[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Storing Lots of Fiddly Bits (was Re: What is XML for?)
> > I don't think it makes sense to build a business-object model on top of DOM, > > but I do think it makes sense to define an exchange protocol that selializes > > objects to XML representations using DOM as a programmatic interface. > > I agree. I'll point out, however, that it is REALLY EASY to generate XML > directly. In your opinion does the DOM actually make it easier? > > If you use a "reverse SAX" interface (instead of a DOM-building interface) > then you could pipe together data consumers and if any of them ever needed > a DOM, it could build it. I think it depends on several things: 1) The language in which you're implementing the serialization. In Python, with its rich string handling and dynamic programming features, I might prefer to generate XML directly, but in Java or C++, I might prefer to go through DOM. 2) Your environment. I have often ended up using DOM because I'm working in a distributed environment, using CORBA, and it makes it very easy and natural to just call DOM interfaces across the ORB as a sort of serialization. 4DOM actually came about because we already had a CORBA-ready API for manipulating HTML-based views of an object across an ORB, and we wanted to expand this so we could take advantage of XML. The W3C's work provided a natural spring-board. Of course, on the same machine, it's probably easier and faster to use an events-based approach (SAX and your "reverse SAX", something like which I remember having cobbled together, in fact). 3) Your object structure. Some of the advocates of DOM as the universal object-model note that they are working in domains that fall into natural tree structures. In this case, there is clearly less impedance mis-match in using the DOM interface, and one can even smartly use the Builder pattern to connect abstraction to serialization interface if he's _very_ confident in the quality of the design. Alas the reality is that such natural tree-representations are not as common in real-life as some would have us believe. Business object models, as you rightly pointed out, more often take on the pattern of a graph (bi-directional, cyclic, and all those other tree-killers). > > I think it also makes sense to use the DOM to develop a user-interface layer > > for such objects, possibly using the same WDDX or XML-RPC mappings in > > association with a set of style-sheets (although this is just one of many > > possible mechanisms). > > Yes, it makes sense to use XML as an "interchange language" between your > business objects and your user interface. On the other hand, if that > interface is meant to be editable the information loss associated with > "dumbing down" to XML may not be acceptable. I agree with this, but in my opinion, user-interface hasn't caught up with object-modeling practice in any case. XML does cause "dumbing-down", but not much more than other user-interface options. How does one go from a typical object model, with as many degrees of freedom as most object models entail, to presenting a linear form as an effective editing interface? I don't claim to have any visionary ideas here, but I get the sense that the next big breakthrough (or hype-engine) in the object community will have to be at the fundamental UI level. Or did it already pass us by in the (over-wrought) forms of OpenDOC or Pink? -- Uche Ogbuji FourThought LLC, IT Consultants uche.ogbuji@f... (970)481-0805 Software engineering, project management, Intranets and Extranets http://FourThought.com http://OpenTechnology.org 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/ and on CD-ROM/ISBN 981-02-3594-1 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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