[XSL-LIST Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: inconsistencies between XSL and XLL
Hi Paul, You said: I hear you discussing information from the XML Linking Language (XLink) WD [1] and Associating stylesheets with XML documents PR [2]. While your observation may be a reasonable one to raise, I don't see that this has anything to do with XSL (as implied by the subject of this message and the mailing list to which you sent it). Am I missing something? paul [1] http://www.w3.org/TR/WD-xlink [2] http://www.w3.org/TR/PR-xml-stylesheet Reply: Here is the issue: I am making a proposal to colleagues (this mailing list participant and that includes W3). That the "media" property is to be used to specify the output format. For example, a XSL engine could be used as a transformation engine to transform XML into OpenGL or an other XML document into RTF, Tex, etc... Of course several way could be used to accomplish this goal. But I restrict my intervention on the xml-stylesheet processing instruction. So, if I include a processing instruction like this: <?xml-stylesheet href="myscript.xsl" type="text/xsl" media="screen, HTML?> <?xml-stylesheet href="myscript.xsl" type="text/xsl" media="print, Tex"?> I indicate to the rendering engine that this style sheet requires an output with the same quality level as HTML model or Tex model. If the current rendering engine do not support such formats, it should degrade to something it can do. If no "media" property is specified, the document is rendered by the default rendering engine with a certain premises like for instance that the media is set by default to "screen" and that the rendering model is what behind HTML and not yet defined by W3. It is implicitly there behind HTML and CSS specs but not explicitly defined. Under certain circumstances, a document may require a certain kind of environment like CAD rendering (high drawing precision, scale, solid modeling, etc...) in that case, the media property becomes necessary to specify that we need a certain format. One day we may have a consortium that will decide what CAD format is politically correct but until then, we have to deal with that. So, until then, a document may include that this XML should be rendered with a de-facto standard (mean here a majority of people are using it) to render the document. This could be for example DXF which implies a certain model. Not the format per se, but the model behind this format (scale definition, naming convention, object relationship, constraints, etc...). Any DXF compliant engine may do the job (DXF is an open format that any can implement). I am not here to judge if the fact that DXF format is there this gives a certain monopoly advantage to AutoDesk. Because we may also come to the same arguments after a certain time about an institution and its possible corruption (just look at the Olympic committee and they are not alone as you know). So, because people call a certain rendering model DXF, a XML document may contain the media property to specify that rendering is to be done with the DXF Quality of service or implicitly following the DXF model. That until a group decide that this no longer called DXF but something else (the real model name). When all rendering models will be specified, we won't have to give format names like DXF or Tex or whatever, but until then, we can use these names. Also, we already have this kind of model with plug-ins. Plug-ins are here because of rendering limits of actual W3 specs (of course it takes time to build a complete world - it is not an easy task). Also, if we do not allow provision for innovation we will go back to middle ages. So plug-ins provide either adaptation to the legacy or ways to integrate new formats. This is what the "media" property can do for XML. But we may agree on a convention and not let a single manufacturer being AOL, SUN or Microsoft decide for us. Thus, The proposal is: a Stylesheet processing instruction may or may not contain a media property. By default, the media property is set to "screen, Default" this means that the document renderer display the document on the screen and with its default rendering model - to be defined by W3 specs and well specified yet - this is a work in progress. Thus, if no media property is present, the default values are used. A browser having no expansion capabilities can ignore the media property and render with the default value. if it does. The media property can specify the output device (print, screen etc...) and the rendering model. The rendering model could be expressed by a format like DXF and thus be implicit or explitly mentionned by a general term like "3D" Where the 3D model is defined somewhere (space model, texture maps models etc...). This means that a certain decoupling between the style sheet engine and the rendering model may exist (i.e the style engine generate rendering instructions instead of writing directly on the screen and thus provide a better engineered solution). This do not imply that the rendering engine is provided by a single vendor. Like for DXF plug-ins, Autodesk is not the sole player. Of course, an intelligent document renderer can know what a DXF model is and render with the same quality, or find a good approximation. So then, I can imagine a XSL engine that could render in 3D or have the XSL engine understand some macros specific to 3D. This until W3 or whatever we will have in the future, has a good rendering model for that. So Paul the issue is not about Xlink but about rendering something not very well grounded yet in the specs and surely not tested in the marketplace. Regards. Didier PH Martin mailto:martind@xxxxxxxxxxxxx http://www.netfolder.com XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list
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