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Inter-Process Communication in .NET Using Named Pipes, Part 1

, 14 Jun 2004
This article explores a way of implementing Named Pipes based Inter-Process Communication between .NET applications
using System;
using System.Security;
using System.Runtime.InteropServices;

namespace AppModule.NamedPipes {
	#region Comments
	/// <summary>
	/// This utility class exposes kernel32.dll methods for named pipes communication.
	/// </summary>
	/// <remarks>
	/// Use the following links for complete information about the exposed methods:
	/// <list type="bullet">
	/// <item>
	/// <description><a href="http://msdn.microsoft.com/library/default.asp?url=/library/en-us/ipc/base/pipe_functions.asp" target="_blank">Named Pipe Functions</a></description>
	/// </item>
	/// <item>
	/// <description><a href="http://msdn.microsoft.com/library/en-us/fileio/base/file_management_functions.asp" target="_blank">File Management Functions</a></description>
	/// </item>
	/// <item>
	/// <description><a href="http://msdn.microsoft.com/library/default.asp?url=/library/en-us/sysinfo/base/handle_and_object_functions.asp" target="_blank">Handle and Object Functions</a></description>
	/// </item>
	/// <item>
	/// <description><a href="http://msdn.microsoft.com/library/default.asp?url=/library/en-us/debug/base/system_error_codes.asp" target="_blank">System Error Codes</a></description>
	/// </item>
	/// </list>
	/// </remarks>
	#endregion
	[SuppressUnmanagedCodeSecurity]
	public sealed class NamedPipeNative {
		#region Comments
		/// <summary>
		/// Outbound pipe access.
		/// </summary>
		#endregion
		public const uint PIPE_ACCESS_OUTBOUND = 0x00000002;
		#region Comments
		/// <summary>
		/// Duplex pipe access.
		/// </summary>
		#endregion
		public const uint PIPE_ACCESS_DUPLEX = 0x00000003;
		#region Comments
		/// <summary>
		/// Inbound pipe access.
		/// </summary>
		#endregion
		public const uint PIPE_ACCESS_INBOUND = 0x00000001;
		#region Comments
		/// <summary>
		/// Pipe blocking mode.
		/// </summary>
		#endregion
		public const uint PIPE_WAIT = 0x00000000;
		#region Comments
		/// <summary>
		/// Pipe non-blocking mode.
		/// </summary>
		#endregion
		public const uint PIPE_NOWAIT = 0x00000001;
		#region Comments
		/// <summary>
		/// Pipe read mode of type Byte.
		/// </summary>
		#endregion
		public const uint PIPE_READMODE_BYTE = 0x00000000;
		#region Comments
		/// <summary>
		/// Pipe read mode of type Message.
		/// </summary>
		#endregion
		public const uint PIPE_READMODE_MESSAGE = 0x00000002;
		#region Comments
		/// <summary>
		/// Byte pipe type.
		/// </summary>
		#endregion
		public const uint PIPE_TYPE_BYTE = 0x00000000;
		#region Comments
		/// <summary>
		/// Message pipe type.
		/// </summary>
		#endregion
		public const uint PIPE_TYPE_MESSAGE = 0x00000004;
		#region Comments
		/// <summary>
		/// Pipe client end.
		/// </summary>
		#endregion
		public const uint PIPE_CLIENT_END = 0x00000000;
		#region Comments
		/// <summary>
		/// Pipe server end.
		/// </summary>
		#endregion
		public const uint PIPE_SERVER_END = 0x00000001;
		#region Comments
		/// <summary>
		/// Unlimited server pipe instances.
		/// </summary>
		#endregion
		public const uint PIPE_UNLIMITED_INSTANCES = 255;
		#region Comments
		/// <summary>
		/// Waits indefinitely when connecting to a pipe.
		/// </summary>
		#endregion
		public const uint NMPWAIT_WAIT_FOREVER = 0xffffffff;
		#region Comments
		/// <summary>
		/// Does not wait for the named pipe.
		/// </summary>
		#endregion
		public const uint NMPWAIT_NOWAIT = 0x00000001;
		#region Comments
		/// <summary>
		/// Uses the default time-out specified in a call to the CreateNamedPipe method.
		/// </summary>
		#endregion
		public const uint NMPWAIT_USE_DEFAULT_WAIT = 0x00000000;
		#region Comments
		/// <summary>
		/// 
		/// </summary>
		#endregion
		public const uint GENERIC_READ = (0x80000000);
		#region Comments
		/// <summary>
		/// Generic write access to the pipe.
		/// </summary>
		#endregion
		public const uint GENERIC_WRITE = (0x40000000);
		#region Comments
		/// <summary>
		/// Generic execute access to the pipe.
		/// </summary>
		#endregion
		public const uint GENERIC_EXECUTE = (0x20000000);
		#region Comments
		/// <summary>
		/// Read, write, and execute access.
		/// </summary>
		#endregion
		public const uint GENERIC_ALL = (0x10000000);
		#region Comments
		/// <summary>
		/// Create new file. Fails if the file exists.
		/// </summary>
		#endregion
		public const uint CREATE_NEW        = 1;
		#region Comments
		/// <summary>
		/// Create new file. Overrides an existing file.
		/// </summary>
		#endregion
		public const uint CREATE_ALWAYS     = 2;
		#region Comments
		/// <summary>
		/// Open existing file.
		/// </summary>
		#endregion
		public const uint OPEN_EXISTING     = 3;
		#region Comments
		/// <summary>
		/// Open existing file. If the file does not exist, creates it.
		/// </summary>
		#endregion
		public const uint OPEN_ALWAYS       = 4;
		#region Comments
		/// <summary>
		/// Opens the file and truncates it so that its size is zero bytes.
		/// </summary>
		#endregion
		public const uint TRUNCATE_EXISTING = 5;
		#region Comments
		/// <summary>
		/// Invalid operating system handle.
		/// </summary>
		#endregion
		public const int INVALID_HANDLE_VALUE = -1;
		#region Comments
		/// <summary>
		/// The operation completed successfully.
		/// </summary>
		#endregion
		public const ulong ERROR_SUCCESS = 0;
		#region Comments
		/// <summary>
		/// The system cannot find the file specified.
		/// </summary>
		#endregion
		public const ulong ERROR_CANNOT_CONNECT_TO_PIPE = 2;
		#region Comments
		/// <summary>
		/// All pipe instances are busy.
		/// </summary>
		#endregion
		public const ulong ERROR_PIPE_BUSY = 231;
		#region Comments
		/// <summary>
		/// The pipe is being closed.
		/// </summary>
		#endregion
		public const ulong ERROR_NO_DATA = 232;
		#region Comments
		/// <summary>
		/// No process is on the other end of the pipe.
		/// </summary>
		#endregion
		public const ulong ERROR_PIPE_NOT_CONNECTED = 233;
		#region Comments
		/// <summary>
		/// More data is available.
		/// </summary>
		#endregion
		public const ulong ERROR_MORE_DATA = 234;
		#region Comments
		/// <summary>
		/// There is a process on other end of the pipe.
		/// </summary>
		#endregion
		public const ulong ERROR_PIPE_CONNECTED = 535;
		#region Comments
		/// <summary>
		/// Waiting for a process to open the other end of the pipe.
		/// </summary>
		#endregion
		public const ulong ERROR_PIPE_LISTENING = 536;
		#region Comments
		/// <summary>
		/// Creates an instance of a named pipe and returns a handle for 
		/// subsequent pipe operations.
		/// </summary>
		/// <param name="lpName">Pointer to the null-terminated string that 
		/// uniquely identifies the pipe.</param>
		/// <param name="dwOpenMode">Pipe access mode, the overlapped mode, 
		/// the write-through mode, and the security access mode of the pipe handle.</param>
		/// <param name="dwPipeMode">Type, read, and wait modes of the pipe handle.</param>
		/// <param name="nMaxInstances">Maximum number of instances that can be 
		/// created for this pipe.</param>
		/// <param name="nOutBufferSize">Number of bytes to reserve for the output buffer.</param>
		/// <param name="nInBufferSize">Number of bytes to reserve for the input buffer.</param>
		/// <param name="nDefaultTimeOut">Default time-out value, in milliseconds.</param>
		/// <param name="pipeSecurityDescriptor">Pointer to a 
		/// <see cref="AppModule.NamedPipes.SECURITY_ATTRIBUTES">SECURITY_ATTRIBUTES</see> 
		/// object that specifies a security descriptor for the new named pipe.</param>
		/// <returns>If the function succeeds, the return value is a handle 
		/// to the server end of a named pipe instance.</returns>
		#endregion
		[DllImport("kernel32.dll", SetLastError=true)]
		public static extern IntPtr CreateNamedPipe(
			String lpName,									// pipe name
			uint dwOpenMode,								// pipe open mode
			uint dwPipeMode,								// pipe-specific modes
			uint nMaxInstances,							// maximum number of instances
			uint nOutBufferSize,						// output buffer size
			uint nInBufferSize,							// input buffer size
			uint nDefaultTimeOut,						// time-out interval
			IntPtr pipeSecurityDescriptor		// SD
			);
		#region Comments
		/// <summary>
		/// Enables a named pipe server process to wait for a client 
		/// process to connect to an instance of a named pipe.
		/// </summary>
		/// <param name="hHandle">Handle to the server end of a named pipe instance.</param>
		/// <param name="lpOverlapped">Pointer to an 
		/// <see cref="AppModule.NamedPipes.Overlapped">Overlapped</see> object.</param>
		/// <returns>If the function succeeds, the return value is nonzero.</returns>
		#endregion
		[DllImport("kernel32.dll", SetLastError=true)]
		public static extern bool ConnectNamedPipe(
			IntPtr hHandle,									// handle to named pipe
			Overlapped lpOverlapped					// overlapped structure
			);
		#region Comments
		/// <summary>
		/// Connects to a message-type pipe (and waits if an instance of the 
		/// pipe is not available), writes to and reads from the pipe, and then closes the pipe.
		/// </summary>
		/// <param name="lpNamedPipeName">Pointer to a null-terminated string 
		/// specifying the pipe name.</param>
		/// <param name="lpInBuffer">Pointer to the buffer containing the data written 
		/// to the pipe.</param>
		/// <param name="nInBufferSize">Size of the write buffer, in bytes.</param>
		/// <param name="lpOutBuffer">Pointer to the buffer that receives the data 
		/// read from the pipe.</param>
		/// <param name="nOutBufferSize">Size of the read buffer, in bytes.</param>
		/// <param name="lpBytesRead">Pointer to a variable that receives the number 
		/// of bytes read from the pipe.</param>
		/// <param name="nTimeOut">Number of milliseconds to wait for the 
		/// named pipe to be available.</param>
		/// <returns>If the function succeeds, the return value is nonzero.</returns>
		#endregion
		[DllImport("kernel32.dll", SetLastError=true)]
		public static extern bool CallNamedPipe(
			string lpNamedPipeName,
			byte[] lpInBuffer,
			uint nInBufferSize,
			byte[] lpOutBuffer,
			uint nOutBufferSize,
			byte[] lpBytesRead,
			int nTimeOut
			);
		#region Comments
		/// <summary>
		/// Creates or opens a file, directory, physical disk, volume, console buffer, 
		/// tape drive, communications resource, mailslot, or named pipe.
		/// </summary>
		/// <param name="lpFileName">Pointer to a null-terminated string that 
		/// specifies the name of the object to create or open.</param>
		/// <param name="dwDesiredAccess">Access to the object (reading, writing, or both).</param>
		/// <param name="dwShareMode">Sharing mode of the object (reading, writing, both, or neither).</param>
		/// <param name="attr">Pointer to a 
		/// <see cref="AppModule.NamedPipes.SecurityAttributes">SecurityAttributes</see> 
		/// object that determines whether the returned handle can be inherited 
		/// by child processes.</param>
		/// <param name="dwCreationDisposition">Action to take on files that exist, 
		/// and which action to take when files do not exist.</param>
		/// <param name="dwFlagsAndAttributes">File attributes and flags.</param>
		/// <param name="hTemplateFile">Handle to a template file, with the GENERIC_READ access right.</param>
		/// <returns>If the function succeeds, the return value is an open handle to the specified file.</returns>
		#endregion
		[DllImport("kernel32.dll", SetLastError=true)]
		public static extern IntPtr CreateFile(
			String lpFileName,						  // file name
			uint dwDesiredAccess,					  // access mode
			uint dwShareMode,								// share mode
			SecurityAttributes attr,				// SD
			uint dwCreationDisposition,			// how to create
			uint dwFlagsAndAttributes,			// file attributes
			uint hTemplateFile);					  // handle to template file
		#region Comments
		/// <summary>
		/// Reads data from a file, starting at the position indicated by the file pointer.
		/// </summary>
		/// <param name="hHandle">Handle to the file to be read.</param>
		/// <param name="lpBuffer">Pointer to the buffer that receives the data read from the file.</param>
		/// <param name="nNumberOfBytesToRead">Number of bytes to be read from the file.</param>
		/// <param name="lpNumberOfBytesRead">Pointer to the variable that receives the number of bytes read.</param>
		/// <param name="lpOverlapped">Pointer to an 
		/// <see cref="AppModule.NamedPipes.Overlapped">Overlapped</see> object.</param>
		/// <returns>The ReadFile function returns when one of the following 
		/// conditions is met: a write operation completes on the write end of 
		/// the pipe, the number of bytes requested has been read, or an error occurs.</returns>
		#endregion
		[DllImport("kernel32.dll", SetLastError=true)]
		public static extern bool ReadFile(
			IntPtr hHandle,											// handle to file
			byte[] lpBuffer,								// data buffer
			uint nNumberOfBytesToRead,			// number of bytes to read
			byte[] lpNumberOfBytesRead,			// number of bytes read
			uint lpOverlapped								// overlapped buffer
			);
		#region Comments
		/// <summary>
		/// Writes data to a file at the position specified by the file pointer.
		/// </summary>
		/// <param name="hHandle">Handle to the file.</param>
		/// <param name="lpBuffer">Pointer to the buffer containing the data to be written to the file.</param>
		/// <param name="nNumberOfBytesToWrite"></param>
		/// <param name="lpNumberOfBytesWritten">Pointer to the variable that receives the number of bytes written.</param>
		/// <param name="lpOverlapped">Pointer to an 
		/// <see cref="AppModule.NamedPipes.Overlapped">Overlapped</see> object.</param>
		/// <returns>If the function succeeds, the return value is nonzero.</returns>
		#endregion
		[DllImport("kernel32.dll", SetLastError=true)]
		public static extern bool WriteFile(
			IntPtr hHandle,											// handle to file
			byte[] lpBuffer,							  // data buffer
			uint nNumberOfBytesToWrite,			// number of bytes to write
			byte[] lpNumberOfBytesWritten,	// number of bytes written
			uint lpOverlapped								// overlapped buffer
			);
		#region Comments
		/// <summary>
		/// Retrieves information about a specified named pipe.
		/// </summary>
		/// <param name="hHandle">Handle to the named pipe for which information is wanted.</param>
		/// <param name="lpState">Pointer to a variable that indicates the current 
		/// state of the handle.</param>
		/// <param name="lpCurInstances">Pointer to a variable that receives the 
		/// number of current pipe instances.</param>
		/// <param name="lpMaxCollectionCount">Pointer to a variable that receives 
		/// the maximum number of bytes to be collected on the client's computer 
		/// before transmission to the server.</param>
		/// <param name="lpCollectDataTimeout">Pointer to a variable that receives 
		/// the maximum time, in milliseconds, that can pass before a remote named 
		/// pipe transfers information over the network.</param>
		/// <param name="lpUserName">Pointer to a buffer that receives the 
		/// null-terminated string containing the user name string associated 
		/// with the client application. </param>
		/// <param name="nMaxUserNameSize">Size of the buffer specified by the 
		/// lpUserName parameter.</param>
		/// <returns>If the function succeeds, the return value is nonzero.</returns>
		#endregion
		[DllImport("kernel32.dll", SetLastError=true)]
		public static extern bool GetNamedPipeHandleState(
			IntPtr hHandle,
			IntPtr lpState,
			ref uint lpCurInstances,
			IntPtr lpMaxCollectionCount,
			IntPtr lpCollectDataTimeout,
			IntPtr lpUserName,
			IntPtr nMaxUserNameSize
			);
		#region Comments
		/// <summary>
		/// Cancels all pending input and output (I/O) operations that were 
		/// issued by the calling thread for the specified file handle.
		/// </summary>
		/// <param name="hHandle">Handle to a file.</param>
		/// <returns>If the function succeeds, the return value is nonzero.</returns>
		#endregion
		[DllImport("kernel32.dll", SetLastError=true)]
		public static extern bool CancelIo(
			IntPtr hHandle
			);
		#region Comments
		/// <summary>
		/// Waits until either a time-out interval elapses or an instance 
		/// of the specified named pipe is available for connection.
		/// </summary>
		/// <param name="name">Pointer to a null-terminated string that specifies 
		/// the name of the named pipe.</param>
		/// <param name="timeout">Number of milliseconds that the function will 
		/// wait for an instance of the named pipe to be available.</param>
		/// <returns>If an instance of the pipe is available before the 
		/// time-out interval elapses, the return value is nonzero.</returns>
		#endregion
		[DllImport("kernel32.dll", SetLastError=true)]
		public static extern bool WaitNamedPipe(
			String name,
			int timeout);
		#region Comments
		/// <summary>
		/// Retrieves the calling thread's last-error code value.
		/// </summary>
		/// <returns>The return value is the calling thread's last-error code value.</returns>
		#endregion
		[DllImport("kernel32.dll", SetLastError=true)]
		public static extern uint GetLastError();
		#region Comments
		/// <summary>
		/// Flushes the buffers of the specified file and causes all buffered data to be written to the file.
		/// </summary>
		/// <param name="hHandle">Handle to an open file.</param>
		/// <returns>If the function succeeds, the return value is nonzero.</returns>
		#endregion
		[DllImport("kernel32.dll", SetLastError=true)]
		public static extern bool FlushFileBuffers(
			IntPtr hHandle);
		#region Comments
		/// <summary>
		/// Disconnects the server end of a named pipe instance from a client process.
		/// </summary>
		/// <param name="hHandle">Handle to an instance of a named pipe.</param>
		/// <returns>If the function succeeds, the return value is nonzero.</returns>
		#endregion
		[DllImport("kernel32.dll", SetLastError=true)]
		public static extern bool DisconnectNamedPipe(
			IntPtr hHandle);
		#region Comments
		/// <summary>
		/// Sets the read mode and the blocking mode of the specified named pipe.
		/// </summary>
		/// <remarks>
		/// If the specified handle is to the client end of a named pipe and if 
		/// the named pipe server process is on a remote computer, the function 
		/// can also be used to control local buffering.
		/// </remarks>
		/// <param name="hHandle">Handle to the named pipe instance.</param>
		/// <param name="mode">Pointer to a variable that supplies the new mode.</param>
		/// <param name="cc">Pointer to a variable that specifies the maximum 
		/// number of bytes collected on the client computer before 
		/// transmission to the server.</param>
		/// <param name="cd">Pointer to a variable that specifies the 
		/// maximum time, in milliseconds, that can pass before a remote 
		/// named pipe transfers information over the network.</param>
		/// <returns>If the function succeeds, the return value is nonzero.</returns>
		#endregion
		[DllImport("kernel32.dll", SetLastError=true)]
		public static extern bool SetNamedPipeHandleState(
			IntPtr hHandle,
			ref uint mode,
			IntPtr cc,
			IntPtr cd);
		#region Comments
		/// <summary>
		/// Closes an open object handle.
		/// </summary>
		/// <param name="hHandle">Handle to an open object.</param>
		/// <returns>If the function succeeds, the return value is nonzero.</returns>
		#endregion
		[DllImport("kernel32.dll", SetLastError=true)]
		public static extern bool CloseHandle(
			IntPtr hHandle);
		#region Comments
		/// <summary>
		/// Sets the security descriptor attributes
		/// </summary>
		/// <param name="sd">Reference to a SECURITY_DESCRIPTOR structure.</param>
		/// <param name="bDaclPresent"></param>
		/// <param name="Dacl"></param>
		/// <param name="bDaclDefaulted"></param>
		/// <returns></returns>
		#endregion
		[DllImport("Advapi32.dll", SetLastError=true)]
		public static extern bool SetSecurityDescriptorDacl(ref SECURITY_DESCRIPTOR sd, bool bDaclPresent, IntPtr Dacl, bool bDaclDefaulted);
		#region Comments
		/// <summary>
		/// Initializes a SECURITY_DESCRIPTOR structure.
		/// </summary>
		/// <param name="sd"></param>
		/// <param name="dwRevision"></param>
		/// <returns></returns>
		#endregion
		[DllImport("Advapi32.dll", SetLastError=true)]
		public static extern bool InitializeSecurityDescriptor(out SECURITY_DESCRIPTOR sd, int dwRevision);
		#region Comments
		/// <summary>
		/// Private constructor.
		/// </summary>
		#endregion
		private NamedPipeNative() {}
	}
	#region Comments
	/// <summary>
	/// Security Descriptor structure
	/// </summary>
	#endregion
	[StructLayout(LayoutKind.Sequential)]
	public struct SECURITY_DESCRIPTOR {
		private byte Revision;
		private byte Sbz1;
		private ushort Control;
		private IntPtr Owner;
		private IntPtr Group;
		private IntPtr Sacl;
		private IntPtr Dacl;
	}
	#region Comments
	/// <summary>
	/// Security Attributes structure.
	/// </summary>
	#endregion
	[StructLayout(LayoutKind.Sequential)]
	public struct SECURITY_ATTRIBUTES {
		public int nLength;
		public IntPtr lpSecurityDescriptor;
		public bool bInheritHandle;
	}
	#region Comments
	/// <summary>
	/// This class is used as a dummy parameter only.
	/// </summary>
	#endregion
	[StructLayout(LayoutKind.Sequential)]
	public class Overlapped {
	}
	#region Comments
	/// <summary>
	/// This class is used as a dummy parameter only.
	/// </summary>
	#endregion
	[StructLayout(LayoutKind.Sequential)]
	public class SecurityAttributes {
	}
}

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About the Author

Ivan L
Web Developer
United Kingdom United Kingdom
Ivan Latunov is a Software Architect with long term commercial experience in the areas of software architecture and engineering, design and development of web and distributed applications and business and technical analysis. Technical blog. Website: ivanweb.com.

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