Pax Logging

Introduction

Pax Logging is an implementation of OSGi Log Service API. Pax Logging 1.x releases implement OSGi org.osgi.service.log package in version 1.3 while Pax Logging 2.x releases will implement OSGi org.osgi.service.log package in version 1.4.

Not only pure OSGi logging API is implemented. Pax Logging hides the OSGi specific interfaces and mechanisms under popular Logging APIs. These include:

• Slf4J

• Apache Commons Logging

• Apache Tomcat JULI Logging (a repackaged version of Apache Commons Logging)

• Avalong Logging API (very ancient)

• JBoss Logging API

• Knopflerfish R6 Logging API

• Log4J 1

• Logback (supported only behind Slf4J facade)

• Log4J 2

• Java Util Logging (supported as special JUL handler)

Developers writing their OSGi bundles have wide choice of Logging APIs to use. All the above are supported and relevant packages are exported from single pax-logging-api bundle.

At backend Pax Logging supports three actual Logging frameworks:

• Log4J 1

• Logback

• Log4J 2

Each of the above is included in respective Pax Logging bundles: pax-logging-service, pax-logging-logback and pax-logging-log4j2. These bundles provide OSGi support for the above frameworks and allow their configuration through OSGi Configuration Admin API.

What's most important is that the choice of Logging API used by any bundle doesn't force developer to use particular Logging backend. For example, Log4j2 API can be used to call logging methods while the actual framework used to write the log statements may be Log4J1.

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