Microsoft has recently enhanced COM to support distributed objects. These enhancements are known as distributed COM, or DCOM. The term distributed objects refers to objects that operate on different machines: a COM client and COM server may be on different parts of the network.
There are a number of reasons why this may be appealing. It allows you to host your objects close to your data; for example, on a server with high-speed access to a database server. Microsoft also has a product available called the Microsoft Transaction Server (MTS) that provides additional facilities for large-scale distributed applications. Alternatively, DCOM may allow you to use specific hardware installed on a remote machine, by running on that machine and controlling it from your own workstation.
One of the key strengths of the DCOM architecture is that in many cases, the objects don’t need to have special code to support distributed objects. DCOM manages all this behind the scenes, and neither the local or remote object need be aware they are not running locally.
DCOM comes with a tool that allows you to configure the DCOM characteristics of the local machine and of each specific object registered on your machine. For each individual object, you can specify the machine where that object should be executed. In addition, the code that creates a new COM object (i.e., the COM client) can specify its own settings by making slight changes to the creation process.
To demonstrate DCOM, let’s ...