title: How to use libpqxx to receive notifications from the PostgreSQL database?
body: <p>I'm writing C++ applicatoin which needs to receive notifications for data changes from PostgreSQL through <a href="http://pqxx.org/development/libpqxx/" rel="nofollow">libpqxx</a> library. But it's <a href="http://pqxx.org/devprojects/libpqxx/doc/4.0/html/Tutorial/" rel="nofollow">tutorial</a> doesn't include such use case. The notifications must be received on multiple channels. Also I'm using <a href="http://www.boost.org/doc/libs/1_61_0/doc/html/boost_asio.html" rel="nofollow">boost::asio</a> as networking library and for me is preferable if possible to use <em>asio</em> socket classes with asynchronous callbacks for notification events instead of polling of raw BSD style sockets. Can someone provide sample code for this or links to some external resources for how this can be achieved?</p>