In this chapter:
You built an
OCRServer component in the last chapter, but you have not built a client to use the IOcrProcessor and ISpell interfaces exposed by
OCRServer’s COM object. In this chapter, we’ll discuss several techniques for using the services exposed by a distributed component. Specifically, we will discuss four different communication techniques to use with distributed components using C++. These techniques, for lack of better terms, include:
The COleDispatchDriver technique
The manual technique
The reusable technique
These techniques can be used to take advantage of the functionality exposed by typical distributed components. There are advantages and disadvantages in each of these methods, and we’ll explore them along the way.
In this chapter, we will build a simple MFC client that will use the published services of the
OCRServer component developed in the previous chapter. Before you begin, you must register
OCRServer either as a service or as a local server on your machine, which requires that you have administrator privileges to the machine that houses
OCRServer. You must perform this registration because COM looks in the registry for information regarding this component; see the end of the previous chapter for details on registering this component.