Database Embedded JVM (OJVM)
The embedded JVM runs Java code in user session (within the dedicated or shared server), in the same memory space as SQL and PL/SQL. These Java modules can be invoked by any database client, similarly to PL/SQL modules.
What for? In-place processing of large datasets (batch operations, LOBs, JSON, XML) without incurring network traffic; In other words, no data shipping. Here are some use cases: