CONNECT: Use of Connection Points

Click to open or copy the CONNECT project files.

Note   This is a modification of the ATL sample Connect, to demonstrate Compiler COM support for connection point sinks. The DRIVE client is a native implementation, whereas the MDRIVE client slightly belabors COM-correctness in using a ClassFactory to create sink objects. Neither DRIVE nor MDRIVE are dependent upon ATL or MFC for any COM support.

This sample illustrates the use and implementation of connection points (the IConnectionPointContainer and IConnectionPoint interfaces) in a multithreaded environment.

The server is implemented in Connect.dll. This DLL allows the creation of a CoRandom COM object, implemented by the CRandom C++ class. The COM object supports IRandom (a dual interface) and IConnectionPointContainer, and it accepts connections for the IRandomEvent interface.

The IRandom interface supports the following methods.

Start

Starts a thread inside the object.

Stop

Stops a thread inside the object.

StopAll

Stops all running threads.

When running, the secondary threads inside the object keep firing events through the connection point.

Two clients are provided: DRIVE and MDRIVE. They can be found in the DRIVE and MDRIVE subdirectories.

• Drive.exe is a simple console application that provides a single object implementing the IRandomEvent interface. It creates a CoRandom object, calls Advise and Unadvise on the connection point, and has the CoRandom object fire events into the drive's object.
  
  
• Mdrive.exe is an MFC dialog-based application, able to create multiple advise sinks and to control the number of threads the server creates. When you run Mdrive.exe, click the Start button at least once, then click the Advise button several times. Each click of the Advise button adds a connection point, which makes the display wider. If you do not click the Advise button, you will see no activity in the display.

To run, build Connect.dll and register it. You can build and run Drive.exe  from a console, or build and run MDrive.exe directly from Visual C++.