[Embedlets-dev] Persistence Check in

[Christopher S. <cs...@oo...>]

After taking some time to feed the family I put some work into the
persistence model.

I have a working  PersistentContainer (OutpostContainer subclass) that gets
loaded from an XML file, creates the services defined in the XML file and
then starts up.


I will be following up with some mode documentation and sample components,
but wanted to get it archived at a plateau and visible for feedback so I
checked it in under the 'Persistence tag'. Please check it out and give me
some feedback good or bad.

This required a number of new interfaces and classes as you might of
expected. I made every effort leave the existing classes intact and only had
to change a couple of exposure levels to public in order to subclass the
various objects and add a few 'setter' methods.

Andrzej please forgive the minor trespasses.

The core concept is the persistence.Persistent and persistence.Properties
interfaces that allow classes to be saved and restored from a variety of
persistent or transient stores. In this case the store is an XML file which
is controlled by the XMLProperties class and XMLPersistenceManager. In a
remotely controlled model the 'store' is a TCP/IP stream. I am converting an
example of this from the OPC components code.

Another important class is the PersistentCollection that provides
aggregation for other Persistent objects, thus supporting the object tree.

References between classes are defined by the href="Identity" attribute

The first cut applies a persistence interface to the Context objects that
Andrzej created. This is done by sub classing the particular Context class
as org.outpost.persistence.PersistentXxxxxContext and implementing the
org.embedlet.persistence.Persistent interface to support loading the
contexts.

I used a small class (org.outpost.persistence.xml.Launcher) to start things
off and create the Container and its services from the persistence source at
run time. This will allow us to use several launch modes and persistence
media with the same container rather than requiring a different container
for each.

To try things out:

1. Update using the tag Persistent
2. Copy the org/outpost/persistence/xml/kxml-min.jar to the outpost/lib
folder. This the parser that I used.
2. Recompile embedlets and outpost using the make.compile
4. Run:
	java -cp
yourClasspath -DConfigFile=YourSrcFolder\org\outpost\persistence\config.xml
org.embedlet.persistence.xml.Launcher

5. It should load and run the container and its services.

I have created three sample components:  a timer, a toggle and a counter.
These will be started with the container on the next go around.

Chris

Christopher Smith
OopScope, LLC.
www.oopscope.com
cs...@oo...
805-276-0598