[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: Logical models, hierarchy, network model
Hi Ken, Thanks for the links, this is very useful information. I followed this thread with a lot of interest. Recently I had to work on new data structures to store objects. After a lot of discussion with different groups it appeared that what developers like about the relational model is the capacity to merge or "blend" data from different sources (i.e. tables, fields). What is appealing in object database is the capacity to link objects or create associations between objects. The problem is that today you only get one or the other. It seems that the ideal storage would be one that allows creating new objects by "blending" other objects and still allowing links or association to other objects. Some people proposed using a subject based approach but very few concrete proposals are on the table form the academic community. In a nutshell the ideal storage system would be as versatile as relational databases to "blend" or merge data and create new ones. In fact, a table can be perceived as a frame (a method-less object). Hence, relational databases allow creating new frames from existing ones. It would also allow creating associations between objects and let us type the links, for instance to allow the creation of standard associations like composition, aggregation, inheritance and new non standard ones. I personally find XML a very good representation language but not very efficient as a permanent storage mechanism. Using XML I found XSLT or XQuery very useful to blend new representations for existing ones. Xlink has been quite good to provide an inheritance mechanism. The more I play with it, the more I find Xlink inheritance mechanism of great value. For example, I can write an Xlink processor able to process any king of documents having elements inheriting the xlink characteristics. It is easier to create a separation of concern when processing data representations. In fact, I was able to re-create the composite pattern using xlink inheritance (or architectural form for SGMLers). I used xlink:role to "type" the kind of link, for example, an aggregate reference would be an xlink:role="aggregator". It's unfortunate that the community wasn't able to recognize the full potential of xlink and in general the inheritance mechanism proposed by such tool. Cheers Didier PH Martin
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