Q:

Showing alerts when Meteor user is updated

I am working on a Meteor application. Occasionally, the server updates the current user with data from an external database. When that happens, I would like to display an alert on whatever page of the application is open on client side. I know the Meteor.user gets updated automatically on the client, but I am clueless as to how and where to get the application to monitor the user for changes and react to them. Any ideas on this?
The user update is triggered via a post to the server:
Router.map(function() {
this.route('/reload_user', {where: 'server'}).post(function() {
    var data = this.request.body;
    var user = Meteor.users.findOne({ "profile.id": data.id });

    var data = Account.getAccountInfo(apiKey, secretKey);           
    Meteor.users.update(user._id, {
        $set: {
            "profile.paywall": data.paywall,
        }
    });
    this.response.end();
});

A:

On the server side, you want to expose a publication for the user collection. On the client, you want to auto subscribe to that publication and handle the changed event:
Meteor.autosubscribe(function() {
  Meteor.users.find().observe({
    changed: function(item) {
      alert(item);
    }
  });
});

