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Showing posts from September, 2015

Displaying progress of Spring application startup in web browser

When you restart your enterprise application, what do your clients see when they open the web browser?

They see nothing, server doesn't respond yet so web browser displays ERR_CONNECTION_REFUSED

Web proxy (if any) in front of your application notices that it's down and display "friendly" error message

The website takes forever to load - it accepted socket connection and HTTP request but waits with response until application actually boots up

Your application is scaled out so that other nodes quickly pick up requests and no one notices (and session is replicated anyway)

...or the application is so fast to start that no one notices any disruption (hey, plain Spring Boot Hello world app takes less than 3 seconds from hitting java -jar ... [Enter] to start serving requests). BTW check out SPR-8767: Parallel bean initialization during startup.

It's definitely better to be in situation 4. and 5., but in this article we'll cover more robust handling of situations 1.…