Zend Framework v2 has been out for a good while now, but there's still applications out there running on the v1 of the popular framework. Since there was such a fundamental change in structure and functionality between v1 and v2, simply upgrading isn't possible - you have to migrate. Fortunately, there's guides like this one from Chris Strosser that shows you how to get there gradually.

Due to the vast nuances of Zend Framework 2, migrating an application from Zend Framework 1 can be very tedious. To make this process a little less painful, there is a way to slowly implement modules from ZF2 without making the application unusable. The methodology illustrated, which implements DoctrineModule and DoctrineORMModule into a Zend Framework 1 project, can be applied to a variety of ZF2 modules, making it an invaluable technique in the migration process.

Using these two ZF1 modules, they show how to integrate them into a typical ZF2 structure. There's a few steps in the process:

• Add init_autoloader.php to application root directory
• Update ZF1′s index.php for Composer compatibility
• Setup ZF2 configuration files
• Setup ZF2 "Application" module
• Relocate existing entities and repositories to ZF2
• Make ZendMvcApplication available in ZF1

It's not an overly complex process, it just requires the right configuration settings and component placement to get the ZF1 module to cooperate in the world of ZF2.