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Re: From Hibernate to straight JPA

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On 19/07/2015 00:24, Martin Gregorie wrote:
> On Sat, 18 Jul 2015 20:48:50 +0100, Eternal Hope wrote:
>
>> As I read this thread I thought it was about time I had a look at this
>> JPA stuff. I've been writing Java for circa 15 years now, I've done
>> everything from writing byte streams to firmware interfaces to high
>> availability container managed business applications and Swing based
>> UIs. In all this time I have relied on a JDBC driver in my classpath,
>> container managed connection pools, hand coded SQL and 'in code'
>> transaction management. I do my own OR mapping; actually we don't call
>> it 'OR mapping' it's just relational database stuff, and quite frankly
>> I've never found the need to use some persistance framework.
>>
> I'm also interested in the answers you get.
>
> I suspect out backgrounds might be similar: I have a fairly solid
> background in relational database design, and the associated skills of
> normalisation, database performance tuning and writing both an RDBMS's
> dialect of SQL and ODBC as well as writing database applications in Perl,
> C and COBOL. So, when I've needed to implement database applications in
> Java, naturally I went for JDBC.


I come from a different direction I suppose.

I would design the Java bit of whatever application I'm working on at 
the moment as a collection of collaborating classes, I like to call this 
my class model. I'd then model the interactions using UML sequence 
diagrams, iterating over the class model as required. Ongoing analysys 
of the problem specification gives me my 'use cases' which I use to test 
my class model. At no time in this process do I concern myself with 
persistance other than to note that at some time, in the future I will 
need to save some data somewhere. I can even do some quick and dirty 
throwaway prototyping to get my head around a paticularly gnarly problem 
using facade stubs for example. What I end up with is what some might 
call an 'Object Oriented' design, I just call it my class model.

Knowing almost nothing about persistence frameworks I would imagine that 
this is the point where I might start to employ a framework to generate 
classes that implement the 'relationalisms' required to store an object 
graph (or the important data therein) in a relational database.

To date I have discovered only two ways to do this 'by hand'
One involves allowing relational data specific data items to creep into 
my nice clean class model (primary keys for example)
The second is to design an OO->RDBMS 'bridge' consisting of composite 
classes containing references to my 'pure' OO classes and relational 
things like primary and foreign keys etc.

Neither of these things is ideal really, in fact the whole concept of 
storing an object graph in a relational database will one day surely 
become obsolete, the two paradigms are so fundamentally different.

I suppose I should really start to read about how a framewok could help 
me with this mapping but I'd be prepared to bet that there's some XML 
involved somewhere and there are so many more interesting things I could 
be doing

Maybe this

http://www.telegraph.co.uk/news/worldnews/northamerica/usa/11748084/Robot-passes-self-awareness-test.html

Will give us a robot who can analyse the code and 'just do' the 
relational stuff as required on the fly.

Make my life a lot easier :-)

<snip>

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Thread

From Hibernate to straight JPA Cecil Westerhof <Cecil@decebal.nl> - 2015-07-10 20:13 +0200
  Re: From Hibernate to straight JPA Jeff Higgins <jeff@invalid.invalid> - 2015-07-11 10:56 -0400
    Re: From Hibernate to straight JPA Cecil Westerhof <Cecil@decebal.nl> - 2015-07-11 21:06 +0200
  Re: From Hibernate to straight JPA Lew <lewbloch@gmail.com> - 2015-07-16 17:15 -0700
    Re: From Hibernate to straight JPA Arne Vajhøj <arne@vajhoej.dk> - 2015-07-16 20:44 -0400
      Re: From Hibernate to straight JPA Cecil Westerhof <Cecil@decebal.nl> - 2015-07-17 10:01 +0200
        Re: From Hibernate to straight JPA Arne Vajhøj <arne@vajhoej.dk> - 2015-07-27 22:18 -0400
  Re: From Hibernate to straight JPA Eternal Hope <laughingspam99@gmail.com> - 2015-07-18 20:48 +0100
    Re: From Hibernate to straight JPA Jeff Higgins <jeff@invalid.invalid> - 2015-07-18 16:51 -0400
    Re: From Hibernate to straight JPA Arne Vajhøj <arne@vajhoej.dk> - 2015-07-18 17:21 -0400
    Re: From Hibernate to straight JPA Martin Gregorie <martin@address-in-sig.invalid> - 2015-07-18 23:24 +0000
      Re: From Hibernate to straight JPA Arne Vajhøj <arne@vajhoej.dk> - 2015-07-18 19:43 -0400
      Re: From Hibernate to straight JPA Jeff Higgins <jeff@invalid.invalid> - 2015-07-18 19:50 -0400
        Re: From Hibernate to straight JPA Arne Vajhøj <arne@vajhoej.dk> - 2015-07-18 20:23 -0400
      Re: From Hibernate to straight JPA Eternal Hope <laughingspam99@gmail.com> - 2015-07-19 09:22 +0100
        Re: From Hibernate to straight JPA Jeff Higgins <jeff@invalid.invalid> - 2015-07-19 06:20 -0400
          Re: From Hibernate to straight JPA Jeff Higgins <jeff@invalid.invalid> - 2015-07-19 07:49 -0400
            Re: From Hibernate to straight JPA Eternal Hope <laughingspam99@gmail.com> - 2015-07-19 13:28 +0100
              Re: From Hibernate to straight JPA Jeff Higgins <jeff@invalid.invalid> - 2015-07-19 09:20 -0400
                Re: From Hibernate to straight JPA Jeff Higgins <jeff@invalid.invalid> - 2015-07-19 09:50 -0400
              Re: From Hibernate to straight JPA Jeff Higgins <jeff@invalid.invalid> - 2015-07-20 13:16 -0400
                Re: From Hibernate to straight JPA Jeff Higgins <jeff@invalid.invalid> - 2015-07-20 13:42 -0400
                Re: From Hibernate to straight JPA Jeff Higgins <jeff@invalid.invalid> - 2015-07-20 14:07 -0400
                Re: From Hibernate to straight JPA Eternal Hope <laughingspam99@gmail.com> - 2015-07-20 20:46 +0100
                Re: From Hibernate to straight JPA Martin Gregorie <martin@address-in-sig.invalid> - 2015-07-20 21:01 +0000
                Re: From Hibernate to straight JPA Jeff Higgins <jeff@invalid.invalid> - 2015-07-20 22:19 -0400
                Re: From Hibernate to straight JPA Jeff Higgins <jeff@invalid.invalid> - 2015-07-20 23:52 -0400
                Re: From Hibernate to straight JPA Joerg Meier <joergmmeier@arcor.de> - 2015-07-21 12:04 +0200
                Re: From Hibernate to straight JPA Eternal Hope <laughingspam99@gmail.com> - 2015-07-21 12:43 +0100
    Re: From Hibernate to straight JPA Jeff Higgins <jeff@invalid.invalid> - 2015-07-18 20:25 -0400
      Re: From Hibernate to straight JPA Jeff Higgins <jeff@invalid.invalid> - 2015-07-18 20:44 -0400

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