the guys touched the concept, but here is the same thing in my words. I recommend you to build a career path for yourself. If you want to get into details of everything that has a j2ee  taste you will never get to the bottom of anything. I suggest you to make a decision on the tier you want to build your skills on. In very simple terms, either be a person with %100 web knowledge and reasonable understanding of lower stack layers, or be a reliable business tier (and lower) person with some knowledge of layers above. That will eliminate the need for reading a whole bunch of stuff  on the net and eventually you will get an in-depth knowledge of certain concepts. Also you will be able to allocate correct time for your study by choosing correct material. Resumes that say ,expert in JSF, JSP and servlet and as the same time top-notch on object modeling, never gains anyone's interest. It just doesn't add up. I hope you understand where I'm going with this. remember that an enterprise project is not a one-person job, it needs right experts for the right place