Meteor.publish('posts', function (options) {
  // It would probably be safer to pass sort and limit as 2 separate params.
  check(options, {
    sort: Object,
    limit: Number
  });
  return Posts.find({}, options);
});

Meteor.publish('singlePost', function (postId) {
  check(postId, String);
  return Posts.find(postId);
});

Meteor.publish('comments', function (postId) {
  check(postId, String);
  return Comments.find({
    postId: postId
  });
});

Meteor.publish('notifications', function () {
  return Notifications.find({
    userId: this.userId,
    read: false
  });
});