The physical structure of the flat buffer is: --------------------------- | SysData | Header | Data | ---------------------------

• "SysData" has fixed length and contains fields with about the buffer used size, elements count, header size;

• "Header" has fixed length, which depends of the number of elements and contains cells, one per element. Each cell contains information about: element type, element data length, the start position of the element data in the flat buffer, "present"/"not present" flag. "Not present" means that no memory is reserved for the element data, but the buffer "knows" what is the element type and element data length; (In the current design there is no "Present"/"Not present flag". If the data position is 0, that indicates the element is "Not present"). See RSqlBufFlat::TCell comments for details.

• "Data" Is the dynamic part of the buffer which may grow during the operations with the flat buffer (setting element data);

RSqlBufFlat bufFlat;
bufFlat.SetCount(N);								//N is the field count
....
bufFlat.Reset();									//Clears the content of the buffer without shrinking it.
ipcArgs.Set(0, bufFlat.MaxSize());					//Tell the server what is the flat buffer max size
ipcArgs.Set(1, &bufFlat.BufPtr());
TInt rc = session.SendReceive(funcNum, ipcArgs);
if(rc > KSqlClientBufOverflowCode)
	{												//the client buffer is not big enough and has to be resized
	rc = bufFlat.ReAlloc(err - KSqlClientBufOverflowCode);
	if(rc != KErrNone)
		{
		return rc;
		}
	ipcArgs.Set(0, bufFlat.MaxSize());
	ipcArgs.Set(1, &bufFlat.BufPtr());
	rc = session.SendReceive(funcNum, ipcArgs);
	}

RSqlBufFlat bufFlat;
bufFlat.SetCount(N);								//N is the field count
....
TPtrC8 ptr(bufFlat.BufDes());
TInt err = session.SendReceive(funcNum, TIpcArgs(ptr.Length(), &ptr));

Case 3 - the server wants to return to the client a flat buffer data.

RSqlBufFlat bufFlat;
bufFlat.SetCount(N);								//N is the field count
....
TInt maxCliBufSize = msg.Int0();					//The max size of the client buffer
if(maxCliBufSize < bufFlat.Size())
	{
	return bufFlat.Size() + KSqlClientBufOverflowCode;//Tell the client that its buffer is too small
	}
msg.WriteL(1, bufFlat.BufDes());

Case 4 - the server wants to receive from the client a flat buffer data.

RSqlBufFlat bufFlat;
bufFlat.SetCount(N);								//N is the field count
....
TInt cliBufFlatLen = aMessage.Int0();
TInt err = bufFlat.ReAlloc(cliBufFlatLen);			//Reallocate memory for the flat buffer
if(err != KErrNone)
	{
	return err;
	}
msg.ReadL(1, bufFlat.BufPtr());

Case 5 - the server (or the client) wants to fill the flat buffer with some data.

RSqlBufFlat bufFlat;
bufFlat.SetCount(N);								//N is the field count
....
TInt err = flatBuf.SetCount(M);						//If the field count has to be changed to M
if(err != KErrNone)
	{
	return err;
	}
//use the TSqlBufWIterator iterator to fill the buffer