Introduction

This is the second part of the previous article about the socket programming. In the earlier article we created a client but that client used to make blocking IO calls ( Receive ) to read data at regular intervals (via clicking the Rx button). But as I said in my earlier article, that model does not work very well in a real world application. Also since Windows is an events-based system, the application (client) should get notifications of some kind whenever the data is received so that client can read it rather than client continuously polling for data.

Well that is possible with a little effort. If you read the first part of this article, you already know that the Socket class in the Systems.Net.Sockets namespace has several methods like Receive and Send which are blocking calls. Besides there are also functions like BeginReceive , BeginSend etc. These are meant for asynchronous IO . For example , there are at least two problems with the blocking Receive:

When you call Receive function the call blocks if no data is present, the call blocks till some data arrives. Even if there is data when you made the receive call , you don't know when to call next time. You need to do polling which is not an efficient way.