One very important thing to mention is that Binder is an RPC mechanism while Bus1 aims to be an IPC mechanism. The crucial consequence of that is, Binder is synchronous - you make an RPC call and you wait for the answer, while Bus1 is asynchronous - you send some data to an address and later on some data is returned to you on another address. That also necessitates the design that with Binder, the called process steals work from the calling process and temporarily executes with the calling process's priority until it's done. Ideally I'd like to see Bus1 also cover Binder RPC calls, or at least some merge of the two technologies.