Sockets in C#.NET

Paint QR Code in C#.NET Sockets

Sockets are the most powerful networking mechanism available in .NET HTTP is layered on top of sockets, and in most cases WCF is too. Sockets provide more or less direct access to the underlying TCP/IP network services they effectively let you speak the native language of the network. This can offer some flexibility and performance benefits over HTTP-based communications, but the downside is that you need to do more work. Also, in corporate environments, communication with the outside world

with ad hoc use of sockets is often blocked, as firewalls may be configured to let through only the traffic they understand and expect. But in cases where those restrictions do not apply, and if the flexibility or (relatively small) performance benefits are worth the effort, sockets are a useful tool. The basic idea of a socket has been around for decades, and appears in many operating systems. The central concept is to present network communication through the same abstractions as file I/O. We already saw something like that with WebClient it can provide Stream support. However, those streams are concerned with the body of an HTTP request or response. With sockets, the streams are at a lower level, encompassing all the data. (If you used a socket-based stream to connect to a web server, you d see all of the details of the HTTP protocol in the stream, not just the body.) Besides the file-like abstraction, socket APIs also have a standard set of operations for establishing connections, and for controlling aspects of those connections behavior. To understand sockets, you need some familiarity with the network protocols they depend on, so as well as introducing the API features the next section incorporates a very quick overview of the TCP/IP family of protocols. If you already know TCP/IP, please feel free to skim through the next section and just look at the examples that illustrate usage.

Sockets can be used with some other protocols besides those in the TCP/ IP family. For example, you can use sockets for IrDA (Infrared) or Bluetooth communications to communicate with local devices. There are other network protocols too, but the TCP/IP family is the most widely used.

The Internet uses a family of protocols typically known collectively as TCP/IP. The lowest level is IP, which is short for Internet Protocol. This is the means by which all network traffic flows across the Internet when you buy an Internet connection, you re buying the ability to deliver information from your computer to the Internet, and vice versa, via IP. IP s main job is the ability to get packets (as individual messages are called in networking) of data between different computer networks (hence internet). For example, data sent by a web server in a data center out of its network port somehow needs to make its way to your home WiFi network. These networks are connected together by routers, whose job is to work out where to send IP packets next; there are well-defined rules for how they should do this, ensuring that data ends up at the machine it s meant for. This process depends on the IP address a number that identifies a machine in a way that makes it possible for routers to work out how to route messages to that machine.

If you re using sockets, you will need to work with IP addresses because they re how you identify the machine you d like to communicate with. You can typically just treat them as opaque identifiers, wrapped by the IPAddress class in the System.Net namespace. But there s one aspect of IP addressing that it s worth being aware of: the distinction between IPv4 and IPv6 addresses. See the sidebar below.