AppFog hits on a real and prevalent problem with many code developments that are directed towards some type of web use. Often, you have to somehow embed your code in a web server and also connect the code or the server to a choice of back end database. Three areas of expertise - front end web pages, web server and database. An alternative is proferred by this book from Nohr and Rabinovitch. We see that a big merit is the possible range of input languages. Ruby, Python, java, PHP and Node.js. Perhaps over time that list could even expand if AppFog takes off. The allure is the ease of deployment. The text gives quick examples in Ruby that collectively are the equivalent of Hello World. Granted, there might be a cost, as the providers of AppFog expect to get paid. But this cost is nominal if you decide from the book that the savings in your time are real. Hooking up your application to a database server seems simple enough in the text's example. There is one slight issue that seems to have been deprecated. It refers to how you set up a database server with a password for the administrator. This is done via a console application that looks for an environment variable. The provided GUI is a simple way to set this variable. But what if you get everything running and eventually days later the machine reboots? Here I'm assuming that you intend for your web server application to run continuously. When the machine starts up, it has to somehow get a value for that environment variable. It has been several years since I did unix/linux sysadmin, but if I recall correctly, ultimately that value must reside somewhere on disk. Perhaps in plaintext form. A potential security risk. However, in defence of the book, if the machine essentially runs only your app and is mostly single user, then you'll be fine. It might be that in a heavy multiuser mode there is a potential risk.