Detect application version change on a single page application

Question

today a question was raised here and I don't have an evident answer.

Assume that we concatenate and minify all resource files (CSS and Javascript) and declare them in the "Master-Page".

On a multi-page app, if a CSS file changes it will be recharged on the next full page load.

On a single-page app, the user can keep working for days and never recharge the main page where the CSS files are declared. The user will never see the changes until a Ctrl-F5 is issued.

I'm sure someone already thought of this and have an experience to share :)

For me, using WebSockets is not an option. First because it's overkill and second because not all my clients support the technology. Same reason applies to all WebSockets fallbacks... I won't keep hitting my servers because of this.

So, any ideas anyone? :)

BTW, we're using AngularJS if that can help for a specific solution.

Thanks!

Answer 1

I've getting through this same problem. My solution which is opiniated and may not respond to your criterias :

When i package my front-app and my server-app, I share a configuration file containing the current version of the front-app.

Front side : 75% of my routes change implicitely call a Webservice (route change resolve). SO each time I call my server I include a custom HTTP header (or a GET/POST param) containing the client version of the front-app.

Server side : I compare the front-app version (the one in the browser of the user, loaded last time user refreshed/loaded the SPA) with the front-app version of the shared configuration file :

• If version matches : I Do nothing.
• If version don't match I send a custom HTTP status error code (418 for example)

Then front side: I added a response Interceptor that intercepts any 418 error code and do a force-refresh of the whole app

That's it. Basically the event that "check" if the front-app version is the latest is a route change (that calls a WS via ajax). But you could add some infinite $interval calling a dedicated WS each 5 minutes or so... I can add some code if needed.

Hope this helps ;)

Answer 2

Assuming that you are using AngularJS' routing via $route service and provider, then you can use $routeChangeSuccess event to perform a server request if there are significant changes that needs to be changed; if there are any then you can do a window.location.reload() to refresh the page and get all the updated resources and htmls.

The following process can be changed depending on how you want to implement it:

1. Setup a config file in your server indicating the app's version. You may also choose to assign different versions for different files but since you have concatenated all your resource files then I guess you may limit your version options in your configuration.

2. Create a service that contains all the necessary information(versions of files from the server) and methods to perform a server request to your server to check against the current file versions stored in the service.

3. Use $routeChangeSuccess event to perform a server request using the service that you have created in step 2, if the request returned a valid confirmation that there were changes then do the force page reload via window.location.reload().