NRAO - Socorro July, 2004

ACS CourseACS CourseACS logging in JavaACS logging in Java

H. Sommer

2

ALMA Project

Socorro, July 2004 ALMA Common Software course

Plain JDK Loggerwith ACS behind the scenes

java.util.logging.Logger• info(String msg)• log(Level, String msg, Throwable)

ContainerServices#getLogger()

Application code(component or comp-client)

creates & configures

getLogger

uses

VM-local ACS log handler

forwards messages

remote ACS logging serviceCentral log display

forwards(XML)

3

ALMA Project

Socorro, July 2004 ALMA Common Software course

Code Snippetsfrom jcontexmpl/HelloLampImpl

m_logger.info("sayHello called...");

catch (Exception ex)

{

m_logger.log(Level.SEVERE, "ex in setLampBrightness impl", ex);

}

4

ALMA Project

Socorro, July 2004 ALMA Common Software course

JDK Logging API

• Standard since JDK 1.4

• Easy API (you’ll only need the Logger class)– short methods with level names (finest, ... info, warning, severe)

each taking a message string.

– More powerful methods log, logp, for logging of values etc.

• Flexible configuration for filtering and formatting (done by ACS)• Automatic retrieval of method names, line numbers etc

(not guaranteed to work always for all VMs though…)

• API: http://java.sun.com/j2se/1.4.2/docs/api/java/util/logging/package-summary.html

• More info: http://java.sun.com/j2se/1.4.2/docs/guide/util/logging/overview.html

5

ALMA Project

Socorro, July 2004 ALMA Common Software course

ACS logging configuration

• Standard configuration file used: module acsjlog/src/almalogging.propertiesacsStartContainer –java frodoContainer

• User may specify different properties file:abeansStart -endorsed -Djava.util.logging.config.file=/x/y/mylogging.properties frodoContainer

• Suppress log levels below INFO (or any other level):alma.acs.logging.AcsLoggingHandler.level = INFO

• Console output level controlled by separate property:java.util.logging.ConsoleHandler.level = INFO

6

ALMA Project

Socorro, July 2004 ALMA Common Software course

Future of Java ACS Logging

• The Logger returned from ContainerServices#getLogger is already configured with a “logger-namespace” unique for the Java component that requests it.

• We could extend that namespace concept to group or filter log entries by the components that produced them

• Log levels for suppressing unimportant messages could be set dynamically, e.g. by the Administrator Client; individually for all components and containers in the system…