content: /*
   * Copyright 1999-2018 Alibaba Group Holding Ltd.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package com.alibaba.csp.sentinel.transport;
  
  /**
   * The heartbeat sender which is responsible for sending heartbeat to remote dashboard
   * periodically per {@code interval}.
   *
   * @author leyou
   * @author Eric Zhao
   */
  public interface HeartbeatSender {
  
      /**
       * Send heartbeat to Sentinel Dashboard. Each invocation of this method will send
       * heartbeat once. Sentinel core is responsible for invoking this method
       * at every {@link #intervalMs()} interval.
       *
       * @return whether heartbeat is successfully send.
       * @throws Exception if error occurs
       */
      boolean sendHeartbeat() throws Exception;
  
      /**
       * Default interval in milliseconds of the sender. It would take effect only when
       * the heartbeat interval is not configured in Sentinel config property.
       *
       * @return default interval of the sender in milliseconds
       */
      long intervalMs();
  }
  