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

[Thomas W. <tho...@gm...>]

James,

I like your idea - it lowers the resistance about moving away from the
existing investments of time, code and money in the existing RDBMS.

As always the first thing first - we need to name what we are doing. I
propose the working name "*XML gateway to RDBMS*". When we refer to this
functionality we can say *"eXist is a XML gateway to existing RDBMS".* This
sounds as a reasonable USP (Unique Selling Proposition) as well.

Let us explore the idea further:
Step 1. Mount a RDBMS as a collection. We may need to use a special prefix
to the mounterd name.
Step 2. Provide means for enumerating the existing db resources:

   - Enumerate all tables and views.
   - Get the metadata for each table in two formats: a) as XML document, b)
   as a schema document. We can use this to generate XQuery for quering data.
   - A function that returns data from a table receiving the name of the
   table, a list of field names and number of records. This will allow the
   newbies coming from RDBMS world to start using eXist right out of the box
   before they become familiar with XQuery.

Step 3. We can even provide a web front end that will allow developers with
no XQuery experience to select the tables and fields they need and then
generate and save an XQuery for extracting the data they need, giving them
an URI that returns the data. This could be very attractive functionality.

Any other ideas?

Thomas


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Thomas White

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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.
> Take the following imaginary developer scenario:
> 'I have an existing RDBMS and I want to use XML database ... I am worried
> about going 'all xml' because RDBMS has served me well, not to mention I
> have a lot of code hanging off the existing database ... if I migrate to
an
> XML database I will have to migrate all those other bits ... this is too
> hard and too much change to attempt in one risky step. 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'
> Thoughts ? Does anyone see this scenario as something that needs to be
> addressed ?
> James Fuller
>
>
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