Detect application version change on a single page application
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
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 ;)