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

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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.