Drupal, like many open source projects, relies on volunteer contributors to keep its ecosystem of development active and current. This is one of the key strengths of open source software; the downside is that people who used to volunteer time to Drupal often drop out when other commitments take over.
As a result, you’ll occasionally discover a module that’s exactly what you need, but the module developer hasn’t upgraded it to Drupal 7 yet. In this chapter, I will upgrade a simple Drupal 6 module to Drupal 7. I’ll examine the different processes to perform module upgrades, and I’ll show you some of the common changes necessary to port a module from Drupal 6 to 7.