TCP/IP code based on boost asio synchronous/asynchronous

Hi All,

As a first step in our project, I need to use boost asio to build a communication protocol above the tcp/ip layer.
So I need to :
establish connection , send and receive messages synchronously and asynchronously.
In the Asynchronous case, I need to give the client a possibility to register his method so I called him back when I receive a message and I deliver to him the message.
something like:

handleEvent ( String Message)
{
}

I need your help to point me to some existing code in boost asio or a similar code that I can adapt it to boost asio lib.

Thanks,

B.T