old_contents: var Camera = function (a) {
    var that = this;
    var a = a || {};
    this.divID = a.divID || 'camera';
    this.unsubscribe = function () {
      if (that.viewer == null) {
        return;
      }
      document.getElementById(that.divID).removeChild(that.viewer);
    };
    this.subscribe = function () {
      if (that.viewer == null) {
        that.viewer = document.createElement('img');
        that.viewer.setAttribute('src',"http://"+location.hostname+":8081/stream?topic=/camera/rgb/image_color");
      }
      document.getElementById(that.divID).appendChild(that.viewer);
    };
  }
  //<img src="http://localhost:8081/stream?topic=/camera/rgb/image_color" alt="http://localhost:8081/stream?topic=/camera/rgb/image_color">
  
new_contents: var Camera = function (a) {
    var that = this;
    var a = a || {};
    this.divID = a.divID || 'camera';
    this.unsubscribe = function () {
      if (that.viewer == null) {
        return;
      }
      document.getElementById(that.divID).removeChild(that.viewer);
      that.viewer == null;
    };
    this.subscribe = function () {
      if (that.viewer == null) {
        that.viewer = document.createElement('img');
        that.viewer.setAttribute('src',"http://"+location.hostname+":8081/stream?topic=/camera/rgb/image_color");
      }
      document.getElementById(that.divID).appendChild(that.viewer);
    };
  }
  //<img src="http://localhost:8081/stream?topic=/camera/rgb/image_color" alt="http://localhost:8081/stream?topic=/camera/rgb/image_color">
  
subject: fix delay camera