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<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">[Changed subject to reflect what we are talking about...]<div class=""><br class=""><br class=""><blockquote type="cite" class="">On Mar 2, 2020, at 4:16 PM, Rizzo, Christopher <<a href="mailto:Christopher.Rizzo@xerox.com" class="">Christopher.Rizzo@xerox.com</a>> wrote:<br class=""><br class="">How do you feel about adding the following (first sentence) to your section 4.2 proposal?<br class=""></blockquote><div class=""><br class=""></div>I *really* don't want to add this to the beginning of the section. First, that isn't the usual format we use in PWG documents, and second we should focus on what *this* specification requires, *not* what a vendor (Apple) required in their own "standard".</div><div class=""><br class=""></div><div class="">Let's keep working on this:</div><div class=""><br class=""></div><blockquote style="margin: 0 0 0 40px; border: none; padding: 0px;" class=""><div class="">4.2 DNS Service Discovery (DNS-SD)</div><div class=""><br class=""></div><div class="">DNS Service Discovery (DNS-SD) [RFC6762] uses service (SRV) records and traditional unicast and multicast DNS (mDNS) [RFC6763] queries. <font color="#ff13ff" class="">Services are identified by a service instance name consisting of a service name, type or sub-type, and domain name.</font> Discovery of Printers is collectively defined in the Bonjour Printing Specification version 1.2.1 [BONJOUR] and extended in this specification.</div><div class=""><br class=""></div><div class="">Printers that support DNS-SD MUST support mDNS and MAY support dynamic DNS updates via Dynamic Updates in the Domain Name System (DNS UPDATE) [RFC2136] and other mechanisms.</div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><font color="#ff13ff" class="">4.2.1 History of Printer Discovery with DNS-SD</font></div><div class=""><font color="#ff13ff" class=""><br class=""></font></div><div class=""><font color="#ff13ff" class="">The Bonjour Printing Specification defines a discovery mechanism for three different printing protocols which are mapped to DNS-SD service types: "_ipp._tcp" for any version of IPP, "_pdl-datastream._tcp" for direct socket communications, and "_printer._tcp" for the Line Printer Daemon (LPD) [RFC1179] protocol. For historical reasons, the primary ("flagship") protocol used for DNS-SD Printer discovery is LPD regardless of whether the Printer actually supports LPD.</font></div><div class=""><font color="#ff13ff" class=""><br class=""></font></div><div class=""><font color="#ff13ff" class="">DNS-SD makes use of service "sub-types" to identify specific types of services, and the Bonjour Printing Specification also defines a well-known "_printer._sub._http._tcp" service sub-type for a Printer's embedded web server to differentiate a Printer web page from a regular web page.</font></div><div class=""><font color="#ff13ff" class=""><br class=""></font></div><div class=""><font color="#ff13ff" class=""><br class=""></font></div><div class=""><font color="#ff13ff" class="">4.2.2 IPP Everywhere™ Service Sub-Types</font></div><div class=""><font color="#ff13ff" class=""><br class=""></font></div><div class=""><font color="#ff13ff" class="">In order for a Client to discover IPP Printers that conform to this specification (and not just [STD92]), the following DNS-SD service sub-types are defined:</font></div><div class=""><font color="#ff13ff" class=""><br class=""></font></div><div class=""><ul class="MailOutline"><li class=""><font color="#ff13ff" class="">"_print._sub._ipp._tcp" for IPP Everywhere™ Printers using the "ipp" URI scheme [RFC3510]; and</font></li><li class=""><font color="#ff13ff" class="">"_print._sub._ipps._tcp" for IPP Everywhere™ Printers using the "ipps" URI scheme [RFC7472].</font></li></ul></div><div class=""><font color="#ff13ff" class=""><br class=""></font></div><div class=""><font color="#ff13ff" class=""><br class=""></font></div><div class="">4.2.<font color="#ff91ff" class="">3</font> Service (SRV) Instance Name</div><div class=""><br class=""></div><div class="">Printers MUST NOT use a service instance name containing a unique identifier by default. A unique identifier MAY be added to the instance if there is a name collision.</div><div class=""><br class=""></div><div class=""><font color="#00ff00" class="">The domain portion of the service instance name MUST BE "local." for mDNS.</font></div><div class=""><br class=""></div><div class="">Printers that support DNS-SD MUST advertise the "_ipp._tcp" (generic IPP) and "_print._sub._ipp._tcp" (IPP Everywhere™) services over mDNS.<font color="#ff13ff" class=""> For example, a Printer named "Example Printer" would have the service instance names "Example Printer._ipp._tcp.local." and "Example Printer._print._sub._ipp._tcp.local.".</font></div><div class=""><br class=""></div><div class="">Printers that support DNS-SD and the "ipps" URI scheme [RFC7472] MUST advertise the "_ipps._tcp" (generic IPPS) and "_print._sub._ipps._tcp" (IPP Everywhere™ Secure) services over mDNS.<span style="caret-color: rgb(255, 23, 255); color: rgb(255, 23, 255);" class=""> For example, a Printer named "Example Printer" would have the service instance names "Example Printer._ipps._tcp.local." and "Example Printer._print._sub._ipps._tcp.local.".</span></div><div class=""><br class=""></div></blockquote><div class=""><blockquote type="cite" class="">Note: The IPP Everywhere required "_print._sub._ipp._tcp" and "_print._sub._ipps._tcp" advertisements, which are used to distinguish between legacy IPP and IPP Everywhere support, should not be confused with "_printer._tcp" and "_printer._sub._http._tcp" advertisements referenced in [BONJOUR]. The first version of the Bonjour Printing Specification was published by Apple shortly after the Internet Printing Protocol was published by the IETF. As the Line Printer Daemon Protocol [RFC1179] was considered the most popular network printing protocol at the time, the "_printer._tcp" DNS-SD service type (LPD) was assigned as the "flagship" protocol for DNS-SD advertisements. Similarly, the HTTP service registration for the embedded web server uses the "_printer._sub._http._tcp" service type, even for IPP Printers.<br class=""></blockquote><br class=""><div class="">________________________<br class="">Michael Sweet<br class=""><br class=""><br class=""></div><br class=""></div></body></html>