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

[Carlos Rimola]

Hello All,

I have a couple of "simple" follow-up questions on IPP USB (IPP-over-USB)
"Host device" support:

Is IPP USB designed to support connecting and printing from a device like a
tablet or smartphone (e.g., iPad, iPhone, Etc.) directly connected to a
printer over USB? If the answer is yes - is there any device that currently
supports this? I imagine a special cable or converter would be needed?

Or is IPP USB designed only for Hosts like Linux or Mac acting as print
servers/gateways for these, and other, devices?

Thanks,

Carlos


On Thu, Feb 27, 2014 at 11:29 AM, Michael Sweet <msweet at apple.com> wrote:

> Carlos,
>
> Any Mac running OS X 10.9 supports IPP USB; note that we have a bunch of
> pending bug fixes (sorry, can't say when the fixes will be released...)
> that address issues found in testing with multiple vendors' implementations
> of IPP USB, but the current 10.9.2 will work with all of the HP printers
> mentioned below.
>
>
> On Feb 27, 2014, at 2:23 PM, Carlos Rimola <crimola at gmail.com> wrote:
>
> 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
>>
>>
>
> _________________________________________________________
> Michael Sweet, Senior Printing System Engineer, PWG Chair
>
>
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