COMlike

COMlike refers to a class of component-based software architectures that emulate the design of Microsoft's Component Object Model (COM). These systems provide language-neutral, binary-compatible components that can be loaded, instantiated, and invoked across process boundaries. Core ideas include interface-based programming, reference counting for object lifetimes, and the use of globally unique identifiers to identify interfaces and classes.

Typically a COMlike platform defines a base interface akin to IUnknown with methods for interface querying (QueryInterface), reference addition and release, and a means to cast between interfaces. Interfaces are described by interface IDs (IIDs) and classes by class IDs (CLSIDs). Objects implement one or more interfaces, enabling clients to rely on a stable contract rather than concrete implementations. Cross-process or cross-language calls are supported through marshaling, with proxies and stubs mediating calls when boundaries exist. Threading models and apartment concepts influence object lifetime and marshaling strategy.

Real-world ecosystems described as COMlike include Mozilla's XPCOM, which uses a similar interface-driven, reference-counted model to enable cross-language components, and other plugin architectures that adopt the same pattern without relying on Windows-specific details. Advantages of COMlike designs include strong encapsulation, language interoperability, and dynamic extensibility. Drawbacks can include complexity of versioning, marshaling overhead, and subtle lifetime bugs from reference counting.

In practice, COMlike systems emphasize careful interface versioning, binary compatibility, and robust component discovery, while offering a path to modular, extensible software. Related topics include the Component Object Model (COM) and XPCOM.