Slides for the Writing Stored Procedures in Oracle RDBMS talk at JavaDay Kiev 2016

1. Writing Java Stored Procedures
with Oracle RDBMS
Martin Toshev

2. Who am I
Software consultant (CoffeeCupConsulting)
BG JUG board member (http://jug.bg)
OpenJDK and Oracle RDBMS enthusiast
Twitter: @martin_fmi

4. Work in progress …

5. Agenda
• PL/SQL vs Java Stored Procedures
• Writing Java Stored Procedures
• Managing Java Stored Procedures
• New features in Oracle Database 12c

6. PL/SQL vs Java Stored Procedures

7. PL/SQL vs Java Stored Procedures
• Both PL/SQL and Java stored procedures are executed
directly on the RDBMS
• Both PL/SQL and Java stored procedures can be
recompiled dynamically when source code changes
• Easier migration of Java stored procedures to/from the
application tier

8. PL/SQL vs Java Stored Procedures
• The PL/SQL Virtual Machine (PVM) is the database
component that executes the PL/SQL bytecode (lower
lever representation of the PL/SQL code that is generated
from the PL/SQL compiler)
• PVM is written in C

9. PL/SQL vs Java Stored Procedures
• Java procedures are executed from a JVM (Java Virtual
Machine) process running inside the Oracle RDBMS:
Oracle
DB
Oracle
RDBMS
PL/SQL JVM
Java
method

10. PL/SQL vs Java Stored Procedures
• Since the Oracle JVM is embedded in the database this
introduces a number of new concepts:
– Oracle JVM process that runs within an Oracle database session
– classloader that loads classes from the database
– no notion of main() method
– loading of system classes from the SYS schema (where they are stored)

11. PL/SQL vs Java Stored Procedures
• Since the Oracle JVM is embedded in the database this
introduces a number of new concepts:
– oracle.aurora.rdbms.DbmsJava.classForNameAndSchema() for
loading a class from a database schema
– The Oracle JVM uses the database memory structures to store data
– The garbage collector makes use of the call and session memory on a
per-user basis

12. PL/SQL vs Java Stored Procedures
• Since the Oracle JVM is embedded in the database this
introduces a number of new concepts:
– no support for JNI
– server-side JDBC driver providing access to Oracle data (using the
"jdbc:default:connection:“ connection URL)
– server-side SQLJ translator – allows embedding of SQL statements in
Java stored procedures

13. Writing Java Stored Procedures

14. Writing Java Stored Procedures
• In order to create a Java stored procedure:
o write the Java class that contains the Java procedure(s) (static
method(s) in the class)
o load the compiled Java procedure in the Oracle database using the
loadjava utility or the CREATE JAVA command
o map a PL/SQL function/procedure to the Java procedure using the
CREATE FUNCTION/PROCEDURE command

15. Writing Java Stored Procedures
• The loadjava utility uses the
CREATE JAVA {SOURCE | CLASS |
RESOURCE}
command to load source/class/resource files

16. Writing Java Stored Procedures
• Example: loading the Sample.java source file using the
orcl user:
• Example: loading the Sample.java source file using the
orcl user and compiling it:
loadjava -u orcl Sample.java
loadjava -u orcl –resolve Sample.java

17. Writing Java Stored Procedures
• Map the Java static function func() from the Sample
class:
CREATE OR REPLACE FUNCTION func
RETURN VARCHAR2 AS
LANGUAGE JAVA NAME
‘Sample.func() return java.lang.String';

18. Writing Java Stored Procedures
• Invoke the func function:
VARIABLE result VARCHAR2(20);
CALL func() INTO :result
PRINT result;

19. Writing Java Stored Procedures
• You can provide privileges for other users to invoke your
class(es) using the loadjava utility or the GRANT
command:
loadjava -grant usr –u orcl Sample.java
GRANT EXECUTE ON Sample TO usr;

20. Writing Java Stored Procedures
demo

21. Managing Java Stored Procedures

22. Managing Java Stored Procedures
• USER_OBJECTS table (OBJECT_TYPE columns is any
of JAVA SOURCE,
JAVA CLASS or JAVA RESOURCE in a valid/invalid
state)

23. Managing Java Stored Procedures
• JMX can be used to monitor the Oracle JVM
• The current user must be granted the JMXSERVER role
• The dbms_java.start_jmx_agent can be used to
start the JMX server for the session

24. Managing Java Stored Procedures
• Java stored procedures can be debugged be debugged by
a JWDP-compliant debugger
• Such as a debugger is provided by jdb and the
JDeveloper IDE
exec DBMS_DEBUG_JDWP.CONNECT_TCP('localhost', 6666);

25. Managing Java Stored Procedures
• Compiler options can be specified:
– in the JAVA$OPTIONS table
– via the loadjava utility
– via the DBMS_JAVA package (that creates/modifies
the JAVA$OPTIONS table)

26. Managing Java Stored Procedures
demo

27. New Features in Oracle Database 12c

28. New features in Oracle Database 12c
• Support for multiple JDK versions (JDK 6 by default but
JDK 7 or earlier can be specified)
• Considering multitenant databases introduced in 12c:
PDBs (pluggable databases) share the same JDK version
specified over the CDB (container database)

29. New features in Oracle Database 12c
• Native Oracle JVM support for JNDI
• Customizing the default java.security resource

30. New features in Oracle Database 12c
• Enhanced support for logging properties lookup
• Secure use of Runtime.exec
• Improved debugging support for Java Stored Procedures
(watchpoints/breakpoints)

31. Thank you !
Q&A