[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?)
"Borden, Jonathan" wrote: > You are missing the point. Since the data is already deserialized, there is > no delay due to processing. The idea is that the data has already been > entered into a database which implements a DOM interface (the database is > free to implement other interfaces as well). I never claimed that the data > was entered as XML or that a serialized XML document ever existed. Oops! Sorry about not getting the context right. *blush* Let me try again. Anyway, I see one context where putting a DOM interface on a relational database would be great, and I see another context where I don't think it would be too hot. Interactive "generic" organizational navigator ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I did something like this at Ford. I found that organizational navigation has these characteristics: a. Only a small fraction of the information in the database is queried. b. It is interactive, the system is best modeled as a bunch of small queries rather than one big query. c. It is hierarchical in nature (Xrefs are rare) as the user goes down a branch, you store all of the primary keys on the stack. The big problem with the implementation was that the mapping from a custom relational-database model to the DOM model is, let's say, non-trivial. On the flip side, however, things are much more cheerful. A wonderful, re-usable CORBA/DOM client could be built (with very good market potential). This results in great re-use from not only a software, but also from a training perspective. Query Extraction Layer ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I can also see an XML stream as the result from a query. In this case, the de-normalized, hierarchical view of the information resulting from a nested query is the stuff reports are made of. I picture the client using XSL on the resulting stream to generate a report. In effect, the XML output stream becomes what you would normally call a view. Then, each "user" can filter/format the information as they would like using a standardized XSL based client. I don't think this is new... and I'm looking forward to mature technology doing this. However, I'm not sure about using DOM as an interface to a relational database in this context. The way Oracle and other databases compute large queries with subordinate tables is, at its heart, stream-oriented. Many of these databases will "drive" off a single table sequentially, collecting the information from the subordinate tables as the query progresses. Therefore, I picture a DOM implementation using thousands of nested queries to generate the same tree that a few large queries would have handled nicely. In this case, the database engine would not be able to take advantage of aggregate indexing and elimination algorithems. In effect, negating the benifits of having corporate information in a relational database. *smile* Anyway, I just can't picture using DOM in this context as an interface to a relational database. For this case I feel using a stream-oriented solution on the server with an object-oriented event processing system on the client seems the better approach. :) Clark 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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