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Simplify Apps Using XML With PHP and DB2
An anonymous reader writes "IBM DeveloperWorks has an article from a little while back that takes a look at the impact of schema evolution on the application. The narrative walks the reader through a usage scenario to illustrate the ease of setting up a PHP environment and integrating DB2 native XML functionality with PHP applications including web services written in PHP and XQuery."
...they implemented "XML databases" by treating XML as BLOB's and adding XML parsing and updating capabilities to SQL. Hybrid indeed. I'd be rather tempted to call it a bastardization of both contepts (relational and XML).
The problem lies not in our parsers, but in our application domains -- and ourselves.
It is trivial to represent flat data structures (or sets of tuples if you prefer) using XML. It isn't hard at all to represent hierarchical or even irregularly structured data using SQL. What's hard is doing any useful processing of data after you've chosen a format whose associated tools don't readily do what you need to do with that data.
It's hard to tighten nuts with a hammer or drive nails with a wrench.
A hybrid tool certainly has it's potential uses in an application that crosses domain boundaries. Such applications are inherently hard in any case; it's not as simple as choosing a wrench or a hammer, it takes expereince. But this is greatly complicated engineers who will invariably choose the wrong tool (often XML these days), who given a hybrid hammer/wrench tool will insist on always hitting things with the wrench.
To be sure there are borderline cases, but you need to solve the problem with the minimal number of parts.
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