Welcome to the official Microsoft documentation for Component Object Model (COM) APIs. This section provides comprehensive information on COM, its principles, interfaces, and how to develop and interact with COM components in various Microsoft technologies.
Understanding COM
The Component Object Model (COM) is a binary-interface standard for software components introduced by Microsoft in 1991. COM is a language-independent, processor-independent, object-oriented system for creating a reusable software component that can be manipulated by other programs even if they are written in different programming languages. COM serves as the foundation for many other Microsoft technologies, including OLE, ActiveX, and DCOM.
Key Concepts
- Interfaces: A contract specifying a set of functions (methods) that a COM object must implement.
- Objects: Instances of a COM class that implement one or more interfaces.
- Reference Counting: A mechanism for managing the lifetime of COM objects.
- Registry: Used to store information about COM components, allowing the system to locate and instantiate them.
- GUIDs (Globally Unique Identifiers): Used to uniquely identify COM interfaces and classes.
Core COM Interfaces
Explore the fundamental interfaces that underpin the COM programming model.
IUnknown
The root interface for all COM interfaces. Provides reference counting and interface querying.
IDispatch
Enables late binding and automation of COM objects, commonly used in scripting and automation scenarios.
IClassFactory
Used to create instances of COM objects.
IEnumVariant
An enumerator interface for collections of VARIANT types.
COM Interoperability
Learn how COM components interact with other technologies and platforms.
COM and .NET
Details on accessing COM components from .NET applications and vice versa.
COM and C++
Programming COM with C++ using ATL and other libraries.
COM and VBA/Scripting
Using COM objects within Visual Basic for Applications and scripting languages.
Getting Started with COM Development
This section provides practical guidance and tutorials for developers looking to build and utilize COM components.
Tutorials & Samples
Reference
Detailed API reference for core COM functions, structures, and constants.
Dive deep into the world of COM to leverage its power and flexibility in your Windows development projects.