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

Quoted 5 lines · Till Kamppeter

First, I want to make a feature request to the kernel to add it. Second, I want to suggest this as a Google Summer of Code project, asking for mentors on the kernel side. Mentoring Organization will be the Linux Foundation, hosting projects for both OpenPrinting and the kernel.

It certainly sounds like a worthy thing, but wasn't the deadline for GSoC last Friday? I know both Subsurface and X.org did that, and got accepted early this week.

Hi,

a new standard not yet supported under Linux but starting to penetrate the market is IPP-over-USB (Internet Printing Protocol over USB).
...
Fortunately, the PWG has added a standard to make it also go into USB printers, IPP-over-USB. Problem is that there is no Linux support for that.

First, I want to make a feature request to the kernel to add it.

Second,
I want to suggest this as a Google Summer of Code project, asking for mentors on the kernel side. Mentoring Organization will be the Linux Foundation, hosting projects for both OpenPrinting and the kernel.

It should not be too complex. Probably one can start on the driver for USB Ethernet or WLAN sticks, as they are also USB devices which introduce a network interface to the system. What one has to do is to create a driver for another, probably similar device, the IPP-over-USB printer. The driver should not be specific to the printer model (it is an open standard protocol) and it also should provide a network interface to the system under which there is only found the printer. The printer should be accessible under this interface via port 80 (web interface), 631 (IPP), and 443 (encrypted).

Till,

Some comments inline...

Quoted 7 lines · Till Kamppeter

Hi,

a new standard not yet supported under Linux but starting to penetrate the market is IPP-over-USB (Internet Printing Protocol over USB).
...
Fortunately, the PWG has added a standard to make it also go into USB printers, IPP-over-USB. Problem is that there is no Linux support for that.

Actually, it was the USB Implementers Forum (USB-IF) that defined and published the IPP USB specification, not the PWG.

Quoted 1 line

First, I want to make a feature request to the kernel to add it.

I don't think the kernel is the right place for this. IPP USB isn't like IP-over-USB, and you'll want the interface to provide arbitration and multiplexing of HTTP requests over the available IPP USB interfaces.

Quoted 4 lines

Second,
I want to suggest this as a Google Summer of Code project, asking for mentors on the kernel side. Mentoring Organization will be the Linux Foundation, hosting projects for both OpenPrinting and the kernel.

This will make an excellent SoC project, but you'll need someone familiar with Avahi, libusb, HTTP, systemd, and general networking for this. This isn't a kernel project.

...
So you want to do this as a userspace library talking directly to the USB device through usbfs/libusb? Or should the kernel provide a basic "pipe-like" functionality to the hardware to make it easier for things to be queued up to the device?

Is there a pointer to the spec somewhere so that I can see what is needed here?

Quoted 8 lines

Quoted 4 lines

Second,
I want to suggest this as a Google Summer of Code project, asking for mentors on the kernel side. Mentoring Organization will be the Linux Foundation, hosting projects for both OpenPrinting and the kernel.

This will make an excellent SoC project, but you'll need someone familiar with Avahi, libusb, HTTP, systemd, and general networking for this. This isn't a kernel project.

That's a non-trivial set of experience to try to find, good luck :)

And why systemd? What is needed from it for this?

Greg,

Quoted 5 lines · Greg KH

...
So you want to do this as a userspace library talking directly to the USB device through usbfs/libusb? Or should the kernel provide a basic "pipe-like" functionality to the hardware to make it easier for things to be queued up to the device?

libusb is enough.

Quoted 2 lines

Is there a pointer to the spec somewhere so that I can see what is needed here?

http://www.usb.org/developers/devclass_docs

Quoted 10 lines

Quoted 8 lines

Quoted 4 lines

Second,
I want to suggest this as a Google Summer of Code project, asking for mentors on the kernel side. Mentoring Organization will be the Linux Foundation, hosting projects for both OpenPrinting and the kernel.

This will make an excellent SoC project, but you'll need someone familiar with Avahi, libusb, HTTP, systemd, and general networking for this. This isn't a kernel project.

That's a non-trivial set of experience to try to find, good luck :)

Agreed.

Quoted 1 line

And why systemd? What is needed from it for this?

Just for the launch-on-demand functionality. Not absolutely required, but it helps to minimize the overall "weight" of the OS when you aren't printing constantly...

_________________________________________________________
Michael Sweet, Senior Printing System Engineer, PWG Chair

Greg,

Quoted 5 lines · Greg KH

...
So you want to do this as a userspace library talking directly to the USB device through usbfs/libusb? Or should the kernel provide a basic "pipe-like" functionality to the hardware to make it easier for things to be queued up to the device?

libusb is enough.

Quoted 2 lines

Is there a pointer to the spec somewhere so that I can see what is needed here?

http://www.usb.org/developers/devclass_docs

Quoted 9 lines · Michael Sweet

Greg,

Quoted 5 lines · Greg KH

...
So you want to do this as a userspace library talking directly to the USB device through usbfs/libusb? Or should the kernel provide a basic "pipe-like" functionality to the hardware to make it easier for things to be queued up to the device?

Quoted 6 lines

libusb is enough.

Quoted 2 lines

Is there a pointer to the spec somewhere so that I can see what is needed here?

http://www.usb.org/developers/devclass_docs

In reading the spec, it looks like some kernel code will have to be written, as the default configuration for the printer device will cause the usblp driver to bind to the device. Are you thinking that libusb will just unbind the printer driver and take over from there? Why not just use the kernel driver to expose another device node and have cups talk to that?

thanks,

greg k-h

Greg,

We already unload the usblp driver - it isn't compatible with most of the multifunction printers out there today...

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".

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.

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?

2) Section 3.2 "Interface Set" paragraph 2 states that "All IPP USB capable 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)?

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?

Carlos,

On Feb 26, 2014, at 9:33 PM, Carlos Rimola <[email protected]> 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,

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 <[email protected]> wrote:
Carlos,

Quoted 8 lines · Carlos Rimola

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.

Quoted 6 lines

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...)

Quoted 3 lines

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.

Quoted 5 lines

2) Section 3.2 "Interface Set" paragraph 2 states that "All IPP USB capable 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.

Quoted 2 lines

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

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 <[email protected]> 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

Quoted 94 lines · Michael Sweet

Carlos,

On Feb 26, 2014, at 9:33 PM, Carlos Rimola <[email protected]> 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...

Quoted 4 lines

_________________________________________________________
Michael Sweet, Senior Printing System Engineer, PWG Chair

_________________________________________________________
Michael Sweet, Senior Printing System Engineer, PWG Chair

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?

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

all non-Windows operating systems). IPP network printers have a lot of advantages compared to USB printers (letting the ability of several computers on a network being able to access them aside):

- Encrypted job transfer