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Re: Whence XQL?

• From: "Roger L. Costello" <costello@m...>
• To: Ed Howland <Ed@d...>
• Date: Thu, 25 Mar 1999 06:58:06 -0500

Have you looked at XML-QL?  I have been playing around with this XML
query tool for a few weeks.  It's quite nice.  It allows you to specify
the grammer of extracted data, query multiple XML documents, etc.  See:
<http://www.research.att.com/sw/tools/xmlql>  /Roger

Ed Howland wrote:
> 
> Ok, so now it is April (or thereabouts) and still no XQL. I've read all the
> hypeware about this and I understand that its just a suggestion for a
> proposal for a note for a draft for a recommendation. Whatever.
> I want my XQL!
> 
> Seriously, all ranting aside, I haven't seen any talk here or in XSL
> listserv land about it yet (recently). The proposal seems complete enough to
> me for someone to have at least announced a beta implementation of it. I'd
> be happy with mostly unfinshed code if it were written in Java.
> 
> So does anybody have a clue about this? I know about XSL so please don't
> send me down that path. I also know about the Datachannel attempt.
> 
> If not, I'm tempted to write something myself. I'm not sure about a couple
> of things because its still just off the top of my head so far.
> 
> Ok, its in Java. It uses some free XML parser, probably XML4J because its
> the one I'm most familiar with. The XQL syntax parser will be written in
> ANTLR, since it outputs nice O-O Java classes. The result set of XQL is well
> formed XML. This can be handled easily by XML4J's ability of any node in any
> tree (or transformed sub-tree) to print itself in XML to any stream. XML4J
> has a nice getNodesByName() mathod that can operate at any level of the tree
> returning a NodeList of siblings with that tag name. Wrapping a result tree
> in <xql:result></xql:result> and iterating the NodeList gets you the
> simplist query.
> 
> Internally the result set is just another DOM tree so you should be able to
> add the .jar file to your Java app and thus satisfy that type of XQL result.
> The input can be done in a variety of ways. I assume that the Perl module
> XML::XQL can be used in a CGI context to extract the XQL query, execute it
> and return either XML or XSL transformed output to the calling app(browser.)
> Likewise, a Java servlet could do the same thing.
> 
> Cons: Xml4J doesn't yet handle PI's so its maybe not the overall best
> solution. (I may be wrong about this, IBM uploaded a new major release that
> may have fixed it.) Its just the one I'm comfortable with, at the moment. On
> my hard drive are XML parsers from Sun, Microsoft, Oracle, James Clark and
> one or two others I haven't had time to play with yet.
> 
> I don't care about efficiency or optimization. All partially created result
> sets will live in memory till they are ready to be output. I also don't care
> about searching multiple files, although that should be realtively easy to
> add. (I'm still confused about XML repositorys. Would XQL have to understand
> directory paths? Does XQL need to be able to follow XLinks?)
> 
> I'm leaving out sequences but I may add them in (much) later. Return values
> (analog to SQL's SELECT) are important to my application, as are
> conditionals.
> 
> Unless someone warns me that I'm clueless (which is usually the case,) I'll
> post a cut of the ANTLR grammer as soon as I get a working one. I'll
> probably put it on my web site.
> 
> Ed
> 
> Ed Howland
> ed@d...
> http://www.dega.com
> "As your attorney, I advise you to take some adrenalchrome"
> 
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• References:
  • Whence XQL?
    • From: Ed Howland <Ed@d...>

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