Proxy servlet is just a simple servlet I deployed to
tomcat ROOT, which just forwards the requests and send responses back. Since the requests and responses available here they can be traced or even modified.
I have set up proxy server in firefox in network setting, I checked the option - use for all protocols. But after I shuted down the proxy servlet the page was still updated in the browser by regular ajax calls. So it look like that ajax is bypassing the proxy server.
Maybe I can try to disable firefox to access internet in firewall settings and see what happens then.