Basics of working with pipes in C# .NET part 4: basic conversation with messages

In this post we saw how a pipe stream client and server can send each other single bytes. In this post we managed to send a single message from the client to the server. It’s time to marry the two concepts. We’ll let the client and server start a conversation.

The server side code has nothing new compared to the posts referred to above:

private static void ConversationWithTheClient()
{
	using (NamedPipeServerStream namedPipeServer = new NamedPipeServerStream("test-pipe", PipeDirection.InOut,
		1, PipeTransmissionMode.Message))
	{
		Console.WriteLine("Server waiting for a connection...");
		namedPipeServer.WaitForConnection();
		Console.Write("A client has connected, send a greeting from the server: ");
		string message = Console.ReadLine();
		byte[] messageBytes = Encoding.UTF8.GetBytes(message);
		namedPipeServer.Write(messageBytes, 0, messageBytes.Length);

		string response = ProcessSingleReceivedMessage(namedPipeServer);
		Console.WriteLine("The client has responded: {0}", response);
		while (response != "x")
		{
			Console.Write("Send a response from the server: ");
			message = Console.ReadLine();
			messageBytes = Encoding.UTF8.GetBytes(message);
			namedPipeServer.Write(messageBytes, 0, messageBytes.Length);
			response = ProcessSingleReceivedMessage(namedPipeServer);
			Console.WriteLine("The client is saying {0}", response);
		}

		Console.WriteLine("The client has ended the conversation.");
	}
}

private static string ProcessSingleReceivedMessage(NamedPipeServerStream namedPipeServer)
{
	StringBuilder messageBuilder = new StringBuilder();
	string messageChunk = string.Empty;
	byte[] messageBuffer = new byte[5];
	do
	{
		namedPipeServer.Read(messageBuffer, 0, messageBuffer.Length);
		messageChunk = Encoding.UTF8.GetString(messageBuffer);
		messageBuilder.Append(messageChunk);
		messageBuffer = new byte[messageBuffer.Length];
	}		
	while (!namedPipeServer.IsMessageComplete);
	return messageBuilder.ToString();
}

Call ConversationWithTheClient from Main in the server console app. The client side code has a couple of new features:

private static void ConversationWithTheServer()
{
	using (NamedPipeClientStream namedPipeClient = new NamedPipeClientStream(".", "test-pipe", PipeDirection.InOut))
	{
		namedPipeClient.Connect();
		Console.WriteLine("Client connected to the named pipe server. Waiting for server to send the first message...");
		namedPipeClient.ReadMode = PipeTransmissionMode.Message;
		string messageFromServer = ProcessSingleReceivedMessage(namedPipeClient);
		Console.WriteLine("The server is saying {0}", messageFromServer);
		Console.Write("Write a response: ");
		string response = Console.ReadLine();
		byte[] responseBytes = Encoding.UTF8.GetBytes(response);
		namedPipeClient.Write(responseBytes, 0, responseBytes.Length);
		while (response != "x")
		{
			messageFromServer = ProcessSingleReceivedMessage(namedPipeClient);
			Console.WriteLine("The server is saying {0}", messageFromServer);
			Console.Write("Write a response: ");
			response = Console.ReadLine();
			responseBytes = Encoding.UTF8.GetBytes(response);
			namedPipeClient.Write(responseBytes, 0, responseBytes.Length);
		}
	}
}

private static string ProcessSingleReceivedMessage(NamedPipeClientStream namedPipeClient)
{
	StringBuilder messageBuilder = new StringBuilder();
	string messageChunk = string.Empty;
	byte[] messageBuffer = new byte[5];
	do
	{
		namedPipeClient.Read(messageBuffer, 0, messageBuffer.Length);
		messageChunk = Encoding.UTF8.GetString(messageBuffer);
		messageBuilder.Append(messageChunk);
		messageBuffer = new byte[messageBuffer.Length];
	}
	while (!namedPipeClient.IsMessageComplete);
	return messageBuilder.ToString();
}

The “.” in the constructor indicates the local machine. There’s no NamedPipeClientStream constructor where you can only set the pipe name and the pipe direction. The pipe transmission mode can be set after the NamedPipeClientStream has been constructed using the ReadMode property.

Call ConversationWithTheServer from Main of the client console application. Run both apps and you can start a simple conversation like this:

Pipe stream simple conversation

Read the next part here.

View the list of posts on Messaging here.

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About Andras Nemes
I'm a .NET/Java developer living and working in Stockholm, Sweden.

2 Responses to Basics of working with pipes in C# .NET part 4: basic conversation with messages

  1. Michal says:

    thanks a lot, finally easy to understand explanation of how named pipes works

  2. Matt says:

    I think there may be a bug: Since UTF8 can have multiple bytes in a character, it seems the byte buffer might end with an incomplete character when you try to decode it (and the next read would begin with a continuation character which can’t be decoded).

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