PLEASE Help me Understand EXAMPLE for RunAsClient RRS feed

  • Question

  • Hi All,

    I downloaded the example code for NamedPipeServerStream.RunAsClient from the MS docs:


    I must be missing something. It hangs at pipeServer.WaitForConnection();

    Can anyone clue me in?


    using System; using System.IO; using System.IO.Pipes; using System.Text; using System.Threading; // EXAMPLE from there :> // https://docs.microsoft.com/en-us/dotnet/api/system.io.pipes.namedpipeserverstream.runasclient?view=net-5.0 public class PipeServer { private static int numThreads = 4; public static void Main() { int i; Thread[] servers = new Thread[numThreads]; Console.WriteLine("\n*** Named pipe server stream with impersonation example ***\n"); Console.WriteLine("Waiting for client connect...\n"); for (i = 0; i < numThreads; i++) { servers[i] = new Thread(ServerThread); servers[i].Start(); } //Thread.Sleep(250); Thread.Sleep(2000); Console.WriteLine("Client threads started for {0} threads.", numThreads); while (i > 0) { for (int j = 0; j < numThreads; j++) { if (servers[j] != null) { //if (servers[j].Join(250)) if (servers[j].Join(3000)) { Console.WriteLine("Server thread[{0}] finished.", servers[j].ManagedThreadId); servers[j] = null; i--; // decrement the thread watch count } else Console.WriteLine("Client thread {0} running ...", servers[j].ManagedThreadId); } } } Console.WriteLine("\nServer threads exhausted, exiting."); } private static void ServerThread(object data) { NamedPipeServerStream pipeServer = new NamedPipeServerStream ("testpipe", PipeDirection.InOut, numThreads); int threadId = Thread.CurrentThread.ManagedThreadId; Console.WriteLine("Client connecting on thread[{0}].", threadId); // Wait for a client to connect // THIS IS WHERE THE PROBLEM IS: // A client never connects. pipeServer.WaitForConnection(); Console.WriteLine("Client connected on thread[{0}].", threadId); try { // Read the request from the client. Once the client has // written to the pipe its security token will be available. StreamString ss = new StreamString(pipeServer); // Verify our identity to the connected client using a // string that the client anticipates. ss.WriteString("I am the one true server!"); string filename = ss.ReadString(); // Read in the contents of the file while impersonating the client. ReadFileToStream fileReader = new ReadFileToStream(ss, filename); // Display the name of the user we are impersonating. Console.WriteLine ("Reading file: {0} on thread[{1}] as user: {2}.", filename, threadId, pipeServer.GetImpersonationUserName()); pipeServer.RunAsClient(fileReader.Start); } // Catch the IOException that is raised if the pipe is broken // or disconnected. catch (IOException e) { Console.WriteLine("ERROR: {0}", e.Message); } pipeServer.Close(); } } // Defines the data protocol for reading and writing strings on our stream public class StreamString { private Stream ioStream; private UnicodeEncoding streamEncoding; public StreamString(Stream ioStream) { this.ioStream = ioStream; streamEncoding = new UnicodeEncoding(); } public string ReadString() { int len = 0; len = ioStream.ReadByte() * 256; len += ioStream.ReadByte(); byte[] inBuffer = new byte[len]; ioStream.Read(inBuffer, 0, len); return streamEncoding.GetString(inBuffer); } public int WriteString(string outString) { byte[] outBuffer = streamEncoding.GetBytes(outString); int len = outBuffer.Length; if (len > UInt16.MaxValue) { len = (int)UInt16.MaxValue; } ioStream.WriteByte((byte)(len / 256)); ioStream.WriteByte((byte)(len & 255)); ioStream.Write(outBuffer, 0, len); ioStream.Flush(); return outBuffer.Length + 2; } } // Contains the method executed in the context of the impersonated user public class ReadFileToStream { private string fn; private StreamString ss; public ReadFileToStream(StreamString str, string filename) { fn = filename; ss = str; } public void Start() { string contents = File.ReadAllText(fn); ss.WriteString(contents); } }


    Monday, November 23, 2020 2:07 AM

All replies

  • Hi Wally9633,

    Thank you for posting here.

    As shown in the document : The server then waits for a NamedPipeClientStream object in a child process to connect to it. 

    So it hangs at 'pipeServer.WaitForConnection()'.

    Check the following complete example.

    How to: Use Named Pipes for Network Interprocess Communication

    Hope it can help you.

    Best Regards,

    Xingyu Zhao

    Visual Basic and CLR forum will be migrating to a new home on Microsoft Q&A! (VB.NET and CLR) We invite you to post new questions in the new home on Microsoft Q&A ! For more information, please refer to the sticky post(VB.NET and CLR).

    Tuesday, November 24, 2020 3:34 AM