CPPSERV is C++ Servlet Engine. It provides Servlet-like API to C++ programmers. This allows them to write small, extremely efficient web applications, with an ease that was only available to Java programmers. At the same time it provides greatest flexibility - since one can use any of the C and C++ libraries, which still outnumber anything available to other languages.
CPPSERV does not provide exactly the same API as Sun's Java Servlet API, but tries to follow its philosophy instead. E.g. ServletRequest::getOutputStream() returns std::ostream-derived object, which does not provide print() and println() functions.
CPPSERV also contains CSP (C++ Server Pages) parser. This allows for JSP-like functionality, although in case of CPPSERV, CSPs are not compiled at run time, but have to be pre-compiled at application deployment time instead. The parser was imported from CXXSP project, which is similar in goals and has very similar public API, but uses different approach to implementation. While CPPSERV is a separate process with front-end web servers talking to it through socket, CXXSP is a purely Apache module.