领域服务,应用服务,领域方法的问题

//应用服务
public class WithDrawFacade {

	public void execute(String acctNo, double amt) throws Exception {

		Repository.beginTransaction();
		Account acct = (Account) Repository.load(Account.class, acctNo);
		// 创建领域服务
		WithDrawService oper = ServiceFactory.createWithDrawOperation(acctNo,
				"90001");
		WithDrawRecord rec = (WithDrawRecord) oper.execute(acct, amt);
		Repository.save(Account.class, acct);
		Repository.save(WithDrawRecord.class, rec);
		Repository.commitTransaction();

	}

}


//领域服务
public class WithDrawService extends Service {

	public Object execute(Account acct, Account cashAcct, double amt)
			throws Exception {
		// 限额判断
		for (LimitRule limit : this.limits) {
			limit.applyRules(amt);
		}
		// 手续费处理
		double f = (Double) fee.applyRules(amt);
		// 创建取款记录
		WithDrawRecord rec = new WithDrawRecord(amt, (acct.getAcctNo()));
		rec.setTransfee(f);
		records.add(rec);
		// 支付
		acct.debit(amt);// 领域方法
		cashAcct.credit(amt);// 领域方法
		return rec;
	}

}