That's very good idea using threadLocal :) , thx very much about these
informations :).
On 5/24/06, Armin Waibel <[EMAIL PROTECTED]> wrote:
ABOU LINA wrote:
> thx for your reply .
>
> looking the example :
>
> // get MetadataManager instance
(1) > MetadataManager mm = MetadataManager.getInstance();
>
> // enable per thread mode if not done before
> mm.setEnablePerThreadChanges(true);
>
(2) > // Load additional object metadata by parsing an repository file
> DescriptorRepository dr_1 =
> mm.readDescriptorRepository("pathOrURLtoFile_1");
> DescriptorRepository dr_2 =
> mm.readDescriptorRepository("pathOrURLtoFile_2");
>
(3) > // add profiles
> mm.addProfile("global", mm.copyOfGlobalRepository());
> mm.addProfile("guest", dr_1);
> mm.addProfile("admin", dr_2);
>
(4) > // now load a specific profile
> mm.loadProfile("admin");
(5) > broker = PersistenceBrokerFactory.defaultPersistenceBroker();
>
>
> MetaManager is a singleton i think. so in this case we will have a
> probleme with
> concurence access. if user A loadProfile("guest") and just after
> loading guest profile another user B (profile admin)
> execute broker = PersistenceBrokerFactory.defaultPersistenceBroker();
> so in this situation
> B got a broker with profile admin because MetaManager is a singleton.
>
> is right ????
If each user (thread) use a different broker instance no. All steps from
(1) to (3) have to be done once at startup of your application. Thus no
concurrency issues are expected.
With step (4) the calling thread was associated with a specific profile
(using ThreadLocale). This call have to be done for each thread to load
the correct profile. Take care when using thread-pools (think e.g.
Tomcat use it) to reassign the correct profile for each calling user.
When OJB returns the broker instance (5) the profile for the current
thread was associated.
In OJB test-suite we test the use of different metadata profiles in
MetadataMultithreadedTest and never detect problems with this feature.
Again if user A and B (different threads) use different broker instances
no concurrency issues are expected.
regards,
Armin
>
>
>
>
>
>
> On 5/24/06, Armin Waibel <[EMAIL PROTECTED]> wrote:
>>
>> Hi,
>>
>> ABOU LINA wrote:
>> > Hi;
>> >
>> > i have two mapping file : repository1.xml and repository2.xml.
>> >
>> > the difference between these two file are the value of auto-*
>> > [auto-retrieve, auto-update ..] ; at runtime sometimes i need to use
>> > repository1.xml and somtimes the repository2.xml .
>> >
>> > what is the best and optimal solution about this conf ???
>> >
>>
>> You can use metadata profiles on per thread base.
>>
>>
http://db.apache.org/ojb/docu/guides/metadata.html#Per+thread+metadata+changes
>>
>>
>>
>>
http://db.apache.org/ojb/docu/guides/metadata.html#Object+metadata+profiles
>>
>>
>> This way you can load a specific metadata profiles (repository1.xml or
>> repository2.xml) for the current thread.
>>
>> Take care of caching issues, e.g. obj1 from rep1 was used in rep2
>> environment will cause undetermined behavior. Thus it's recommended to
>> use the two-level cache or only a session based (per broker) cache.
>>
>> regards,
>> Armin
>>
>>
>> > thx in advance
>> >
>>
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