rfc1759.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

2.  Printer Model

   In order to accomplish the management of the printer, an abstract
   model of the printer is needed to represent the sub-units from which
   the printer is composed. A printer can be described as consisting of
   13 types of sub-units. It is important to note that the sub-units of
   a printer do not necessarily relate directly to any physically
   identifiable mechanism. Sub-units can also be a set of definable
   logical processes, such as interpreters for page description
   languages or command processors that set various operating modes of
   the printer.

























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RFC 1759                      Printer MIB                     March 1995


   Figure 2 shows a block diagram of the printer and its basic 13 sub-
   units.

                     Figure 2 - Printer  Block Diagram

                           Physical Connections
                                   |
                                +-----------+
                                |           |
                            +-------------+ |
                            | Interface   |-+
                            | (RFC1213)   |
                            +-------------+
                                   |
                                +-----------+
                                |           |
                            +-------------+ |    +-----------+
                            | Channel     |-+    | Operator  |
                            |             |      |  Console  |
                            +-------------+      +-----------+
                                   |
                                +-----------+        +---------+
                                |           |        |         |
        +-----------+       +-------------+ |    +-----------+ |
        |  General  |       | Interpreter |-+    |  Alerts   |-+
        |  Printer  |       |             |      |           |
        +-----------+       +-------------+      +-----------+
                                   |
                   +-------------------------------+
                   |        System Controller      |
                   |     (This is the Host MIB)    |
                   +-------------------------------+

   +------+                    +--------+                  +--------+
   |      |                    |        |                  |        |
+-------+ |    +-------+    +---------+ |    +-------+   +--------+ |
| Input |-+  +--------+|    |  Marker |-+  +--------+|   | Output |-+
|       |===>|        |+<==>|         |<==>|        |+==>|        |
+-------+    +--+  +--+     +---------+    +--+  +--+    +--------+
   \            |  ||                         |  ||         \
    \           |  ||                         |  ||          \
     \          |  ||                         |  ||           \
    +--------+  |  |+-------------------------|  ||         +---------+
    |        |  |  +--------------------------+  ||         |         |
+----------+ |  |            Media Path          |+      +----------+ |
|  Media   |-+  +--------------------------------+       | Finisher |-+
|(optional)|                                             |(optional)|
+----------+                                             +----------+



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RFC 1759                      Printer MIB                     March 1995


2.1.  Overview of the Printer Model

   The model has three basic parts: (1) the flow of a print file into an
   interpreter and onto the marker, (2) the flow of media through the
   marker and (3) the auxiliary sub-units that control and facilitate
   the two prior flows.  The flow of the print data comes through a
   physical connection on which some form of transport protocol stack is
   running.  The data provided by the transport protocol (interface)
   appears on a channel which is the input to an interpreter. The
   interpreter converts the print data into a form suitable for marking
   on the media.

   The media resides in Input sub-units from which the media is selected
   and then transported via a Media Path first to a Marking sub-unit and
   then onto an Output sub-unit with (optionally) some finishing
   operations being performed.  The auxiliary sub-units facilitate
   control of the printer, inquiry/control of the operator panel,
   reporting of alerts, and the adaptation of the printer to various
   natural languages and characters sets. All the software sub-units run
   on the System Controller which represents the processor, memory and
   storage systems of the Printer.  Each of the sub-units is discussed
   in more detail below.

   All of the sub-units other than the Alerts report only state
   information, either a description or a status. The Alerts sub-unit
   reports event information.

2.2.  Printer Sub-Units

   A printer is composed of 13 types of sub-units, called groups.  The
   following sections describe the different types of sub-units.

2.2.1.  General Printer

   The general printer sub-unit is responsible for the overall control
   and status of the printer. There is exactly one general printer sub-
   unit in a printer. The general printer sub-unit is represented by the
   General Printer Group in the model. In addition to the providing the
   status of the whole printer and allowing the printer to be reset,
   this Group provides information on the status of the packaging of the
   printer, in particular, the covers. The general printer sub-unit is
   usually implemented on the system controller.

   The localization portion of the general printer sub-unit is
   responsible for identifying the natural language, country, and
   character set in which character strings are expressed. There may be
   one or more localizations supported per printer. The available
   localizations are represented by the Localization table.



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RFC 1759                      Printer MIB                     March 1995


   Localization is only performed on those strings in the MIB that are
   explicitely marked as being localized.  All other character strings
   are returned in ASCII.

   The character set portion of the general printer sub-unit is
   responsible for identifying the possible character sets that are used
   by the interpreters, the operator console, and in network management
   requests for display objects. There may be one or more character sets
   per printer.  The understood character sets are represented by the
   Character Set Table.

2.2.2.  Inputs

   Input sub-units are mechanisms that feed media to be marked on into
   the printer. A printer contains one or more input sub-units. These
   are represented by the Input Group in the model. The model does not
   distinguish fixed input bins from removable trays, except to report
   when a removable tray has been removed.

   There are as many input sub-units as there are distinctly selectable
   input "addresses".  For example, if a tray has an option for manually
   feeding paper as well as automatically feeding from the tray, then
   this is two input sub-units if these two sources can be (must be)
   separately selected and is one input sub-unit if putting a sheet in
   the manual feed slot overrides feeding from the contents of the tray;
   that is, in the second case there is no way to separately select or
   address the manual feed slot.

2.2.3.  Media

   An input sub-unit can hold one or more instances of the media on
   which marking is to be done. Typically, there is a large set of
   possible media that can be associated with an input. The Media Group
   is an extension of the Input Group which represents that media that
   is in an input sub-unit. The Media Group only describes the current
   contents of each input and not the possible content of the input
   sub-unit.

2.2.4.  Outputs

   Output sub-units are mechanisms that receive media that has been
   marked on. A printer contains one or more output mechanisms. These
   are represented by the Output Group in the model. The model does not
   distinguish fixed output bins from removable output bins, except to
   report when a removable bin has been removed.

   There are as many output sub-units as there are distinctly selectable
   output "addresses".  Output sub-units can be addressed in two



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RFC 1759                      Printer MIB                     March 1995


   different ways: (1) as a set of "mailboxes" which are addressed by a
   specific mailbox selector such as a bin number or a bin name, or (2)
   as a set of "slots" into which multiple copies are collated.
   Sometimes both modes of using the output sub-units can be used on the
   same printer.  All that is important from the viewpoint of the model
   is that the output units can be separately selected.

2.2.5.  Finishers

   A finisher is a sub-unit that performs some operations on the media
   other than marking.  The finisher sub-units are represented by the
   Finisher Group in the model.  Some examples of finishing processes
   are stapling, punching, binding, inserting, or folding.  Finishing
   processes may have supplies asssociated with the process.  Stapling,
   binding, and punching are examples of processes that have supplies. A
   printer may have more than one finishing sub-unit and each finishing
   sub-unit may be associated with one or more output sub-units.
   Finishers are not described in this MIB.

   The exact interaction and sequencing between an output device and its
   associated finisher is not specified by the model. It depends on the
   type of finishing process and the exact implementation of the printer
   system. This standard allows for the logical association of a
   finishing process with an output device but does not put any
   restrictions on the exact sequence or interaction with the associated
   output device. The output and finisher sub-units may or may not be
   separate identifiable physical mechanisms depending on the exact
   implementation of a printer.  In addition, a single output device may
   be associated with multiple finishing sub-units and a single
   finishing sub-unit may be associated with multiple output devices.

2.2.6.  Markers

   A marker is the mechanism that produces marks on the print media. The
   marker sub-units and their associated supplies are represented by the
   Marker Group in the model. A printer can contain one or more marking
   mechanisms.  Some examples of multiple marker sub-units are: a
   printer with separate markers for normal and magnetic ink or an
   imagesetter that can output to both a proofing device and final film.
   Each marking device can have its own set of  characteristics
   associated with it, such as marking technology and resolution.

   In this model the marker sub-unit is viewed as very generalized and
   encompasses all aspects of a marking process. For example, in a
   xero-graphic process, the marking process as well as the fusing
   process would be included in the generalized concept of the marker.
   With the generalized concept of a marking process, the concept of
   multiple marking supplies associated with a single marking sub-unit



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RFC 1759                      Printer MIB                     March 1995


   results. For example, in the xerographic process, there is not only a
   supply of toner, but there can also be other supplies such as a fuser
   supply that can be consumed and replaced separately. In addition
   there can be multiple supplies of toner for a single marker device,
   as in a color process.

2.2.7.  Media Paths

   The media paths encompass the mechanisms in the printer that move the
   media through the printer and connect all other media related sub-
   units: inputs, outputs, markers and finishers. A printer contains one
   or more media paths. These are represented by the Media Path Group in
   the model.  The Media Path group has some objects that apply to all
   paths plus a table of the separate media paths.

   In general, the design of the media paths determines the maximum
   speed of the printer as well as the maximum media size that the
   printer can handle. Media paths are complex mechanisms and can
   contain many different identifiable sub-mechanisms such as media
   movement devices, media buffers, duplexing units and interlocks. Not
   all of the various sub-mechanisms reside on every media path.  For
   example, one media path may provide printing only on one surface of
   the media (a simplex path) and another media path may have a sub-
   mechanism that turns the media over and feeds it a second time
   through the marker sub-unit (a duplex path).  The duplex path may
   even have a buffer sub-mechanism that allows multiple copies of the
   obverse side to be held before the reverse side of all the copies are
   marked.

2.2.8.  System Controller

   The System Controller is the sub-unit upon which the software
   components of the Printer run. The System Controller is represented
   in the model by the Host MIB. This MIB allows for the specification
   of the processor(s), memory, disk storage, file system and other
   underlying sub-mechanisms of the printer. The controller can range