Allow from a webpage and get immediate response

I am new in J2EE. Can anyone tell me:

1. What is one way to allow from a web page to start a long running server process but get an immediate response back?
2. Why are HTML checkboxes sometimes problematic for managing true/false val开发者_C百科ues via form submissions?

Thanks in advance

1) It's called comet. This takes considerable resources because of the number of connections the server must keep open. This also sticks users to one server.

2) Programmer error.