INT GetMessage(
	LONG nMessageId,
	LPBYTE lpBuffer,
	LPDWORD lpdwLength
);

INT GetMessage(
	LONG nMessageId,
	HGLOBAL* lpBuffer,
	LPDWORD lpdwLength
);

INT GetMessage(
	LONG nMessageId,
	CString& strBuffer
);

The GetMessage method retrieves the specified message and copies the contents to a local buffer.

Parameters

nMessageId

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

lpBuffer

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

lpdwLength

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

Return Value

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

Remarks

The GetMessage method is used to retrieve an message from the server and copy it into a local buffer. The method 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 lpBuffer 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 lpBuffer parameter point to a global memory handle which will contain the message data when the method 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 method must be freed by the application, otherwise a memory leak will occur. See the example code below.

This method 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 EnableEvents, or by registering a callback function using the RegisterEvent method.

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

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 = pClient->GetMessage(nMessageId, &hgblBuffer, &cbBuffer);

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

Minimum Desktop Platform: Windows 7 (Service Pack 1)
Minimum Server Platform: Windows Server 2008 R2 (Service Pack 1)
Header File: cstools10.h
Import Library: cspopv10.lib

See Also

EnableEvents, GetMessageHeaders, GetTransferStatus, RegisterEvent

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