Introduction
Let's ensure we understand the foundational concepts before delving further into the subjects. Here is a brief introduction if you are unfamiliar with the Active Template Library.
Active Template Library (ATL), a collection of C++ classes built using templates, makes programming Component Object Model (COM) objects easier. For building and consuming software components on Windows, COM is a binary specification. It is strongly advised to be familiar with COM to better use ATL.
This article explains the details of ATL module classes, in which we will talk about CComModule Replacement Classes and Reasons for Distributing CComModule Functionality.
Without further ado, let's get started.
Introduction to COM
The "object model" upon which ActiveX Controls and OLE are based is COM. Using COM, a component can expose its capabilities to host apps and other components. It specifies how the object exposes itself and how this exposure operates across networks and processes. COM also defines the life cycle of an object.
📂 These ideas form the basis of COM:
🎯 Interfaces — the mechanism via which an item exposes its capabilities.
🎯 IUnknown — the basic interface on which all others are based. It puts into practise the reference counting and interface querying processes used by COM.
🎯 Reference counting — the process by which an object (or, strictly speaking, an interface) determines when it is no longer required and may thus be removed from the system
🎯 QueryInterface — the technique for searching an object for a specific interface
🎯 Marshaling — the method that allows for the location-independent use of objects across the thread, process, and network borders.
🎯 Aggregation — the use of one thing to benefit from another.
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