Newsletter sign-up

View all newsletters

Enterprise Java Newsletter
Stay up to date on the latest tutorials and Java community news posted on JavaWorld

Robust event logging with Syslog

Syslog is a fast, flexible, and easily extendable logging system

By Nate Sammons, JavaWorld.com, 04/06/01

An important part of any project, logging can be used as a debugging tool during development, and a troubleshooting tool once a system has been deployed in a production environment. Because most developers only implement logging if time permits, it is often implemented haphazardly. However, logging provides a way to see what is happening, good or bad, inside a running system. As such, it should be addressed with care and forethought rather than as a last minute burden.

Syslog is an open source logging system that allows programmers to easily add diagnostic and status logging to their Java programs. It separates the act of logging an event from the actual handling of that event. Simple configurations may instruct Syslog to write all log messages to the console. In more elaborate configurations, Syslog can separate messages by almost any criteria, including severity, and send them to different files. These files can rotate based on time or file size and send email across a network via Remote Method Invocation (RMI) or Java Message Service (JMS). API calls allow configuration modification at runtime, and Syslog can save running configuration to an XML file for further refinement at a later time. In the case of application servers hosting multiple applications running in the same VM, message channels allow Syslog to route log messages coming from each application and handle them accordingly.

A list of log message handlers essentially constitutes Syslog. Each handler has a log policy that determines what messages it should consider. If the policy determines that the handler should deal with a given message, the logger uses a message formatter to prepare the message, and the handler then writes the message to a file or sends an email. The architecture is based on interfaces so that custom modules can replace each step.

Syslog provides the following features:

• Simple, all-static logging API
• Message severities
• Pluggable log message handlers
• Pluggable log-formatting modules for each handler
• Pluggable log policy modules for each handler
• Arbitrary log channels
• A configuration that can be modified on the fly while running
• A running configuration that can be written to a file for reload later
• Email integration
• Remote logging capabilities -- using RMI
• JMS integration

Licensed under the GNU LGPL v2, Syslog is free for commercial and noncommercial use, with source code included. Though it was originally based loosely on the Unix Syslog facility, it now shares only its name. In this article, you'll learn how to easily integrate the Syslog package into your system by adding simple instrumentation to your Java code. You'll also uncover more elaborate ways to leverage Syslog in projects as an integral part of new system development. Syslog allows developers to concentrate on developing application code, not on how an operations department or hosting provider will handle logging.

Syslog for developers

Two groups of people will benefit from a logging system: developers and operations staffs. Developers need to be able to instrument their code with little effort; otherwise they'll never perform event logging. As you'll observe, you can instrument code with Syslog calls in a number of ways, ranging from the simple to the complicated.

 

XpoLog Center Correlate application logs with server metrics - XpoLog

About Us | Advertise | Contact Us | Terms of Service/Privacy

Copyright, 2006-2008 Network World, Inc. All rights reserved.