Re: [Exist-development] thoughts about next steps with RDBMS integration

[Adam R. <ad...@ex...>]

On 31 March 2010 06:45, James Fuller <jam...@ex...> wrote:
> whilst doing xproc development, I have had great fun integrating some of
> eXist existing extension functionality as extension steps ... a thought
> occurred to me about the current state of integration with RDBMS.
> Currently we have the nice SQL extension module (written by Adam Retter)
> which uses JDBC to query a relational database ... this means we can easily
> query an RDBMS through xquery using SQL statements. I think this module
> enables a lot of scenarios but misses off the primary scenario for the
> masses of people out there with data currently existing in RDBMS but want to
> use XML database.
> I would like to
> install eXist and provide in some registry a connection string which
> effectively 'mounts' the RDBMS as a collection ... from which here on out I
> can use pure xquery to work on. For now a read only view of the data is all
> I need but someday I would like to be able to do updates as well on the
> RDBMS data. Lastly I should be able to configure cache characteristics if
> the database connection is intermittent'

Phew!!! For a moment then I thought you were going to ask for a SQL
layer atop eXist-db and a JDBC driver for eXist-db.

This would actually be pretty easy to achieve :-)

Imagine the collection namespace root starting at /sql as opposed to /db.

Configuration could go into /sql/system/sql/{database}/{schemaName}/{tableName}

And the database configuration could again be defined in conf.xml
files in the /sql/system/sql collections. Caching and connection
property characteristics could also be placed in conf.xml files in the
appropriate sql configuration collection.

Almost all of the existing infrastructure could be reused. You would
simply need to extend the Collection function so that in the case of a
"/sql" collection it defered the document set building to code that is
very similar to that of the sql module. You would also need to come up
with a collection xml serialization scheme for displaying the
available sql schemas and tables as sub-collections but thus should
not be very hard and should be as close to possible (if not the same)
as the existing ones for the db collections.

This is quite exciting - I like :-)

Can I help?


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-- 
Adam Retter

eXist Developer
{ United Kingdom }
ad...@ex...
irc://irc.freenode.net/existdb