Java in the Database

Java in the Database

Oracle Java Components

Oracle JServer (Aurora JVM) – Java Virtual Machine that runs in the Oracle Server address space. Is JDK 1.1.6 compliant. Provides a runtime environment for Java objects. Main components of the Oracle JVM are:
Library Manager - Loads Java source, class, and resource files into the database.
Memory Manager – Takes care of garbage collection
Compiler – Creates Java bytecode
Interpreter - Interprets and executes Java bytecode
Class Loader - Locates, loads and initializes Java classes stored in the database, based upon requests from the run-time system. Allows Java binaries to be exchanged between the Oracle JVM and other non-Oracle systems.
Verifier – Prevents the execution of “spoofed” Java class files. Both Oracle security and Java security work with the verifier to protect apps.
Server-side JDBC Driver – Provides access to the Oracle RDBMS for non-Oracle applications. Supports Oracle specific datatypes, NLS, and stored procedures.
Server-side SQLJ Translator – A Java program that translates SQL imbedded within a Java program (SQLJ) into Java classes that implement the embedded SQL statements.
Jserver Accelerator – Speeds up the execution of Java programs in Oracle by translating Java class files into native code via a platform-dependent C compiler. This eliminates the overhead of the interpreter.
Loadjava/Dropjava - Command line utilities that automate the loading and unloading of Java Stored Procedures. Replaces the need to use the CREATE JAVA CLASS statement in SQL*Plus. Among other things, the LOADJAVA command compiles source code Java files into standard class files. The LOADJAVA command can also set various options that affect the processing of Java Stored Procedures.
SQLJ - Provides the ability to include static SQL within Java code. Is made up of both a translator and a runtime component. SQLJ allows anonymous PL/SQL blocks and has a syntax for calling PL/SQL procedures and functions.
Enterprise Java Beans (EJB’s) – Distributed Java components. Oracle8I Jserver implements the EJB 1.0 specification. Current Jserver supports session beans. Entity beans will be supported in a future release. Stateless beans do not share state or identity between methods; best suited for middle-tier apps performing frequent short requests like those in an OLTP application. Stateful beans maintain their state between methods and are best for sessions with a longer duration.
CORBA ( Common Object Request Broker Architecture)Services – An international standard for cross-platform and cross-language development. The Jserver has various tools and services to support CORBA development.
Java and EJB CORBA servers require the use of the Oracle 8I Multi threaded Server(MTS)!!!
iFS (Internet File system) – A Java app that runs within the Oracle8I Java Virtual Machine. Allows for “file system/network drive” type of interface to manage various types of files within the Oracle database. Supports many standard protocols. iFS can be accessed via windows Explorer, a Web browser, and an FTP client or e-mail client.