After my previous simple article in introduction and preliminary of .NET remoting, now let’s get coding, cause quite often that the code makes us more understand about some concepts than a thousand of words.
We will make a simple, cannonical program, call this ‘hello world’ program that executed remotely, the program consist of, at least, three portions, server, remotable object, and client.
The server and client communicate through a channel, and when a request for a remote object come the proxy is created, this proxy will acts as if remote object.
An important thing here that we will try not distributed all of the implementation, but give the clients an interface (or abstract base class that in some cases behaves like interface). So here we define an interface for the remote object, the code will look like this :
// IRemoteObject.cs
using System;
namespace SimpleLibrary
{
public interface IRemoteObject
{
string HelloWorld();
}
}
Compile the above program : csc /t:library IRemoteObject.cs
Put IRemoteObject.cs in a folder and named this folder as ‘Server’.
Next step is let’s write the implementation of IRemoteObject, the important note here is that implementation will reside in server, because distributes the full implementation are often bad ideas, why? first, that make the aims of distributed programming futile, second, distributes full implementation will take us in more problem of versioning, third distribute full library implementation make possible to disassembly the library using disassembler tools (ie. ildasm), and more reasons that ensure us to give the client program only what they need, I mean as much as possible give the interfaces not implementations.
The implementation is quite simple, of course because this is a ‘hello world’ program, remember this is first maneuver :
// SimpleLibrary.cs
using System;
namespace SimpleLibrary
{
public class RemoteObject : MarshalByRefObject, IRemoteObject
{
public RemoteObject()
{
Console.WriteLine(“RemoteObject.ctor()”);
}
public string HelloWorld()
{
return “Hello, world!!!”;
}
}
}
Compile the above program : csc /t:library SimpleLibrary.cs
Next lets build an host application for that program :
//Puts the following code in folder that was created (Server), and named Server.cs //csc /r:IRemoteObject.dll,SimpleLibrary.dll Server.cs
using System;
using System.Runtime.Remoting;
using System.Runtime.Remoting.Channels;
using System.Runtime.Remoting.Channels.Http;
using SimpleLibrary;
namespace ServerSide
{
class Server
{
static void Main()
{
HttpChannel chnl = new HttpChannel(8888);
ChannelServices.RegisterChannel(chnl);
RemotingConfiguration.RegisterWellKnownServiceType(
typeof(RemoteObject),
“first.rem”,
WellKnownObjectMode.SingleCall
);
// keeps the server running until key press
Console.ReadLine();
}
}
}
Now, the next is build the client that will consume our remote object, for simplicity we will build the client as console application, but we can build the client on the other form (ie. WinForms, with some modifications). Create a folder and named it Client, put the Client.cs (code that will consume remote object). But before go through the client code we need to copy the IRemoteObjcet.dll to the Client folder.
// Client.cs [csc /r:IRemoteObject.dll Client.cs]
using System;
using System.Runtime.Remoting;
using System.Runtime.Remoting.Channels;
using System.Runtime.Remoting.Channels.Http;
using SimpleLibrary;
namespace ClientSide
{
class Client
{
static void Main()
{
IRemoteObject remObj = (IRemoteObject) Activator.GetObject(typeof(IRemoteObject), “http://localhost:8888/first.rem”);
Console.WriteLine(remObj.HelloWorld());
}
}
}
To run the programs, open a command prompt that point to the location where the server.exe resides (in the above example inside Server folder), simply write Server.exe and run it.
Open the other command prompt that point to the location of client.exe (in example in Client folder), write client.exe and run it.
The important thing to be noted here is that the server must run first before the client, or we will get an exception.
Well, the simple ‘hello world’ remoting program has accomplished…
Read, With the Name of Your Lord Who Created 