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From: Brian McCallister <brianm@apache.org>
Subject: Re: [DISCUSS] use backport-concurrent instead of repackaged
 concurrent classes
Date: Mon, 4 Jun 2007 18:55:06 -0700
To: dev@openjpa.apache.org


On Jun 4, 2007, at 6:39 PM, Patrick Linskey wrote:

> I'm allergic to re-namespacing... why do you think that we should  
> do so?

Avoiding collisions. The majority case is that people don't care  
about the extra 327k but they care a lot about not hitting conflicts  
with libraries. Dug Lea's libraries are not a great example of this,  
but Hibernate *is* a good example -- it relies on EHCache by default,  
going from 3.0 to 3.1 to 3.2 is a major non-backwards compatible  
change, and you cannot use EHCache 1.2 with 3.0, so you are trapped  
unable to upgrade dependencies. Weblogic and ANTLR (a couple versions  
back) is another great example.

Basically, if you are a library (which OpenJPA is) you want to  
minimize the degree to which you place constraints on the runtime  
environment of your users. I can easily imagine someone using a home- 
rolled build of the concurrent backport which was subtly  
incompatible. Yes, your user could renamespace then, but it is better  
if they *never have the issue*

-Brian

>
> -Patrick
>
> On 6/4/07, Brian McCallister <brianm@apache.org> wrote:
>> I would suggest using backports and repackaging -- though I have
>> trouble imaging the interfaces on backports changing. I, personally,
>> am of the opinion that if at all possible, small dependencies should
>> be re-namespaced and bundled.
>>
>> -Brian
>>
>> On Jun 4, 2007, at 4:22 PM, Patrick Linskey wrote:
>>
>> > Hi,
>> >
>> > In the process of doing some concurrency-related work on  
>> OpenJPA, I've
>> > run across the need for a ReentrantReadWriteLock, akin to what  
>> is in
>> > Java 5's java.util.concurrent package, Emory University's
>> > edu.emory.mathcs.backport package, and Doug Lea's EDU.oswego.cs.dl
>> > package.
>> >
>> > Currently, OpenJPA has repackaged copies of some of the code from
>> > EDU.oswego.cs.dl, but not everything. I'd like to get rid of the
>> > repackaged copies, and move to the versions in
>> > edu.emory.mathcs.backport. According to Doug Lea's website, the
>> > backport classes are preferable to the EDU.oswego.cs.dl classes at
>> > this point.
>> >
>> > This change is independent of future changes to allow for  
>> pluggability
>> > of the concurrent implementation, and only impacts those classes  
>> that
>> > we are already directly repackaging.
>> >
>> > Thoughts?
>> >
>> > -Patrick
>> >
>> > --
>> > Patrick Linskey
>> > 202 669 5907
>>
>>
>
>
> -- 
> Patrick Linskey
> 202 669 5907