top

2. Quick start

If you are in a hurry to have Apache Karaf up and running right away, this section will provide you with some basic steps for downloading, building (when needed) and running the server in no time. This is clearly not a complete guide so you may want to check other sections of this guide for further information.

All you need is 5 to 10 minutes and to follow these basic steps.

• #Background
• #Getting the software
• #Start the server
• #Deploy a sample application

Background

Apache Karaf is a small and lightweight OSGi based runtime. This provides a small lightweight container onto which various bundles can be deployed.

#top

Getting the software

At this time you have one option to get the software. The fastest and easiest way is to get the binary directly from the Apache site. Since this article is intended to help you to have Apache Karaf up and running in the fastest way only the binary download will be covered at this time.

Prerequisites

Although this installation path is the fastest one, still you will need to install some software before installing Karaf.

Karaf requires a Java 5 environment to run. Refer to http://java.sun.com for details on how to download and install J2SE 1.5 or greater.

Download binaries

Depending on the platform you plan to install and run Karaf you will select the appropriate installation image. Open a Web browser and access the following URL, there you will find the available packages for download (binaries and source code).

http://karaf.apache.org/download.html

Select the file compression format compatible with your system (zip for windows, tar.gz for unixes) by clicking directly on the link, download it and expand the binary to your hard drive in a new directory; for example in z:\karaf - from now on this directory will be referenced as <KARAF_HOME>. Please remember the restrictions concerning illegal characters in Java paths, e.g. !, % etc.

The installation of Karaf is as simple as uncompressing the .zip or .tar files. The next step is to start the server.

#top

Start the server

With Karaf already installed, open a command line console and change directory to <KARAF_HOME>. To start the server, run the following command in Windows:

respectively on Unix:

You should see the following informations on the command line console:

You can now run your first command. Simply type the <tab> key in the console.

You can then grab more specific help for a given command using the --help option for this command:

Note that the console supports tab completion, so you just need to enter ad <tab> cr <tab> instead of admin:create.
#top

Deploy a sample application

While you will learn in the remainder of this guide how to use and leverage Apache Karaf, we will just use the pre-built packaging for now.

In the console, run the following commands:

The example installed is using Camel to start a timer every 2 seconds and output a message on the console. The previous commands download the Camel features descriptor and install the example feature.

Stopping and uninstalling the sample application

To stop this demo, run the following command:

Common Problems

1. Launching Karaf can result in a deadlock in Felix during module dependency resolution. This is often a result of sending a SIGINT (control-C) to the process when it will not cleanly exit. This can corrupt the caches and cause startup problems in the very next launch. It is fixed by emptying the component cache: rm -rf data/cache/*

Stopping Karaf

To stop Karaf from the console, enter ^D in the console:

Alternatively, you can also run the following command:

Summary

This document showed you how simple it is to have Apache Karaf up and running. The overall time for getting the server running should be less than five minutes if you have the prerequisite (Java 1.5) already installed. Additionally, this article also showed you how to deploy and test a simple Apache Camel application in less than five minutes.

#top