Please note: although this question mentions Angular and Spring Boot (Java), and it would be great to get an answer from someone with experience in that stack, I think this is more of an architectural question at heart and certainly doesn't require Angular or Java/Spring experience to answer it.
So, I am designing out a web app that I would like to consist of the following architecture:
- frontend web app (Angular) talks to a single RESTful backend web service (Java/Spring Boot)
- the backing web service itself talks to many other smaller services, databases, etc.
- the frontend web app serves up the UI and does all normal frontend stuff
- backend service houses business logic and other stuff that I don't want exposed to the frontend and ultimately browswer
In designing this out a scenario occurred to me that I can't figure out a good solution for, and wasn't sure what the generally-accepted options/solutions for it are.
Here is the scenario:
- A user is logged into the app and has their browser pointed to, say,
- An admin of the app decides they want to suspend the user for 30 days and does so through an admin web app (or by running a script, whatever). When suspended, users can log in but should be redirected to a "You've been suspended!" splash page, and should not be able to navigate anywhere else inside the app. Only when the suspension is lifted should they be able to resume using the app
The problem here is, unless the frontend web app makes a call to the backend web service on each and every page load/reload, and on each and every AJAX/asynchronous call from the browser that warrants the application doing anything meaningful, there is no way for the frontend web app to "know" that the user has been banned and to implement the correct redirection (to the suspension page mentioned above).
Obviously, if this happens while the user is logged out, it would be easy to have the web app to call the
GET user/state endpoint upon next login and determine if they are suspended or not. But if we want to have this suspension take effect while they are using the app, I'd have to add a call to that endpoint everywhere and that is nasty and smells.
So what are the common solution(s) here? How does the backend web service communicate changed state to a specific user logged in to the frontend web app? Websockets come to mind, but not sure if thats the right tool for the job as I have no concrete experience with them and am not sure if they apply for web service -> web app communication or just web app -> browser communication.
Thanks in advance for any and all help here!