[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: How far current XSLT processors will be useful in real applications?
> -----Original Message----- > From: owner-xml-dev@x... [mailto:owner-xml-dev@x...] On Behalf Of > Simon Wilson > You could take this further and say that, due to the fact that > next to nobody processes XML directly, but rather uses standardized API's/models > (DOM/SAX) for processing the XML content, it should be possible to 'virtualize' > XML and access ANY hierarchical data via the DOM API. Danger, part 1. XML is not about closely coupled interfaces. Do I smell CORBA in your suggestion ? Integrating systems via direct, synchronous method calls on objects is a thing XML should overcome, and not perpetuate. Like http, XML draws its power from the exchange of self contained, stateless documents. > An OODB engine might, for example, provide a DOM interface for accessing its object as > if they were XML structures. This would be preferable to extracting an XML > representation from the DBMS (expensive), feeding it to SAX/DOM, and then doing > your processing. Danger, part 2. While reading virtual XML documents is a pretty tempting idea, the nightmare begins when you try to synchronize update operations. However, the DOM contains methods that *write* into your document. How to update a virtual XML document of autonomous, distributed sources ? > > In the end you would have a vendor independent API for the extraction and querying of > hierarchical data. Kind of a web-standardized ODBC for hierarchical stuff with > everything looking like XML/DOM, and seeing that hierarchies can be used to > model both relational data and objects, you would have a pretty powerful > general purpose data access interface. Danger, part 3. Objects have the tendency not to be hierarchical for even trivial n:m relations like "student takes courses and courses are taken by students". This would result in objects graphs rather then hierarchical DOMs. The results are no longer realizable in XML in a standard way. You need to overload XML with marshalling/serialization semantics for object graphs. This takes away basic properties of XML, such as its tree structure and freedom of DTD design. > This idea seems so good that someone must be implementing it already... I bet. Ever looked at RDF, W3C's model for object graphs ? > Out with ODBC/OLEDB and in with "VXML/DOM" or whatever you might > want to call it! Agreed, but don't call the result XML just because XML syntax is used. We no longer have hierarchical data structures. Beside RDF, you may also want to have a look at SOAP and it's object serialization algorithm (http://www.develop.com/soap/). Regards, ++im *************************************************************************** This is xml-dev, the mailing list for XML developers. To unsubscribe, mailto:majordomo@x...&BODY=unsubscribe%20xml-dev List archives are available at http://xml.org/archives/xml-dev/ ***************************************************************************
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