.Net Framework Essentials

Distributed Components

A component technology should support distributed computing, allowing you to activate and invoke remote services, as well as services in another application domain.^[24] Distributed COM, or DCOM, is the wire protocol that provides support for distributed computing using COM. While DCOM is fine for distributed computing, it is inappropriate for the global cyberspace because it doesn’t work well in the face of firewalls and NAT software. Some other shortcomings of DCOM are expensive lifecycle management, protocol negotiation, and binary formats.

To eliminate or at least mitigate these shortcomings, .NET provides a host of different distributed support. The Remoting API in .NET allows you to use a host of channels, such as TCP and HTTP (which uses SOAP), for distributed computing. It even permits you to plug in your own custom channels, should you require this functionality. Best of all, since the framework is totally object-oriented, distributed computing in .NET couldn’t be easier. To show you how simple it is to write a distributed application in .NET, let’s look at an example using sockets, otherwise known as the TCP channel in .NET.

Distributed Hello Server

In this example, we’ll write a distributed Hello application, which outputs a line of text to the console whenever a client invokes its exposed method, SayHello( ). Since we’re using the TCP channel, we’ll tell the compiler that we need the definitions in the System.Runtime.Remoting and System.Runtime.Remoting.Channels.Tcp ...