Source: actionlib/ActionClient.js

/**
 * @fileOverview
 * @author Russell Toris - rctoris@wpi.edu
 */

var Topic = require('../core/Topic');
var Message = require('../core/Message');
var EventEmitter2 = require('eventemitter2').EventEmitter2;

/**
 * An actionlib action client.
 *
 * Emits the following events:
 *  * 'timeout' - if a timeout occurred while sending a goal
 *  * 'status' - the status messages received from the action server
 *  * 'feedback' -  the feedback messages received from the action server
 *  * 'result' - the result returned from the action server
 *
 *  @constructor
 *  @param options - object with following keys:
 *   * ros - the ROSLIB.Ros connection handle
 *   * serverName - the action server name, like /fibonacci
 *   * actionName - the action message name, like 'actionlib_tutorials/FibonacciAction'
 *   * timeout - the timeout length when connecting to the action server
 */
function ActionClient(options) {
  var that = this;
  options = options || {};
  this.ros = options.ros;
  this.serverName = options.serverName;
  this.actionName = options.actionName;
  this.timeout = options.timeout;
  this.omitFeedback = options.omitFeedback;
  this.omitStatus = options.omitStatus;
  this.omitResult = options.omitResult;
  this.goals = {};

  // flag to check if a status has been received
  var receivedStatus = false;

  // create the topics associated with actionlib
  var feedbackListener = new Topic({
    ros : this.ros,
    name : this.serverName + '/feedback',
    messageType : this.actionName + 'Feedback'
  });

  var statusListener = new Topic({
    ros : this.ros,
    name : this.serverName + '/status',
    messageType : 'actionlib_msgs/GoalStatusArray'
  });

  var resultListener = new Topic({
    ros : this.ros,
    name : this.serverName + '/result',
    messageType : this.actionName + 'Result'
  });

  this.goalTopic = new Topic({
    ros : this.ros,
    name : this.serverName + '/goal',
    messageType : this.actionName + 'Goal'
  });

  this.cancelTopic = new Topic({
    ros : this.ros,
    name : this.serverName + '/cancel',
    messageType : 'actionlib_msgs/GoalID'
  });

  // advertise the goal and cancel topics
  this.goalTopic.advertise();
  this.cancelTopic.advertise();

  // subscribe to the status topic
  if (!this.omitStatus) {
    statusListener.subscribe(function(statusMessage) {
      receivedStatus = true;
      statusMessage.status_list.forEach(function(status) {
        var goal = that.goals[status.goal_id.id];
        if (goal) {
          goal.emit('status', status);
        }
      });
    });
  }

  // subscribe the the feedback topic
  if (!this.omitFeedback) {
    feedbackListener.subscribe(function(feedbackMessage) {
      var goal = that.goals[feedbackMessage.status.goal_id.id];
      if (goal) {
        goal.emit('status', feedbackMessage.status);
        goal.emit('feedback', feedbackMessage.feedback);
      }
    });
  }

  // subscribe to the result topic
  if (!this.omitResult) {
    resultListener.subscribe(function(resultMessage) {
      var goal = that.goals[resultMessage.status.goal_id.id];

      if (goal) {
        goal.emit('status', resultMessage.status);
        goal.emit('result', resultMessage.result);
      }
    });
  }

  // If timeout specified, emit a 'timeout' event if the action server does not respond
  if (this.timeout) {
    setTimeout(function() {
      if (!receivedStatus) {
        that.emit('timeout');
      }
    }, this.timeout);
  }
}

ActionClient.prototype.__proto__ = EventEmitter2.prototype;

/**
 * Cancel all goals associated with this ActionClient.
 */
ActionClient.prototype.cancel = function() {
  var cancelMessage = new Message();
  this.cancelTopic.publish(cancelMessage);
};

module.exports = ActionClient;