Learning DCOM

Chapter 10. Connecting Objects

In this chapter:

• Object Reference

• Referrers

• Connection Points

• Event Sources

• Event Sinks

• Performance Impact of Connection Points

• Security Impact of the OBJREF

Thus far, you’ve written only uncomplicated interfaces with methods that take and return simple data types. In this chapter, you will develop a simple distributed architecture that involves passing interface pointers from one object to another—and from this second object to yet a third object. Interface pointers can be passed around in this fashion to maintain connections among peers.

You’ll exploit the sharing of interface pointers by building a simple distributed system that includes a referrer (also called a middleman or a broker), a server, and a client. Figure 10-1 shows the architectural view of this system, which names these three distributed components ChatBroker, ChatServer, and ChatClient, respectively. Briefly, this system works as follows:

1. A ChatServer registers itself with a ChatBroker.

2. A ChatClient connects to the ChatBroker and requests to join a chat discussion, which is managed by a ChatServer.

3. Once a ChatClient has joined a discussion, it can directly send chat messages to the ChatServer that manages the discussion, without any further collaboration with the ChatBroker. In other words, once a client has connected to the server, the broker is virtually out of the picture.

4. Upon receiving a chat message, the ChatServer broadcasts the message to all connected ChatClients.

Figure 10-1. The chat ...