Cart
|
[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Re: Where does the "nothing left but toolkits" myth come f
 > Can you elaborate a bit more about this? What are the problems > that you are referring to? Also, I dont understand how PI's can reduce > portability. It seems to me that PI's are intended to achieve the > opposite effect : if additional knowledge (than is visible to a basic > XML processor) is visible to an XML application specific processor, > then the PI serves as a signal to activate the application level > processor. This doesnt change any the semantics of the data w.r.t. > non-application specific data. One of the fundamental problems that I see with XSD is that it is, at its root, a type definition language, at least as I've come to understand it. Now for many applications, this CAN be a very good thing - web services being an obvious example - but in other cases, such as in the case of documents, type is very much a secondary consideration and can even end up proving to be a limiting factor in terms of what kinds of documents can be created. DTDs of course lacked all sense of type, and as a general purpose language doesn't work in the data-centric world, but the task of creating sufficiently open-ended XML in the document-centric world shows that perhaps one can have too much of a good thing. I personally prefer Relax-NG in this respect - it considers type itself to be simply another definable property, with no intrinsic semantics associated with that type, and sees type definition consequently as an application level property. Of course, your mileage may vary. As Michael Champion wrote superbly well in a follow-up to this, PIs have a tendency to step on one another in the presence of multiple applications that use the same XML. I think they also impose a non-XML semantic that can interfere with applications - consider the simple case of an XML document being processed that also has an <?xml-stylesheet?> PI - does the processing occur before the stylesheet is applied, after it, or is it ignored altogether in that context? PIs essentially induce application specific logic that could render the document in many different ways depending upon the degree to which the parser recognizes the PIs at all. I don't think you can get rid of PIs completely, but if you strongly discourage their use in all but a very limited number of circumstances, you generally end up with happier programs and happier programmers. -- Kurt Cagle 
|
PURCHASE STYLUS STUDIO ONLINE TODAY!Purchasing Stylus Studio from our online shop is Easy, Secure and Value Priced! 
Download The World's Best XML IDE!Accelerate XML development with our award-winning XML IDE - Download a free trial today! Subscribe in XML format
|
|||||||||
