Re: Relational-to-OOP Tax

On Feb 25, 3:23 pm, Jerry Coffin <jcof...@xxxxxxxxx> wrote:
In article <1172422104.994840.113...@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
freb...@xxxxxxxxx says...

XQuery is a language for hierarchical data. The hierarchical model has
been abandoned for 30 years but has showed up in LDAP and XML again
showing all its disadvantages. If you want to learn the disadvantages
with the hierarchical model, please consult Wikipedia or some other
resource.

I know more about it than you seem to -- while the hierarchical model
cerainly has _some_ disadvantages, the relational model does too. In
theory, the relational model is a generalization of the hierarchical
model, so if you're honestly convinced it's better, why don't you show
us an implementation of an LDAP directory service that uses a relational
model internally?

The issue is context.

Hierarchical representations of data have been very successful - when
placed within a specific context. Modern programming representations
of data tend to be hierarchical, transport formats sent over a wire
are increasingly being represented in a hierarchical XML format, the
older SWIFT formats are hierarchical, a marked up document is
hierarchical. In all these cases there is clear context in which the
data is used, the application, the receiver of a transport format,
etc. It's also useful to have a standard querying language to query
these things, so XQuery is useful, even potentially for programming
constructs, particularly for expressing constraints declaratively
outside of the application proper, allowing configuration. This has
been observed practice, and if Topmind and frebe don't like it, well
they can make whatever claims they like, but the world moves on.

When there isn't a specific context, when data is intended to be held
as data, servicing many uses, then it's hard to beat the RDBMS. XML
databases appear to be poor to mediocre as generic representations of
data.

Regards,
Daniel Parker
http://servingxml.sourceforge.net/

.

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