I read the boost asio http server example code (see http://www.boost.org/doc/libs/1_54_0/doc/html/boost_asio/example/cpp11/http/server/connection.cpp) and find the aut
This is done in order to make sure that connection object outlives the asynchronous operation: as long as the lambda is alive (i.e. the async. operation is in progress), the connection instance is alive as well.