JPA in Web Tier: Up from Little-G, or Down from Java EE 5 Certified?

[Doug Reeder <re...@gmail.com>]

I have a small web application which uses JPA from the web tier (i.e.  
I don't use any EJB).   The Java application server needs to run with  
as small a memory footprint as possible, since it will run on a VPS  
with only 96 MB of memory.

The question is: Is it easier to start with Little-G and add the  
necessary components, or start with the Java EE 5 Certified  
configuration and disable unnecessary services?

Little-G appears to come configured to support JTA transactions, but  
not JPA.  There's a plugin for "Application-Managed JPA" at www.geronimoplugins.com 
, but this only supports TopLink and RESOURCE_LOCAL transactions,  
unlike the OpenJPA and JTA support in the Java EE 5 Certified  
configuration.   Is there documentation on how OpenJPA  was integrated  
into the Java EE 5 Certified configuration?  I haven't found anything  
at openjpa.apache.org nor cwiki.apache.org.

Re: JPA in Web Tier: Up from Little-G, or Down from Java EE 5 Certified?

[Kevan Miller <ke...@gmail.com>]

On Oct 28, 2008, at 11:55 PM, Doug Reeder wrote:

> I have a small web application which uses JPA from the web tier  
> (i.e. I don't use any EJB).   The Java application server needs to  
> run with as small a memory footprint as possible, since it will run  
> on a VPS with only 96 MB of memory.
>
> The question is: Is it easier to start with Little-G and add the  
> necessary components, or start with the Java EE 5 Certified  
> configuration and disable unnecessary services?
>
> Little-G appears to come configured to support JTA transactions, but  
> not JPA.  There's a plugin for "Application-Managed JPA" at www.geronimoplugins.com 
> , but this only supports TopLink and RESOURCE_LOCAL transactions,  
> unlike the OpenJPA and JTA support in the Java EE 5 Certified  
> configuration.   Is there documentation on how OpenJPA  was  
> integrated into the Java EE 5 Certified configuration?  I haven't  
> found anything at openjpa.apache.org nor cwiki.apache.org.

Neither? ;-) Well, definitely not by disabling services in an EE 5  
server.

You should first create a plugin for your web application. Using this  
plugin you can then create a custom server assembly using several  
mechanisms:

1) build a customized server using maven and the car-maven-plugin -- http://cwiki.apache.org/GMOxDOC21/plugin-infrastructure.html#Plugininfrastructure-Assemblingaserverusingmaven 
.

2) Generate a server from an existing server -- http://cwiki.apache.org/GMOxDOC21/plugin-infrastructure.html#Plugininfrastructure-Extractingaserverfromanexistingserver 
.

3) Starting from a framework or minimal server and install the  
application plugin (and any associated dependencies, e.g. JPA)

--kevan