Logging transactions in the new vdmspace

As a follow-up to the previous post about vdmspace, I've implemented a simple SpaceWriter TransactionParticipant that can be used to log all transaction contexts to the highly reliable VoldemortSpace (vdm:space). It can be added to your transaction flow like this:

The code looks like this:

package org.jpos.transaction;

import java.io.Serializable;
import org.jpos.space.Space;
import org.jpos.space.SpaceFactory;
import org.jpos.core.Configurable;
import org.jpos.core.Configuration;
import org.jpos.core.ConfigurationException;

public class SpaceWriter implements AbortParticipant, Configurable {
    Space sp;
    String prefix;
    Configuration cfg;
    public int prepare (long id, Serializable o) {
        return PREPARED | READONLY;
    }
    public int prepareForAbort (long id, Serializable o) { 
        return PREPARED | READONLY;
    }
    public void commit (long id, Serializable o) { 
        outContext (id, (Context) o);
    }
    public void abort  (long id, Serializable o) { 
        outContext (id, (Context) o);
    }
    private void outContext (long id, Context ctx) {
        if (sp == null)
            sp = SpaceFactory.getSpace (cfg.get ("space", null));
        sp.out (prefix + Long.toString (id), ctx);
    }
    public void setConfiguration (Configuration cfg) {
        this.cfg = cfg;
        prefix = cfg.get ("prefix", "");
    }
}

You can add this participant to the very end of your transaction flow. All persistent entries in your Context would get stored.