public static synchronized String getKey() throws OkuyamaClientException {
		
		Long key = null;
		OkuyamaClient client = null;
		try {
			client = getClient();
			Object[] result = client.incrValue(OkuyamaKeyName.INCREMENT_KEY_MANAGER.getKeyName(), 1L);
			
			if (result[0].equals(true)) {
				key = (Long)result[1];
			}
			
			if (key == null) {
				throw new OkuyamaClientException("Fail to get key.");
			}
		} finally {
			if (client != null) {
				client.close();
			}
		}
		
		return key.toString();
	}