How I can handle dynamic data

[Marek Mosiewicz <ma...@poczta.onet.pl>]

Hello

OJB is really good think. 
I have question about report queries. I need to handle fully dynamic data which cant be known at compile time. Can report query be used with relation ?  I plan to create some kind of dataset ala Delphi or ADO.Net DataSet. 
I believe that I can fill it with my own rowreader but I dont know how OJB saves data (what I have to modify to instruct OJB to take data from my dataset when saving changes is ?)  OJB must also know how navigate via my DataSet relations
It would be good to create such standart dataset for Java. Only known solution to me is Borland dataset avaialable in JBuilder. It would be great to have OpenSource equivalent or maybe someone knows any. It could be one more API to OJB which could be dynamic by nature (Sun seems to ignore such need as only standard datamodel in Java is JavaBean which is static)


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Re: How I can handle dynamic data

[Thomas Mahler <th...@apache.org>]

Hi Marek,

Marek Mosiewicz wrote:
 > Hello
 >
 > OJB is really good think. I have question about report queries. I
 > need to handle fully dynamic data which cant be known at compile
 > time. Can report query be used with relation ?

Yes, ReportQueries can be used smoothly in such a scenario!
But also *normal* queries could be an option, as the whole OJB metadata 
layer is completely dynamic and can be manipulated as runtime!

 > I plan to create some
 > kind of dataset ala Delphi or ADO.Net DataSet.

But aren't these technologies quite similar to JDBC ResultSet?
Those technologies don't provide O/R mapping features, but a thin 
abstraction of a database cursor!

 > I believe that I can
 > fill it with my own rowreader but I dont know how OJB saves data
 > (what I have to modify to instruct OJB to take data from my dataset
 > when saving changes is ?)  OJB must also know how navigate via my
 > DataSet relations It would be good to create such standart dataset
 > for Java. Only known solution to me is Borland dataset avaialable in
 > JBuilder.

Which is quite similar to the delphi stuff!

 > It would be great to have OpenSource equivalent or maybe
 > someone knows any. It could be one more API to OJB which could be
 > dynamic by nature (Sun seems to ignore such need as only standard
 > datamodel in Java is JavaBean which is static)

The Delphi and ADO approach of datasets make sense if you are using 
databound GUI widgets. These techniques have been used in typical 
2-layer applications.

But in modern multi-tier applications developer prefer to use proper O/R 
tools to avoid the inherent deficits of 2-tier architectures.

Maybe I am missing something fundamental here, but I don't see the 
benefit of your proposed solution. Can you give some further explanation?

cheers,
Thomas


 >
 > --------------r-e-k-l-a-m-a-----------------
 >
 > Super tanie kwatery narciarskie. Od 300 zł/osoba/tydzień
 > http://wycieczki.onet.pl