xml-dev - RE: Interesting Monday.

["Matthew Sergeant (EML)" <Matthew.Sergeant@eml.ericsson.se>]

> -----Original Message-----
> From:	James Robertson [SMTP:jamesr@steptwo.com.au]
> 
> At 19:11 2/02/1999 , Matthew Sergeant (EML) wrote:
> 
>   | 	This generates probably 5% more overhead than I have already (the
>   | RDBMS). XML doesn't parse quickly (well, OK, it parses quickly, but
> not
>   | compared to reading data from an RDBMS). When you are processing tens
> of XML
>   | files per second this becomes a huge problem.
> 
> Well, I guess you have to balance elegance & expandability vs raw
> performance. Not an uncommon trade-off ...
> 
	Indeed.

> But, that being said ... 
> 
> Creating XML from an RDBMS is very quick, particularly when you
> do it using straightforward non-XML code.
> 
> True, XML->HTML is not as quick as would be liked, but it
> again depends on the nature of the work. If your HTML needs 
> a lot of complex cross-linking, tables of contents, navigation
> bars, etc, then doing this straight from the RDBMS can be
> a real bitch.
> 
	Actually, the thing I really like about the XML solution - and I
think others will agree, is that it's a whole lot easier to update your XML
structure than it is to update your database. Changing code that accesses a
database is a lot harder than changing code that format's XML.

> Also, the speed of processing XML will depend on the tool.
> Have you considered using something like Omnimark, instead
> of DOM, etc?
> 
	We don't use DOM. We use expat (using perl's XML::Parser and my
CGI::XMLForm module). Expat is very quick. E.g. we can raw-parse (doing
nothing in the parse phase) 100 of our files in 0.25 seconds, but it's 30
seconds to do the same with XML::DOM (another perl module - although that
module has large overheads because it's a pure-perl solution). Of course
that's not a very fair benchmark, because it's a lot easier to manipulate
DOM than it is using expat, but the performance/flexibility tradeoff is
worth it.

	Matt.


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