Everything is handled by the application server behind the scene.
You don't have to worry about servlets or http requests.
You should read some stuff about web services and how they work, but in brief, web services are implemented as SOAP over HTTP. When you deploy a new web service to the server, it binds the service to some URL, and when some client access this URL the server dispatches the request to your code. The whole decoding process from SOAP/HTTP to java invocation is done by glassfish internally.
Hope that helps.
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