Can the DB Alias be changed dynamically?

[Joss Wright <jo...@talk21.com>]

I am using OJB and HSQLDB in a web application. I would like to store my
HSQLDB files in the WEB-INF folder of the web application, without having to
define the whole path in the repository.xml file, just the database name.

I put OJB.properties in my WEB-INF/class folder so I use the class loader to
get the path to the OJB.properties file, then chop off the
class/OJB.properties part of the path to get the path to my WEB-INF
directory, e.g.:

	C:/Documents and Settings/My Documents/My Workspace/My WebApp/WEB-INF/

I then want to add this to the default dbalias defined in the
repository.xml, e.g. file to give:

	C:/Documents and Settings/My Documents/My Workspace/My
WebApp/WEB-INF/my-database

Then I'd like to create my PersistenceBroker with the dynamically defined
dbalias. The reason for this is that I can move my web application around
from server to server without having to redefine the path each time, just
the name.

I use the ServiceLocator pattern to return a PersistenceBroker and thought I
could do the following.

repository.xml:

	<jdbc-connection-descriptor
		jcd-alias="my-database"
   		default-connection="true"
   		platform="hsqldb"
   		jdbc-level="2.0"
   		driver="org.hsqldb.jdbcDriver"
   		protocol="jdbc"
   		subprotocol="hsqldb"
   		dbalias="my-database"
   		username="sa"
   		password="">
	...
	</jdbc-connection-descriptor>

ServiceLocator:

	public PersistenceBroker getPersistenceBroker() throws
ServiceLocatorException {
		PersistenceBroker broker = null;
		try {
			JdbcConnectionDescriptor descriptor = getDefaultDescriptor(); // see
getDefaultDescriptor() below
			if (descriptor != null) {
				// Get the path of OJB.properties
				StringBuffer path = new StringBuffer(

descriptor.getClass().getClassLoader().getResource("OJB.properties").getPath
());
				path = path.delete(path.indexOf("OJB.properties"), path.length());
				String separator = path.substring(path.length()-1);
				path = path.deleteCharAt(path.length()-1);
				path = path.delete(path.lastIndexOf(separator)+1, path.length());
				path = path.append(descriptor.getDbAlias());
				descriptor.setDbAlias(path.toString());
			}
			broker = PersistenceBrokerFactory.createPersistenceBroker(new
PBKey(descriptor.getJcdAlias(),
				descriptor.getUserName(), descriptor.getPassWord()));
			return broker;
		} catch (PBFactoryException e) {
			throw new ServiceLocatorException(
				"PBFactoryException occurred while getting default PeristenceBroker in
ServiceLocator.", e);
		}
	}

	private JdbcConnectionDescriptor getDefaultDescriptor() {
		List descriptors =
MetadataManager.getInstance().connectionRepository().getAllDescriptor();
		for (Iterator i = descriptors.iterator(); i.hasNext(); ) {
			JdbcConnectionDescriptor descriptor =  (JdbcConnectionDescriptor)
i.next();
			if (descriptor.isDefaultConnection()) {

MetadataManager.getInstance().connectionRepository().getDescriptor(descripto
r.getPBKey());
				return descriptor;
			}
		}
		return null;
	}

However my call to descriptor.setDbalias(path) does not set the new dbalias.
Do I have to somehow save the JdbcConnectionDescriptor back to the
ConnectionRepository, or can I not intermix part pre-defined values with
dynamic values, i.e. do I have to create my JdbcConnectionDescriptor
completely dynamically.

Any help would be much appreciated,

Joss Wright
PS: I have studied all examples in the mail list and JavaDoc, already.
That's how I got this far!


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