code: function(app, opts) {
    opts = opts || {};
    this.app = app;
    this.channels = {};
    this.prefix = opts.prefix;
    this.store = opts.store;
    this.broadcastFilter = opts.broadcastFilter;
    this.channelRemote = new ChannelRemote(app);
  }
docs: Create and maintain channels for server local.
  
  ChannelService is created by channel component which is a default loaded
  component of pomelo and channel service would be accessed by `app.get('channelService')`.
  
  @class
  @constructor