I would like to know if there is (and how can I) develop an application that is made up of several other applications and to access these other parts of the application I need to be logged in.
Do I believe that this concept is linked to microservices or am I mistaken? Is it possible to develop this interceptor that will check logins on the projects running on these ports?
Splitting an application into smaller ones is part of the concept of microservices, but that's not all. There are several definitions, but one important thing is that each microservice must reflect a relevant aspect of the system.
Communication between services is usually done using HTTP and some higher level protocol. It can be an ad hoc with REST and even JSON or something more elaborate like Google Protobuf.
When authenticating, you might want to study theAuth and look for some implementation of Single Sign-On (SSO). There are a number of ways to implement this, and there are a few ready-made frameworks (I remember Josso , but it's been a while, there must be something better today.)
The basic operation looks something like this:
But, remembering, all this can be abstracted. There are even some services available on the internet that you can use if you want more productivity to focus on the business and not waste time creating your own solution, such as Auth0 .
A common technique in microservices is to create a "façade" service containing the entire external API of your application. It may be responsible for authenticating and authorizing each request. So you do not have to expose each service on the internet on different ports and the implementation of the microservices is transparent to the customers.
