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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Inheritance in XML (was Re: Problems parsing XML)
 At 03:56 PM 4/17/98 -0400, Paul Prescod wrote: >> Take for example an Excel spreadsheet. > >You can modify it reliably if the DTD/schema is complete. If not, you >guess, just as with a partially documented API. Excel was perhaps a bad example, but in general I disagree because the DTD isn't enough to capture all of the various integrity constraints that may exist between elements representing components of a data structure. It may be possible to represent some of these constraints through content models, but certainly not all of them. If the schema was all you needed, then there wouldn't be much point to the OO concept of the "setter" method. You would just make all of your data members public, and tell everyone not to break the rules, however complicated those may be. In practice, this doesn't work, and there is a lot of value to be had in using methods (an API) to ensure that the constraints are not violated. >Not in my experience. There are dozens of tools that I can download that >work with RTF, Frame MIF or PDF, and a small handful that talk to the >Word, FrameMaker or Adobe Acrobat APIs. Furthermore, the formats >described above have multiple independent implementations. The APIs do >not. Certainly there will be a few important and widely used data models around, especially for the representation of documents, and XML is perfect for this. The semantics of the data model will be well understood, enabling anyone with enough time on their hands to write dozens of tools that operate reliably upon the data. To me though, this is still an API, my application isn't parsing the file, its poking at it through the "tool" which is where the semantics have been encapsulated. If XML makes it easier for these eager tool hackers to do their thing, then great, I'm all for it. However, lets say I'm the vendor of some relatively esoteric thing, and I need to design a file format to capture the state of my application. Do I use XML? Sure why not, but do I really gain anything from this? The hackers with time on their hands are busy writing tools to edit RTF and DOOM levels, they don't care about my nuclear power plant application. Even if someone did decide to write a nifty utility that operates on my files, if they get it wrong, then Cleveland starts glowing, so I probably don't want their help anyway. I'm not against XML, I think its a great thing, and we should encourage the vendors of major applications to support it, along with the copious DTD documentation that will be necessary to do anything useful with it. However, I think the notion that just storing my application data in XML will automatically make it more useful to the world is a bit presumptuous. Jeff xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i... Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ To (un)subscribe, mailto:majordomo@i... the following message; (un)subscribe xml-dev To subscribe to the digests, mailto:majordomo@i... the following message; subscribe xml-dev-digest List coordinator, Henry Rzepa (mailto:rzepa@i...) 
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