Neither KParts nor D-Bus are better than COM though. KParts is just some way to expose a Qt widget, at best comparable to something like ActiveX (a very specif

Neither KParts nor D-Bus are better than COM though. KParts is just some way to expose a Qt widget, at best comparable to something like ActiveX (a very specific use of COM, not the entirety of what you can do with COM), but even the functionality it exposes is limited. Hell, it might be closer to OLE 1 than even OLE 2. It feels like it was made by someone looking at a specific use of COM/OLE2 in some popular Windows application back in the 90s and decided that that's everything the tech is all about and can do - so you could probably make something like custom WordPad controls with it (though from the docs i don't see any way to store instance-specific data, so you probably can't even get OLE-like functionality) but you couldn't make something like, say, Visual Basic / VBA. Of course being written for Qt it is also inherently limited to be usable only in terms of C++ and with specific Qt versions, which certainly makes is less generic than COM. D-Bus is a bit closer to COM in that like COM it can be used to have a centralized registry of methods exposed via interfaces in objects to call, but is still also more limited in that it is only meant for passing messages across processes - you can't, e.g., use it to create a "decoder" object with a method you call from several threads in which you give it two memory pointers, one with a buffer of encoded bytes and another to place the decoded bytes into. The closest with D-Bus would be to communicate details for the decoding (perhaps via other IPC methods like shared memory, but that'd be outside of D-Bus itself), though with little control over how it is done. Also FWIW D-Bus has nothing KDE-specific in it (if anything it came out of the GNOME world). COM might have seen little improvement since Windows 95 but even COM in Windows 95 provides more functionality than what KParts or D-Bus do in modern Linux, so i wouldn't call the latter more technically advanced at all. The only benefit they have is being designed a few years after COM so they didn't had the constraint of having to run in systems with 8MB of RAM.