Archive for April, 2012

OSGi Sling Service Example

I’m posting a simple example of an OSGi Service for Sling. I believe this is enough to get you started with a simple service. First, I want to share a great blog by Moritz Havelock called “In the Sling”. I used this example but changed the file structure of the POM to fit my needs. I’ll be using this as a base for some of my services development. This example is taken from lesson 5.

For my project I’m using Maven 3.0.4, Java 1.6.0_31 and I have tested both CQ 5.4 and CQ 5.5. This should also work fine within Apache Sling but I haven’t tested it.

If you’re like me you just want to get the POM and run it to see if it works for you. First create the file folders based on the structure below. Create 3 Java classes the jsp and a json file. You’ll need to have Maven and Java installed on your system and then just execute the POM.xml with >mvn install

Once the build is completed execute the following URL http://localhost:4502/content/osgitest/test to verify the test. You should see that the service returns “Hello World!”.

I also included a unit test within this example because it’s really easy to create a few tests for the services and if I add it into the example I’m more apt to write a few. To verify that the Unit test works simply change the “Hello World!” to something else and see the failure.

If you’re new to Maven I suggest reading “In the Sling” to really understand what is happening.

│   pom.xml
│
└───src
    ├───main
    │   ├───java
    │   │   └───com
    │   │       └───adobe
    │   │           └───support
    │   │               └───examples
    │   │                   └───osgi
    │   │                       └───service
    │   │                               SampleService.java
    │   │                               SampleServiceImpl.java
    │   │
    │   └───resources
    │       ├───META-INF
    │       └───SLING-INF
    │           └───initial-content
    │               ├───apps
    │               │   └───samples
    │               │       └───osgitest
    │               │               GET.esp
    │               │
    │               └───content
    │                   └───osgitest
    │                           test.json
    │
    └───test
        └───java
                SampleServiceTest.java

<project 	xmlns="http://maven.apache.org/POM/4.0.0" 
			xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
			xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
			
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.adobe.support.examples</groupId>
	<artifactId>com.adobe.support.examples.osgi.service</artifactId>
	<version>1.0.0</version>
	<packaging>bundle</packaging>
	<name>OSGi Service Example</name>
	<url>http://blogs.adobe.com/kmossman</url>
	<description>Adobe Developer Support OSGi Service Example</description>
	<!--  
	Credit: This example is based on Moritz Havelock's http://in-the-sling.blogspot.com/ 
	
	I suggest you use the most current versions of the plugin's. 
	Search the Central Repository for the most current versions http://search.maven.org/
	
	Use the search strings below and update the appropriate versions
	
	// Felix
	g:"org.apache.felix" a:"org.apache.felix.framework"
	g:"org.apache.felix" a:"maven-bundle-plugin"
	g:"org.apache.felix" a:"maven-scr-plugin"
	g:"org.apache.felix" a:"org.osgi.core"
	// Maven
	g:"org.apache.maven.plugins" a:"maven-compiler-plugin"	
	// Sling
	g:"org.apache.sling" a:"maven-sling-plugin"
	-->
	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.build.java.version>1.6</project.build.java.version>
		<!-- Felix -->
		<org.apache.felix.framework.version>4.0.2</org.apache.felix.framework.version> 
    	<org.apache.felix.maven-bundle-plugin.version>2.3.7</org.apache.felix.maven-bundle-plugin.version>    
    	<org.apache.felix.maven-src-plugin.version>1.7.4</org.apache.felix.maven-src-plugin.version>
    	<org.apache.felix.org.osgi.core>1.4.0</org.apache.felix.org.osgi.core>
    	<!-- Maven -->
		<org.apache.maven.plugins.maven-compiler-plugin.version>2.3.2</org.apache.maven.plugins.maven-compiler-plugin.version>
		<org.apache.maven.plugins.maven-surefire-plugin.version>2.12</org.apache.maven.plugins.maven-surefire-plugin.version>
    	<!-- Sling -->
    	<org.apache.sling.maven-sling-plugin.version>2.1.0</org.apache.sling.maven-sling-plugin.version>
  	</properties>
	<build>
	
		<plugins>
			<!--  Maven will compile our source java classes using
			 the "project.build.java.version" specified -->
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>${org.apache.maven.plugins.maven-compiler-plugin.version}</version>
		        <configuration>
		          <source>${project.build.java.version}</source>
		          <target>${project.build.java.version}</target>
		        </configuration>
			</plugin>
			<!--  this will install the OSGi bundle into Sling for us 
			we now upload the jar file automatically when we build with this plug-in -->
			<plugin>
				<groupId>org.apache.sling</groupId>
				<artifactId>maven-sling-plugin</artifactId>
				<version>${org.apache.sling.maven-sling-plugin.version}</version>
				<executions>
					<execution>
						<id>install-bundle</id>
						<goals>
							<goal>install</goal>
						</goals>
						<configuration>
							<slingUrl>http://localhost:4502/system/console/install</slingUrl>
							<user>admin</user>
							<password>admin</password>
						</configuration>
					</execution>
				</executions>
			</plugin>
			<plugin>
				<!-- This will create the OSGI-INF for us that handles the Activator Class for us
				we now auto-generate the details in our bundle with this plug-in-->
			    <groupId>org.apache.felix</groupId>
			    <artifactId>maven-scr-plugin</artifactId>
			    <extensions>true</extensions>
			    <version>${org.apache.felix.maven-src-plugin.version}</version>
			    <executions>
			        <execution>
			            <id>generate-scr-scrdescriptor</id>
			            <goals>
			                <goal>scr</goal>
			            </goals>
			        </execution>
			    </executions>
			</plugin>			
			<plugin>
				<!-- This will create the OSGi /META-INF/MANIFEST.MF for us
				we now auto-generated the file for us with this plug-in -->
				<groupId>org.apache.felix</groupId>
				<artifactId>maven-bundle-plugin</artifactId>
				<extensions>true</extensions>
				<version>${org.apache.felix.maven-bundle-plugin.version}</version>
				<configuration>
					<instructions>
						<Export-Package>com.adobe.support.examples.osgi.service</Export-Package>
						<Import-Package>org.osgi.framework;version="1.3.0"</Import-Package>
						<Bundle-SymbolicName>${project.artifactId}</Bundle-SymbolicName>
						<Bundle-Name>${project.name}</Bundle-Name>
						<Bundle-Vendor>Kurt Mossman</Bundle-Vendor>
						<!-- 
							Inserting content into the JCR and installing some files on the server with your bundle. 
						
							Sling-Initial-Content
							
								The first line will overwrite the contents of the node at content/osgitest with test.json 
								NOTE: uninstall:=false says that it will not remove the content when I remove the package. 
									This could be set to true to also remove the content when the package is removed the choice is yours. 
								
								The second line will overwrite the path will install the files and overwrite them if you re-install. 
						 -->
						<Sling-Initial-Content>
							SLING-INF/initial-content/content/osgitest;path:=/content/osgitest;overwrite:=true;uninstall:=false,
							SLING-INF/initial-content/apps/samples/osgitest;path:=/apps/samples/osgitest;overwrite:=true;uninstall:=true
						</Sling-Initial-Content>
					</instructions>
				</configuration>
			</plugin>
			<!--  use the surefire plugin to run the test cases
			we use a thread count of 4 to increase the performance of the test time. -->
			<plugin>
			   <groupId>org.apache.maven.plugins</groupId>
			   <artifactId>maven-surefire-plugin</artifactId>
			   <version>${org.apache.maven.plugins.maven-surefire-plugin.version}</version>
			   <configuration>
			     	<parallel>methods</parallel>
			     	<threadCount>4</threadCount>
			   </configuration>
			</plugin>
		</plugins>
	</build>
	<dependencies>
		<dependency>
		  	<groupId>org.apache.felix</groupId>
		  	<artifactId>org.osgi.core</artifactId>
		  	<version>${org.apache.felix.org.osgi.core}</version>
		</dependency>
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>4.8.2</version>
		</dependency>
	</dependencies>
</project>

SampleService.java

package com.adobe.support.examples.osgi.service;

public interface SampleService {
	public String sayHello();
}


SampleServiceImpl.java

package com.adobe.support.examples.osgi.service;

// src.component
// declares the class component. This will provide a wrapped ManagedService component in the OSGI container. 

// src.service interface="SampleService" 
// declares the service we are offering. Actually, the interface attribute is superflous, as by default, all implemented Interfaces are used. 

/**
  @scr.component
  @scr.service interface="SampleService"
 */

public class SampleServiceImpl implements SampleService {
	public String sayHello() {
		return "Hello World!";
	}
}


GET.esp

<%
var service = sling.getService(Packages.com.adobe.support.examples.osgi.service.SampleService);
%>
<br>
The service says: "<%= service.sayHello() %>"


test.json

{
	"jcr:primaryType" : "nt:unstructured",
	"sling:resourceType" : "samples:osgitest"
}


SampleServiceTest.java

import com.adobe.support.examples.osgi.service.SampleService;  
import com.adobe.support.examples.osgi.service.SampleServiceImpl;

import junit.framework.Assert;

import org.junit.Test;

public class SampleServiceTest {
	
	@Test
	public void test() { 
		SampleService ss = new SampleServiceImpl(); 
		String msg = ss.sayHello(); 
		Assert.assertEquals("Hello World!", msg); 
	}
	
}
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How to search for updated Maven plugin’s? The Central Repository of course!

I have used Maven in the past but I’m no expert. I’m also new to some of the plugin’s used with CQ and I tend to learn best by example so I started looking at all the pom.xml files I could. During my search I found a great example of an OSGi service example called “In the Sling”. The only problem with this example is that it’s an old post and the plugin’s versions are also old in the pom.xml. The information is great and still relevant so I simply needed to update the file with new Maven plugin’s.

The official Maven Central Repository is here: http://search.maven.org 

You can use the advanced search or simply search by Group ID “g:” and Artifact ID “a:” together. This was the quickest way to find the most current version of my plugin’s.

Here are a few examples of how quickly you can retrieve the most current version of a plugin. Just past in the search strings below to get the most current version.

g:”org.apache.felix” a:”maven-bundle-plugin”
g:”org.apache.felix” a:”maven-scr-plugin”
g:”org.apache.maven.plugins” a:”maven-compiler-plugin”
g:”org.apache.sling” a:”maven-sling-plugin”

I added the following within my pom.xml so developers who access my pom.xml files will be able to search quickly for the most current version.

It may seem like a no-brainer but it took me a little while to figure out the most current versions of all the plugin’s for my example.

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CQ Developer Support a new direction

Over the past five years I have been helping developers with ActionScript and Flex. I just recently moved into a role where I’ll be helping CQ developers and I’m starting to learn the product myself. During my learning process I hope to share some of the issues that are blocking me or just some interesting tips and tricks I find along the way.

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