Object with links to objects from a different database

[Ian Hunter <ih...@hunterweb.net>]

I have a system that uses one database for storing 95% of it's data, but 5%
of it lives in a separate ERP that I'm linking to.  OJB is talking to both
databases just fine, but when I try to load an object that has auto-retrieve
turned on that also happens to reference an object in a different database,
OJB can't figure out that the "subobject" lives elsewhere and tries to
access its table in the current database.

Help?!?!

---
Aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it deosn't mttaer in waht
oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the frist
and lsat ltteer be at the rghit pclae. The rset can be a total mses and you
can sitll raed it wouthit porbelm. Tihs is bcuseae the huamn mnid deos not
raed ervey lteter by istlef, but the wrod as a wlohe.


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Re: Object with links to objects from a different database

[Armin Waibel <ar...@apache.org>]

Hi Ian,

Ian Hunter wrote:
> I have a system that uses one database for storing 95% of it's data, but 5%
> of it lives in a separate ERP that I'm linking to.  OJB is talking to both
> databases just fine, but when I try to load an object that has auto-retrieve
> turned on that also happens to reference an object in a different database,
> OJB can't figure out that the "subobject" lives elsewhere and tries to
> access its table in the current database.

OJB doesn't support materialization of objects made up of different DB. 
There is a feature request to support this but I don't like it, because 
of the complications on insert/update/delete of these composed objects 
(in that case need a 'OJB internal' distributed transaction support to 
guarantee synchronization of databases).

So you have to handle this stuff by your own using a thin layer on top 
of OJB. Here a simple example how you can handle this:

broker_1 ---> DB_1
broker_2 ---> DB_2

MyObject composed = (MyObject) broker_1.getObjectByIdentity(oid);
broker_2.retrieveReference(composed, "refFieldNameToLoadFromDB_2");

That's all! Now the object should have data from DB_1 and the reference 
read from DB_2.

regards,
Armin

> 
> Help?!?!
> 
> ---
> Aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it deosn't mttaer in waht
> oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the frist
> and lsat ltteer be at the rghit pclae. The rset can be a total mses and you
> can sitll raed it wouthit porbelm. Tihs is bcuseae the huamn mnid deos not
> raed ervey lteter by istlef, but the wrod as a wlohe.
> 
> 
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> To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
> For additional commands, e-mail: ojb-user-help@db.apache.org
> 
> 
> 

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