[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Elements order:
Nicolas LEHUEN wrote: > What if we add an <age> element now ? Then a <gender> element ? The content > model will explode... > > The problem is that when serializing certain data structure, it is not > always easy to guarantee a particular element order. > > For example, if you serialize an hashtable by iterating over its cells, you > can't predict the key ordering because it depends on the hash code > algorithm, the size of the hashing array, etc. There are three scenarios that account for a very high percentage of circumstances - you generally have a degree of certainty about: a) the existence of the elements but not the order - a content model of (age | gender | name | surname)+ would be sufficient. b) the order of the elements but not the existence - a content model of (age?, gender?, name?, surname?) works fine. c) neither the order nor the existence - I'd be loathe to spend too much modeling this carefully. Time might be better spent analysing the data and trying to determine what the baseline is. This might involve a process that introduces order to the elements anyway. > This is all the more annoying that for structured data, it does not matter > that the <name> element precedes the <surname> or not. Agreed, and I acknowledge that the approaches above aren't ideal - I'm just not certain that this situation manifests as A Big Problem very often. -- Regards, Marcus Carr email: mrc@a... ___________________________________________________________________ Allette Systems (Australia) www: http://www.allette.com.au ___________________________________________________________________ "Everything should be made as simple as possible, but not simpler." - Einstein
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