QRE: How do Java Xquery technologies fit ?

[paul agbetile]

Thanks very much ! that has been really helpful !

On Fri, Jun 20, 2008 at 2:24 PM, Michael Kay <http://x-query.com/mailman/listinfo/talk> wrote:

>  First point is that XQJ is an interface - a way that XQuery users can
> talk to XQuery implementations. It is not itself an XQuery implementation.
> XQJ is to Saxon as SQL is to relational databases.
>
> >What I am also wondering is the extent to which products like datadirect
> Xquery have utilised the XQJ API to provide easy access to a relational
> database and how an XML view of a relational database can be derrived ?
> That's a question very specific to the DataDirect product.
>
> >My only guess at the moment is that it makes an SQL call to retrieve all
> the column names and builds some sort of internal schema using this ?
> Well, I guess there's a lot more to it than that, but I expect you're along
> the right lines.
>
> >I'm I right in thinking that the XQJ API alone offers no such automatic
> connection to table columns in a non XML relational database.
>
> XQJ is just a pipe down which you can send XQuery requests. Unless there's
> someone listening at the other end, it can't do anything.
>
> >If this is the case my questions is whether Saxon can be modified to do
> this (if at all advisable) and what work I would need to do to achieve this.
> It's possible in theory but it's a *very* significant amount of work -
> especially for someone who isn't already aware that it's a large project.
> >I noticed when playing with the evaluation version of DataDirect Xquery
> that it loaded what appears to be a saxon module
>
> DataDirect XQuery uses some component technology acquired from Saxonica. It
> does a lot more than Saxon (by distributing a query to multiple data sources
> and assembling the results), but it reuses some of the Saxon technology to
> do parts of the query processing.
>
> Michael Kay
> Saxonica
>
>  ------------------------------
> *From:* http://x-query.com/mailman/listinfo/talk [mailto:http://x-query.com/mailman/listinfo/talk] *On
> Behalf Of *paul agbetile
> *Sent:* 20 June 2008 12:15
> *To:* http://x-query.com/mailman/listinfo/talk
> *Subject:*  How do Java Xquery technologies fit ?
>
>  Hi, I am about to embark on a project that will require me accessing XML
> sources as well as relational databases and would really appreciate some
> help in trying to navigate through alot of what has me confused.
>
> Firstly I should mention I am new to XQJ and Xquery. I started a few days
> ago with Michael Kay's "Learn XQuery in 10 Minutes" tutorial which I found
> really helpful and have written a few queries since.
> I am struggling to understand where XQJ ends and products like Saxon and
> datadirect Xquery begin. What I am also wondering is the extent to which
> products like datadirect Xquery have utilised the XQJ API to provide easy
> access to a relational database and how an XML view of a relational database
> can be derrived ?
> My only guess at the moment is that it makes an SQL call to retrieve all
> the column names and builds some sort of internal schema using this ?
>
> I'm I right in thinking that the XQJ API alone offers no such automatic
> connection to table columns in a non XML relational database. If this is the
> case my questions is whether Saxon can be modified to do this (if at all
> advisable) and what work I would need to do to achieve this.
>
> At present my assumptions range from having to write my own JDBC driver
> (that can generically talk to several databases) as well as devising some
> sort of Xquery to SQL translation. I noticed when playing with the
> evaluation version of DataDirect Xquery that it loaded what appears to be a
> saxon module ? This again has me confused as to how all these technologies
> fit in with one another.
>
> Thanks,
> Paul
>
>
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