Zebra_Session is a PHP class that acts as a wrapper for PHP’s default session handling functions. Instead of storing session data in flat files, it stores them in a MySQL database, thus providing both better security and better performance. The Zebra_Session class is also a solution for applications that are scaled across multiple Web servers (using a load balancer or a round-robin DNS) and where the user’s session data needs to be available, since storing sessions in a database makes them available to all of the servers. Zebra_Session‘s code is heavily commented and generates no warnings, errors, or notices when PHP’s error reporting level is set to E_ALL.
Scache is a different approach for PHP session data management. It provides a generic key-value data cache to use for transient session data storage. Scache also provides a shared keyspace, shared counters, and simple cache features. Scache's difference to other implementations is a tree-structured keyspace where one can easily operate only on required parts of stored session data and also invalidate groups of stored data by expiring whole subtrees. Despite its name, scache is not a cache. Scache stores all session data inserted until data is deliberately destroyed and so reduces the need to redundantly store the same data somewhere else. Scache consists of a daemon and a PHP extension.