That's pretty cool. Are there also other editors that could, at a stretch, pick up similar tasks? Emacs always seems so singular in these accounts (or in the it's-an-OS-sense) but I just wonder what some other editors in that class, or close to it, might be.
Probably not as easily. One way to look at Emacs is as a Lisp system in which someone has written an editor. It has scads of functions for file and network IO, a zillion useful general functions, and a decent, well-tested runtime. While Emacs Lisp is most often used to write functions that manipulate documents and files, there’s no constraint at all on what you can use it for. I mean people have implemented web browsers, window managers, MP3 players, and other wild stuff in it.
Now, I think you could theoretically implement all those things in Vimscript, in the sense that both are Turing complete. However, Emacs Lisp is a decent general-purpose programming language in its own right. I wouldn’t necessarily choose it over other modern languages for implementing non-text-editing related things, but if that were the only option conveniently available to me, I wouldn’t cry too much about it.
Pretty much every modern IDE with a plugin system could be repurposed into a message router, since they all have underlying code execution in their respective runtime environment (just as how in this case, Emacs was really just a Lisp runtime).
Certainly any of the major Java-based IDEs (Eclipse, IDEA, etc.) could host a message router, although this is quite boring as it's just Java. Amusingly though, Volkswagen's automotive dealership service tool, called ODIS, is built in Eclipse.
