Java applications can now inside the database unlike some competing technologies where the java process runs out of the database and use the shared memory inside the database. Oracle's product comes with built in Java VM, EJB support, Corba Compliant ORB, Built in JDBC and SQLJ it comes with support for Java Beans Server, JDBC, SQLJ, Enterprise. More over oracle just released its XML tool kit that allows standard sql to return XML Documents. The oracle 8i server has a foot print of 40kb for each Java Virtual Machine, and it there by allows the server to run thousands of virtual machines. So, oracle can run individual virtual machines for individual sessions and scale up to 1000's of transactions without having to code threads in the application logic.
Speed is handled by native compilation.
The Java Server Program, as well as all of the supporting Java classes are compiled to C and then dynamically linked into the server kernel for execution. The Aurora JVM actually runs in the same process and address space as the Oracle kernel, sharing memory heaps and therefore directly accessing its relational data. Getting Started Jserver comes with the oracle 8i Enterprise Server and if you install a typical or custom seed database, the setup routines automatically initialize, configure and enable java in the database. Since we typically do not use seed databases, lets see how to initialize the Java VM in the database. There are a few things that you need to set before you initialize the Jserver manually.