code: @Override
      public int write2DB() throws VMException {
          try {
              VmIdJpaController controller = new VmIdJpaController(
                      getEntityManagerFactory());
              VmId vmId;
              if (getId() == null) {
                  vmId = new VmId();
                  update(vmId, this);
                  controller.create(vmId);
                  setId(vmId.getId());
              } else {
                  vmId = getEntity();
                  update(vmId, this);
                  controller.edit(vmId);
              }
              update();
              return getId();
          }
          catch (Exception ex) {
              LOG.log(Level.SEVERE, null, ex);
              throw new VMException(ex);
          }
      }
docs: write to db