JPOX uses a series of categories, and logs all messages to these categories. Currently JPOX uses the following

• JPOX.JDO - All messages general to JDO
• JPOX.Cache - All messages relating to the JPOX Cache
• JPOX.MetaData - All messages relating to MetaData
• JPOX.General - All general operational messages
• JPOX.Utility - All messages from JPOX utilities (e.g SchemaTool)
• JPOX.Transaction - All messages relating to transactions
• JPOX.RDBMS - All messages specific to the RDBMS persistence process
• JPOX.RDBMS.DDL - All Data Definition Language messages
• JPOX.RDBMS.SQL - All JDBC SQL messages (excluding DDL)
• JPOX.RDBMS.Schema - All messages relating to the schema with the RDBMS persister
• JPOX.OLAP - All messages specific to the OLAP persistence process.
• JPOX.FileIO - All messages specific to the FileIO persistence process.
• JPOX.Enhancer - All messages from the JPOX Enhancer.
• JPOX.IDE - Messages from the JPOX IDE.

Log4J allows you to log messages at various severity levels. These are DEBUG, INFO, WARN, ERROR, FATAL. Each message is logged at a particular level to a category (as described above).

To enable the JPOX log, you need to provide a Log4J configuration file when starting up your application. This may be done for you if you are running within a J2EE application server (check your manual for details). If you are starting your application yourself, you would set a JVM parameter as

-Dlog4j.configuration=file:log4j.lcf
                    

The configuration file is very simple in nature, and you typically define where the log goes to (e.g to a file), and which logging level messages you want to see. Here's an example

log4j.rootCategory=, A1

# Define the log to be a file
log4j.appender.A1=org.apache.log4j.FileAppender
log4j.appender.A1.File=jpox-test.log

# Appender A1 uses the PatternLayout.
log4j.appender.A1.layout=org.apache.log4j.PatternLayout
log4j.appender.A1.layout.ConversionPattern=%d{DATE} %-5p %c - %m%n

# Global Threshold - overridden by any Categories below.
#log4j.appender.A1.Threshold=INFO

# JPOX Categories
log4j.category.JPOX.JDO=INFO
log4j.category.JPOX.Cache=INFO
log4j.category.JPOX.MetaData=INFO
log4j.category.JPOX.General=INFO
log4j.category.JPOX.Utility=INFO
log4j.category.JPOX.Transaction=INFO

log4j.category.JPOX.RDBMS=DEBUG
log4j.category.JPOX.RDBMS.Schema=DEBUG
log4j.category.JPOX.RDBMS.DDL=DEBUG
log4j.category.JPOX.RDBMS.SQL=DEBUG

log4j.category.JPOX.OLAP=INFO

log4j.category.JPOX.FileIO=INFO

log4j.category.JPOX.Enhancer=INFO

log4j.category.JPOX.IDE=INFO
                

In this example, I am directing my log to a file (jpox-test.log). I have defined a particular "pattern" for the messages that appear in the log (to contain the date, level, category, and the message itself). In addition I have assigned a level "threshold" for each of the JPOX categories. So in this case I want to see all messages down to DEBUG level for the JPOX RDBMS persister.

Here is a sample of the type of information you may see in the JPOX log

21:26:09,000 INFO  JPOX.RDBMS - Adapter initialised : MySQLAdapter, MySQL version 4.0.11a-gamma'-Max' major 4 minor 0
21:26:09,365 INFO  JPOX.RDBMS - Creating table null.DELETE_ME1080077169045
21:26:09,370 DEBUG JPOX.RDBMS.DDL - CREATE TABLE DELETE_ME1080077169045
(
    UNUSED INTEGER NOT NULL
) TYPE=INNODB
21:26:09,375 DEBUG JPOX.RDBMS.DDL - Execution Time = 3 ms
21:26:09,388 WARN  JPOX.RDBMS.Schema - Schema Name could not be determined for this datastore
21:26:09,388 INFO  JPOX.RDBMS - Dropping table null.DELETE_ME1080077169045
21:26:09,388 DEBUG JPOX.RDBMS.DDL - DROP TABLE DELETE_ME1080077169045
21:26:09,392 DEBUG JPOX.RDBMS.DDL - Execution Time = 3 ms
21:26:09,392 INFO  JPOX.RDBMS.Schema - Initialising Schema "" using "SchemaTable" auto-start option
21:26:09,401 DEBUG JPOX.RDBMS - Retrieving type for table JPOX_TABLES
21:26:09,406 INFO  JPOX.RDBMS - Creating table null.JPOX_TABLES
21:26:09,406 DEBUG JPOX.RDBMS.DDL - CREATE TABLE JPOX_TABLES
(
    CLASS_NAME VARCHAR (128) NOT NULL UNIQUE ,
    `TABLE_NAME` VARCHAR (127) NOT NULL UNIQUE 
) TYPE=INNODB
21:26:09,416 DEBUG JPOX.RDBMS.DDL - Execution Time = 10 ms
21:26:09,417 DEBUG JPOX.RDBMS - Retrieving type for table JPOX_TABLES
21:26:09,418 DEBUG JPOX.RDBMS - Validating table : null.JPOX_TABLES
21:26:09,425 DEBUG JPOX.RDBMS - Execution Time = 7 ms
                

So you see the time of the log message, the level of the message (DEBUG, INFO, etc), the category (JPOX.RDBMS, etc), and the message itself. So, for example, if I had set the JPOX.RDBMS.DDL to DEBUG and all other categories to INFO I would see *all* DDL statements sent to the database and very little else.