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last update: 20 July 2004. JADE 3.2
JADE – Java Agent DEvelopment Framework is a framework to develop multi-agent systems in compliance with the FIPA specifications. JADE successfully passed the 1st FIPA interoperability test in Seoul (Jan. 99) and the 2nd FIPA interoperability test in London (Apr. 01).
Copyright (C) 2000 CSELT S.p.A. (C) 2001 TILab S.p.A. (C) 2002 TILab S.p.A.
This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, version 2.1 of the License.
This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 59 Temple Place – Suite 330, Boston, MA 02111-1307, USA.
TABLE OF CONTENTS
JADE LOGGING SERVICE
1 Logging Service Overview
The goal of this document is to provide an overview of the key elements of the JADE logging service. The logging service class provides a uniform way to produce logging printouts by hiding to applications the characteristics of the device (e.g. on a MIDP device a RecordStore is used). The full implementation running in a JAVA5 (or later) environment is a pure extension of the java.util.logging.Logger class and provides the whole set of functionalities of java.util.logging. When using the LEAP Add-on, the implementation for MIDP and PJAVA environments, instead, provide the same API but a reduced set of functionalities: please refer the documentation provided for class jade.util.Logger for further information about this topic. The class jade.util.Logger is, infact, the main class on which applications make logging calls.
2 Logging Mechanism
JADE classes and user’s applications use logging service by making logging calls on jade.util.Logger objects. Because its implementation is based upon the java.util.logging package, loggers are organized into a hierarchical name space and child can inherit properties from parents.
When the user instantiates a logger object, he assigns it a unique name, which can be, for instance, the name of the class in which the object has been created. The usage of the following coding style is recommended in order to create a Logger object for class mypackage.MyClass
Logger logger = jade.util.Logger.getMyLogger(this.getClass().getName());
Notice that the static method getMyLogger is used instead of the class constructor.
Logger objects provide an easy mean to produce messages of interest to end users and/or software developers and to log them to different kinds of destinations such as, for instance, the standard output or a file. (cfr LOG HANDLERS). Each log message has an associated log Level. The Level gives a rough guide to the importance and urgency of a log message (cfr LOG LEVELS). The usage of the following coding style is recommended in order to log a message with a certain level of importance:
logger.log(jade.util.Logger.myLevel, “this is the message to log”);
where myLevel will be one of the levels allowed ( for instance jade.util.Logger.SEVERE). Notice that testing if the level is loggable before actually calling the log method allows relevant performance improvements.
3 Log levels
4 Log Handlers
5 Logging Configuration
User can change the log level for a logger object and the handlers associated with it. JADE provides two ways to control the logging configuration:
– at deployment time: the JVM can be launched by passing a logging configuration file that specifies logging level and handlers for each class
– at execution time: the Log Manager Agent can be launched at anytime during the execution of JADE. This graphical tool allows to change the logging configuration (again level and handler) on a per-class basis.
5.1 Logging Configuration File
Here is an example of a logging configuration file (myLogging.properties) :
# Properties file which configures the operation of the JDK
# logging facility.
# The system will look for this config file, first using
# a System property specified at startup:
# >java -Djava.util.logging.config.file=C:\Jade\myLogging.properties
# If this property is not specified, then the config file is
# retrieved from its default location at:
# Global logging properties.
# The set of handlers to be loaded upon startup.
# Comma-separated list of class names.
# Default global logging level.
# Loggers and Handlers may override this level
# Loggers are usually attached to packages.
# Here, the level for each package is specified.
# The global level is used by default, so levels
# specified here simply act as an override.
# — ConsoleHandler —
# Override of global logging level
# — FileHandler —
# Override of global logging level
# Naming style for the output file:
# (The output file is placed in the directory
# defined by the “user.home” System property.)
# Limiting size of output file in bytes:
# Number of output files to cycle through, by appending an
# integer to the base file name:
LogManager Agent can be launched via the JADE RMA gui using the icon shown below.
After LogManager Agent has been launched the gui shown in Figure 1 will appear.
Figure 1 : LogManager Agent user interface
The column LoggerName shows a list of the logger objects currently instantiated in the platform. For each logger, you can change the log level at runtime by setting it using the combo box as shown in Figure 2. The column Handlers shows the handlers currently settled for the logger object on the same row. The column Set Log File allows you to create a file at runtime and send your logs to it. In the example shown in the picture above, the logs generated by class jade.content.shema.AgentActionSchema will be sent both to console and to file logFile.txt.