# DispSink Attributes Sample: Handles Events Fired from a Singleton COM Server Through a Dispatch Interface

The DispSink attributes sample demonstrates a singleton server object (an object that can have only one instance) that has its own dual interface and a dispatch interface used for firing off events.

The Attributes Tutorial includes step-by-step procedures for creating the DispSink attributes sample.

The DispSink sample is the nonattributed version of this sample.

Security Note
This sample code is provided to illustrate a concept and should not be used in applications or Web sites, as it may not illustrate the safest coding practices.

# Building and Running the Sample

#### To build and run this sample

1. Open the solution file DispSink.sln.

2. From the Build menu, click Build Solution.

3. Open two or more instances of the ActiveX Control Test Container and insert the client control, DispCtl, into each instance. See Testing Properties and Events with Test Container for information on how to access the test container.

4. Invoke the Connect method on all of the controls.

5. Invoke the Send method on one of the controls. Change the Parameter Type field of the Invoke Methods dialog box to VT_BSTR and then type any string into the Parameter Value box. Click the Invoke button. The string will be displayed in the center of all connected controls.

6. Invoke the Disconnect method on all controls prior to deleting them.

# How the Sample Works

The server is a singleton object that has its own dual interface as well as a dispatch interface used for firing off events. The dispatch interface is placed in the .idl file using the dispinterface attribute. The server object receives data through its dual interface Send method and transmits it to all connected components through the Transfer event on its dispatch interface. The Dispserver uses the event_source attribute, and the Dispclient uses the event_receiver attribute.

The client is an ActiveX control that contains a server object. The control responds to the Transfer event fired by the server object. It has a dual interface that has Connect, Send, and Disconnect methods. If the Transfer event is fired with a variant containing a BSTR, the string is displayed in the center of the control.

# Attributes

This sample uses the following attributes:

- DISPSINK/DispClient coclass, dual, event_receiver, helpstring, id, module, object, pointer_default, registration_script, threading, uuid, version, vi_progid

- DISPSINK/DispServer coclass, default, dispinterface, dual, event_source, helpstring, id, module, object, pointer_default, threading, uuid, vi_progid

# Keywords

This sample uses the following keywords:

#import; CComAutoThreadModule; CComSimpleThreadAllocator; CoCreateInstance; DECLARE_CLASSFACTORY_AUTO_THREAD; FireViewChange

Note
Some of the samples, such as this one, have not been modified to reflect the changes in the Visual C++ wizards, libraries, and compiler, but still demonstrate how to complete your desired task.