easysw-firewire-design.txt [plain text]
Preliminary Design for CUPS Firewire Printer Backend - 03/19/2002
Easy Software Products will develop an IEEE-1394, a.k.a.
Firewire, printing interface for its Common UNIX Printing
System ("CUPS") for initial use under the Linux operating
system. A follow-on implementation for MacOS X is
anticipated as well.
The operating system interfaces for IEEE-1394 ports vary
widely; the CUPS printing interface will abstract the OS
layer to a simpler interface geared towards discovering,
opening, reading from, writing to, and closing IEEE-1394
The initial development of the CUPS backend will be targeted
at the EPSON Stylus Pro 10000 large format printer, which
requires the bandwidth provided by Firewire in order to
print at full speed. This printer supports printing via
Serial Bus Protocol 2 (SBP-2) using the SCSI and PWG command
sets. The CUPS backend will implement the PWG command set on
LUN 0 only.
OS ABSTRACTION LAYER
The OS abstraction layer will be a thin client library that
implements the following functions:
The "ieee1394_list" function will list all of the available
printer devices on the bus. The device information will
consist of the device URI (ieee1394:/something) used to
access the device and the make and model information, if
available, for the device ("EPSON Stylus Printer").
The "ieee1394_open" and "ieee1394_close" functions will open
and close a connection to the printer, respectively.
The "ieee1394_read" and "ieee1394_write" functions will read
and write data to and from the printer, respectively. The
read function will be non-blocking, returning data only if
there is data coming back from the printer.
The "ieee1394_error" function will return a string
describing the last error or NULL if no error occurred.
The library will be responsible for creating any background
threads that are needed to monitor the connection to the
The CUPS backend will use the OS abstraction layer to list
and access the Firewire printers. The "main" function will
read and write printer data, while the "list_devices"
function will be called as necessary to identify the
The CUPS 1.1 backend will record any status information in
the error log file, while the 1.2 backend will supply it to
the printer driver process.