[smila-dev] BinaryStorage JPA Implementation

[<Daniel.Stucky@xxxxxxxxxxx>]

Hi all,

I have added a BinaryStorage persistence implementation based on
EclipseLink with JPA and updated
http://wiki.eclipse.org/SMILA/Documentation/Binary_Storage. There are 2
new bundles you have to check out:
- eclipse.smila.binarystorage.persistence.jpa
- eclipse.smila.binarystorage.persistence.jpa.test

To use the JPA implementation just set
implementationClass="org.eclipse.smila.binarystorage.persistence.jpa.JPA
BinaryPersistence" in file
org.eclipse.smila.binarystorage.impl/BinaryStorageConfiguration.xml. 

The JPA implementation comes with its own configuration file
org.eclipse.smila.binarystorage.persistence.jpa/persistence.properties.
All configuration options (except implementationClass) of
BinaryStorageConfiguration.xml are not used !

I propose to change this configuration, as configuration of different
implementations may vary highly (we can see this now as the JPA
configuration has nothing in common with io or EFS). Each persistence
bundle should have its own configuration file (as we did it with other
bundles, too) and the BinaryStorage service should not need to pass it's
configuration file to the persistence layer, as it only needs to know
what persistence implementation to use.


I compared the JPA implementation to our default configuration
(IOHierarchicalManager with a pathDepth of 2). 
The JPA implementation was a little faster (no real magnitude) but it
consumed about 60% more memory (in this case about 100 MB more). The
disk space used was almost identical, but cleaning up the JPA
implementation is way faster (no file hierarchy to delete).


Feedback is most welcome.

Bye,
Daniel