12.4. Creating message-driven POJOs

During one summer in college, I had the privilege of working in Yellowstone National Park. The job wasn’t one of the high-profile jobs like park ranger or the guy who turns Old Faithful on and off. Instead, I held a position in housekeeping at Old Faithful Inn, changing sheets, cleaning bathrooms, and vacuuming floors. Not glamorous, but at least I was working in one of the most beautiful places on Earth.

Every day after work, I’d head over to the local post office to see if I had any mail. I was away from home for several weeks, so it was nice to receive a letter or card from my friends back at school. I didn’t have my own post box, so I’d walk up and ask the man sitting on the stool behind the counter if I had received any mail. That’s when the wait would begin.