Opening Connections Asynchronously

In some cases, especially when working with Internet, Wide Area Network (WAN), or Remote Access Service (RAS) connections, the time required to establish a connection can increase dramatically. While a few seconds should be enough for a typical LAN connection, a WAN might take several minutes or more to connect. There are several ways to pre-empt problems when attempting to make these connections:

• Set the LoginTimeout property to a high-enough value to account for the delay.
  
  
• Use the rdAsyncEnable option to return control to your application before the connection is established so that the user can be informed that the connection is being attempted without blocking the application.
  
  
• Establish an event procedure to capture the Connect event instead of polling with the StillConnecting property.
  
  
• Use the BeforeConnect event to warn the user that the connection might take an exceptionally long time.

The most important aspect of these techniques is to keep the user informed and to prevent the application from blocking. If your application, through no fault of its own, seems to lock up while attempting to establish a connection, the user will have a tendency to try to cancel the operation in any way that presents itself — including rebooting the computer.