Recipe 24.5. Disconnecting from a Socket Server

Problem

You want to disconnect from a socket server, or be notified when the server disconnects you.

Solution

Invoke the Socket.close( ) or XMLSocket.close( ) method to explicitly close the connection, or listen for the close event to be notified when the server closes the connection for you.

Discussion

A general rule to follow when programming is to clean up after yourself. That is, if you create an object, you should also delete it when it is no longer necessary. In this case, whenever you connect to a socket server, you should explicitly close the connection when you're done. Leaving an unused socket connection open is a waste of resources and should be avoided if at all possible. If you don't close a connection, then the server may continue to keep an open socket connection that is not being used, which can quickly cause a server to overrun its allotment of allowed socket connections.

Closing a socket connection is the same for both Socket and XMLSocket instances. All you need to do is invoke the close( ) method on the socket instance:

// Assume socket is a connected Socket instance socket.close(  );  // Disconnect from the server

Using an XMLSocket is exactly the same:

// Assume xmlSocket is a connected XMLSocket instance xmlSocket.close(  );  // Disconnect from the server

The close( ) method is useful for letting the server know that the client wants to disconnect. To be notified when the server closes the connection on its own, you should listen for the close event by calling addEventListener( ) on the Socket or XMLSocket instance with Event.CLOSE as the event type; for example:

var socket:Socket = new Socket(  );        // Add an event listener to be notified when the server disconnects // the client socket.addEventListener( Event.CLOSE, onClose );

Invoking the close( ) method does not raise the close event. Instead, the close event is raised only when the server initiates the disconnection.

Once a socket is closed, it is no longer capable of reading or writing data. If you'd like to reuse the socket, you have to establish a connection again as described in Recipe 24.1.

See Also

Recipe 24.1