How to manage the session.

[alexliyu7352]

I did not found any code to manage the session of client.
In most time when we make a server, we should need session for two-way communication.
But I did not know how should do it with wangle.
e.g. sometimes I will send some message to the one client which is use keepalive, and I do not want to do this things like (receive message from client---->server send message), I want the server could direct send message to client in anytime to client.
Could you give me some best tips?