Re: [Objectbridge-jdo-dev] Object store (automated database creation)

[Thomas M. <tho...@ho...>]

Hi Travis

tr...@th... wrote:

 > I've been having this idea running through my head for the past
 > couple weeks so I thought i'd run it by the list.
 >
 > Lets say you wanted to make the database transparent (other than the
 >  connection info obviously) so we could have a quasi object store.
 >
 > My thoughts on how to implement speaking from jdo implementation
 > perspective.
 >
 > Basically you have jdo file with persistent fields.  If a table not
 > found error occurs on a query, you create the table on the fly.  If
 >  a column not found error occurs, you compare ResultSet metadata
 > with jdo metadata and create any columns that dont' match.
 >
 > This could be done at load time when jdo file is first read, or on
 > the fly on an as needed basis.
 >
 > The benefit of this is that the jdo file would become a sort of
 > database schema that the programmer wouldn't even think about.  And
 >  ojb would be very, very easy to install and implement.
 >
 > Thoughts?
 >

Yes, That's cool idea.In certain production environments it won't be 
allowed to create tables on the fly (e.g. in my company all database 
tables you want to be created must be qa'ed by the DBA team...).

But for all others this kind of thing could be quite helpful.

I'm planing to have a whole toolset for metadata operations in OJB 2.0.
This toolset will allow to
- forward engineer java classes to Metadata and DDL (possibly with on 
the fly generation in the db)
  With this kind of tool it will be easy to build for instance a 
persistent XML DOM implementation as one would need in an XML data 
server... (this is one of the demos that's on my todo list for a very 
long time...)

- reverse engineering from relational database to Java classes and Metadata

- a Mapping workbench to allow manual mapping from Java classes to RDBMS 
tables.

Of course it must also be possible to parse *.jdo files to Ojb Metadata 
and to generat *.jdo files from the MetaData layer.

This can be done by extending the RepositoryPersistor.

So there will be a lot of interesting things to do for OJB 2.0 ...

cheers,

Thomas


 > Travis
 >
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 >
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