In the late ’90s I thought COM (Microsoft’s Component Object Model) was the way of the future. The whole architecture starting with the
IUnknown interface was very elegant. And to hear Don Box explain it, COM was almost inevitable.
To me, the prohibition of inspecting the representation of other objects is one of the defining characteristics of object oriented programming. …
One of the most pure object-oriented programming models yet defined is the Component Object Model (COM). It enforces all of these principles rigorously. Programming in COM is very flexible and powerful as a result.
And yet programming COM was painful. I wondered at the time why something so elegant in theory was so difficult in practice. I have some ideas on this, but I haven’t thought through them enough to write them down.
Just as I was starting to grok COM, someone from Microsoft told me “COM is dead” and hinted at a whole new approach to software development that would be coming out of Microsoft, what we now call .NET.
COM had some good ideas, and some of these ideas have been reborn in WinRT. I’ve toyed with the idea of a blog post like “Lessons from COM,” but I doubt I’ll ever write that. This post is probably as close as I’ll get.
By the way, this post speaks of COM in the past tense as is conventional: we speak of technologies in the past tense, not when they disappear, but when they become unfashionable. Countless COM objects are running on countless machines, including on Mac and Unix systems, but COM has definitely fallen out of fashion.