We use a number of technologies in this chapter, mainly revolving around the Ruby programming language and its various libraries. Most of them have been described in Chapter 1. In addition to Ruby and its libraries we also use mashups, which are described next.
As with previous chapters, while the main features in the applications are all implemented within the chapters itself, sometimes we still depend on other services provided by other providers. In this chapter we use four such external services—RPX for user web authentication, Gravatar for avatar services, Amazon Web Services S3 for photo storage, and Facebook Connect for reaching out to users on Facebook. RPX, Gravatar, and AWS S3 have been explained in previous chapters.