I just happened to write a blog post about this a while ago: http://obdurodon.silvrback.com/navigating-a-large-codebase http://obdurodon.silvrback.com/navigati

I just happened to write a blog post about this a while ago: http://obdurodon.silvrback.com/navigating-a-large-codebase http://obdurodon.silvrback.com/navigating-a-large-codebase Short version: document everything as you learn, master your tools, look at message and data formats before code, follow some of the important code paths, change something and see how the system responds.