I am coding network stuff via tcp/ip.
Specifically I have been using boost::asio.
Recently, to ease coding, I started using boost::asio::ip::tcp::iostream.
It can be useful for fast developing! But I am not sure whether it uses async_read or async_write.
Does anybody know whether it does?
No it cannot. That's most of what makes it so simple.
However, you can force a full-duplex experience using boost::asio::ip::tcp::iostream with some tweaks. You'll need to run the reading/writing tasks on separate threads to achieve the parallellism without having asynchrony.
An examples of this - what I consider to be a - hack, is here:
How to avoid data race with `asio::ip::tcp::iostream`?
That answer does also give the asynchronous approach, so that may help remove the intimidation factor because you can simply compare side-by-side both approaches.