[DAS2] query language description

[Andrew Dalke]

Hi Chris,

> I presume one constraint is that you want to preserve standard CGI URL 
> syntax?

Yes.

>  I think this is the best that can be done using that constraint, 
> which is to say, fairly limited.

Then again, the functionality we need is also fairly limited.

>  This lacks one of the most important features of a real query 
> language, composability. These ad-hoc constraint syntaxes have their 
> uses but you'll eventually want to go beyond the limits and end up 
> adding awkward extensions. Why not just forego the URL constraint and 
> go with a composable extendable query language in the first place and 
> save a lot of bother downstream?

Because no one can decide on a generic language which is more
powerful than this.

Anything more powerful would need to support .. boolean algebra?
numeric searches?  regexps?  What about quoting rules for "multiple
word phrases"?

Is it SQL-like?  XPath/XQuery-like?  Is it a context-free grammar?
How easy is it to implement and work cross-platform?

For what people need now, this search solution seems good.

For the future we can have

   <CAPABILITY type="xpath-query" query_uri="http://whatever" />

and clients which understand that interface will know that it's
there.

					Andrew
					dalke at dalkescientific.com