CreateNamedPipe

CreateNamedPipe is a Windows API function that creates an instance of a named pipe, providing a server end for interprocess communication. It supports local and remote clients and can operate in synchronous or overlapped I/O patterns, depending on how the handle is used.

The function has ANSI and Unicode variants, CreateNamedPipeA and CreateNamedPipeW. The parameters specify the pipe name, access, type, and behavior. The lpName parameter must specify a pipe path such as \\.\pipe\PipeName for local access or \\ServerName\pipe\PipeName for remote access. The dwOpenMode parameter selects the desired access (for example, PIPE_ACCESS_DUPLEX, PIPE_ACCESS_INBOUND, or PIPE_ACCESS_OUTBOUND). The dwPipeMode parameter defines the communication mode and data transmission method (for example, PIPE_TYPE_BYTE or PIPE_TYPE_MESSAGE, PIPE_READMODE_BYTE or PIPE_READMODE_MESSAGE). nMaxInstances sets how many concurrent instances may be created. nOutBufferSize and nInBufferSize specify the outbound and inbound buffer sizes, and nDefaultTimeOut sets the default timeout in milliseconds. lpSecurityAttributes controls security and handle inheritance.

On success, CreateNamedPipe returns a handle to the server end of the named pipe. On failure, it returns INVALID_HANDLE_VALUE and extended error information is available via GetLastError. Typical usage involves calling CreateNamedPipe, then using ConnectNamedPipe to wait for client connections, followed by ReadFile and WriteFile for data transfer. For multiple clients, additional pipe instances can be created up to nMaxInstances. When communication ends, DisconnectNamedPipe or closing the handle completes the lifecycle.

Named pipes created with CreateNamedPipe can be used for remote as well as local IPC, subject to network permissions and security attributes. Related functions include ConnectNamedPipe, DisconnectNamedPipe, and CreateFile (used by clients to connect to the pipe). CreatePipe provides anonymous, non-named IPC.