static class MyDestinationDataProvider implements DestinationDataProvider {
    private DestinationDataEventListener eL;
    private HashMap<String, Properties> secureDBStorage = new HashMap<String, Properties>();

    public Properties getDestinationProperties(String ABAP_AS) {
        try {
            //read the destination from DB
            Properties p = secureDBStorage.get(ABAP_AS);

            if(p!=null) {
                //check if all is correct, for example
                if(p.isEmpty())
                    throw new DataProviderException(DataProviderException.Reason.INVALID_CONFIGURATION, "destination configuration is incorrect", null);

                return p;
                }

            return null;
            } catch(RuntimeException re) {
            throw new DataProviderException(DataProviderException.Reason.INTERNAL_ERROR, re);
        }
    }

    //An implementation supporting events has to retain the eventListener instance provided
    //by the JCo runtime. This listener instance shall be used to notify the JCo runtime
    //about all changes in destination configurations.
    public void setDestinationDataEventListener(DestinationDataEventListener eventListener) {
        this.eL = eventListener;
    }

    public boolean supportsEvents() {
        return true;
    }

    //implementation that saves the properties in a very secure way
    void changeProperties(String ABAP_AS, Properties properties) {
        synchronized(secureDBStorage) {
            if(properties==null) {
                if(secureDBStorage.remove(ABAP_AS)!=null)
                    eL.deleted(ABAP_AS);
            } else {
                secureDBStorage.put(ABAP_AS, properties);
                eL.updated(ABAP_AS); // create or updated
            }
        }
    }
} // end of MyDestinationDataProvider

//business logic
void executeCalls(String ABAP_AS) {
    JCoDestination dest;
    try {
        dest = JCoDestinationManager.getDestination(ABAP_AS);
        dest.ping();
        System.out.println("Destination " + ABAP_AS + " works");
    } catch(JCoException e) {
        e.printStackTrace();
        System.out.println("Execution on destination " + ABAP_AS + " failed");
    }
}

static Properties getDestinationPropertiesFromUI() {
    //adapt parameters in order to configure a valid destination
    Properties connectProperties = new Properties();
    connectProperties.setProperty(DestinationDataProvider.JCO_ASHOST, "XXX");
    connectProperties.setProperty(DestinationDataProvider.JCO_SYSNR,  "XX");
    connectProperties.setProperty(DestinationDataProvider.JCO_CLIENT, "XXX");
    connectProperties.setProperty(DestinationDataProvider.JCO_USER,   "XXX");
    connectProperties.setProperty(DestinationDataProvider.JCO_PASSWD, "XXX");
    connectProperties.setProperty(DestinationDataProvider.JCO_LANG,   "XX");
    createDestinationDataFile(ABAP_AS, connectProperties);
    return connectProperties;
}

static void createDestinationDataFile(String ABAP_AS, Properties connectProperties) {
    File destCfg = new File(ABAP_AS + ".jcoDestination");
    try {
        FileOutputStream fos = new FileOutputStream(destCfg, false);
        connectProperties.store(fos, "for tests only!");
        fos.close();
    } catch (Exception e) {
        throw new RuntimeException("Unable to create the destination files", e);
    }
}