Re: opening multiple databases from same program

That sounds like a good idea, and I tried in my last project. Turns out it's much harder than it seems.
Firstly, you need lots of extra boilerplate code. But I can live with that.

More importantly, I have to be very very careful about disabling relevant pieces of the UI so I don't end up having 2
background queries stomping on each other.
It is really really easy to have the user click on 2 things in succession, the 2 queries both execute in the background,
and then my applications state becomes horribly messed up.

Basically, it's more pain than it's worth, especially since 99.9% of the time my queries execute fast enough that I
don't need to execute them in the background.

And I believe that libraries like SimpleORM should strive to make my life easier, not harder.
Especially when all I asking for is a way to disable some checking.

After all, I am the programmer, should I not be in control of the situation, rather than having the library force me
into one way of doing things?

-- Noel.

Thomas Leichner wrote:
> You can have a Swing desktop application and work with many threads. You can 
> send the Swing event thread a command with the  EventQueue.invokeLater 
> function. You can also send a command from the Swing event thread to your own 
> threads, implementing the same mechanism, which is used by the EventQueue 
> class. This will be much easier than changing the SimpleORM source code. And 
> it is much more flexible. For example, your swing application is still able to 
> react, when a long drawn database sql-statement is executed. In the Java 
> standard library you can find everything you need to implement such a solution.
>
>
> Thomas
>
>
>
> Am Dienstag, 21. September 2010, um 14:33:29 schrieben Sie:
>> I'm effectively running several smaller apps inside the same Java VM.
>> Each app has it's own database.
>> Since this is a Swing desktop application, most of the action happens on
>> the Swing event dispatch thread. This means that I end up talking to
>> multiple databases from the same thread, triggering the check.
>>
>> Sigh. I keep having this problem.
>> Everybody is developing web-applications these days, which means that all
>> of the ORM frameworks are designed around the HTTP request-response cycle.
>> I ended up dumping Hibernate because it won't play nice with desktop
>> applications.
>>
>> Luckily SimpleORM is relatively straight-forward code, so I'm probably just
>> going to run my own private branch of it, since my changes don't seem to
>> meet with popular approval.
>>
>> -- Noel
>>
>> [email protected] wrote:
>>> It is actually possible to dissassociate sessions from threads, and thus
>>> have several. But that is a very odd thing to want to do. What are you
>>> trying to achieve?
>>>
>>> (Ususally trying to open a session on a thread that already has an open
>>> session means that you did not close the previous session, leading to a
>>> connection leak, which is why SimpleOrm fails fast.)
>>>
>>> Anthony
>>>
>>> At 02:02 AM 10/07/2010, you wrote:
>>>> Hi,
>>>>
>>>> well, AFAIK, you can't do that... !
>>>>
>>>> SSessionJdbc has built-in checks that a connection is single threaded
>>>> using a ThreadLocal object. [I think Hibernate has some kind of best
>>>> practice to achieve the same goal (I'm not formal here, I didn't use
>>>> hibernate for years)]
>>>>
>>>> There is only one dataSource per SSessionJdbc and one SSessionJdbc per
>>>> thread.
>>>>
>>>> You could implement a different strategy to handle this part. Some work
>>>> was done along this path in a previous version of Simpleorm, for using a
>>>> single JTA transaction per session. But it is not maintained.
>>>> See simpleorm/extras/SConnectionEJB.java
>>>>
>>>> My question would be : what are you trying to achieve ?
>>>>
>>>> Franck
>>>>
>>>> Le vendredi 09 juillet 2010 à 17:11 +0200, Noel Grandin a écrit :
>>>>> Hi
>>>>>
>>>>> I'm opening multiple different databases from the same thread, which
>>>>> is triggering this check:
>>>>>
>>>>> simpleorm.utils.SException$Error: Thread's SSession already open [SS
>>>>> 1.SkyMon]
>>>>> [0@17:08:40.976] !SE>: at
>>>>> simpleorm.sessionjdbc.SSessionJdbc.innerOpen(SSessionJdbc.java:129)
>>>>> [0@17:08:40.976] !SE>: at
>>>>> simpleorm.sessionjdbc.SSessionJdbc.open(SSessionJdbc.java:88)
>>>>> [0@17:08:40.976] !SE>: at
>>>>> simpleorm.sessionjdbc.SSessionJdbc.open(SSessionJdbc.java:108)
>>>>>
>>>>>
>>>>> What do I do?
>>>>>
>>>>> Thanks, Noel Grandin
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
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