Architecture of Open Source Applications is a very well-reviewed series of books that gives a high-level view of the architecture of various open-source software projects. This second volume focuses on well-known projects, such as GDB, Git, nginx, Processing.js, Pypy, and Twisted.- Architecture of Open Source Applications　is a very well-reviewed series of books that gives a high-level view of the architecture of various open-source software projects. This second volume focuses on well-known projects, such as GDB, Git, nginx, Processing.js, Pypy, and Twisted.