backend/easysw-firewire-design.txt

   1 Preliminary Design for CUPS Firewire Printer Backend - 03/19/2002
   2 -----------------------------------------------------------------
   3
   4 OVERVIEW
   5
   6     Easy Software Products will develop an IEEE-1394, a.k.a.
   7     Firewire, printing interface for its Common UNIX Printing
   8     System ("CUPS") for initial use under the Linux operating
   9     system.  A follow-on implementation for MacOS X is
  10     anticipated as well.
  11
  12     The operating system interfaces for IEEE-1394 ports vary
  13     widely; the CUPS printing interface will abstract the OS
  14     layer to a simpler interface geared towards discovering,
  15     opening, reading from, writing to, and closing IEEE-1394
  16     printers.
  17
  18     The initial development of the CUPS backend will be targeted
  19     at the EPSON Stylus Pro 10000 large format printer, which
  20     requires the bandwidth provided by Firewire in order to
  21     print at full speed.  This printer supports printing via
  22     Serial Bus Protocol 2 (SBP-2) using the SCSI and PWG command
  23     sets. The CUPS backend will implement the PWG command set on
  24     LUN 0 only.
  25
  26
  27 OS ABSTRACTION LAYER
  28
  29     The OS abstraction layer will be a thin client library that
  30     implements the following functions:
  31
  32         ieee1394_list
  33         ieee1394_open
  34         ieee1394_close
  35         ieee1394_read
  36         ieee1394_write
  37         ieee1394_error
  38
  39     The "ieee1394_list" function will list all of the available
  40     printer devices on the bus.  The device information will
  41     consist of the device URI (ieee1394:/something) used to
  42     access the device and the make and model information, if
  43     available, for the device ("EPSON Stylus Printer").
  44
  45     The "ieee1394_open" and "ieee1394_close" functions will open
  46     and close a connection to the printer, respectively.
  47
  48     The "ieee1394_read" and "ieee1394_write" functions will read
  49     and write data to and from the printer, respectively.  The
  50     read function will be non-blocking, returning data only if
  51     there is data coming back from the printer.
  52
  53     The "ieee1394_error" function will return a string
  54     describing the last error or NULL if no error occurred.
  55
  56     The library will be responsible for creating any background
  57     threads that are needed to monitor the connection to the
  58     printer.
  59
  60
  61 CUPS BACKEND
  62
  63     The CUPS backend will use the OS abstraction layer to list
  64     and access the Firewire printers.  The "main" function will
  65     read and write printer data, while the "list_devices"
  66     function will be called as necessary to identify the
  67     available devices.
  68
  69     The CUPS 1.1 backend will record any status information in
  70     the error log file, while the 1.2 backend will supply it to
  71     the printer driver process.