Running an app server for a long time and redeploy apps to it is just one of them. To be honest, rarely used nowadays.
Many Jakarta EE products support:
* deploying apps on startup, just like Tomcat * bundling the server into a self-contained app, just like what SpringBoot does with Tomcat * running an app from command line, which Tomcat doesn't support - you have to drop the app into a predefined directory, SpringBoot doesn't support it either - the only option is to bundle the app and the server together during build
Some app servers are very lean, start in seconds, just like SpringBoot. Yeah, Tomcat starts faster, but only with a small app. If you add more libraries, you'd likely get to the same startup speed as SpringBoot or Embedded GlassFish.
I think the perception that JEE means big app servers where you deploy multiple apps and rarely restart the server, is very outdated. Nobody really uses Jakarta EE like that anymore. In fact, Jakarta EE is just APIs, the implementation can vary. Quarkus and Embedded GlassFish are perfect examples. Quarkus, although not fully Jakarta EE, can even build apps to native binaries. And Embedded GlassFish can run the same apps designed to run on app servers, on command line, without any installation of an app server.