For channel types
        that do not specify a prtChannelInformation value, its value
        shall be null (0 length).  


        When a new PrtChannelType enumeration value is registered, its
        accompanying description must specify the encoding and
        interpretation of the prtChannelInformation value for the
        channel type.  prtChannelInformation semantics for an existing
        PrtChannelType may be added or amended in the same manner as
        described in section 2.4.1 for type 2 enumeration values. 


        The prtChannelInformation specifies values for a collection of
        channel attributes, represented as text according to the
        following rules: 


         1. The prtChannelInformation is coded in the NVT ASCII
            character set.  It is not affected by localization. 


         2. The prtChannelInformation is a list of entries representing
            the attribute values.  Each entry consists of the following
            items, in order: 
             a. a keyword, composed of alphabetic characters (A-Z,
                a-z), that identifies a channel attribute,
             b. an Equals Sign (=) to delimit the keyword,
             c. a data value, consisting of NVT ASCII graphics
                characters (codes 32-126),
             d. a Line Feed character (code 10) to delimit the data
                value. 
            No other characters shall be present. 


            Keywords are case-sensitive.  Conventionally, keywords are
            capitalized (including each word of a multi-word keyword),
            and, since they occupy space in the prtChannelInformation,
            they are kept short. 


         3. If a channel attribute has multiple values, it is
            represented by multiple entries with the same keyword, each
            specifying one value.  Otherwise, there shall be at most
            one entry for each attribute. 


         4. By default, entries may appear in any order.  If there are
            ordering constraints for particular entries, these must be
            specified in their definitions. 


         5. The prtChannelInformation value may represent information
            that is not normally coded in textual form, or that is coded
            in a character set other than NVT ASCII.  In these cases,
            whatever symbolic representation is conventionally used for
            the information should be used for encoding the
            prtChannelInformation.  (For instance, a binary port value
            might be represented as a decimal number, Unicode would
            be represented in UTF-8 format.) 


         6. For each PrtChannelType for which prtChannelInformation
            entries are defined, the descriptive text associated with the
            PrtChannelType enumeration value shall specify the following
            information for each entry: 
            Title:          Brief description phrase, e.g.: "Port name,"
                            "Service Name,"
            Keyword:        The keyword value, eg: "Port," "Service"
            Syntax:         The encoding of the entry value, if it
                            cannot be directly represented by NVT ASCII,
            Status:         "Mandatory," "Optional," or "Conditionally
                            Mandatory,"
            Multiplicity:   "Single" or "Multiple," to indicate whether
                            the entry may be present multiple times,
            Description:    Description of the use of the entry, other
                            information required to complete the
                            definition (e.g.: ordering contstraints,
                            interactions between entries). 


        Applications that interpret prtChannelInformation should ignore
        unrecognized entries, so they are not affected if new entry
        types are added. 
        "
    ::= { prtChannelEntry 9 }




Here are proposed prtChannelInformation definitions for selected
PrtChannelType values: 


    chLPDServer(8),     -- ...
                        -- prtChannelInformation entries:
                        --   Printer queue name
                        --     Keyword:       Queue
                        --     Syntax:        name
                        --     Status:        mandatory
                        --     Multiplicity:  single
                        --     Description:   queue name as defined in RFC 1179
    chDECLAT(32),       -- ...
                        -- prtChannelInformation entries:
                        --   Port name
                        --     Keyword:       Port
                        --     Syntax:        name
                        --     Status:        conditionally mandatory
                        --                    (see note below)
                        --     Multiplicity:  single
                        --     Description:   LAT port name
                        --   Service name
                        --     Keyword:       Service
                        --     Syntax:        name
                        --     Status:        conditionally mandatory
                        --                    (see note below)
                        --     Multiplicity:  single
                        --     Description:   LAT service name
                        -- The LAT channel may be identified by either a
                        -- port or service, so either a Port or Service
                        -- entry must be provided, but not both. 
    chPortTCP(37),      -- ...
                        -- prtChannelInformation entries:
                        --   Port number
                        --     Keyword:       Port
                        --     Syntax:        decimal number
                        --     Status:        mandatory
                        --     Multiplicity:  single
                        --     Description:   TCP port number
    chBidirPortTCP(38), -- ...
                        -- prtChannelInformation entries:
                        --   Port number
                        --     Keyword:       Port
                        --     Syntax:        decimal number
                        --     Status:        mandatory
                        --     Multiplicity:  single
                        --     Description:   TCP port number



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