Is SOAP considered a viable comms method for local processes as an > alternative to D-BUS, DCOP, etc? I am worried that it's just to slow and > if I commit to using it that in the future I will realise it doesn't scale > up. How can we answer that when we don't know how fast you need it to be? KDE tried using CORBA for IPC, and that was too slow. SOAP is much slower than CORBA (at least with good ORBs). But whether it's too slow or not is impossible to say. If you're worried, apply a strategy pattern with a factory class and make it easy for you to switch to another IPC layer later.