I'm just curious - we have a Servlet and its subclasses like HttpServlet. The latter one is about 99% of all the Servlets implemented.
My question is: what about the missing 1%? What are those Servlets? Do you know any real-life examples of Servlets which works on different protocol than HTTP?
Secondly, there is a JspContext and PageContext. The latter one is used in Servlet environment and is quite popular.
The question is similar to the first one: do you know any real-life examples of JSPs and ELs used in different environment than Servlets? What environment could it be?
Regarding Servlet and HTTP Servlet question, I can think of other protocols like SMTP or FTP. For these protocols, you can implement Servlet interface or extend GenericServlet to provide FTP specific protocol implementation.