ConnectNamedPipe - Win32 Programmer's Reference

Win32 Programmer's Reference

Home Index Search About

Overview

Group

Quick Info

Windows NT
Yes
Win95
No
Win32s
No
Import Library
kernel32.lib
Header File
winbase.h
Unicode
No
Platform Notes
None

ConnectNamedPipe

The ConnectNamedPipe function enables a named pipe server process to wait for a client process to connect to an instance of a named pipe. A client process connects by calling either the CreateFile or CallNamedPipe function.

BOOL ConnectNamedPipe(

HANDLE hNamedPipe,	// handle to named pipe to connect
LPOVERLAPPED lpOverlapped	// pointer to overlapped structure
);

Parameters
hNamedPipe

Identifies the server end of a named pipe instance. This handle is returned by the CreateNamedPipe function.

lpOverlapped

Points to an OVERLAPPED structure.

Return Values
If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero. To get extended error information, call GetLastError.

Remarks
A named pipe server process can use ConnectNamedPipe with a newly created pipe instance. It can also be used with an instance that was previously connected to another client process; in this case, the server process must first call the DisconnectNamedPipe function to disconnect the handle from the previous client before the handle can be reconnected to a new client. Otherwise, ConnectNamedPipe returns FALSE, and GetLastError returns ERROR_NO_DATA if the previous client has closed its handle or ERROR_PIPE_CONNECTED if it has not closed its handle.

The behavior of ConnectNamedPipe depends on two conditions: whether the pipe handle's wait mode is set to blocking or nonblocking and whether the function is set to execute synchronously or in overlapped mode. A server initially specifies a pipe handle's wait mode in the CreateNamedPipe function, and it can be changed by using the SetNamedPipeHandleState function.

If hNamedPipe was opened with FILE_FLAG_OVERLAPPED, the lpOverlapped parameter must not be NULL. It must point to a valid OVERLAPPED structure. If hNamedPipe was opened with FILE_FLAG_OVERLAPPED and lpOverlapped is NULL, the function can incorrectly report that the connect operation is complete.

If hNamedPipe was created with FILE_FLAG_OVERLAPPED and lpOverlapped is not NULL, the OVERLAPPED structure pointed to by lpOverlapped must contain a handle to a manual-reset event object (which the server can create by using the CreateEvent function).

If hNamedPipe was not opened with FILE_FLAG_OVERLAPPED and lpOverlapped is NULL, the function does not return until a client is connected or an error occurs. Successful synchronous operations result in the function returning TRUE if a client connects after the function is called. If a client connects before the function is called, the function returns FALSE and GetLastError returns ERROR_PIPE_CONNECTED. This can happen if a client connects in the interval between the call to CreateNamedPipe and the call to ConnectNamedPipe. In this situation, there is a good connection between client and server, even though the function returns FALSE.

If hNamedPipe was not opened with FILE_FLAG_OVERLAPPED and lpOverlapped is not NULL, the operation executes asynchronously. The function returns immediately with a return value of FALSE. If a client process connects before the function is called, GetLastError returns ERROR_PIPE_CONNECTED. Otherwise, GetLastError returns ERROR_IO_PENDING, which indicates that the operation is executing in the background. When this happens, the event object in the OVERLAPPED structure is set to the nonsignaled state before ConnectNamedPipe returns, and it is set to the signaled state when a client connects to this instance of the pipe.

The server process can use any of the wait functions or SleepEx

to determine when the state of the event object is signaled, and it can then use the GetOverlappedResult function to determine the results of the ConnectNamedPipe operation.

If the specified pipe handle is in nonblocking mode, ConnectNamedPipe always returns immediately. In nonblocking mode, ConnectNamedPipe returns TRUE the first time it is called for a pipe instance that is disconnected from a previous client. This indicates that the pipe is now available to be connected to a new client process. In all other situations when the pipe handle is in nonblocking mode, ConnectNamedPipe returns FALSE. In these situations, GetLastError returns ERROR_PIPE_LISTENING if no client is connected, ERROR_PIPE_CONNECTED if a client is connected, and ERROR_NO_DATA if a previous client has closed its pipe handle but the server has not disconnected. Note that a good connection between client and server exists only after the ERROR_PIPE_CONNECTED error is received.

Note that nonblocking mode is supported for compatibility with Microsoft LAN Manager version 2.0, and it should not be used to achieve asynchronous input and output (I/O) with named pipes.

See Also
CallNamedPipe, CreateEvent, CreateFile, CreateNamedPipe, DisconnectNamedPipe, GetOverlappedResult, SetNamedPipeHandleState, SleepEx, OVERLAPPED

Last news from Greatis Software

    Nostalgia .Net     .Net is powerful, but not all-powerful, so sometimes we need to use Win32 API for our .Net applications. It's simple enough with Platform Invoke if you have Win32 skill, but we do not always have time to dig the ancient documentation, declare the special types that are compatible with Win32, find the values of the Win32's constants and so on. Nostalgia .Net offers several simple-to-use classes, and components that will allow you to forget about the headache of Win32 and just use the power of Win32 in your application the same way as you use the native. Net classes. More »

Recommended software for developers

    Ultimate Pack     Component pack for Delphi and C++ Builder that contains runtime form designer, runtime object inspector, print suite and much more for the very special price. More »

    Form Designer .Net     Unique runtime form design solution that allows to edit any form in .Net WinForms application at runtime without manual coding. Full C# source codes are available More »

    Print Suite .Net     Print Suite .Net is a set of components for easy printing texts, images and grids from your WinForms applications. Full C# source codes are available More »

    Gradient Controls .Net     Gradient Controls .Net offers controls with gradient background feature. Labels, panels and so on... Full C# source codes are available More »

    Greatis iGrid     iGrid plots drawing grid right over your desktop, so you can use it everywhere, with any drawing application without any special plugins for different graphic editors. More »

More Online Helps

Win32 Programmer's Reference
Win32 Multimedia Programmer's Reference
OLE Programmer's Reference
Microsoft Windows Pen API Programmer's Reference
Microsoft Windows Sockets 2 Reference
Microsoft Windows Telephony API (TAPI) Programmer's Reference
Unix Manual Pages

greatis just4fun network