Chapter 1, Installing Apache Karaf, provides a quick installation reference for users new to Apache Karaf.

Chapter 2, Commanding the Runtime, starts with an under-the-hood discussion of how Apache Karaf commands work. We then dive into a review of the most commonly used commands and ways to access them.

Chapter 3, System Configuration and Tuning, describes an Apache Karaf installation containing several default configuration options that most users will want to alter. This chapter dives into the contents of the Apache Karaf's etc folder.

Chapter 4, Provisioning, explains how the applications go about gathering all of the artifacts required for runtime, before we can begin deploying them into Apache Karaf. Apache Maven repositories and feature descriptors are introduced and explained.

Chapter 5, Deploying Applications, discusses how to deploy various application assemblies into Apache Karaf. We touch upon OSGi and non-OSGi JARs, feature descriptors, WARs, and other formats.

Chapter 6, Deploying Production-grade Apache Karaf, discusses production deployment concepts for Apache Karaf, including offline repositories, improving application logging, high availability / failover, and basic security configuration.

Chapter 7, Apache Karaf Cellar, forms our primer for Apache Karaf's clustering solution.

Chapter 8, Our Final Programming Project, helps us bring together our learned concepts to build a sample application following the best practices, now that we've studied Karaf.

Appendix, Apache Karaf Commands, provides a quick reference for the core Apache Karaf commands.

The authors have taken great care to keep the quantity of software required to explore Apache Karaf to a minimum. You will need to obtain the following before trying out the samples included in this text:

Learning Apache Karaf is for developers and system administrators who need to discover and understand how to use Apache Karaf as an operating environment in the best possible way. Developers will learn the best practices for designing applications that fully integrate into the system, while administrators gain operational experience.

In this book you will find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning.

Code words in text are shown as follows: "We can include other contexts through the use of the include directive."

A block of code is set as follows:

package com.your.organization;
import org.apache.felix.gogo.commands.Command;
import org.apache.karaf.shell.console.OsgiCommandSupport;

@Command(scope = "LAK", name = "commandname", description = "This is a sample custom command.")
public class CommandName extends OsgiCommandSupport {
    protected Object doExecute() throws Exception {
        System.out.println("Executing command commandname");
        return null;
    }
}

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

<?xml version="1.0" encoding="UTF-8"?>
<blueprint xmlns=http://www.osgi.org/xmlns/blueprint/v1.0.0
         Xmlns:cm="http://aries.apache.org/blueprint/xmlns/blueprint-cm/v1.0.0">

<command-bundle xmlns="http://karaf.apache.org/xmlns/shell/v1.0.0">
    <command name="LAK/commandname">
        <action class="com.your.organization.CommandName">
        </action>
        <completers>
            <ref component-id="ourCommandCompleter" />
            <null />
        </completers>
    </command>
</command-bundle>
<bean id="ourCommandCompleter" class="com.your.organization.CommandCompleter" />
</blueprint>

Any command-line input or output is written as follows:

@echo off
REM execute setup.bat to setup environment variables.
set JAVA_HOME=C:\Program Files\Java\jdk1.6.0_31
set MAVEN_HOME=c:\x1\apache-maven-3.0.4
set PATH=%JAVA_HOME%\bin;%MAVEN_HOME%\bin;%PATH%echo %PATH%

New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: "clicking the Next button moves you to the next screen."

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