I had a few chances to write a book in the past, but when Packt called me shortly before my 50th birthday, I agreed almost immediately. Scala? Machine learning? Big data? What could be a worse combination of poorly understood and intensely marketed topics? What followed was eight months of sleep deprived existence, putting my ideas on paper—computer keyboard, actually—during which I was able to experimentally find out that my body needs at least three hours of sleep each night and a larger break once in a while. As a whole, the experience was totally worth it. I really appreciate the help of everyone around me, first of all of my family, who had to deal with a lot of sleepless nights and my temporary lack of attention.

I would like to thank my wife for putting up with a lot of extra load and late night writing sessions. I know it's been very hard. I also give deep thanks to my editors, specifically Samantha Gonsalves, who not only nagged me from time to time to keep me on schedule, but also gave very sound advice and put up with my procrastination. Not least, I am very grateful to my colleagues who filled in for me during some very critical stages of E8 Security product releases—we did go through the GA, and at least a couple of releases during this time. A lot of ideas percolated into the E8 product. Particularly, I would like to thank Jeongho Park, Christophe Briguet, Mahendra Kutare, Srinivas Doddi, and Ravi Devireddy. I am grateful to all my Cloudera colleagues for feedback and discussions, specifically Josh Patterson, Josh Wills, Omer Trajman, Eric Sammer, Don Brown, Phillip Zeyliger, Jonathan Hsieh, and many others. Last, but not least, I would like to thank my Ph.D. mentors Walter A. Harrison, Jaswinder Pal Singh, John Hennessy, and Daphne Koller for bringing me into the world of technology and innovation.