[Printing-architecture] Google Summer of Code 2014 - IPP-over-USB printer support - Joint project idea for OpenPrinting and the kernel

[Carlos Rimola]

Michael,

Thanks for the comprehensive response to my questions on IPP USB and
confirming my assumptions.

The only remaining question I have for the list at this time is - are there
any Hosts, including model, OS and OS version (or other S/W requirements),
presently available on the market (or otherwise) which support IPP USB as
per the Specification?

Thanks again,

Carlos Rimola


On Thu, Feb 27, 2014 at 7:37 AM, Michael Sweet <msweet at apple.com> wrote:

> Carlos,
>
> On Feb 26, 2014, at 9:33 PM, Carlos Rimola <crimola at gmail.com> wrote:
>
> Hi All,
>
> I have some quick and general questions regarding IPP over USB ("IPP USB"
> for short). Some are related to Till's proposed project "Google Summer of
> Code 2014 - IPP-over-USB printer support". Any help and feedback will be
> greatly welcomed. I should mention that I am in favor of the proposed
> project for this event.
>
> Assumptions (please confirm or correct):
>
> 1) This first one may be obvious but to be sure - I am assuming that we
> are referring to IPP USB as defined in the "USB Print Interface Class IPP
> Protocol Specification Revision 1.0" dated 12/5/2012 and published by
> USB-IF and authored by HP's Smith Kennedy and Andrew R. Mitchell. I'll
> refer to it as the "IPP USB Spec".
>
> Correct.
>
> 2) As I understand the IPP USB Spec, there is NO network interface, NOR
> TCP/IP involved. The Communication Protocol to be used between Host and
> Device (Printer) is *purely HTTP + IPP directly over USB*. A place where
> this is noted is section 6.2 - "HTTP Headers" which states the following:
>
> *Since there is NO network interface connection, NO DNS hostnames or IP
> addresses, and NO TCP port numbers associated with USB connection, the
> requirements of the HTTP Host field is addressed by requiring that the
> value of this header MUST be "localhost".*
>
> Please correct me if I am wrong on either of these assumptions.
>
>
> Correct (a port number can be passed by the "client" over USB to allow
> gateways/proxies to work...)
>
> Questions:
>
> 1) I know the Spec is already cast in stone but I would like to understand
> what function HTTP serves and if it is only used for identifying "Host:
> localhost" and the "/ipp/printer" path? In other words, could pure IPP
> Requests/Responses and IPP expected format "Print Data" have sufficed?
>
> While you might get away with that for simple IPP messages, that wouldn't
> work for document data since IPP by itself has no framing or other niceties
> - you'd never know when the data ended.
>
> Also, the HTTP portion is used for the embedded web server, doing firmware
> updates, and so forth.
>
>  2) Section 3.2 "Interface Set" paragraph 2 states that "All IPP USBcapable
> Print class interfaces provided by a device MUST be functionally equal
> from an IPP operation or HTTP perspective.  In other words, any IPP
> operation or resource path that is valid over one IPP USB interface MUST
> be reachable via any and all of the IPP USB interfaces."
>
> Does this imply that, for example, a Request from the host can be sent
> over one interface (I/F #1) and the response received over a different
> interface (e.g., I/F #2)?
>
> No, each interface is an independent channel to the printer.
>
> The reason for this requirement is to prevent having an IPP USB endpoint
> just for printing, and another just for scanning, and so forth.
>  Effectively IPP USB defines an interface protocol that allows arbitrary
> HTTP and IPP requests to be performed.
>
> 3) The last question is much simpler but would be helpful to an
> implementor - what specific printers (manufacturer, line and model) *on
> the market* support IPP USB? I have seen references to HP Photosmart and
> OfficeJet but no model given. Similarly, what Host(s) on the market,
> including OS and version, support the IPP USB protocol with these Printers?
>
> Here is the latest list we have from HP:
>
>     Deskjet 3520
>     Envy 120
>     Envy 4500
>     Envy 5530
>     Officejet 3620
>     Officejet 4630
>     Officejet 7610
>     Officejet Pro 276 MFP
>     Officejet Pro X576 dw
>     Photosmart 5520
>     Photosmart 6520
>     Photosmart 7520
>
> I know of four other manufacturers that either have shipping products or
> will soon be shipping - will post here when I can do so publicly...
>
> _________________________________________________________
> Michael Sweet, Senior Printing System Engineer, PWG Chair
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20140227/f914bdf8/attachment-0001.html