Re: [eclipselink-users] RCP and Eclipse Link (again)

[csergiu77 <csergiu77@xxxxxxxxx>]

This is more that i expected and very clear explanations

I can't say more then a big : THANK YOU !!!!





tch wrote:
> 
> Hi, I'm the one of the authors of that blog post:
> 
> Very simply this means, your entities must be in the same
> plugin/bundle as your EntityManager _at this time_. People are working
> on ways around this.
> 
> When you create an an EntityManagerFactory in eclipselink osgi, you
> must pass in the classloader that contains your persistence unit xml
> and your entity classes.
> 
> Now, that being said, let's say you wanted a security plugin that
> contained all your user entities and security logic. You could still
> create that plugin, it just would have to have it's own
> EntityManagerFactory and entities that were obtained by one
> EntityManagerFactory can't be persisted into another.
> 
> So we couldn't have our user login (select user using an EM from our
> security plugin). Then take that same user and try to merge it into an
> EntityManager obtained from our Products plugin. That doesn't mean the
> products plugin can't read the User entity, after all it's just a
> POJO.
> 
> To give you a real life example, we found that things like User
> entities are reused through almost every plugin, due to relationships
> on business tables via a created by to a user table. Unfortunately we
> had to duplicate that same User entity throughout each business area
> plugin that was already defined. Now take note of what I said -- we
> still have multiple plugins broken up by business area, just each
> plugin needs to have natural boundries where it doesn't require entity
> sharing -- in our situation bundle=schema. So it wouldn't make sense
> to break up your plugins across a schema that is all inter-related on
> itself.
> 
> Like I say in the article, for me -- it's not really a show stopper at
> this point. You still get tons of benefit from EclipseLink, and steps
> are being taken by the community to enable true module Entity sharing
> across the classloader boundry, so we'll get there eventually.
> 
> As for getting started on your own app, I recommend you get the
> official Comics example and the one from our blog. (you can use the
> same derby DB for both). Build them both, and learn how they work, you
> can then adapt the techniques to work for how you like to code.  Also,
> don't get caught up in all the weaving black magic, you don't NEED it
> to write a great EclipseLink based RCP app, it's neat stuff however,
> and something you can add in later once your application is done,
> without the need to change any code.
> 
> ./tch
> 
> 
> 
> On Sat, Jan 17, 2009 at 2:57 AM, csergiu77 <csergiu77@xxxxxxxxx> wrote:
>>
>> I read an very nice article
>> :http://www.weheartcode.com/2008/08/27/eclipselink-in-j2se-rcp-applications/
>>
>> but there is a phrase like :
>>
>> "Common Gotcha - sharing Entities ..................."
>>
>> "This isn't as much of a deal breaker as it sounds at first, you just
>> have
>> to violate DRY for Entity Classes, which aren't all that interesting in
>> the
>> first place. There's nothing stopping you from defining common interfaces
>> or
>> Abstract classes that entities from multiple bundles share."
>>
>> 1 )Can someone explain this in more detail ,maybe just a short example
>> plz ?
>>
>> I want to build a modular application :
>>
>> 2)So i have to put all entities in one module ?
>>
>> 3)Or is possible a configuration like this ? :
>>
>> base ,security module (user entities)
>>
>> partner module  depends on base
>>
>> products module depends on base
>>
>> invoice module depneds on base,partener,products
>>
>>  And i saw a gigantic post related to osgi rcp ,hooking ,waving
>> etc......do
>> i need to read all those post in order to create a rcp ,eclipselink
>> applicaiton ?
>>
>> There are missing things from that article covered in this older posts ?
>>
>> THX A LoT
>>
>> Regards
>>
>> --
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>>
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> 

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