What is CWnd in mfc?
What is CWnd in mfc?
The CWnd object is a C++ window object, distinct from the HWND that represents a Windows window but containing it. Use CWnd to derive your own child window classes, or use one of the many MFC classes derived from CWnd .
What is the use of CCmdTarget?
CCmdTarget includes member functions that handle the display of an hourglass cursor. Display the hourglass cursor when you expect a command to take a noticeable time interval to execute. Dispatch maps, similar to message maps, are used to expose OLE automation IDispatch functionality.
What is CWnd?
Congestion Window (cwnd) is a TCP state variable that limits the amount of data the TCP can send into the network before receiving an ACK. The Receiver Window (rwnd) is a variable that advertises the amount of data that the destination side can receive.
Does MFC do data exchange?
The MFC framework provides an efficient mechanism for transferring and validating data in a dialog box through the DDX and DDV routines. Dialog Data Exchange (DDX) is an easy way to initialize the controls in a dialog box and gather data input by the user.
What is CWND in TCP congestion control?
How does congestion control work?
The size of cwnd(congestion window) increases additive. After each RTT cwnd = cwnd + 1. Congestion Detection Phase : multiplicative decrement – If congestion occurs, the congestion window size is decreased. The only way a sender can guess that congestion has occurred is the need to retransmit a segment.
What is DDX_Text?
DDX_Text. The DDX_Text function manages the transfer of int , UINT , long , DWORD , CString , float , or double data between an edit control in a dialog box, form view, or control view and a CString data member of the dialog box, form view, or control view object.
What is the use of OnInitDialog?
For a modeless dialog box, OnInitDialog is called when Create is called. You typically override OnInitDialog to initialize the dialog box’s controls, such as setting the initial text of an edit box. You must call the OnInitDialog member function of the base class, CDialog , from your OnInitDialog override.
What is CWND?
Can CWND be greater than RWND?
1 Answer. The unacknowledged data at the sender side must be less than or equal to the minimum of cwnd and rwnd.
What are the types of congestion control?
Closed Loop Congestion Control
- Backpressure : Backpressure is a technique in which a congested node stops receiving packets from upstream node.
- Choke Packet Technique : Choke packet technique is applicable to both virtual networks as well as datagram subnets.
- Implicit Signaling :
- Explicit Signaling :
What is DoDataExchange?
Dialog Data Exchange. UpdateData works in both directions, as specified by the BOOL parameter passed to it. To carry out the exchange, UpdateData sets up a CDataExchange object and calls your dialog class’s override of CDialog ‘s DoDataExchange member function. DoDataExchange takes an argument of type CDataExchange .
What is DDX and DDV?
Dialog data exchange (DDX) is an easy way to initialize the controls in your dialog box and to gather data input by the user. Dialog data validation (DDV) is an easy way to validate data entry in a dialog box.
What is CDialog?
A CDialog object is a combination of a dialog template and a CDialog -derived class. Use the dialog editor to create the dialog template and store it in a resource, then use the Add Class wizard to create a class derived from CDialog . A dialog box, like any other window, receives messages from Windows.
How do I know what size congestion window I need?
- After 1 round trip time, congestion window size = (2)1 = 2 MSS.
- After 2 round trip time, congestion window size = (2)2 = 4 MSS.
- After 3 round trip time, congestion window size = (2)3 = 8 MSS and so on.
What is choke packet?
A choke packet is used in network maintenance and quality management to inform a specific node or transmitter that its transmitted traffic is creating congestion over the network. This forces the node or transmitter to reduce its output rate. Choke packets are used for congestion and flow control over a network.
What is the principle of congestion control?
Network-assisted congestion control. With network-assisted congestion control, network-layer components (i.e., routers) provide explicit feedback to the sender regarding the congestion state in the network. This feedback may be as simple as a single bit indicating congestion at a link .
What is Begin_message_map?
BEGIN_MESSAGE_MAP. Begins the definition of a message map (must be used in the class implementation). BEGIN_TEMPLATE_MESSAGE_MAP. Begins the definition of a message map on a class type containing a single template argument.
How does MFC message map work?
MFC uses a technique called Message Maps. A Message Map is a table that associates messages with functions. When you receive a message, MFC will go through your Message Map and search for a corresponding Message Handler.
How do I use oncmdmsg?
Command targets use OnCmdMsg to determine whether they can handle a command and to route it to another command target if they cannot handle it. Each command-target class may override the OnCmdMsg member function. The overrides let each class route commands to a particular next target.
What are the classes derived from CCmdTarget?
Key framework classes derived from CCmdTarget include CView, CWinApp, CDocument, CWnd, and CFrameWnd. If you intend for a new class to handle messages, derive the class from one of these CCmdTarget -derived classes.
What is CCmdTarget in Ole?
CCmdTarget includes member functions that handle the display of an hourglass cursor. Display the hourglass cursor when you expect a command to take a noticeable time interval to execute. Dispatch maps, similar to message maps, are used to expose OLE automation IDispatch functionality.