INT PopGetMessage(
	HCLIENT hClient,
	LONG nMessageId,
	LPVOID lpvBuffer,		// pointer to buffer which will contain the message
	LPDWORD lpdwLength,
	DWORD dwReserved
);

The PopGetMessage function retrieves the specified message and copies the contents to a local buffer.

Parameters

hClient

Handle to the client session.

nMessageId

Number of message to retrieve from the server. This value must be greater than zero.

lpvBuffer

A pointer to a byte buffer which will contain the data transferred from the remote server, or a pointer to a global memory handle which will reference the data when the function returns.

lpdwLength

A pointer to an unsigned long integer which should be initialized to the maximum number of bytes that can be copied to the buffer specified by the lpvBuffer parameter. If the lpvBuffer parameter points to a global memory handle, the length value should be initialized to zero. When the function returns, this value will be updated with the actual length of the file that was downloaded.

dwReserved

A reserved parameter. This value should always be zero.

Return Value

If the function succeeds, the return value is the server result code. If the function fails, the return value is POP_ERROR. To get extended error information, call PopGetLastError.

Remarks

The PopGetMessage function is used to retrieve an message from the server and copy it into a local buffer. The function may be used in one of two ways, depending on the needs of the application. The first method is to pre-allocate a buffer large enough to store the contents of the message. In this case, the lpvBuffer parameter will point to the buffer that was allocated, the value that the lpdwLength parameter points to should be initialized to the size of that buffer.

The second method that can be used is have the lpvBuffer parameter point to a global memory handle which will contain the message data when the function returns. In this case, the value that the lpdwLength parameter points to must be initialized to zero. It is important to note that the memory handle returned by the function must be freed by the application, otherwise a memory leak will occur. See the example code below.

This function will cause the current thread to block until the complete message has been retrieved, a timeout occurs or the operation is canceled. During the transfer, the POP_EVENT_PROGRESS event will be periodically fired, enabling the application to update any user interface controls. Event notification must be enabled, either by calling PopEnableEvents, or by registering a callback function using the PopRegisterEvent function.

To determine the current status of a transfer while it is in progress, use the PopGetTransferStatus function.

Example

HGLOBAL hgblBuffer = (HGLOBAL)NULL;
LPBYTE lpBuffer = (LPBYTE)NULL;
DWORD cbBuffer = 0;

// Return the message into block of global memory allocated by
// the GlobalAlloc function; the handle to this memory will be
// returned in the hgblBuffer parameter
nResult = PopGetMessage(hClient,
                        nMessageId,
                        &hgblBuffer,
                        &cbBuffer,
                        0);

if (nResult != POP_ERROR)
{
    // Lock the global memory handle, returning a pointer to the
    // message text
    lpBuffer = (LPBYTE)GlobalLock(hgblBuffer);
    
    // After the data has been used, the handle must be unlocked
    // and freed, otherwise a memory leak will occur
    GlobalUnlock(hgblBuffer);
    GlobalFree(hgblBuffer);
}

Requirements

Client: Requires Windows Vista, Windows XP or Windows 2000 Professional.
Server: Requires Windows Server 2008, Windows Server 2003 or Windows 2000 Server.
Header: Include cstools6.h.
Library: Use cspopav6.lib.

See Also

PopEnableEvents, PopGetMessageHeaders, PopGetTransferStatus, PopRegisterEvent

Copyright © 2008 Catalyst Development Corporation. All rights reserved.