The Java Service Wrapper makes it possible to install a Java Application as a Windows Service. Likewise, the scripts shipped with the Wrapper also make it very easy to install a Java Application as a Daemon process on UNIX systems.

The Wrapper correctly handles "user's logouts" under Windows, service dependencies, and the ability to run services which interact with the desktop.

Please visit the documentation pages below for instructions:

• How to run a Java application as a Windows Service
• How to run a Java application as a UNIX Daemon

As the use of Java expands, your applications have been written to provide a variety of mission and critical services. These services must be able to provide a high level of reliability. In an ideal world, only software which is 100% bug free will ever be released and installed. However, history has shown this not to be the case. Almost every application suffers from quality issues at one point or another during their life-cycle. Applications hang, crash, run out of memory or suffer from any number of problems. Where possible, problems are fixed quickly without significant service outages. There are times however, when fixing a problem can be prohibitively expensive or impossible to solve in a short time period.

The Wrapper monitors a JVM process and automatically restarts it if the JVM has crashed or hung. This process takes just a few seconds once the Wrapper has decided there is a problem. There is also a way to configure the Wrapper to monitor the console output of a JVM and react to certain strings by restarting or shutting down the JVM.

While these advanced features of the Java Service Wrapper will not make every problem go away, they will help you to sleep easier knowing that if there is a problem, the Wrapper will be there to keep things up and running until you can get into the office to check the logs. Say goodbye to those emergency phone calls!

Write once, run everywhere configuration. Java has been marketed as a "Write Once, Run Everywhere" programming language. While this is true for many aspects of an application, the developer is often plagued with having to write complicated, platform-specific scripts, which are tasked with building up class paths and collecting other system information necessary to launch an application.

The Java Service Wrapper helps to relieve the developer of the troublesome task by providing a set of scripts for a wide range of platforms that can be used as is to launch and run almost any Java Application controlled by the Wrapper.

The Wrapper moves all JVM configuration into a platform independent configuration file wrapper.conf. See the examples on Summary of Integration Methods section for details.

The Java Service Wrapper provides a way for a Java Application to request that its own JVM be restarted. This can be useful in a number of cases. Applications may wish to restart after having had their configuration files modified. Or the application may simply need to be restarted to avoid problems with a memory or resource leak of some kind.

JVM restarts can be triggered from within the JVM by making a call to WrapperManager.restart(). See the WrapperManager.restart() in JavaDocs for more details.

There are also more passive ways to trigger restarts. The Wrapper has the ability to monitor console output and trigger shutdowns or restarts whenever certain text is detected.

The Wrapper can also be configured to either restart another JVM instance or shutdown normally depending on the exit code returned by a JVM.

The Java Service Wrapper provides a wide range of configuration properties which can be used to configure the JVM in any way possible from the command line. The Wrapper configuration file "wrapper.conf" also provides a number of properties to allow you to configure things like logging and how the Wrapper is installed as a service.

See the Configuration Properties section for details on what is possible. Be sure you have read over the Summary of Integration Methods section before jumping into the configuration file wrapper.conf.

By using the Wrapper's standard scripts, and relative paths in the configuration file wrapper.conf, it is usually possible to create an application which requires no further complicated installation than simply expanding an archive file into a directory of the user's choice.

While the Java Service Wrapper does not attempt to, nor should it, replace any of the great Logging Tools available, it does provide a number of properties to configure how "stdout" and "stderr" output to the JVM console is handled. This output can be logged to any combination of the console, a file, or the "Event Log" (Windows) or "syslog" (UNIX).

Logging the output to the JVM console can be critical to tracking down problems with an application. Without the Wrapper, when a JVM is being run as a Service under Windows, or as a Daemon under UNIX, the console output would normally be lost. The Wrapper makes sure that all console output is logged.

Java-based Logging Tools are only capable of logging output generated from within the JVM. If the JVM crashes or prints out low level messages such as thread dumps, there is normally no way to log it. The Wrapper logs all console output from the JVM process, regardless of its source. This means that the records of any crashes will survive even after the Wrapper has restarted the JVM.

See the Logging Configuration section for further details.