Dr. Frank Grützmacher has worked for several major German firms in the area of large distributed systems. He was an early user of different Corba implementations in the past.
He got his Ph.D. in the field of electrical engineering, but with the focus on distributed heterogeneous systems. In 2010, he was involved in a project, which changed parts of the Android platform for a manufacturer. From there, he got his knowledge about the android NDK and native processes on this platform.
He has already worked as a reviewer for another Android 3.0 book.
Robert Mitchell is an MIT graduate with over 40 years experience in Information Technology and is semiretired. He has developed software for all the big iron companies: IBM, Amdahl, Fujitsu, ...