How to Enable Logging

This page provides simple instructions for enabling OGSA-DAI logging. OGSA-DAI logging is based upon Apache Log4J. For full details of Apache Log4J configuration please refer to the Log4J documentation.

What are the OGSA-DAI logging levels?

The levels we use are those used by Apache Log4J. These levels, and the information within OGSA-DAI which is logged at those levels, are as follows:

FATAL - for server-side problems encountered when a service is initialised or when accessing resource-related information.
ERROR - for server-side problems of concern to a service or resource deployer.
WARN - for server-side problems that are viewed as of no great concern (e.g. exceptions that are gulped) or for problems caused by information from a client that is in some way problematic.
INFO - for general status and progress information that may be of use to a service or resource deployer.
DEBUG - for general debugging information that may be of use to a developer.

As logging carries an overhead we recommend that the minimum level you use in a production system is INFO and that you only enable the DEBUG when you have encountered serious problems (typically the OGSA-DAI team will recommend this when assisting in resolving any support queries for example).

How to enable logging within OGSA-DAI WSI

The steps below explain how to configure Log4J to log all messages to a rolling file. This is a file with a limited size and when the limit is reached the file will be renamed by appending a count to the filename, then a new file will be created.

If you have not already done so, create a file called log4j.properties.
- Copy the following content into the file:
```
# Categories
log4j.rootLogger=YOUR-LEVEL, ROLLINGFILE
log4j.category.org.apache=ERROR, ROLLINGFILE
log4j.category.org.globus=ERROR, ROLLINGFILE

# ROLLINGFILE appender
log4j.appender.ROLLINGFILE=org.apache.log4j.RollingFileAppender
log4j.appender.ROLLINGFILE.Threshold=YOUR-LEVEL
log4j.appender.ROLLINGFILE.layout=org.apache.log4j.PatternLayout
log4j.appender.ROLLINGFILE.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n
log4j.appender.ROLLINGFILE.File=LOGFILE
```
  where
  - YOUR-LEVEL is your chosen logging level (one of DEBUG INFO, WARN ERROR, OR FATAL)
  - LOGFILE is the file in which logs are to be written.
    - This may specify the filename alone, for example ogsa-dai-debug.log, or may specify the path to the file, for example /home/user/ogsa-dai-debug.log.
    - On Windows, if you specified the path to the file then you must use '/' rather then '\' to seperate directories.
    - If you specified a filename alone then you may have to search around within your Web services container distribution for the log file - a starting point is the bin directory.
Move the file to the classes directory of your container.
- The Where Do Files Reside After Deployment? page tells you where this directory is located.
Shutdown and restart your container.

To enable logging within OGSA-DAI WSRF

The steps below explain how to configure Log4J to log all messages to the a log file - if using Tomcat - or the console - if using the Globus Toolkit Web services container.

Edit one of the following files:
- If you are using Tomcat:
```
TOMCAT/webapps/wsrf/WEB-INF/classes/log4j.properties
```
- If you are using the Globus Toolkit container:
```
GLOBUS_LOCATION/container-log4j.properties
```
Beneath the line:
```
log4j.category.org.globus=INFO
```
Add the following line:
```
log4j.category.uk.org.ogsadai=YOUR-LEVEL
```
where YOUR-LEVEL is your chosen logging level (one of DEBUG INFO, WARN ERROR, OR FATAL)
Save the file.
Ensure the container's lib directory contains the log4j jar file (e.g. log4j-1.2.8.jar).
- If you are using Tomcat the lib directory will be:
```
TOMCAT/webapps/wsrf/WEB-INF/lib
```
- If you are using the GlobusToolkit container the lib directory will be:
```
GLOBUS_LOCATION/lib
```
Restart the container.

To log messages to a file instead of the console for the Globus Web services container, it is necessary to add a file appender or rolling file appender to the Log4J configuration file. This approach is shown in the OGSA-DAI WSI example above and is explained in more detail in the Log4J manual. Note that for the Globus container, console log messages are displayed within the console in which the container was started.