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I like Bob's analysis. I think the Semantic Model will be most useful taking this approach. ---------------------------------------------- Harry Lewis IBM Printing Systems ---------------------------------------------- <table width=100%> <tr valign=top> <td> <td>"TAYLOR,BOB (HP-Vancouver,ex1)" <robert_b_taylor@hp.com> Sent by: owner-ps@pwg.org 07/16/2002 09:13 PM <td>                To:        Norbert Schade <norbertschade@attbi.com>, Print Services group <ps@pwg.org>         cc:        UPD group <upd@pwg.org>         Subject:        RE: PS> Semantic model: media handling        </table> Hi Norbert, all,   One of the things we (HP) have been suggesting for the semantic model is the separation of the raw "attribute/element" definitions from the structures/model that pull them together for a particular use.  As you not, UPDF has done this structuring in a different way than IPP - which is also somewhat different than UPnP & PSI, etc.  I'm not sure we want to try codify any one structure as part of the core semantic model - these will tend to vary by market segment and domain, and I'm not sure we can do this one-size-fits-all.  What we would like to see, though, is common definition of the core "attributes/elements" - this seems much more reusable across models & domains.  It does make sense, though, to publish some of the "common models" as at least examples of structural models - IPP, UPDF, etc. are likely candidates for this.  This exposes some of useful constructs (such as the composite feature you describe below) for reuse.   thanks,   bt   --------------------------------------------------- Bob Taylor                                       Senior Architect                           IPG Strategic Technology Development Hewlett-Packard Co.       <a href=mailto:robertt@vcd.hp.com>mailto:robertt@vcd.hp.com</a>                       phone: 360.212.2625/T212.2625                   fax: 208.730-5111                 ---------------------------------------------------   -----Original Message----- From: Norbert Schade [mailto:norbertschade@attbi.com] Sent: Monday, July 08, 2002 7:32 AM To: Print Services group Cc: UPD group Subject: PS> Semantic model: media handling I have problems to follow two different ways to specify media handling and UPDF would have problems to support that. I'm fine with the specification of single media attributes like size, type, etc. I agree that there should exist a media instance a level higher, which is a media element with a number of media attributes. The number of attributes can vary. In one sample it may be just size and type, in another it may be something like the IPP media collection.   My point is that the attributes a media is described by may vary. There should not be a predefined media collection in a common Semantic Model representing one implementation.   Feel free to check the composite feature definition we have in UPDF. Open the UPDF.xsd schema to do this and follow the path down to PrintCapabilities.Features. The current sample description xml of an imaginary LJ9000 has a 'Media' composite feature.  We can compose any number of features to a new feature, be it Media, Quality or anything else. This is a very flexible structure and is expected to be used frequently. We got very positive feedback once we finished it last year.   We'd appreciate if  the Semantic Model does something down that path. Otherwise the spec is ambiguous.     Another statement: We've seen the current schema of the Semantic Model. We know there are a number of ways to write schemas. The UPDF group made the experience that working with attributes instead of assigning text to elements directly has advantages. Validation is easier and we can define constraints (these are really constraints and not dependencies) for attributes. You may think that over.   Regards   Norbert Schade 69 Prescott Drive North Chelmsford, MA 01863 978-251-1017 <a href=mailto:norbertschade@attbi.com>norbertschade@attbi.com</a>