attachment-0002
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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Mike,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I think the figure in RFC 2911, page 10 needs to be viewed in conjunction with the figure in section 2.1, which deals with the relation of IPP to the Printer Object and the output device. This second diagram makes clear that the Client to Printer interface is IPP, but that the Printer to Output device interface is ‘any’, possibly-- IPP. This could be taken in support of your statement that the “</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Service <-> Output Device interface has never been defined.”</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> Unfortunately, the diagram does not show an IPP interface in an IPP Printer to IPP Printer (or Print Server to Print Service) communication, although it is alluded to in the text in terms of a client function added to the print server.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Your contention that an IPP Printer could have a thin connection to an output device, and perhaps even that that connection could use IPP, may be supported in RFC 2911. I agree that an output device could exist without an embedded IPP Printer. But I still have difficulty with the notion that software in a device that accepts and responds to IPP operations is something other than an IPP Printer or that, from a Semantic Model viewpoint, an MFD or Print Device which accepts and responds to the SM-defined print service operations from a Client function does not embed a Print Service. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>We can avoid the question in the Cloud Printing Model by noting that we wish to use the semantic model elements in the User Client to Cloud Server interface because it is a well established interface that has proven effective. We would also like to use this interface in the Cloud Print Server to end destination interface. However, for various reasons, the Cloud Print Server may not be able to access to the destination device. Therefore, we define a set of operations which a function at the destination can initiate to effect the same information communication that the Cloud Print Server would if it were able. We name this function the Cloud Print Manager.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>That is, by concentrating on enabling the communication, either in general terms for the semantic model or specifically for IPP, and the fact that in Cloud Printing (and possibly in other circumstances) there are factors that interfere with what may be called a forward communication path, we can address a solution to the communication problem and avoid the point of contention. Actually, we may consider that we are defining a ‘reverse’ interface that could be used in any case where IPP (or more generally, SM compatible) communication cannot be initiated by a User Client (or equivalent) function. This alternate interface could be used, conceivably when a Print Service is behind a firewall with respect to a User Client, without the need for postulating any Cloud Print Server (although there would have to be some way of alerting the Print Service Client to start communication),<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Thanks,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Bill Wagner <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Michael Sweet [<a href="mailto:msweet@apple.com">mailto:msweet@apple.com</a>] <br><b>Sent:</b> Monday, April 01, 2013 2:18 PM<br><b>To:</b> William A Wagner<br><b>Cc:</b> <a href="mailto:cloud@pwg.org">cloud@pwg.org</a><br><b>Subject:</b> Re: [Cloud] Cloud Print Manager Operations<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Bill,<o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal>On 2013-04-01, at 1:21 PM, William A Wagner <<a href="mailto:wamwagner@comcast.net">wamwagner@comcast.net</a>> wrote:<o:p></o:p></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><div><p class=MsoNormal><span style='color:black'>...</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>But, as I indicated in my comments to the proposed introduction, I am uncomfortable with the notion of the semantic model defining an interface to an ‘Output Device’ which does not contain a Print Service.</span><o:p></o:p></p></div></div></blockquote><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>RFC 2911 has the following ASCII art diagram on page 10:<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><div><p class=MsoNormal> | --+<o:p></o:p></p></div><div><p class=MsoNormal> +--------+--------+ |<o:p></o:p></p></div><div><p class=MsoNormal> | IPP Server | |<o:p></o:p></p></div><div><p class=MsoNormal> +--------+--------+ |<o:p></o:p></p></div><div><p class=MsoNormal> | |<o:p></o:p></p></div><div><p class=MsoNormal> +-----------------+ | IPP Printer<o:p></o:p></p></div><div><p class=MsoNormal> | Print Service | |<o:p></o:p></p></div><div><p class=MsoNormal> +-----------------+ |<o:p></o:p></p></div><div><p class=MsoNormal> | --+<o:p></o:p></p></div><div><p class=MsoNormal> +-----------------+<o:p></o:p></p></div><div><p class=MsoNormal> | Output Device(s)|<o:p></o:p></p></div><div><p class=MsoNormal> +-----------------+<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal style='margin-bottom:12.0pt'>Basically, an IPP Printer is an IPP Server and Print Service that talks to one or more Output Devices. Contrast this with the two forms of the model described in section 4.2 of IPPSIX (I should probably include figures for this...):<o:p></o:p></p></div><div><p class=MsoNormal> IPP MANAGER AS THIN GATEWAY<o:p></o:p></p></div><div><p class=MsoNormal> ---------------------------<o:p></o:p></p></div><div><div><div><p class=MsoNormal><o:p> </o:p></p></div><div><div><p class=MsoNormal> | --+<o:p></o:p></p></div><div><p class=MsoNormal> +--------+--------+ |<o:p></o:p></p></div><div><p class=MsoNormal> | IPP Server | |<o:p></o:p></p></div><div><p class=MsoNormal> +--------+--------+ |<o:p></o:p></p></div><div><p class=MsoNormal> | |<o:p></o:p></p></div><div><p class=MsoNormal> +-----------------+ | IPP Infrastructure Printer<o:p></o:p></p></div><div><p class=MsoNormal> | Print Service | |<o:p></o:p></p></div><div><p class=MsoNormal> +-----------------+ |<o:p></o:p></p></div><div><p class=MsoNormal> | --+<o:p></o:p></p></div><div><p class=MsoNormal> |<o:p></o:p></p></div></div><div><div><div><p class=MsoNormal> ...<o:p></o:p></p></div><div><p class=MsoNormal> |<o:p></o:p></p></div><div><p class=MsoNormal> | --+<o:p></o:p></p></div><div><p class=MsoNormal> +------+------+ |<o:p></o:p></p></div><div><p class=MsoNormal> | IPP Client | | IPP Manager w/o Local Print Support<o:p></o:p></p></div><div><p class=MsoNormal> +------+------+ |<o:p></o:p></p></div><div><p class=MsoNormal> | --+<o:p></o:p></p></div><div><p class=MsoNormal> |<o:p></o:p></p></div><div><p class=MsoNormal> +---------+---------+<o:p></o:p></p></div><div><p class=MsoNormal> | Output Device(s) |<o:p></o:p></p></div><div><p class=MsoNormal> +-------------------+<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><div><p class=MsoNormal> IPP MANAGER AS FULL PRINT SERVICE<o:p></o:p></p></div><div><p class=MsoNormal> ---------------------------------<o:p></o:p></p></div><div><div><div><p class=MsoNormal><o:p> </o:p></p></div></div></div></div></div></div></div></div><div><div><p class=MsoNormal> | --+<o:p></o:p></p></div><div><p class=MsoNormal> +--------+--------+ |<o:p></o:p></p></div><div><p class=MsoNormal> | IPP Server | |<o:p></o:p></p></div><div><p class=MsoNormal> +--------+--------+ |<o:p></o:p></p></div><div><p class=MsoNormal> | |<o:p></o:p></p></div><div><p class=MsoNormal> +-----------------+ | IPP Infrastructure Printer<o:p></o:p></p></div><div><p class=MsoNormal> | Print Service | |<o:p></o:p></p></div><div><p class=MsoNormal> +-----------------+ |<o:p></o:p></p></div><div><p class=MsoNormal> | --+<o:p></o:p></p></div><div><p class=MsoNormal> |<o:p></o:p></p></div><div><p class=MsoNormal> | +-------------+<o:p></o:p></p></div><div><p class=MsoNormal> ... |Local Clients|<o:p></o:p></p></div><div><p class=MsoNormal> | +------+------+<o:p></o:p></p></div><div><p class=MsoNormal> | |<o:p></o:p></p></div><div><p class=MsoNormal> | | --+<o:p></o:p></p></div><div><p class=MsoNormal> +------+------+ +------+------+ |<o:p></o:p></p></div><div><p class=MsoNormal> | IPP Client | | IPP Server | |<o:p></o:p></p></div><div><p class=MsoNormal> +------+------+ +------+------+ |<o:p></o:p></p></div><div><p class=MsoNormal> | | | IPP Manager w/Local Print Support<o:p></o:p></p></div><div><p class=MsoNormal> +------+---------------+------+ |<o:p></o:p></p></div><div><p class=MsoNormal> | Print Service | |<o:p></o:p></p></div><div><p class=MsoNormal> +-------------+---------------+ |<o:p></o:p></p></div><div><p class=MsoNormal> | --+<o:p></o:p></p></div><div><p class=MsoNormal> +---------+---------+<o:p></o:p></p></div><div><p class=MsoNormal> | Output Device(s) |<o:p></o:p></p></div><div><p class=MsoNormal> +-------------------+<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div></div></div><div><p class=MsoNormal>The Manager is an IPP Client that acts as a gateway/proxy for getting jobs to the Output Device(s), and providing status and configuration back towards the client. It *may* also be an IPP Server to service local clients.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>By my understanding, the Semantic Model defines the interface between a Client function and a logical imaging Service. I would extend that to say that something that accepts that interface IS an imaging service. By saying that an Output Device (which I understand to represent a physical entity equivalent to a Print Device) does not contain a Print Service is contrary to the MFD Model spec definition (which, I admit, I wrote.)</span><o:p></o:p></p></div></div></blockquote><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Not necessarily, since the Service <-> Output Device interface has never been defined. One could argue that a thin gateway protocol between the Service and Output Device is 100% in agreement with the Semantic Model and IPP: an Output Device with a (thin) IPP Manager component and no local IPP Printer component need not have its own Semantic Model/IPP Print Service - it can use the IPP Infrastructure Printer/Cloud Print Service to provide that functionality, and this is no different from a local printer that is hosted by a PC or other print server.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Even by my understanding of RFC 2911 (which is less clear after 14 or so years), IPP deals with the interface between client software (including a client component within a print server) and an IPP Printer (which may or may not be contained in an Output Device. ) Granted, the RFC also indicated that IPP may or may not be used between an IPP Printer (a logical entity) and an Output Device (a physical entity, I think). But the software component in the Output Device is not named, and therefore suggests a confusing logical to hardware interface.</span><o:p></o:p></p></div></div></blockquote><div><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal>It actually suggests nothing since (at the time, and even today) the interfaces between Print Service and Output Device vary widely, i.e., "magic happens", and all we care about is the information transferred and operations performed.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Nothing in the current definition of the Cloud Print Manager/IPP Manager requires a local Print Service since the Manager's primary role is as a Client and not a Server. We've already defined the Server role...<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><div><p class=MsoNormal><span style='font-size:13.5pt;font-family:"Andale Mono","serif";color:black'>_________________________________________________________<br>Michael Sweet, Senior Printing System Engineer, PWG Chair<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p></div></div><br />--
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