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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: [SUMMARY #1] Why is there little usage of XML on the 'v
 Didier PH Martin said: > Hello Peter, > > Here are, to my knowledge the different strategies I found during my > experiment in Didier's labs. > > a) Increase the adaptive power of information units with declarative > code. > Units can be reused and combined. In fact, part of the main problem with XML is that cannot combine previous information units. Take like examples the original grocery example either you chose a XML way <grocery-list> or a HTML <ul> to markup; therefore you obtain or an accurate markup is not understood online (the visible web) or a generic markup with losing of information. Browsers developers cannot implement basically the same stuff again and again for the 600 different markup language based in XML known, more the new stuff is becoming from the non-XML word such as next HTML5. The idea is that if <ul> is already here, reuse it! instead duplicating it from zero with <grocery-list>. Reusing is one of the reasons i invented (at my best current knowledge nobody did before) the concept of multimarkup. The idea is that i can complement <ul> with <grocery> generating a composed tag <<ul><grocery>>. In that case only the grocery part may be implemented whereas reusing the <ul> already available. Of course, <<ul><grocery>> cannot be done in XML because its hierachic-oriented markup, but i can be done in alternative approaches For instance in CanonML. [::ul content-here] [::ul::grocery content-here] Of course, you can define your own tag if desire (e.g. ::grocery-list) but its semantics would be based in already available one, i.e. ::grocery-list ==> ::ul::grocery Moreover, if by some reason the ::grocery tag is not implemented in your browser it would be ignored but still the browser could access to the ul part and understand at least part of your datument. With XML either your software understand <grocery-list> or not. It is a kind of binary. Yes XML has no concept of multimarkup, but XML people would search a way to _simulate_ this so much as posible since i think it will become a fundamental feature when markup languages explosion (i believe that current 600 XML languages are just the begining). > b) Think of browsers as interpreters able to interpret declarative > languages (HTML) and imperative languages (javascript). > > If we focus too much on the information unit and its incarnated > document, we may forget that once loaded into a browser they are > interpreted into different object. For example, HTML elements are > translated into visual objects. A <div> or a <p> is translated into a > block area. Therefore when loaded into a browser they are no longer a > <div> or a <p> but more a block area with all its implicit or explicit > rules and behaviours. I do not understand you. Yes visually both <p> and <div> are not differentiable (unless specific styles), but the DOM tree is able to differentiate both. You can in source-view that both are retained when the page loaded. > Practical strategies I used in browsers: > > I use a lot XML and XSLT because I came to master what "model driven" > development means. I create a data model encoded into XML then transform > it into a visual model using one of the rendering languages I get on > hand (HTML, VML, SVG, SMIL, etc...) Yes, but one is forced to use the available constructs and cannot be combined and extended. By combined i do not mean a mized datument with XHTML as host language and MathML and SVH islands in different namespaces but i explained above with multimarkup and reuse. By extension i mean that one of ironies of the eXtensible language per excellence today (XML) is being it does not adressed the extensibility at the client side, only at the author side. I can extend SVH or HTML inventing new tags but none browser will understand them. I do not think that was a problem of the browser community, i think it is one of main design errors of XML. > I tend to see XSLT templates as constructors. For example, An RDF or > PDML documents are translated into the same visual structure incarnated > by a hierarchy of <div> to build a treeView. This way I can RE-USE the > same javascript behaviours. I like more a XSLT-JS-like approach rather than a Java-plugin or a X3D-like (semantic layers over a basic 3D XML host language) approach. Both the Java-plugin and the X3D-like approach may be suitable for addition of small extensions or semantic layers) over a common basis. In fact i think that main interest of the CML comunity (I wait prof. Murray-Rust can correct me if wrong) is in adding the need funcionality/extensions for the processing of CML units encoded on a host language, probably XHTML based. > You can notice though that all strategies need the help of javascript > code to set the proper environment. I soon discovered that relying > solely to declarative code and its related meaning for different browser > is doomed to failure. We need a buffer between the environment > variations, this is like mitigating risk. Most information unit > publishers are publishing at risk. Like in the finance world we probably > need an index of the publication at risk. If we rely too much on browser > developers for that, is like being dependent on big brother to make a > good living. Therefore, actually, for everything out of the browser box > and therefore everything outside of the basic HTML interpretation, we > need to provide some adaptation code because outside of the HTML box, > the information unit is at risk of not being well interpreted. Try to > explain to your dog the string theory (I would not even try with my > neighbour :-) So why do we think that the browser would interpret > properly any out of the box language. Just to recall, for browsers at > large anything outside of HTML is something out of the box. Interesting! Do you mean some kind of automatic quality-check of the client browser or what? Someting like the common bottom line in many sites: this site is better display with ... you need JS enabled ... but in the heading of the doc. > Didier PH Martin > http://didier-martin.com Juan R. Center for CANONICAL |SCIENCE) 
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